Draft Regulatory Impact Analysis:

Proposed Rulemaking to Establish Greenhouse Gas 

Emissions Standards and Fuel Efficiency Standards for 

Medium- and Heavy-Duty Engines and Vehicles

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

and

National Highway Traffic Safety Administration

U.S. Department of Transportation

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NHTSA-2010-XXXX¶

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TABLE OF CONTENTS

CHAPTER 1:INDUSTRY CHARACTERIZATION

1.1 Introduction 1-3

1.2 Heavy-Duty Truck Categories 1-8

1.3 Heavy-Duty Truck Segments 1-10

1.4 Operations 1-15

1.5 Tire Manufacturers 1-27

1.6 Current U.S. and International GHG Voluntary Actions and Regulations 1-31

1.7 Trailers 1-34

1.8 Hybrids 1-38

CHAPTER 2:TECHNOLOGIES, COST, AND EFFECTIVENESS

2.1 Overview of Technologies 2-3

2.2 Overview of Technology Cost Methodology 2-4

2.3 Heavy-Duty Pickup Truck and Van Technologies and Costs 2-12

2.4 Heavy-Duty Engines 2-21

2.5 Class 7/8 Day Cabs and Sleeper Cabs 2-35

2.6 Class 2b-8 Vocational Vehicles 2-64

2.7 Air Conditioning 2-75

2.8 Trailers and GHG Emission Reduction Opportunities 2-78

2.9 Other Fuel Consumption and GHG Reducing Strategies2-83

2.10 Summary of Technology Costs Used in this Analysis 2-91

CHAPTER 3:TEST PROCEDURES

3.1 Heavy-Duty Engine Test Procedure 3-2

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3.2 Aerodynamic Assessment 3-6

3.3 Tire Rolling Resistance 3-21

3.4 Drive Cycle 3-23

3.5 Tare Weights and Payload 3-27

3.6 Heavy-Duty Chassis Test Procedure 3-30

3.7 Hybrid Powertrain Test Procedures 3-31

3.8 HD Pickup Truck and Van Chassis Test Procedure 3-42

CHAPTER 4:VEHICLE SIMULATION MODEL

4.1 Purpose and Scope 4-2

4.2 Model Code Description 4-3

4.3 Feasibility of Using a Model to Simulate Testing 4-5

4.4 EPA and NHTSA Vehicle Compliance Model 4-8

4.5 Application of Model for Certification 4-19

CHAPTER 5:EMISSIONS IMPACTS

5.1 Executive Summary 5-2

5.2 Introduction 5-3

5.3 Program Analysis and Modeling Methods 5-5

5.4 Greenhouse Gas Emission Impacts 5-12

5.5 Non-Greenhouse Gas Emission Impacts 5-13

CHAPTER 6:RESULTS OF PROPOSED AND ALTERNATIVE STANDARDS

6.1 What Are the Alternatives that the Agencies Considered? 6-2

6.2 How Do These Alternatives Compare in Overall GHG Emissions Reductions and 

Fuel Efficiency and Cost? 6-15

CHAPTER 7:TRUCK COSTS AND COSTS PER TON OF GHG EMISSIONS REDUCED

7.1 Costs Associated with the Proposed Program 7-2

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7.2 Cost per Ton of GHG Emissions Reduced 7-5

7.3 Impacts of Reduction in Fuel Consumption 7-7

7.4 Key Parameters Used in the Estimation of Costs and Fuel Savings 7-8

CHAPTER 8:HEALTH AND ENVIRONMENTAL IMPACTS

8.1 Health and Environmental Effects of Non-GHG Pollutants 8-2

8.2 Air Quality Impacts of Non-GHG Pollutants 8-34

8.3 Quantified and Monetized Non-GHG Health and Environmental Impacts 8-39

8.4 Changes in Atmospheric CO2 Concentrations, Global Mean Temperature, Sea 

Level Rise, and Ocean pH Associated with the Proposal’s GHG Emissions Reductions

8-46

8.5 Monetized CO2 Impacts 8-54

CHAPTER 9:ECONOMIC AND SOCIAL IMPACTS

9.1 Framework for Benefits and Costs 9-2

9.2 Rebound Effect 9-3

9.3 Other Economic Impacts 9-13

9.4 The Effect of Safety Standards and Voluntary Safety Improvements on Vehicle 

Weight 9-18

9.5 Petroleum and energy security impacts 9-22

9.6 Summary of Benefits and Costs 9-33

CHAPTER 10: SMALL BUSINESS FLEXIBILITY ANALYSIS

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List of Acronyms

2008$ U.S. Dollars in calendar year 2008

μg Microgram

μg/m3 Microgram per Cubic Meter

μm Micrometers

AC Alternating Current

ACES Advanced Collaborative Emission Study

APU Auxiliary Power Unit

AQCD Air Quality Criteria Document

ASPEN Assessment System for Population Exposure Nationwide 

ATA American Trucking Association

ATRI Alliance for Transportation Research Institute

avg Average

BAC Battery Air Conditioning

BenMAP Benefits Mapping and Analysis Program

bhp Brake Horsepower

bhp-hrs Brake Horsepower Hours

BTS Bureau of Transportation 

BTU British Thermal Unit

CAA Clean Air Act

CAE Computer Aided Engineering

CAFE Corporate Average Fuel Economy

CARB California Air Resources Board 

CCP Coupled Cam Phasing

Cd Coefficient of Drag

CDC Centers for Disease Control

CFD Computational Fluid Dynamics

CFR Code of Federal Regulations

CH4 Methane

CILCC Combined International Local and Commuter Cycle

CITT Chemical Industry Institute of Toxicology

CMAQ Community Multiscale Air Quality

CO Carbon Monoxide

CO

2 Carbon Dioxide

COI Cost of Illness

COPD Chronic Obstructive Pulmonary Disease

CoV Coefficient of Variation

CRGNSA Columbia River Gorge National Scenic Area

CSI Cambridge Systematics Inc.

CVD Cardiovascular Disease

DE Diesel Exhaust

DEAC Cylinder Deactiviation

DEF Diesel Exhaust Fluid

DHHS U.S. Department of Health and Human Services

DOC Diesel Oxidation Catalyst

DOE Department of Energy

DOT Department of Transportation

DPF Diesel Particulate Filter

DPM Diesel Particulate Matter

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DR Discount Rate

DRIA Draft Regulatory Impact Analysis

EC Elemental Carbon

ED Emergency Department

EGR Exhaust Gas Recirculation

EIA Energy Information Administration (part of the U.S. Department of Energy)

EMS-HAP Emissions Modeling System for Hazardous Air Pollution

EO Executive Order

EPA Environmental Protection Agency

EPS Electric Power Steering

EPS Electrified Parking Spaces

ERG Eastern Research Group

EV Electric Vehicle

F Frequency

FHWA Federal Highway Administration

FIA Forest Inventory and Analysis

FOH Fuel Operated Heater

FR Federal Register

g Gram 

g/ton-mile Grams emitted to move one ton (2000 pounds) of freight over one mile

gal Gallon

gal/1000 tonmile Gallons of fuel used to move one ton of payload (2,000 pounds) over 1000 miles

GDP Gross Domestic Product

GEOS Goddard Earth Observing System

GHG Greenhouse Gases

GIFT Geospatial Intermodal Freight Transportation

GUI Graphical User Interface

GVW Gross Vehicle Weight Rating

GWP Global Warming Potential

HAD Diesel Health Assessment Document

HC Hydrocarbon

HD Heavy-Duty

HDUDDS Heavy Duty Urban Dynamometer Driving Cycle

HEI Health Effects Institute 

HES Health Effects Subcommittee 

HEV Hybrid Electric Vehicle

HFET Highway Fuel Economy Dynamometer Procedure

hp Horsepower

hrs Hours

HSC High Speed Cruise Duty Cycle

HTUF Hybrid Truck User Forum

hz Hertz

IARC International Agency for Research on Cancer

ICCT International Council on Clean Transport

ICD International Classification of Diseases

ICF ICF International

IMPROVE Interagency Monitoring of Protected Visual Environments

IRIS Integrated Risk Information System

ISA Integrated Science Assessment

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JAMA Journal of the American Medical Association

k Thousand

kg Kilogram

km Kilometer

kW Kilowatt

L Liter

lb Pound

LD Light-Duty

LSC Low Speed Cruise Duty Cycle

m2 Square Meters

m3 Cubic Meters

MD Medium-Duty

mg Milligram

mi mile

min Minute

MM Million

MOVES Motor Vehicle Emissions Simulator

mpg Miles per Gallon

mph Miles per Hour

MSAT Mobile Source Air Toxic

MY Model Year

N2O Nitrous Oxide

NA Not Applicable

NAAQS National Ambient Air Quality Standards

NAICS North American Industry Classification System 

NAS National Academy of Sciences

NATA National Air Toxic Assessment 

NCAR National Center for Atmospheric Research

NCI National Cancer Institute

NCLAN National Crop Loss Assessment Network

NEC Net Energy Change Tolerance

NEI National Emissions Inventory

NESCCAF Northeast States Center for a Clean Air Future

NESHAP National Emissions Standards for Hazardous Air Pollutants

NHTSA National Highway Traffic Safety Administration

NiMH Nickel Metal-Hydride

NIOSH National Institute of Occupational Safety and Health

NMHC Nonmethane Hydrocarbons

NMMAPS National Morbidity, Mortality, and Air Pollution Study

NO Nitrogen Oxide

NO2 Nitrogen Dioxide

NOAA National Oceanic and Atmospheric Administration 

NOx Oxides of Nitrogen

NPRM Notice of Proposed Rulemaking

NPV Net Present Value

NRC National Research Council

NVH Noise Vibration and Harshness

O&M Operating and maintenance

O3 Ozone

OAQPS Office of Air Quality Planning and Standards

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OC Organic Carbon

OE Original Equipment

OEHHA Office of Environmental Health Hazard Assessment

OEM Original Equipment Manufacturer

OHV Overhead Valve

OMB Office of Management and Budget

ORD EPA's Office of Research and Development

OTAQ Office of Transportation and Air Quality

Pa Pascal

PAH Polycyclic Aromatic Hydrocarbons

PEMS Portable Emissions Monitoring System

PHEV Plug-in Hybrid Electric Vehicles

PM Particulate Matter

PM10 Coarse Particulate Matter (diameter of 10 μm or less)

PM2.5 Fine Particulate Matter (diameter of 2.5 μm or less)

POM Polycyclic Organic Matter

ppb Parts per Billion

ppm Parts per Million

psi Pounds per Square Inch

PTO Power Take Off

R&D Research and Development

RBM Resisting Bending Moment

RESS Rechargeable Energy Storage System

RfC Reference Concentration

RIA Regulatory Impact Analysis

rpm Revolutions per Minute

RRc Rolling Resistance Coefficient

SAB Science Advisory Board

SAB-HES Science Advisory Board - Health Effects Subcommittee

SAE Society of Automotive Engineers

SBA Small Business Administration

SBAR Small Business Advocacy Review

SBREFA Small Business Regulatory Enforcement Fairness Act

SCC Social Cost of Carbon

SCR Selective Catalyst Reduction

SER Small Entity Representation

SGDI Stoichiometric Gasoline Direct Injection

SIDI Spark Ignition Direct Injection

SO

2 Sulfur Dioxide

SOC State of Charge

SOHC Single Overhead Cam

SOx Oxides of Sulfur

STB Surface Transportation Board

SUV Sport Utility Vehicle

SVOC Semi-Volatile Organic Compound

TIAX TIAX LLC

Ton-mile One ton (2000 pounds) of payload over one mile

TRU Trailer Refrigeration Unit

TSD Technical Support Document

TSS Thermal Storage

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U/DAF Upward and Downward Adjustment Factor

UCT Urban Creep and Transient Duty Cycle

UFP Ultra Fine Particles

USDA United States Department of Agriculture

UV Ultraviolet

UV-b Ultraviolet-b

VIUS Vehicle Inventory Use Survey

VMT Vehicle Miles Travelled

VOC Volatile Organic Compound

VSL Value of Statistical Life

VVT Variable Valve Timing

WTP Willingness-to-Pay

WTVC World Wide Transient Vehicle Cycle

WVU West Virginia University

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Executive Summary

The Environmental Protection Agency (EPA) and the National Highway Traffic Safety 

Administration (NHTSA), on behalf of the Department of Transportation, are each proposing 

rules to establish a comprehensive Heavy-Duty National Program that would reduce greenhouse 

gas emissions and increase fuel efficiency for on-road heavy-duty vehicles, responding to the 

President’s directive on May 21, 2010, to take coordinated steps to produce a new generation of 

clean vehicles. NHTSA’s proposed fuel consumption standards and EPA’s proposed carbon 

dioxide (CO2) emissions standards would be tailored to each of three regulatory categories of 

heavy-duty vehicles: (1) Combination Tractors; (2) Heavy-duty Pickup Trucks and Vans; and 

(3) Vocational Vehicles, as well as gasoline and diesel heavy-duty engines. EPA’s proposed

hydrofluorocarbon emissions standards would apply to air conditioning systems in tractors, 

pickup trucks, and vans, and EPA’s proposed nitrous oxide (N2O) and methane (CH4

Table 1 shows the agencies’ estimated lifetime discounted cost, benefits and net benefits 

for all vehicles projected to be sold in model years 2014-2018. 

) emissions 

standards would apply to all heavy-duty engines, pickup trucks, and vans. 

Table 1 Estimated 2014-2018 Model Year Lifetime Discounted Costs, 

Benefits, and Net Benefits assuming the $22/ton SCC Value

(2008 dollars)

a,b,c,d

3% Discount Rate $billions

Costs $7.7

Benefits $49

Net Benefits $41

7% Discount Rate

Costs $7.7

Benefits $34

Net Benefits $27

Notes: a Although the agencies estimated the benefits associated with four different values of a one ton 

CO2 reduction (SCC: $5, $22, $36, $66), for the purposes of this overview presentation of 

estimated costs and benefits we are showing the benefits associated with the marginal value

deemed to be central by the interagency working group on this topic: $22 per ton of CO2, in 2008 

dollars and 2010 emissions and fuel consumption. As noted in Section VIII.F of the preamble, 

SCC increases over time.

b Note that net present value of reduced GHG emissions is calculated differently than other 

benefits. The same discount rate used to discount the value of damages from future emissions 

(SCC at 5, 3, and 2.5 percent) is used to calculate net present value of SCC for internal 

consistency. Refer to Section VIII.F of the preamble for more detail.

This Regulatory Impact Analysis (RIA) provides detailed supporting documentation to 

the EPA and NHTSA joint proposal under each of their respective statutory authorities. Because 

there are slightly different requirements and flexibilities in the two authorizing statutes, this RIA 
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provides documentation for the primary joint proposed provisions as well as for provisions 

specific to each agency. 

This RIA is generally organized to provide overall background information, 

methodologies, and data inputs, followed by results of the various technical and economic 

analyses. A summary of each chapter of the RIA follows. 

Chapter 1: Industry Characterization. In order to assess the impacts of greenhouse gas 

(GHG) and fuel efficiency regulations upon the affected industries, it is important to understand 

the nature of the industries impacted by the regulations. The heavy-duty vehicle industries 

include the manufacturers of Class 2b through Class 8 trucks, engines, and some equipment. 

This chapter provides market information for each of these affected industries, as well as the 

variety of ownership patters, for background purposes. Vehicles in these classes range from over 

8,500 pounds (lbs) gross vehicle weight rating (GVWR) to upwards of 80,000 lbs and can be 

used in applications ranging from ambulances to vehicles that transport the fuel that powers 

them. The heavy-duty segment is very diverse both in terms of its type of vehicles and vehicle 

usage patterns. Unlike the light-duty segment whose primary mission tends to be transporting 

passengers for personal travel, the heavy duty segment has many different missions. Some 

pickup trucks may be used for personal transportation to and from work with an average annual 

mileage of 15,000 miles. Class 7 and 8 combination tractors are primarily used for freight 

transportation, can carry up to 50,000 pounds of payload, and can travel more than 150,000 miles 

per year. 

 Chapter 2: Technology Packages, Cost and Effectiveness. This chapter presents 

details of the vehicle and engine technology packages for reducing greenhouse gas emissions and 

fuel consumption. These packages represent potential ways that the industry could meet the 

proposed CO2

Chapter 3: Test Procedures. Laboratory procedures to physically test engines, vehicles, 

and components are a crucial aspect of the proposed heavy-duty vehicle GHG and fuel 

consumption program. The proposed rulemaking would establish several new test procedures 

for both engine and vehicle compliance. This chapter describes the development process for the 

test procedures being proposed, including methodologies for assessing engine emission 

performance, the effects of aerodynamics and tire rolling resistance, as well as procedures for 

chassis dynamometer testing and their associated drive cycles.

and fuel consumption stringency levels, and they provide the basis for the 

technology costs and effectiveness analyses.

 Chapter 4: Vehicle Simulation Model. An important aspect of a regulatory program is 

its ability to accurately estimate the potential environmental benefits of heavy-duty truck 

technologies through testing and analysis. Most large truck manufacturers employ various 

computer simulation methods to estimate truck efficiency. Each method has advantages and 

disadvantages. This section will focus on the use of a type truck simulation modeling that the 

agencies have developed specifically for assessing tailpipe GHG emissions and fuel consumption

for purposes of this rulemaking. The agencies are proposing to use this newly-developed 

simulation model -- the “Greenhouse gas Emissions Model (GEM)” -- as the primary tool to 

certify vocational and combination tractor heavy-duty vehicles (Class 2b through Class 8 heavyduty vehicles that are not heavy-duty pickups or vans) and discuss the model in this chapter. 
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Chapter 5: Emissions Impacts. This proposal estimates anticipated impacts from the 

proposed CO2 emission and fuel efficiency standards. The agencies quantify emissions from the 

GHGs carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and hydrofluorocarbons 

(HFCs). In addition to reducing the emissions of greenhouse gases and fuel consumption, this 

proposal would also influence the emissions of “criteria” air pollutants, including carbon 

monoxide (CO), fine particulate matter (PM2.5) and sulfur dioxide (SOX) and the ozone 

precursors hydrocarbons (VOC) and oxides of nitrogen (NOX

The agencies used EPA’s Motor Vehicle Emission Simulator (MOVES2010) to estimate 

downstream (tailpipe) emission impacts, and a spreadsheet model based on emission factors the 

“GREET” model to estimate upstream (fuel production and distribution) emission changes 

resulting from the decreased fuel. Based on these analyses, the agencies estimate that this 

proposal would lead to 72 million metric tons (MMT) of CO

); and several air toxics (including 

benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein), as described further in 

Chapter 5.

2 equivalent (CO2

Chapter 6: Results of Proposed and Alternative Standards. The heavy-duty truck 

segment is very complex. The sector consists of a diverse group of impacted parties, including 

engine manufacturers, chassis manufacturers, truck manufacturers, trailer manufacturers, truck 

fleet owners and the public. The agencies have largely designed this proposal to maximize the 

environmental and fuel savings benefits of the program, taking into account the unique and 

varied nature of the regulated industries. In developing this proposal, we considered a number of 

alternatives that could have resulted in fewer or potentially greater GHG and fuel consumption 

reductions than the program we are proposing. Chapter 6 section summarizes the alternatives we 

considered. 

EQ) of annual 

GHG reduction and 5.8 billion gallons of fuel savings in the year 2030, as discussed in more 

detail in Chapter 5.

Chapter 7: Truck Costs and Costs per Ton of GHG. In this chapter, the agencies 

present our estimate of the costs associated with the proposed program. The presentation 

summarizes the costs associated with new technology expected to be added to meet the proposed 

GHG and fuel consumption standards, including hardware costs to comply with the air 

conditioning (A/C) leakage program. The analysis discussed in Chapter 7 provides our best 

estimates of incremental costs on a per truck basis and on an annual total basis. 

Chapter 8: Environmental and Health Impacts. This chapter discusses the health effects 

associated with non-GHG pollutants, specifically: particulate matter, ozone, nitrogen oxides 

(NOX), sulfur oxides (SOX

 

), carbon monoxide and air toxics. These pollutants would not be 

directly regulated by the standards, but the standards would affect emissions of these pollutants 

and precursors. Reductions in these pollutants would be co-benefits of the final rulemaking (that 

is, benefits in addition to the benefits of reduced GHGs).
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Chapter 9: Economic and Social Impacts. This chapter provides a description of the 

net benefits of the proposed HD National Program. To reach these conclusions, the chapter 

discusses each of the following aspects of the analyses of benefits:

Rebound Effect: The VMT rebound effect refers to the fraction of fuel savings expected 

to result from an increase in fuel efficiency that is offset by additional vehicle use. 

Energy Security Impacts: A reduction of U.S. petroleum imports reduces both financial 

and strategic risks associated with a potential disruption in supply or a spike in cost of a 

particular energy source. This reduction in risk is a measure of improved U.S. energy security. 

Other Impacts: There are other impacts associated with the proposed GHG emissions 

and fuel efficiency standards. Lower fuel consumption would, presumably, result in fewer trips 

to the filling station to refuel and, thus, time saved. The increase in vehicle-miles driven due to a 

positive rebound effect may also increase the societal costs associated with traffic congestion, 

motor vehicle crashes, and noise. The agencies also discuss the impacts of safety standards and 

voluntary safety improvements on vehicle weight.

Chapter 9 also presents a summary of the total costs, total benefits, and net benefits 

expected under the proposal. 

Chapter 10: Small Business Flexibility Analysis. This chapter describes the agencies’

analysis of the small business impacts due to the joint proposal. 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Industry Characterization

1

CHAPTER 1: INDUSTRY CHARACTERIZATION ..........................................3

1.1 Introduction.....................................................................................................................3

1.1.1 Overview................................................................................................................3

1.1.2 Freight Moved by Heavy-Duty Trucks...............................................................4

1.1.3 Greenhouse Gas Emissions from Heavy-Duty Vehicles....................................5

1.1.4 Fuel Economy of Heavy-Duty Vehicles ..............................................................6

1.2 Heavy-Duty Truck Categories.......................................................................................8

1.2.1 Heavy-Duty Vehicles Sales...................................................................................9

1.3 Heavy-Duty Truck Segments.......................................................................................10

1.3.1 Heavy-Duty Pickup Trucks and Vans..............................................................10

1.3.2 Vocational Vehicles ............................................................................................11

1.3.3 Tractors...............................................................................................................13

1.3.4 Buses ....................................................................................................................14

1.4 Operations .....................................................................................................................16

1.4.1 Trucking as a Mode of Freight Transportation...............................................16

1.4.2 Operational Costs...............................................................................................18

1.4.3 Operators.............................................................................................................19

1.4.4 Heavy-Duty Truck Operating Speeds ..............................................................20

1.4.5 Trucking Roadways............................................................................................20

1.4.6 Weigh Stations....................................................................................................22

1.4.7 Types of Freight Carried ...................................................................................23

1.4.8 Heavy-Duty Trucking Traffic Patterns............................................................24

1.4.9 Intermodal Freight Movement..........................................................................25

1.4.10 Purchase and Operational Related Taxes........................................................26

1.4.11 Heavy-Duty Vehicle Age Trends.......................................................................27

1.5 Tire Manufacturers ......................................................................................................28

1.5.1 Single Wide Tires................................................................................................28

1.5.2 Retreaded Tires ..................................................................................................31

1.6 Current U.S. and International GHG Voluntary Actions and Regulations............32

1.6.1 U.S. EPA SmartWayTM Transport Partnership..............................................32

1.6.2 The 21st Century Truck Partnership ................................................................33

1.6.3 California Assembly Bill 32 ...............................................................................33

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1.6.4 U.S. Energy Independence and Security Act...................................................34

1.6.5 International GHG Emissions Activities..........................................................34

1.7 Trailers...........................................................................................................................35

1.7.1 Overview..............................................................................................................35

1.7.2 Trailer Types.......................................................................................................35

1.7.3 Trailer Manufacturers.......................................................................................37

1.7.4 Trailer Operations..............................................................................................38

1.8 Hybrids...........................................................................................................................39

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Industry Characterization

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Industry Characterization

1.1 Introduction

1.1.1 Overview

In order to assess the impacts of greenhouse gas (GHG) regulations upon the affected 

industries, it is important to understand the nature of the industries impacted by the 

regulations. These industries include the manufacturers of Class 2b through Class 8 trucks, 

engines, and some equipment. This chapter provides market information for each of these 

affected industries for background purposes. Vehicles in these classes range from over 8,500 

pounds (lbs) gross vehicle weight rating (GVWR) to upwards of 80,000 lbs and can be used in 

applications ranging from ambulances to vehicles that transport the fuel that powers them.

Figure 1-1 shows the difference in vehicle classes in terms of GVWR and the different 

applications found in these classes. 

Figure 1-1 Description and Weight Ratings of Vehicle Classes

Source: Commercial Carrier Journal http://www.ccjmagazine.com

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Regulatory Impact Analysis 

4

Heavy-duty trucks in this rulemaking are defined as on-highway vehicles with a

GVWR greater than 8,500 lbs and are not defined as Medium-Duty Passenger Vehicles

(MDPV). The EPA and NHTSA jointly developed the Light-Duty Vehicle Greenhouse Gas 

Emissions Standards and Corporate Average Fuel Economy Standards; Final Rule 75 FR 

25323 (May 7, 2010) which sets standards for Light Duty Vehicles, Light-Duty Trucks, and 

Medium-Duty Passenger Vehicles (EPA-420-F-10-014). Light-duty trucks are vehicles with 

GVWR less than 8,500 lbs. MDPV are vehicles with GVWR less than 10,000 pounds which 

meet the criteria outlined in 40 C.F.R. §86.1803-01. This grouping typically includes large 

sport utility vehicles, small trucks, and mini-vans. 

The heavy-duty segment is very diverse both in terms of its type of vehicles and 

vehicle usage patterns. Unlike the light-duty segment whose primary mission tends to be 

transporting passengers for personal travel, the heavy duty segment has many different 

missions. Some pickup trucks may be used for personal transportation to and from work with 

an average annual mileage of 15,000 miles. Class 7 and 8 combination tractors are primarily 

used for freight transportation, can carry up to 50,000 pounds of payload, and can travel more 

than 150,000 miles per year. For the purposes of this report, heavy-duty segment has been 

separated as follows: Class 2b and 3 pickup trucks and vans (also referred to as HD pickup 

trucks and vans), Class 2b through 8 vocational vehicles, Class 7 and 8 combination tractors, 

trailers, and transit buses.

1.1.2 Freight Moved by Heavy-Duty Trucks

In 2008, heavy-duty trucks carried more freight in terms of tonnage and value in the 

U.S. than all other modes of freight transportation combined, and are expected to move freight 

at an even greater rate in the future.

1

 According to the U.S. Department of Transportation 

(DOT), the U.S. transportation system moved, on average an estimated 59 million tons of 

goods worth an estimated $55 billion (in U.S. $2008) per day in 2008, or over 21 billion tons 

of freight worth more than $20 trillion in the year 2008.

2

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Of this, trucks moved over 13 

billion tons of freight worth an estimated $13 trillion in 2008, or an average of nearly 36 

million tons of freight worth $37 billion a day. The DOT’s Freight Analysis Framework 

estimates that this tonnage will increase nearly 73 percent by 2035, and that the value of the 

freight moved is increasing faster than the tons transported. Figure 1-2 shows the total tons of 

freight moved by each mode of freight transportation in 2002, 2008 and projections for 2035.

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5

Figure 1-2 Total Weight of Shipments by Transportation Mode (millions of tons)

1.1.3 Greenhouse Gas Emissions from Heavy-Duty Vehicles

The importance of this proposed rulemaking is highlighted by the fact that heavy-duty 

trucks are the largest source of GHG emissions in the transportation sector after light-duty 

vehicles. This sector represents approximately 22 percent of all transportation related GHG 

emissions as shown in Figure 1-3. Heavy-duty trucks are also a fast growing source of GHG 

emissions; total GHG emissions from this sector increased over 72 percent from 1990-2008 

while GHG emissions from passenger cars grew approximately 20 percent over the same 

period.

3

 Available technologies developed through EPA’s SmartWay program and through 

DOE’s 21st Century Truck Partnership can achieve reductions from 10-20 percent and are 

applicable to the majority of heavy-duty vehicles; examples of these technologies include 

aerodynamic bumpers, mirrors, and fairings.4 

Source: U.S. DOT, Federal Highway Administration, “Freight Facts and Figures 

Notes: [a] Intermodal includes U.S. Postal Service and courier shipments and all intermodal combinations, 

except air and truck. Intermodal also includes oceangoing exports and imports that move between ports and 

interior domestic locations by modes other than water.

[b] Pipeline also includes unknown shipments as data on region-to-region flows by pipeline are statistically 

uncertain.

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Figure 1-3 Transportation Related Greenhouse Gas Emissions (Tg CO2 Eq.) in 2008

1.1.4 Fuel Economy of Heavy-Duty Vehicles

While there is a corporate average fuel economy (CAFE) program for light-duty 

trucks and vehicles, the nature of the commercial truck market can present complications to 

such a structure in particular due to the production process, diversity of products, and usage 

patterns. 5

The agencies recognize that while historic fuel economy and GHG emissions on a 

mile per gallon basis from heavy-duty trucks has been largely flat for more than 30 years, we 

 For example, in the light-duty market a manufacturer builds a complete vehicle 

and therefore, is responsible to certify that vehicle. In the heavy-duty truck market, there may 

be separate: chassis, engine, body and equipment manufacturers that contribute to the build 

process of a single truck; in addition, there are no companies that produce trucks and trailers 

and a given tractor may pull hundreds of different trailer types over the course of its life. 

Further, fuel economy is highly dependent on the configuration of a truck, for example: the 

type of body or box, engine, axle/gear ratios, cab, or other equipment installed on the vehicle; 

whether or not a truck carries cargo or has a specialized function (e.g. a bucket truck). Due to 

the varying needs of the industry, many of these trucks are custom built resulting in literally 

thousands of different truck configuration. Finally, usage patterns and duty cycles also 

greatly affect fuel economy, for example how trucks are loaded (cubed or weighed out) and 

how they are driven (delivery trucks travel at lower speeds and make frequent stops compared 

to a line-haul combination tractor). The potential to reduce fuel consumption, therefore, is 

also highly dependent on the truck configuration and usage.

Source: U.S. EPA, Inventory of Greenhouse Gas Emissions and Sinks: 1990-2008, published April, 2010

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cannot conclude with certainty that future improvements absent regulation would not occur. A

Programs like EPA’s SmartWay program are not only helping the industry improve logistics 

and operations, but are also helping to encourage greater use of truck efficiency technologies. 

Looking at the total fuel consumed, total miles traveled, and total tons shipped in the U.S. or 

the average payload specific fuel consumption for the entire heavy-duty fleet from 1975 

through 2005, the amount of fuel required to move a given amount of freight a given distance 

has been reduced by more than half as a result of improvements in technology, as shown in 

Figure 1-4.

1-4 U.S. Average Payload-Specific Fuel Consumption of the Heavy-Duty Fleet

5 

Currently, manufacturers of vehicles with a GVW of over 8,500 pounds are not 

required to test and report fuel economy values, however, fuel economy ranges as of 2007 by 

vehicle class are presented in a study completed by the National Academy of Sciences (NAS), 

the U.S. Department of Transportation (DOT), and the National Highway Traffic Safety 

Administration (NHTSA). As one would expect, the larger the truck class the lower the fuel 

economy, for example, a typical mile per gallon (mpg) estimate for Class 2b vehicle is 10-15 

mpg where a typical Class 8 combination tractor is estimated to get 4-7.5 mpg, as shown in

Table 1-1.

Table 1-1 Estimated Fuel Economy by Truck Class

CLASS EXAMPLE 

PRODUCTION 

VEHICLE

GVW TYPICAL 

MPG RANGE 

IN 2007

TYPICAL 

TONMPG

ANNUAL FUEL 

CONSUMPTION RANGE

(THOUSANDS OF 

GALLONS)

 

A Over the last 30 years the average annual improvement in fuel economy has been 0.09%. See U. S. 

Department of Transportation, Federal Highway Administration, Highway Statistics 2008, Washington, DC, 

2009, Table VM1 averaging annual performance for the years from 1979-2008.

(Source: NAS, Technologies and Approaches to Reducing Fuel Consumption of Medium- and HeavyDuty Vehicles) available here: http://www.nap.edu/openbook.php?record_id=12845&page=R1

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2b Dodge Ram 2500 

Pickup Truck

8,501-10,000 10-15 26 1.5-2.7

3 Chevrolet Silverado 

3500 Pickup Truck

10,001-14,000 8-13 30 2.5-3.8

4 Ford F-450 14,001-16,000 7-12 42 2.9-5.0

5 Kenworth T170 16,001-19,500 6-12 39 3.3-5.0

6 Peterbilt Model 330 19,501-26,000 5-12 49 5.0-7.0

7 Kenworth T370 26,001-33,000 4-8 55 6.0-8.0

8 Combination 

Trucks

International Lone Star 33,001-80,000 4-7.5 155 19 - 27

8 Other Mack Granite GU814 33,001-80,000 2.5-6 115 10 - 13

1.2 Heavy-Duty Truck Categories

This program addresses vehicles that fall into the following four categories: 

HD pickups and vans (typically Class 2b and 3), Vocational vehicles (typically Class 

2b-8), Tractors (typically Class 7 and 8), and Heavy-Duty engines.

B

 Class 2b and 3 

pickups and vans are used for commercial purposes such as ambulances, shuttle buses, 

etc. The U.S. Energy Information Administration (EIA) estimates that Class 2b 

vehicles get approximately 14.5 – 15.6 miles per gallon (mpg) in 2010.

6

 Class 2b-8 

vocational vehicles encompass a wide range of heavy-duty vehicles such as delivery 

trucks, school buses, etc. Fuel economy estimates for Class 3-6 are 7.8 mpg in 2010.7 

Class 8 combinations tractors operate as either short-haul or long-haul trucks. 

Combination tractors that operate as short-haul trucks also known as day cabs, are 

tractor trailers that do not have sleeping quarters for the driver and haul trailers only 

short distances, typically into metropolitan areas. Combination tractors that operate as 

long-haul trucks are those equipped with sleeping quarters for the driver, and tend to 

drive well over 1,000 miles per trip; this category contributed the most GHG 

emissions of these four categories at just over 38 percent of the total CO2

Figure 1-5

emissions in 

2005 as shown in . The EIA estimates that in 2010, Class 8 freight hauling 

trucks get slightly over 6 mpg.6

 

B For purposes of this document, the term “heavy-duty” or “HD” is used to apply to all 

highway vehicles and engines that are not within the range of light-duty vehicles, light-duty 

trucks, and medium-duty passenger vehicles (MDPV) covered by the GHG and Corporate 

Average Fuel Economy (CAFE) standards issued for model years (MY) 2012-2016. Unless 

specified otherwise, the heavy-duty category incorporates all vehicles rated at a gross vehicle 

weight of 8,500 pounds, and the engines that power them, except for MDPVs.

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Figure 1-5 Tons of CO2 Emitted from Heavy-Duty Trucking in 2005

1.2.1 Heavy-Duty Vehicles Sales

Although not first in terms of GHG emissions, Class 2b and 3 pickup trucks and vans 

are first in terms of sales volumes, with sales of over 1.3 million units in 2005, or nearly 66

percent of the heavy-duty market. Sales of Class 3-8 vocational vehicles are the second most 

numerous, selling over one-half million units in 2005, or nearly 25 percent of the heavy-duty 

market. Since 2005, sales of all heavy-duty trucks have decreased as the economy contracted; 

the U.S. EPA’s MOVES model based on proprietary sales projections combined with the U.S. 

Energy Information Administration’s Annual Energy Outlook reflects a slow recovery in 

sales.6 Figure 1-6 and Figure 1-7 show the sales volumes for 2005 and projected sales for 

2014 respectively, reflecting the market slowdown and recovery, while Table 1-2 shows sales 

projections by market segment for 2014-2018.

Table 1-2 Sales Projection by Market Segment 2014-2018

SALES 

ESTIMATES

2B/3 

PICKUPS/VANS 

VOCATIONAL

VEHICLES

COMBINATION 

SHORT HAUL

COMBINATION 

LONG HAUL

TOTAL

2014 785,000 555,000 50,000 73,000 1,460,000

2015 730,000 573,000 50,000 74,000 1,430,000

2016 713,000 592,000 51,000 75,000 1,430,000

2017 708,000 611,000 52,000 77,000 1,450,000

2018 717,000 630,000 53,000 78,000 1,480,000

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Figure 1-6 2005 Heavy-Duty Truck Sales by Category

Figure 1-7 Projected Truck Sales for 2014 by Category

1.3 Heavy-Duty Truck Segments

1.3.1 Heavy-Duty Pickup Trucks and Vans

Class 2b and 3 pickup trucks and vans rank highest in terms of sales volumes, but 

together make up the third largest sector contributing to the heavy-duty truck GHG emissions 

(Class 2b through Class 8). There are number of reasons to explain this difference, but 

mainly it is the vehicle usage patterns and engine size. Class 2b/3 consists of pickup trucks 

and vans with a GVW between 8,500 and 14,000 pounds. Class 2b/3 truck manufacturers are 

predominately GM, Ford, and Chrysler, with Isuzu, Daimler, Mitsubishi FUSO, and Nissan 

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11

also offering vehicles in this market segment. Figure 1-8 shows two examples of this 

category, a GM Chevrolet Express G3500 and a Dodge Ram 3500HD.

Figure 1-8 Examples of Class 2b and 3 Pickup Trucks and Vans

Class 2b/3 vehicles are sold either as complete or incomplete vehicles. For example a 

‘complete vehicle’ can be a chassis cab (engine, chassis, wheels, and cab) or a rolling chassis 

(engine, chassis and wheels), while an ‘incomplete chassis’ could be sold as an engine and 

chassis only - no wheels. The technologies that can be used to reduce GHG emissions from 

this segment are very similar to the ones used for lighter pickup trucks and vans (Class 2a), 

which are part of the Light Duty GHG program. These technologies include engine 

improvements such as friction reduction, cylinder deactivation, cam phasing, and gasoline 

direct injection; aerodynamic improvements; low rolling resistance tires; and transmission 

improvements. The Class 2b/3 gasoline trucks and vans are currently certified with chassis 

dynamometer testing. The Class 2b/3 diesel trucks have an option to certify using the chassis 

dynamometer test procedure.

1.3.2 Vocational Vehicles

This market segment includes a wide range of heavy-duty vehicles ranging from 8,501

pounds to greater than 33,000 pounds GVW. In 2005, sales of these vehicles were the second 

most numerous sold in the heavy-duty truck market, with over 500,000 units sold, making up 

nearly one-quarter of all heavy-duty truck sales. The vocational vehicle segment was also 

responsible for emitting 15.3 percent of the GHG emissions in 2005 from the total heavy-duty 

truck market. A majority of these vehicles are powered by diesel engines; primary examples 

of this truck type include delivery trucks, dump trucks, cement trucks, buses, cranes, etc. 

Figure 1-9 shows two examples of this vehicle category including a United Parcel Service 

(UPS) delivery truck, and a Ford F750 Bucket Truck.

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Figure 1-9 Examples of Class 3-8 Vocation Truck Applications

Class 2b – 8 vocational vehicles are typically sold as an incomplete chassis with 

multiple “outfitters” for example, an engine manufacturer, a body manufacturer, and an 

equipment manufacturer (e.g. a crane manufacturer). Manufacturers of vehicles within this 

segment vary widely and shift with class, as Figure 1-10 highlights. Vocational vehicles

manufacturers include: GM, Ford, Chrysler, Isuzu, Mitsubishi, Volvo, Daimler, International, 

and PACCAR, while engine manufacturers include: Cummins, GM, Navistar, Hino, Isuzu, 

Volvo, Detroit Diesel, and PACCAR. Manufacturers of vocational vehicle bodies are 

numerous, according to the 2002 Census, there were 759 companies classified under the 

North American Industry Classification System (NAICS) 336211, “Motor Vehicle Body 

Manufacturers,” examples of these companies include: Utilimaster and Heller Truck Body 

Corp. 

Opportunities for GHG reductions can include both engine and vehicle 

improvements. Currently, there are a limited number of available Class 2b-8 vocational

vehicles produced in a hybrid configuration. International (owned by Navistar) makes the 

DuraStarTM Hybrid and claims that this option offers a 30 to 40 percent fuel economy benefit 

over standard in-city pickup and delivery applications, and offers a more than a 60 percent 

increase in fuel economy in utility-type applications where the vehicle can be shut off while

electric power still operates the vehicle.8 

www.versalifteast.com/Rent-Bucket-Trucks.htm www.seedmagazine.com/images/uploads/upstruck.jpg

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Figure 1-10 Class 3-8 Vocational Vehicle Manufacturer Shift with Class

Source: ICCT

1.3.3 Tractors

Class 7 and 8 trucks are the largest and most powerful trucks of the heavy duty vehicle 

fleet. These trucks use almost two-thirds of all truck fuel, and are typically categorized into 

two smaller segments – short-haul and long-haul. 9

Long-haul combination tractors typically travel at least 1,000 miles along a trip route. 

Long-haul operation occurs primarily on highways and accounts for 60 to 70 percent of the 

fuel use in this class. The remaining 30 to 40 percent of fuel is used by other short-and 

medium-haul regional applications.

Combination tractors operating as shorthaul trucks are tractor trailers typically used for routes less than 500 miles, and tend to travel 

at lower average speeds than long-haul trucks. Short-haul combination tractors therefore, do 

not include sleeping accommodations for the driver. 

10

Figure 1-11

 The most common trailer hauled by both short- and 

long-haul combination tractors is a 53-foot dry box van trailer, which accounts for nearly 60 

to 70 percent of heavy-duty Class 8 on-road mileage. Leading U.S. manufacturers of Class 8

trucks include companies such as International, Freightliner, Peterbilt, PACCAR, Kenworth, 

Mack, Volvo, Western Star; while common engine manufacturers include companies such as

Cummins, Navistar, and Detroit Diesel. shows example Class 8 day cab and 

sleeper cab combination tractors. The price of a new Class 8 vehicle can range from $90,000 

to well over $110,000 for fully equipped models.

11

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Figure 1-11 Example Day Cab and Sleeper Cab Tractors

1.3.4 Buses

Buses generally fall into either Class 6 or Class 7 categories and can come in many 

forms, including: transit buses, large school buses, small school buses, and motorcoaches. 

Typically, most bus manufacturers assemble the entire chassis from systems manufactured by 

a variety of suppliers, while their engines are commonly manufactured by companies such as 

Detroit Diesel, and Navistar.

12 Typically, transit buses have about a 12 year lifespan, and 

approximately 5000-5500 units a year enter the fleet, where school buses can last upwards of 

fifteen years or longer as school buses are not eligible for Federal Transit Administration 

funding as most transit buses are.

13

In 2008, transit buses were responsible for moving 53 percent of all unlinked 

passenger mass-transit trips which is just over 5.5 billion passenger trips.

Currently, about 32 percent of U.S. buses have an 

alternative energy source and are powered by a source other than diesel or gas. According to 

the American Public Transportation Association's (APTA) “2008 Public Transportation Fact 

Book,” in 2007, 22 percent of approximately 80,000 transit buses operated on alternative 

power, primarily compressed or liquefied natural gas (as well as recent interest in and growth 

of hybrid electric buses). Additionally, according to the Union of Concerned Scientists’ 

“School Bus Pollution Report Card 2006 Grading the Schools” (May, 2006), less than 1 

percent (4,145) of the approximately 505,000 school buses in the U.S. run on LNG/CNG; less 

than 2 percent (8,632) run on biodiesel, mostly B20. There are several types of bus fleets 

operating on alternative power. For example, CNG (Los Angeles Metropolitan Transit 

Authority) has the largest operational fleet, HEV (GM-Allison Transmission, BAE Systems, 

ISE Corporation, and Ebus (22’ shuttles)) manufacture hybrid buses, while New York City 

Transit had a pilot program, and BEV (Proterra), Fuel Cell (fuel cell bus projects with New 

Flyer, Van Hool, Gilig, Daimler (Orion), EBus).

14 In addition, 

APTA reports that in terms of passenger miles by mode, busing is also responsible for the 

Source: www.internationaltrucks.com/Trucks/Trucks/Series/LoneStar Source: www.freightlijnertrucks.com/media/pdf/coronado_brochure.pdf 

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largest share (over 39 percent) of passenger transportation, at nearly 22 billion passenger 

miles. Although the number of buses manufactured in the U.S. is less than 5,500 per year, the 

number of manufacturing facilities involved in producing these buses is spread throughout the 

U.S., as shown in Figure 1-12.

15

Figure 1-12 Selected U.S. Manufacturing Locations for Transit Buses and Components

 While transit buses are typically used for two full shifts 

nearly every day and can average up to 30,000 miles per year of usage, school buses are used 

only twice a day and only on days when school is in session and typically accumulate just 

over 11,000 miles per year. School buses transport over 25 million children each year with a 

fleet of buses that is 94 percent diesel engine powered.

Compared to other modes of mass transit, and even other types of heavy-duty truck 

operations, buses travel generally operates at the lowest speed and tends to stop much more 

frequently than other HD vehicles. Figure 1-13 shows a comparison of average operational 

speed and length of trip for different modes of mass transit. Buses also make up one of the 

largest fleets of vehicles within the HD sector, having over 66,000 buses available for service 

in 2008. At the beginning of 2009 they were approximately 7.5 years old with 5.5 percent

having been rehabilitated during their lifetime. 

Source: Center on Globalization, Governance & Competitiveness, 2009

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Figure 1-13 Vehicle Speed vs. Trip Length by Mode in 2008

1.4 Operations

1.4.1 Trucking as a Mode of Freight Transportation

Trucks travel over a considerably larger domain than trains do, for example, in 2007 

there were over 4 million miles of public roads compared to 140,000 miles of track.16 In 2007 

there were over 2 million combination tractors registered in the U.S, and over 5.5 million 

trailers (including all commercial type vehicles and semitrailers that are in private or for hire 

use).17 Table 1-3 presents the number of trucks compared to the number of vessels and other 

modes of transportation that move freight.

Source: 2009 APTA Fact Book

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Table 1-3 Number of U.S. Vehicles, Vessels, and Other Conveyances: 1980-2007

Source: The Federal Highway Administration “Freight Facts and Figures 2009.”

Trucks move more than one-half of all hazardous materials within the U.S.; however, 

truck ton miles of hazardous shipments account for only about one-third of all transportation 

ton-miles due to the relatively short distances these materials are typically carried. In terms of 

growing international trade, trucks are the most common mode used to move imports and 

exports between both borders and inland locations. Table 1-5 shows the tons and value 

moved by truck compared to other transportation methods. 

Table 1-4 Domestic Mode of Exports and Imports by Tonnage and Value in 2002 and Projections for 

2035.32

MILLIONS OF 

TONS

BILLIONS OF 

DOLLARS (U.S. 

$2002)

2002 2035 2002 2035

Truck 797 a 2116 1198 6193

Rail 200 397 114 275

Water 106 168 26 49

Air, air and truck 9 b 54 614 5242

Intermodal 22 c 50 52 281

Pipeline and 

unknown

524 d760 141 238

Notes: a Excludes truck moves to and from airports. b Includes truck moves to and from airports. c Intermodal includes U.S. Postal Service and courier shipments and all intermodal combinations, except air and 

truck. In this table, oceangoing exports and imports that move between ports and domestic locations by single 

modes are classified by the domestic mode rather than the intermodal. d Pipeline and unknown shipments are combined because data on region-to-region flows by pipeline are statistically 

uncertain.

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Conversely, transportation of foreign trade is dominated by movement via water with 

trucks hauling approximately 16 percent of imported freight followed by rail and pipeline.18

As of 2009, Canada was the top trading partner with the United States in terms of the value of 

the merchandise traded ($430 billion in U.S. $2009), second was China ($366 billion in U.S. 

$2009), and third was Mexico ($305 billion in U.S. $2008).19

Figure 1-14

 Truck traffic dominates 

transportation modes from the two North American trade partners. As of 2009, over 58 

percent of total imported and exported freight moved between the U.S. and Canada was 

hauled by truck between Canada and the U.S., while over 68 percent of total imported and 

exported freight moved between the U.S. and Mexico was hauled by truck between Mexico 

and the U.S, as shown in .

20

Figure 1-14 North American Transborder Freight

The number of truck configurations is only limited by technical compatibility and 

customer demand; order lead times can vary from a few months to a year when demand is 

high. Truck purchasers (individual owner-operators and fleets) custom order their trucks to 

meet very specific needs, e.g. fleets in Kansas choose high gear ratios for good fuel economy 

on flat roads, fleets in the Rocky Mountains choose lower gear ratios to allow adequate 

performance in the mountains, etc. 

1.4.2 Operational Costs

One of the largest components of truck operational costs can be fuel costs, although 

this is dependent on the price of fuel, and can be as much as $70,000 - $125,000 annually per 

truck.33 High fuel price is a key driver for adopting new technologies as the lifetime fuel cost 

to operate a Class 8 truck is nearly five times that of the original price of the truck, compared 

to about a one-to-one ratio for passenger vehicle. HD truck fleets typically operate on a very 

thin profit margin (1-2 percent); therefore, increased truck fuel economy can greatly increase 

a company’s profitability.31 New technologies are generally introduced on Class 8 vehicles 

first, and then are quickly implemented into other truck class segments due to the similarity of 

these vehicles.

Source: Bureau of Transportation Statistics: North American Transborder Freight Data

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1.4.3 Operators

There are nearly nine million people in trucking related jobs, with 15 percent involved 

in manufacturing of the vehicles and trailers, and the majority of over three million, working 

as truck drivers. Many drivers are not part of large fleets, but are independent owneroperators where the driver independently owns his or her vehicle, leaving 87 percent of 

trucking fleets operating less than 6 percent of all trucks.

The U.S. Department of Transportation’s Federal Motor Carrier Safety Administration 

has developed Hours-of-Service regulations that limit when and how long commercial motor 

vehicle drivers may drive (Table 1-5 summarizes these rules). In general, drivers must take a 

ten consecutive hour rest / break per 24 hour day, and they may not drive for more than a 

week without taking a 34 consecutive hour break. These regulations have increased the 

importance of idle reduction technologies, as drivers can have a significant amount of 

downtime during a trip in order to comply with these mandates. During their required offduty hours, drivers face additional regulations they must abide by if they rest in their truck 

and idle the main engine to provide cab comfort. Currently, regulations that prohibit trucks 

from idling can differ from state to state, county to county, and city to city. The American 

Transportation Research Institute has compiled a list of nearly 45 different regulations that 

exist in different locals with fines for non-compliance ranging from $50 to $25,000 and can 

include up to two years in prison.

The need for auxiliary cab heating, cooling, and sources of electricity such as those 

provided by idle reduction devices such as auxiliary power units, is highlighted by the fact 

that driver comfort is not typically included as an exemption to allow idling, nor are, in some 

cases, the idling of trailer refrigeration units that require power to keep freight at a controlled

temperature.

Table 1-5 Summary of Hours of Service Rules

PROPERTY-CARRYING CMV DRIVERS PASSENGER-CARRYING CMV DRIVERS

11-Hour Driving Limit 10-Hour Driving Limit

May drive a maximum of 11 hours after 10 consecutive hours 

off duty.

May drive a maximum of 10 hours after 8 consecutive hours off 

duty.

14-Hour Limit 15-Hour On-Duty Limit

May not drive beyond the 14th consecutive hour after coming 

on duty, following 10 consecutive hours off duty. Off-duty 

time does not extend the 14-hour period.

May not drive after having been on duty for 15 hours, following 8 

consecutive hours off duty. Off-duty time is not included in the 15-

hour period.

60/70-Hour On-Duty Limit 60/70-Hour On-Duty Limit

May not drive after 60/70 hours on duty in 7/8 consecutive 

days. A driver may restart a 7/8 consecutive day period after 

taking 34 or more consecutive hours off duty.

May not drive after 60/70 hours on duty in 7/8 consecutive days.

Sleeper Berth Provision Sleeper Berth Provision

Drivers using the sleeper berth provision must take at least 8 

consecutive hours in the sleeper berth, plus a separate 2 

consecutive hours either in the sleeper berth, off duty, or any 

combination of the two.

Drivers using a sleeper berth must take at least 8 hours in the 

sleeper berth, and may split the sleeper-berth time into two periods 

provided neither is less than 2 hours.

Source: Federal Motor Carrier Safety Administration

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1.4.4 Heavy-Duty Truck Operating Speeds

In addition to the federal operating regulations, drivers must be aware of the variety of 

speed limits along their route, as these can vary both interstate and intrastate. 21,22

Table 1-6

 Currently, 

eight states have different speed limits for cars than they do for trucks, one state has different 

truck speed limits for night and day, and one state has a different speed limit for hazmat 

haulers than other trucks. In all, there are thirteen different car and truck speed combinations 

in the U.S. today; shows the different combination of vehicle and truck speed 

limits, as well as the different speed limits by location.

Table 1-6 U.S. Truck and Vehicle Speed Limits

SPEED LIMIT STATES WITH THE SAME SPEED LIMIT

Trucks 75 / Autos 75 Arizona, Colorado, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, South 

Dakota, Utahc

Trucks 70 / Autos 70

, Wyoming

Alabama, Florida, Georgia, Iowa, Kansas, Louisiana, Minnesota, Mississippi, 

Missouri, North Carolina, South Carolina, Tennessee, West Virginia, 

Trucks 65 / Autos 65 Alaska, Connecticut, Delaware, Illinois, Kentuckya, Maine, Maryland, Massachusetts, 

New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, 

Vermont, Virginiad

Trucks 60 / Autos 60

, Wisconsin

Hawaii

Trucks 55 / Autos 55 District of Columbia

Trucks 65 / Autos 75 Montana, Idaho

Trucks 65 / Autos 70 Arkansas, Indiana

Trucks 60 / Autos 70 Washington, Michigan

Trucks 55 / Autos 70 California

Trucks 55 / Autos 65 Oregon

Trucks 65 

(on the Turnpike Only)

Ohio

Trucks and Autos 70 

(65 at night)

Texas

Hazmat Trucks 55mph

b

Alabama

1.4.5 Trucking Roadways

The main function of the National Network is to support interstate commerce by 

regulating the size of trucks. Its authority stems from the Surface Transportation Assistance 

Act of 1982 (P.L. 97-424) which authorized the National Network to allow conventional 

combinations on “the Interstate System and those portions of the Federal-aid Primary System 

... serving to link principal cities and densely developed portions of the States ... [on] high 

volume route[s] utilized extensively by large vehicles for interstate commerce ... [which do] 

not have any unusual characteristics causing current or anticipated safety problems.”23 The 

Notes: [a] Effective as of July 10, 2007, the posted speed limit is 70 mph in designated areas on I-75 and I-71.

[b] In sections of I-10 and I-20 in rural West Texas, the speed limit for passenger cars and light trucks is 80 mph. For large trucks, the speed 

limit is 70 mph in the daytime and 65 mph at night. For cars, it is also 65 mph at night. 

[c] Based on 2008 Utah House Bill 406, which became effective on May 5, 2008, portions of I-15 have a posted limit of 80 mph.

[d] Effective July 1, 2006, the posted speed limit on I-85 may be as high as 70 mph.

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National Network has not changed significantly since its inception and is only modified if 

states petition to have segments outside of the current network added or deleted, Figure 1-15

shows the National Network of the U.S.

Additionally, there is the National Highway System (NHS), which was created by the 

National Highway System Designation Act of 1995 (P.L. 104-59). The main focus of the 

NHS is to support interstate commerce by focusing on federal investments. Currently, there is 

a portion of the NHS that is over 4,000 miles long which supports a minimum of 10,000 

trucks per day and can have sections where at least every fourth vehicle is a truck.

C

24 Both the 

National Network and the NHS are approximately the same length, roughly 200,000 miles, 

but the National Network includes approximately 65,000 miles of highways in addition to the 

NHS, and the NHS includes about 50,000 miles of highways that are not in the National 

Network.

 

C Tractors with one semitrailer up to 48 feet in length or with one 28-foot semitrailer and one 

28-foot trailer, and can be up to 102 inches wide. Single 53-foot trailers are allowed in 25 

states without special permits and in an additional 3 states subject to limits on distance of 

kingpin to rearmost axle.

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Figure 1-15 The National Network for Conventional Combination Trucks

1.4.6 Weigh Stations

Individual overweight trucks can damage roads and bridges; therefore, both federal 

and state governments are concerned about trucks that exceed the maximum weight limits

operating without permits on U.S. roadways. In order to ensure that the trucks are operating 

within the correct weight boundaries, weigh stations are distributed throughout the U.S. 

roadways to ensure individual trucks are in compliance. In 2008, there were approximately 

200 million truck weight measurements taken with less than one percent of those found to 

have a violation.24

There are two types of weigh stations, dynamic, or ‘weigh-in-motion’, where the 

operator drives across the scales at normal speed, and static scales where the operator must 

stop the vehicle on the scale to obtain the weight. As of 2008, 60 percent of the scales in the 

U.S. were dynamic and 40 percent were static. The main advantage of the dynamic weigh-inmotion scales are that they allow weight measurements to be taken while trucks are operating 

at highway speeds, reducing the time it takes for them to be weighed individually, as well as

reducing idle time and emissions.

 

25,26 Officers at weigh stations are primarily interested in 

ensuring the truck is compliant with weight regulations; however, they can also inspect 

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equipment for defects or safety violations, and review log books to ensure drivers have not 

violated their limited hours of service. 

1.4.7 Types of Freight Carried

Prior to 2002, the U.S. Census Bureau completed a “Vehicle Inventory and Use 

Survey” (VIUS), which has since been discontinued. It provided data on the physical and 

operational characteristics of the nation’s private and commercial truck fleet, and had a 

primary goal of producing national and state-level estimates of the total number of trucks. 

The VIUS also tallied the amount and type of freight that was hauled by heavy-duty trucks. 

The most prevalent type of freight hauled in 2002, according to the survey was mixed freight, 

followed by nonpowered tools. Three fourths of the miles traveled by trucks larger than panel 

trucks, pickups, minivans, other light vans, and government owned vehicles were for the 

movement of products from electronics to sand and gravel. Most of the remaining mileage is 

for empty backhauls and empty shipping containers, Table 1-7 shows the twenty most 

commonly hauled types of freight in terms of miles moved.

24

Table 1-7 Top Twenty Types of Freight Hauled in 2002 in Terms of Mileage

TYPE OF PRODUCT CARRIER MILLIONS OF MILES

Mixed freight 14,659

Tools, nonpowered 7,759

All other prepared foodstuffs 7,428

Tools, powered 6,478

Products not specified 6,358

Mail and courier parcels 4,760

Miscellaneous manufactured products 4,008

Vehicles, including parts 3,844

Wood products 3,561

Bakery and milled grain products 3,553

Articles of base metal 3,294

Machinery 3,225

Paper or paperboard articles 3,140

Meat, seafood, and their preparations 3,056

Non-metallic mineral products 3,049

Electronic and other electrical equipment 3,024

Base metal in primary or semi-finished forms 2,881

Gravel or rushed stone 2,790

All other agricultural products 2,661

All other waste and scrape (non-EPA manifest) 2,647

Source: The U.S. Census Bureau “Vehicle Inventory and Use Survey” 2002

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1.4.8 Heavy-Duty Trucking Traffic Patterns

One of the advantages inherent in the trucking industry is that trucks can not only 

carry freight over long distances, but due to their relatively smaller size and increased 

maneuverability they are able to deliver freight to more destinations than other modes such as 

rail. Figure 1-16 shows the different modes of freight transportation and the average length of 

their routes. However, this also means they are in direct competition with light-duty vehicles 

for road space, and that they are more prone to experiencing traffic congestion delays than 

other modes of freight transportation.

Figure 1-16 Lengths of Routes by Type of Freight Transportation Mode

Source: http://www.bts.gov/publications/national_transportation_statistics/

The Federal Highway Administration (FHWA) projects that long-haul trucking

between places which are at least 50 miles apart will increase substantially on Interstate 

highways and other roads throughout the U.S, forecast data indicates that this traffic may 

reach up to 600 million miles per day.24

Deleted: 17

 In addition, the FHWA projects that segments of the 

NHS supporting more than 10,000 trucks per day will exceed 14,000 miles, an increase of

almost 230 percent over 2002 levels. Furthermore, if no changes are made to alleviate current 

congestion levels, the FHWA predicts that these increases in truck traffic combined with 

increases in passenger vehicle traffic could slow traffic overall on nearly 20,000 miles of the 

NHS and create stop-and-go conditions on an additional 45,000 miles. Figure 1-17 shows the 

projected impacts of traffic congestion. These predicted congestion areas would also have an 

increase in localized engine emissions; advances in hybrid truck technology could provide 

large benefits and help combat the increased emissions that occur with traffic congestion.

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Figure 1-17 Federal Highway Administration's Projected Average Daily Long-Haul Truck Traffic on the 

National Highway System in 2035

Source: The Federal Highway Administration: 2009 Facts and Figures

1.4.9 Intermodal Freight Movement

Since trucks are more maneuverable than other common modes of freight shipment, 

trucks are often used in conjunction with these modes to transit goods across the country, 

known as intermodal shipping. Intermodal traffic typically begins with containers carried on 

ships, then they are loaded onto railcars, and finally transported to their end destination via 

truck. There are two primary types of rail intermodal transportation which are trailer-onflatcar (TOFC) and container-on-flatcar (COFC), both are used throughout the U.S. with the 

largest usage found on routes between West Coast ports and Chicago, and between Chicago 

and New York. The use of TOFCs (see Figure 1-18) allows for faster transition from rail to 

truck, but is more difficult to stack on a vessel; therefore the use of COFCs (see Figure 1-19)

has been increasing steadily.

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Figure 1-18 Trailer-on-Flatcar (TOFC)

Figure 1-19 Container-on-Flatcar (COFC)

1.4.10 Purchase and Operational Related Taxes

Currently, there is a Federal retail tax of 12 percent of the sales price (at the first retail 

sale) on heavy trucks, trailers, and tractors. This tax does not apply to truck chassis and bodies 

suitable for use with a vehicle that has a gross vehicle weight of 33,000 pounds or less. It also 

does not apply to truck trailer and semitrailer chassis or bodies suitable for use with a trailer 

or semitrailer that has a gross vehicle weight of 26,000 pounds or less. Tractors that have a 

gross vehicle weight of 19,500 pounds or less and a gross combined weight of 33,000 pounds 

or less are excluded from the 12 percent retail tax.27

There is also a tire tax for tires used on some heavy-duty trucks. This tax is based on 

the pounds of maximum rated load capacity over 3,500 pounds rather than the actual weight 

of the tire, as was done in the past.

This tax is applied to the vehicles as well 

as any parts or accessories sold on or in connection with the sale of the truck. However, idle 

reduction devices affixed to the tractor and determined by the Administrator of the EPA, in 

consultation of the Secretary of Energy and Secretary of Transportation are generally exempt 

from this tax. There are other exemptions for certain truck body types, such as refuse packer 

truck bodies with load capacities of 20 cubic yards or less, other specific installed equipment, 

and sales to certain entities such as state or local governments for their exclusive use. 

28

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 Singlewide tires can provide some tax savings both in 

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27

terms of a lower tax rate and the weight reduction achieved as these tires typically weigh less 

than two standard tires, mostly due to the elimination of two sidewalls. 

A new method of calculating the federal excise tax (FET) on tires was included in the 

American Jobs Creation Act that changed the method for calculating the FET on truck tires. 

Previously, the tax was based on the actual weight of the tire, where before, for a tire 

weighing more than 90 pounds there was a 50¢ tax for every 10 pounds of weight above 90 

pounds plus a flat fee of $10.50. Since truck and trailer tires can weigh on average 120 

pounds, this would carry a tax penalty of approximately $25 per tire; this method gave 

singlewide tires a tax advantage as they weigh less in part because they have two fewer 

sidewalls. The new FET is based on the load-carrying capacity of the tire. For every 10-

pound increment in load-carrying capacity above 3,500 pounds, a tax of 9.45¢ cents is levied.

A typical heavy-duty tire has a load carrying capacity of over approximately 6,000 pounds 

and would therefore carry a similar tax burden as before.29

Finally, there is a usage tax for heavy duty vehicles driven over 5,000 miles per year 

(or over 7,500 miles for agricultural vehicles). This tax is based on the gross weight of the 

truck, and includes a rate discounted 25 percent for logging trucks.

 The change, however, is that the 

tax rate for bias ply and single wide tires is half that of a standard tire. 

30

1.4.11 Heavy-Duty Vehicle Age Trends

 For trucks with a GVW 

of 55,000 – 75,000 pounds the tax rate is $100 plus $22 for each additional 1,000 pounds in 

excess of 55,000 pounds; trucks with a GVW over 75,000 pay $550.

Class 8 long-haul combination tractors are typically sold after the first three to five

years of ownership and operation by large fleets, however, smaller fleets and owner-operators 

will continue to use these trucks for many years thereafter.

31 As of 2009, the average age of 

the U.S. Class 8 fleet was 7.87 years.32 These newest trucks travel between 150,000 –

200,000 miles per year, and 50 percent of the trucks in this Class 8 segment use 80 percent of 

the fuel.

33 Although the overall fleet average age is less than ten years old, Figure 1-20 shows

that nearly half of all of Class 4-8 trucks live well past 20 years of age, and that smaller Class 

4-6 trucks typically remain in the U.S. fleet longer than other classes.
Regulatory Impact Analysis 

28

Figure 1-20 Survival Probability of Class 4-8 Trucks

1.5 Tire Manufacturers

The three largest suppliers to the U.S. commercial new truck tire market (heavy-duty 

truck tires) are Bridgestone Americas Tire Operations LLC, Goodyear Tire and Rubber 

Company, and Michelin North America, Incorporated. Collectively, these companies account 

for over two-thirds of the new commercial truck tire market. Continental Tire of the 

Americas LLC, Yokohama Tire Company, Toyo Tires U.S.A. Corporation, Hankook Tire 

America Corporation, and others also supply this market. New commercial tire shipments 

totaled 12.5 million tires in 2009. This number was down nearly 20 percent from the previous 

year, due to the economic downturn, which hit the trucking industry especially hard.

34

1.5.1 Single Wide Tires

A typical configuration for a combination tractor-trailer is five axles and 18 wheels 

and tires, hence the name, “18-wheeler.” There are two wheel/tire sets on the steer axle, one 

at each axle end, and four wheel/tire sets on each of the two drive and two trailer axles, with 

two at each axle end (dual tires), Figure 1-21 shows the position and name of each axle.

Steer tires and dual drive and trailer tires vary in size. A typical tire size for a tractortrailer highway truck is 295/75R22.5. This refers to a tire that is 295 millimeters (or 11.6”) 

wide with an aspect ratio (the sidewall height to tire section width, expressed as a percent) of 

75, for use on a 22.5” wheel. The higher the aspect ratio the taller the tire is relative to its 

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29

section width. Conversely, the lower the aspect ratio the shorter the tire is relative to its 

section width. Truck tires with a sidewall height between 70 percent and 80 percent of the 

tire section width use this metric sizing; other common highway truck tire sizes are 

275/80R22.5, 285/75R24.5, and 275/80R24.5. Tire size can also be expressed in inches. 

11R22.5 and 11R24.5 refer to tires that are 11 inches wide for use on a 22.5” and 24.5” wheel, 

respectively. Tires expressed in this non-metric nomenclature typically have an aspect ratio 

of 90, meaning the sidewall height is 90 percent of the tire section width.

Figure 1-21 Class 8 Standard "18 Wheeler" Axle Identification

Single wide tires have a much wider “base” or section width than tires used in dual 

configurations and have a very low aspect ratio. A typical size for a single wide tire used on a 

highway tractor trailer is 455/50R22.5. This refers to a tire that is 455 millimeters wide with a 

sidewall height that is 50 percent of its section width, for use on a 22.5” wheel. As implied by 

its name, a single wide tire is not installed in a dual configuration. Only one tire is needed at 

each end of the four drive and trailer axles, effectively converting an “18-wheeler” heavyduty truck into a 10-wheeler, including the two steer tires. Except for certain applications like 

refuse trucks, in which the additional weight capacity over the steer axle could be beneficial, 

single wide tires are not used on the steer axle. 

Proponents of single wide tires cite a number of advantages relative to conventional 

dual tires. These include lower weight, less maintenance, and cost savings from replacing 16 

dual tire/wheel sets with 8 single wide tire/wheel sets; improved truck handling and braking, 

especially for applications like bulk haulers that benefit from the lower center of gravity;

reduced noise; fewer scrapped tires to recycle or add to the waste stream; and better fuel 

economy. A recent in-use study conducted by the Department of Energy’s Oak Ridge 

National Laboratory found fuel efficiency improvement for single wide tires compared to dual 

tires of at least 6 percent up to 10 percent. These findings are consistent with assessments by 

EPA using vehicle simulation modeling and in controlled track testing conducted by EPA’s 

SmartWay program.

35

Sales of single wide tires have grown steadily since today’s single wide tires entered 

the U.S. market in 2000. However, overall market share of single wide tires is still low

relative to dual tires. There are several reasons why trucking fleets or drivers might be slow

to adopt single wide tires. Fleets might be concerned that in the event of a tire failure with a 

single wide tire, the driver would need to immediately pull to the side of the road rather than 

“limping along” to an exit. “Limping along” on one dual tire after the other dual tire fails

places the entire weight of the axle end on the one remaining good tire. In most cases, this is 

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30

a dangerous practice that should be avoided regardless of tire type; however, some truck 

operators still use “limp along” capability. Fleets might also be concerned that replacement 

single wide tires are not widely available on the road. As single wide tires continue to gain 

broader acceptance, tire availability will increase for road service calls. Trucking fleets might 

not want to change tire usage practices. For example, some fleets like to switch tires between 

the steer and trailer axles or retreaded steer tires for use on trailers. Since single wide tires are 

not used on the steer position of tractor-trailers, using single wide tires on the trailer 

constrains steer-trailer tire and retreaded tire interchangeability. 

New trucks and trailers can be ordered with single wide tires, and existing vehicles can 

be retrofit to accommodate single wide tires. If a truck or trailer is retrofit with single wide 

tires, the dual wheels will need to be replaced with wider single wheels. Also, if a trailer is 

retrofit or newly purchased with single wide tires, it may be preferable to use the heavier, 

non-tapered “P” type trailer axles rather than the narrow, lighter, tapered “N” spindle axles, 

because of changes in load stress at the axle end. Single wide tires are typically outset by 2

inches due to the wider track width, and outset wheels may require a slight de-rating of the 

hub load. Industry is developing advanced hub and bearing components optimized for use 

with single wide wheels and tires, which could make hub load de-rating unnecessary. 

Whatever type of wheels and tires are used, it is important that trucking fleets follow the 

guidance and recommended practices issued by equipment manufacturers, the Tire and Rim 

Association, and the American Trucking Association’s Technology and Maintenance Council,

regarding inflation pressure, speed and load ratings.

When today’s single wide tires were first introduced in 2000, there were questions

about adverse pavement impacts. This is because in the early 1980’s, a number of “super 

single” tires were marketed which studies subsequently showed to be more detrimental to 

pavement than dual tires. These circa-1980s wide tires were fundamentally different than 

today’s single wide tires. They were much narrower (16 percent to 18 percent) and taller,

with aspect ratios in the range of 70 percent, rather than the 45 – 55 percent of today’s single 

wide tires. The early wide tires were constructed differently as well, lacking the engineering 

sophistication of today’s single wide tires. The steel belts were oriented in a way that 

concentrated contact stresses in the crown, leading to increased pavement damage. The tires 

also flexed more, which increased rolling resistance.

In contrast, today’s single wide tires are designed to provide more uniform tirepavement contact stress, with a tire architecture that allows wider widths at low aspect ratios

and reduces the amount of interaction between the crown and sides of the tire, to reduce 

flexing and improve rolling resistance. Research on pavement response using instrumented 

roads and finite element modeling shows that depending upon pavement structure, single wide 

tires with a 55 percent aspect ratio produce similar bottom-up cracking and rutting damage as 

dual tires, and improve top-down cracking. Single wide tires with a 45 percent aspect ratio

showed slightly more pavement damage. The new studies found that earlier research failed to 

take into account differences in tire pressure between two tires in a dual configuration; a 

situation that is common in the real world. Uneven inflation pressure with dual tire

configurations can be very detrimental to pavement. The research also found that 

conventional steer tires damage pavement more than other tires, including single wide tires.

36 
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31

Research is ongoing to provide pavement engineers the data they need to optimize road and 

pavement characteristics to fit current and emerging tire technologies.

1.5.2 Retreaded Tires

Although retreading tires is no longer a common practice for passenger vehicles, it is 

very common in commercial trucking. Even the federal government is directed by Executive 

Order to use retreaded tires in its fleets whenever feasible.37 Retreading a tire greatly 

increases its mileage and lifetime, saving both money and resources. It costs about one-third

to one-half of the cost of a new truck tire to retread it, and uses a lot less rubber. On average, 

it takes about 325 pounds of rubber to produce a new medium- or heavy-duty truck tire, but 

only about 24 pounds of rubber to retread the same tire.

38

The Department of Transportation Federal Motor Carrier Safety Administration 

(FMSCA) issues federal regulations that govern the minimum amount of tread depth 

allowable before a commercial truck tire must be retreaded or replaced. These regulations 

prohibit “Any tire on any steering axle of a power unit with less than 4/32 inch tread when 

measured at any point on a major tread groove. ...All tires other than those found on the 

steering axle of a power unit with less than 2/32 inch tread when measured at any point on a 

major tread groove.”39 Trucking fleets often retread tires before tire treads reach this 

minimum depth in order to preserve the integrity of the tire casing for retreading. If the 

casing remains in good condition, a truck tire can be safely retreaded multiple times. Heavy 

truck tires in line haul operation can be retread 2 to 3 times and medium-duty truck tires in 

urban use can be retread 5 or more times.40

In 2009, the number of retreaded tires sold to the commercial trucking industry 

outsold the number of new replacement tire shipments by half a million units – 13 million 

retreaded tires were sold, versus 12.5 million replacement tires.

 To accommodate this practice, many commercial 

truck tire manufacturers warranty their casings for up to five years, excluding damage from 

road hazards or improper maintenance.

41 Retreaded tire sales 

(without casings) totaled $1.64 billion in 2009.42 All the top commercial truck tire 

manufacturers are involved in tire retread manufacturing. Bridgestone Bandag Tire Solutions 

accounts for 42 percent of the domestic retreaded truck tire market with its Bandag retread 

products; Goodyear Tire and Rubber Company accounts for 28 percent, mostly through its 

Wingfoot Commercial Tire Systems; Michelin Retread Technologies Incorporated, with 

Megamile, Oliver, and Michelin retread products, accounts for 23 percent. Other tire 

companies like Continental and independent retread suppliers like Marangoni Tread North 

America (which also produces the Continental “ContiTread” retread product) make up the 

remaining 7 percent.43

Although the “big 3” tire companies produce the majority of retread products through 

their retread operations, the retreading industry itself consists of hundreds of retreaders who 

sell and service retreaded tires, often (but not always) using machinery and practices 

identified with one of the “big 3” retread producers. There are about 800 retread plants in 

North America.

 

44

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 The top 100 retreaders in the U.S. retread 47,473 truck tires per day. They 

also retread 2,625 light truck tires and 625 off road tires daily. Tire retreaders are industryDeleted: 

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Regulatory Impact Analysis 

32

ranked by the amount of rubber they use annually in their businesses. In 2009, the top 12 

retreaders in the US accounted for nearly 150 million pounds of rubber used to retread tires. 45

1.6 Current U.S. and International GHG Voluntary Actions and 

Regulations

Heavy-duty trucks in the U.S. today are not required to meet national GHG standards 

or regulations. The only national requirement for heavy-duty trucks is currently for non-GHG 

emissions, as the heavy-duty engines must meet Non-Methane Hydrocarbons (NMHC),

nitrous oxides (NOx), particulate matter (PM), and carbon monoxide (CO) standards. U.S. 

efforts to reduce GHG emissions from the heavy-duty truck sector to date have been limited 

to voluntary measures and actions by the States. Congress has mandated the U.S. Department 

of Transportation to take action to set fuel efficiency standards for heavy-duty trucks through 

the Energy Independence and Security Act (EISA) of 2007. International GHG regulations 

have been implemented in Japan and are under consideration in other countries.

Additionally, there are existing heavy-duty engine certification and useful life 

requirements, as shown for example in Figure 1-22. Heavy-Duty Engines have a single full 

life standard. Manufacturers certify results are cleaner than their test results to account for 

production and testing variability. Manufacturers also develop a deterioration factor which is 

used to demonstrate compliance at end of life.

Figure 1-22 Current Heavy-Duty Useful Life Years and Miles

ENGINE TYPE YEARS MILES

Spark Ignited (SI) Engines 10 110,000

Light Heavy-Duty Diesel Engines 10 110,000

Medium-Heavy Duty Diesel Engines 10 185,000

Heavy-Heavy-Duty Diesel Engines 10 435,000

1.6.1 U.S. EPA SmartWayTM

While there are currently no national regulations for the heavy-duty trucking sector, 

there is a highly recognized voluntary program established in the U.S. The U.S. EPA 

SmartWay Transport Partnership is a collaborative program between EPA and the freight 

industry that will increase the energy efficiency of heavy-duty trucks while significantly 

reducing air pollution and GHG emissions. The Partnership provides strong market-based 

incentives to companies shipping products and the truck companies delivering these products, 

to improve the environmental performance of freight operations. SmartWay Transport 

partners improve their energy efficiency, save money, reduce greenhouse gas emissions and 

improve air quality.

Transport Partnership

SmartWay is a collaborative effort between the government and business, to improve 

the efficiency of goods movement from global supply chains while reducing fuel consumption 

and emissions. SmartWay was launched by the Environmental Protection Agency in 2004 

with full support of the trucking industry and their freight shipping customers. SmartWay 

started with fifty initial partners including 15 Charter Partners. Since that time, the number of 

Partners has grown to over 2,700 members including most of the largest trucking fleets in the 

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United States, and many of the largest multi-national shippers. SmartWay trucking fleet 

partners operate over 650,000 trucks, which represent 10 percent of all heavy-duty trucks. 

The SmartWay program promotes the benefits of key truck technologies including idle 

reduction, aerodynamics, efficient tires, and operational strategies that include enhanced 

logistics management, reduced packaging, driver training, equipment maintenance, and 

intermodal options. SmartWay partners employ these strategies and technologies on new and 

existing equipment to reduce emissions and save fuel, contributing to environmental, energy 

security, and economic goals. SmartWay partners have helped to reduce CO2

1.6.2 The 21

emissions 

from trucks by nearly 15 million metric tons, NOx by 215,000 tons, and PM by 8,000 tons, 

and have saved 1.5 billion gallons of diesel fuel as well as $3.6 billion in fuel costs. Other 

countries have expressed significant interest in SmartWay, and EPA has participated in 

workshops and pilot projects to demonstrate SmartWay tools and approaches internationally. 

Beginning in 2007, working with truck, trailer and engine manufacturers as well as states and 

public interest groups, SmartWay developed specifications to designate the cleanest and most 

efficient Class 8 tractor-trailers. SmartWay-certified trucks now represent more than 5

percent of new Class 8 sleeper truck sales, and every major truck maker offers at least one 

EPA SmartWay Certified Tractor.

st

Additionally, the DOE, EPA, DOT, Department of Defense (DOD), and national 

laboratories together with members of the heavy-duty truck industry work toward making 

freight and passenger transportation more efficient, cleaner, and safer under the 21

Century Truck Partnership

st Century 

Truck Partnership.

47

• Integrated vehicle systems research and development to validate and deploy 

advanced technologies.

 The Partnership has several activities related to reducing greenhouse gas 

emissions, including:

• Research for engine, combustion, exhaust aftertreatment, fuels, and advanced 

materials to achieve both higher efficiency and lower emissions.

• Research on advanced heavy-duty hybrid propulsion systems, reduced parasitic 

losses, and reduced idling emissions.

The Partnership provides a forum for parties to exchange information on the heavyduty sector across government and industry. The Partnership has developed, among many 

other aspects, the widely referenced vehicle energy balance for heavy trucks and specific 

research goals for improvement efficiency.

1.6.3 California Assembly Bill 32

The state of California passed the Global Warming Solutions Act of 2006 (Assembly 

Bill 32), enacting the state’s 2020 greenhouse gas emissions reduction goal into law. 

Pursuant to this Act, the California Air Resource Board (ARB) was required to begin 

developing early actions to reduce GHG emissions. Accordingly, the California Air Resource 

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Regulatory Impact Analysis 

34

Board issued the Regulation to Reduce Greenhouse Gas Emissions from Heavy-Duty 

Vehicles in December 2008. 49

This regulation reduces GHG emissions by requiring improvement in the efficiency of 

heavy-duty tractors and 53 foot or longer dry and refrigerated box trailers which operate in 

California. The program begins in 2010, although small fleets are allowed special compliance 

opportunities to phase in the retrofits of their existing trailer fleets through 2017. The 

regulation requires that new tractors and trailers subject to the rule be certified by SmartWay 

and existing tractors and trailers are retrofit with SmartWay verified technologies. The 

efficiency improvements are achieved through the use of aerodynamic equipment and low 

rolling resistance tires on both the tractor and trailer.

 

1.6.4 U.S. Energy Independence and Security Act 

The U.S. Energy Independence and Security Act (EISA) of 2007 was enacted by 

Congress in December of 2007.50 EISA requires the Department of Transportation, in 

consultation with DOE and EPA, to study the fuel efficiency of heavy-duty trucks and 

determine: the appropriate test procedures and metric for measuring and expressing fuel 

efficiency; of MD/HD vehicles; the range of factors that affect fuel efficiency of such 

vehicles; and factors that could have an impact on a program to improve these vehicles’ fuel 

efficiency. In addition, EISA directed the Department of Transportation, in consultation with 

DOE and the EPA, to implement, via rulemaking and regulations, ‘‘a commercial heavy-duty 

on-highway vehicle and work truck fuel efficiency improvement program’’ and to ‘‘adopt and 

implement appropriate test methods, measurement metrics, fuel economy standards, and 

compliance and enforcement protocols that are appropriate, cost-effective, and 

technologically feasible for commercial heavy-duty on-highway vehicles and work trucks.’’ 

Section 108 of the Act directed the Secretary of Transportation to execute an 

agreement with the National Academy of Sciences (NAS) to develop a report evaluating 

heavy-duty truck fuel economy standards. The study included an assessment of technologies 

and costs to evaluate MD/HD vehicle fuel economy; an analysis of existing and potential 

technologies to improve such vehicles’ fuel economy; analysis of how the technologies may 

be integrated into the manufacturing process; assessment of how technologies may be used to 

meet fuel economy standards; and associated costs and other impacts on operation. The NAS 

panel published this study, titled “Technologies and Approaches to Reducing the Fuel 

Consumption of Medium- and Heavy-duty Vehicles” March 31, 2010.”

This authority permits DOT to set ‘‘separate standards for different classes of vehicles.’’ The 

standards must provide at least 4 full model years of regulatory lead time and 3 full model 

years of regulatory stability. 

1.6.5 International GHG Emissions Activities

The international regulatory actions to reduce GHG emissions from heavy-duty trucks 

have been limited in scope. Japan has been at the forefront of heavy-duty truck GHG 

regulations while other nations, such as China and the European Union, are still in the 

development stage of potential regulatory programs for this sector.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Industry Characterization

35

Japan introduced legislation which set the minimum fuel economy standards for new 

heavy-duty vehicles with Gross Vehicle Weight Rating (GVWR) of greater than 7,700 pounds 

beginning in 2015 model year. 

1.7 Trailers 

1.7.1 Overview

A trailer is a vehicle designed to haul cargo while being pulled by another powered 

motor vehicle. It may be constructed to rest upon the tractor that tows it (a semi-trailer), or be 

constructed so no part of its weight rests on the tractor (a full trailer or a semitrailer equipped 

with an auxiliary front axle called a “converter dolly.”) The most common configuration of 

large freight trucks consists of a Class 7 or 8 tractor hauling one or more semi-trailers. A 

truck in this configuration is called a “tractor-trailer.” The semi-trailer is attached to the 

tractor by a coupling consisting of a horseshoe-shaped coupling device called a fifth wheel on 

the rear of the towing vehicle, and a coupling pin (or king pin) on the front of the semi-trailer 

or converter dolly. A tractor can also pull an ocean container mounted on an open-frame 

chassis, which when driven together on the road functions as a trailer. The Department of 

Transportation issues federal regulations that govern trailer length (separately or in 

combination), width, height, and weight, as well as trailer safety requirements (lights, 

reflective materials, bumpers, turn signals, tire and rim specifications, brakes, load-securing 

devices, tow balls, etc.) The Truck Trailer Manufacturers Association, an industry trade 

group for manufacturers of Class 7 and 8 truck trailers, also provides technical bulletins 

covering many aspects of trailer manufacture. Each trailer, like any other road vehicle, must 

have a Vehicle Identification Number (VIN).

1.7.2 Trailer Types

There are numerous types of trailers hauled by Class 7 and 8 tractors that are designed 

to handle any freight transport need. Dry box van trailers are enclosed trailers that can haul 

most types of mixed freight. Despite their similar shape and purpose, box trailers can vary 

widely in size and configuration although most are commonly found in 28’, 48’, and 53’ 

lengths and 102” or 96” widths. Drop floor trailers have a lowered floor, often seen in 

moving vans. Other van trailers are curtain-sided with tarp or have roll up doors on the sides, 

as seen in beverage haulers. Another type of specialty box trailer is the refrigerated van trailer 

(reefer). This is an enclosed, insulated trailer that hauls temperature sensitive freight, with a

transportation refrigeration unit (TRU) mounted in the front of the trailer powered by a small 

(9-36 hp) diesel engine. Enclosed box trailers – whether dry van, reefer, curtainside, drop 

floor, or other configuration, can have different axle configurations (single axle, fixed tandem, 

sliding tandem, tag-along axle) and door types (roll up, side-by-side). Figure 1-23 shows an 

example of a dry freight van semi-trailer with side-by-side doors.

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Regulatory Impact Analysis 

36

Figure 1-23 Example Dry Box Van Trailer

Source: http://www.wabashnational.com/Images/popups/DuraPlatePop.jpg

Flatbed trailers are platform-type trailers which also come in different configurations 

from standard flatbed platform trailers to gooseneck and drop deck flatbeds which are built 

such that the trailer platform is lower to the ground than the hitch would normally allow. 

There are also a number of other specialized trailers such as grain trailers (with and without 

hoppers), dump trailers (frameless, framed, bottom dump, demolition), automobile hauler 

trailers (open or enclosed), livestock trailers (belly or straight), dry bulk and liquid tanker 

trailers, construction and heavy-hauling trailers (tilt bed, hydraulic), even trailers designed to 

travel on both highways and railroad tracks. Figure 1-24 shows an example of a drop-deck 

platform trailer.

Figure 1-24 Example Drop-Deck Trailer

Source: http://www.transcraft.com/Transcraft/images/products/D-Eagle.jpg

The most common type of trailer in use today is the dry van trailer. Table 1-8 shows 

the various trailer types and their share of the trucking market. Despite considerable 

improvements in suspension, material, safety, durability, and other advancements, the basic 

shape of the van trailer has not changed much over the past decades, although its dimensions 

have increased incrementally from what used to be the industry’s standard length of 40’ to 

today’s standard 53’ long van trailer. The van trailer’s boxy shape – while not particularly 

aerodynamic – is designed to maximize cargo volume hauling capacity, since the majority of 

freight shipped by truck cubes out (is volume-limited) before it grosses out (is weightlimited). EPA’s SmartWay program has demonstrated that adding aerodynamic features to 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Industry Characterization

37

van trailer designs and the use of low rolling resistance tires can substantially reduce fuel 

consumption from tractor trailers. SmartWay verifies aerodynamic equipment and low 

rolling resistance tires for use on SmartWay-certified trailers, which can be new or retrofit.

Table 1-8 Trailer Types and Volumes (Source: ICCT Report) 

Van, 55%

Van Refrigerated, 4%

Tagalong, 3%

Enclosed Tagalong, 2%

Container Chassis, 6%

Flatbed, 7%

Flatbed Drop Deck, 2%

Tank, 1%

Tank MC, 1%

Tank Pneumatic, 0%

Beverage, 0%

All other, 9%

1.7.3 Trailer Manufacturers

This diverse variety of van, platform, tanker and specialty trailers are produced by a 

large number of trailer manufacturers. The twelve manufacturers with the largest overall 

North American output are: Utility Trailer Manufacturing, Great Dane Limited Partnership, 

Wabash National Corporation, Hyundai Translead, Timpte Inc., Wilson Trailer Company, 

Stoughton Trailers, Heil Trailer International, Fontaine Trailer Company, MANAC, Vanguard 

National Trailer Corporation, and Polar Tank Trailer. Trailer manufacturing is still done 

mostly by hand, although the various trailer parts can be mass-produced and even shipped 

from abroad for assembly in the U.S. Altogether, 30-some companies account for most of 

this industry’s manufacturing base, although there are dozens and dozens additional 

manufacturers producing for niche trailer markets. Despite this variety, trailers are far less 

mechanically complex than are the trucks that haul them. This low barrier to entry for trailer 

manufacturing accounts in part for the large numbers of trailer manufacturers. Nearly half of 

all trailer manufacturers – including those that might be considered “large” in their industry 

segment -- meet SBA’s definition of a small business.

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Regulatory Impact Analysis 

38

The trailer industry was particularly hard hit by the recent recession. Trailer 

manufacturers saw deep declines in new trailer sales of 46 percent in 2009; some trailer 

manufacturers saw sales drop as much as 71 percent. This followed overall trailer industry 

declines of over 30 percent in 2008. The 30 largest trailer manufacturers saw sales decline 

72% overall from their highest recent sales volumes, from 277,992 in 2006, to only 78,258 in 

2009. 51

1.7.4 Trailer Operations

 Several trailer manufacturers shut down entire production facilities and a few went 

out of business altogether. Of the most common trailer types of trailers sold, refrigerated 

trailers were the least affected; platform trailers were the most affected. As of mid-2010, the 

trailer industry has yet to recover from the devastating effects of the economic downturn.

Trailers are the primary vehicle for moving freight in the United States. Despite their 

significance to the goods movement industry and opportunities to improve fuel efficiency and 

reduce greenhouse gas emissions from trailer improvements, the broad diversity of the trailer 

industry and its end-user practices make this a challenging industry to address and engage.

Truck drivers and trucking fleets frequently do not control all or even any of the 

trailers that they haul. Trailers can be owned by freight customers, large equipment leasing 

companies, third party logistics companies (3PLS), and even other trucking companies. 

Containers on chassis, which function as trailers, are rarely owned by truck operators. Rather, 

they are owned or leased by ocean-going shipping companies, port authorities or others. This 

distinction between who hauls the freight and who owns the equipment in which it is hauled 

means that truck owners and operators have limited ability to be selective about the trailers 

they carry, and very little incentive or ability to take steps to reduce the fuel use of trailers that 

they neither own or control.

The ratio of the number of trailers in the fleet relative to the number of tractors in the 

legacy fleet is typically three-to-one.52

For refrigerated trailers, the story is slightly different. These trailers are used more 

intensely and accumulate more annual miles than other trailers. Over time, refrigerated 

trailers can also develop problems that interfere with their ability to keep freight temperaturecontrolled. For example, the insulating material inside a refrigerated trailer’s walls can 

gradually lose its thermal capabilities due to aging or damage from forklift punctures. The 

door seals on a refrigerated trailer can also become damaged or loose with age, which greatly 

affects the insulation characteristics of the trailer, similar to how the door seal on a home 

refrigerator can reduce the efficiency of that appliance. As a result of age-related problems 

and more intense usage, refrigerated trailers tend to have shorter procurement cycles than dry 

 At any one time, two trailers are typically parked 

while one is on the road. For certain private fleets, this ratio can be greater, as high as six-toone. This means that on average a trailer will travel only one third of the miles travelled by a 

tractor. Lower annual mileage combined with the less complex machinery of a trailer mean 

that trailers do not need to be purchased as frequently as the trucks that haul them. The initial 

owner may keep a trailer for a decade or even longer; typically, the initial owner of a Class 7 

or 8 tractor keeps his or her vehicle for three to six years. Less frequent procurement cycles 

result in slower turnover of trailers in the in-use fleet, with many older trailers still in use. 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Industry Characterization

39

van trailers, which means a faster turnover rate, although still not nearly as fast as for trucks in 

their first use.

1.8 Hybrids

Following the trends in the lighter duty passenger vehicles, heavy-duty trucks are 

starting to look at hybrid vehicles to help optimize their performance and exhaust emissions. 

There are three primary hybrid designs that can be applied to heavy-duty trucks and vehicles

including: hydraulic, electric, and ‘plug-in’ which are discussed in more detail below. 

Typically, trucks that have shorter or ‘stop and go’ type operations, such as utility (bucket) 

trucks, pickup and delivery, refuse, busses, and combination tractors, are the best candidates

for a hybrid vehicle. On average, the conventional annual sales for these truck types range 

from 10,000 – 150,000 units per year. 

Hydraulic hybrids use a combination of pumps, motors, and accumulators in 

conjunction with the diesel engine. The engine powers a hydraulic pump-motor, which 

charges a high-pressure accumulator, which in turn drives an additional pump-motor at the 

rear of the vehicle to provide propulsion. There are two main types of hydraulic hybrids, those 

that operate in parallel and those that operate in series. The parallel hydraulic vehicle has a 

conventional driveline that is supplemented by hybrid (also known as hydraulic launch assist). 

This type of vehicle is best suited for stop-and-go duty cycles such as refuse and bus.

The series style hydraulic hybrid vehicle does not have a conventional driveline as it

is replaced by hybrid system; therefore, the transmission is removed. This allows the engine 

to operate in a “sweet spot”, and to shut-off the engine when it is not needed. These vehicle 

types have broader applications than the parallel hybrids, but their best benefit is still in stopand-go duty cycles. Typical applications for these hybrids include refuse, commercial 

construction, yard hostler, etc.

Electric hybrids operate by combining the traditional internal combustion engine with 

an electric propulsion system. There are several types of electric hybrid combinations within 

the heavy-duty fleet. Motive type blends diesel and electric power as demanded and operates 

in a parallel system. Motive & Auxiliary power type hybrid provides motive power from 

diesel and electric motors and provides electric auxiliary power to the vehicle. Dual Mode 

hybrid operates as a series hybrid at low speeds and parallel hybrid at higher speeds. Typical 

applications for electric hybrids include utility, bus, pickup and delivery, etc.

The third type of HD hybrid design is a ‘plug-in’ which operates on the same principle 

as the electric hybrid only adds the capability to recharge the hybrid battery using an external 

power source. These trucks can use electric power for auxiliary system power and operations 

and can have range-extended batteries as they can switch propulsive power to the diesel 

engine when the battery runs low. Typical applications for this type of vehicle include utility 

(powering the grid), small pickup and delivery trucks, and shuttle buses.

There are many companies currently designing, demonstrating, and / or producing 

hybrid systems for the HD trucking industry, as well as industry associations such as Hybrid 

Truck Users Forum (H-TUF), Next Energy Hydraulic Hybrid Working Group, and the 

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are typically outfitted to ‘plug-into’ an electrical 

outlet

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Regulatory Impact Analysis 

40

Electric Drive Transportation Association. By creating these vehicles for the HD industry, 

CO2

Today for hybrid trucks there are several incentive programs in place. The federal 

government has Federal Tax incentives, for purchasers to receive up to 40 percent of the 

incremental cost of the hybrid, dependent on the fuel economy improvement. Additionally, 

there are currently 13 states that have hybrid incentive programs, and some of the smaller 

localities also have incentive programs. Government funding through programs such as the 

National Clean Diesel Program, SmartWay, Clean Automotive Technology, and Clean Cities

is also available. 

, NOx, HC, and PM emissions will all be reduced, the vehicle’s overall noise will be 

reduced due to engine-off idling, and owners should notice a reduction in maintenance and 

operating costs as there is reduced usage of brakes and engine operating hours.

As with any new technology, there are some issues that arise with hybrid technologies. 

For example the overall system cost is generally more than conventional power systems, and 

some of the battery technology (such as size, weight, cold weather operations, charging time, 

etc) is still relatively untested – and in some cases – unknown. Additionally, to maximize the 

efficiency of the vehicle, the hybrid technology needs to be properly matched to the 

applicable duty cycle, and the engines need to be properly optimized for the vehicle and its 

operation.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Industry Characterization

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and Transportation Efficiency

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38 Modern Tire Dealer, Top Retreaders (April, 2010), accessed August 2, 2010, at 

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%2fstats%2fMTD-32-40-1.pdf

39 Appendix G to Subchapter B—Minimum periodic inspection standards: 49 CFR Subtitle B Chapter III 

Subchapter B Appendix G

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41 Modern Tire Dealer, Top Retreaders (April, 2010), accessed at 

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42 Manges, Mike, Retreaders Look for a Better Year, Commercial Tire Dealer (February 19, 2010), accessed 

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2010, at http://www.moderntiredealer.com/Article/Print/Story/2009/06/Breaking-down-the-top-100-

retreaders.aspx

47 U.S. Department of Energy, Energy Efficiency & Renewable Energy – Vehicle Technologies Program. 21st

Century Truck Partnership. Viewed 12/8/2009 at 

http://www1.eere.energy.gov/vehiclesandfuels/about/partnerships/21centurytruck/

49 California Air Resource Board, Heavy-Duty Vehicle Greenhouse Gas Measure. Viewed 12/8/2009 at 

http://www.arb.ca.gov/cc/hdghg/hdghg.htm

50 One Hundred Tenth Congress of the United States of America. Energy Independence and Security Act of 

2007. January 2007. Viewed 12/8/2009 at http://frwebgate.access.gpo.gov/cgibin/getdoc.cgi?dbname=110_cong_bills&docid=f:h6enr.txt.pdf

51 Trailer Body Builders, 2009 North American Truck Trailer Output (Table - March 2010), and 2008 North 

American Truck Trailer Output (Table - March 2009), both tables accessed August 2, 2010, at http://trailerbodybuilders.com/trailer-output/output/2009-trailer-output-0301/. Also, Polk Commercial Vehicle Solutions, 

Commercial Vehicle Market Intelligence Report (March, 2009), accessed August 2, 2010, at 

http://www.polk.com/KC/PolkAR_CVR_200905.pdf

52 TIAX. “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles. November 

2009. Page 4-49.
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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CHAPTER 2: TECHNOLOGIES, COST, AND EFFECTIVENESS............. 2-2

2.1 Overview of Technologies............................................................................................2-2

2.2 Overview of Technology Cost Methodology..............................................................2-3

2.2.1 Markups to Address Indirect Costs.................................................................2-3

2.2.2 Learning Effects on Technology Costs............................................................2-9

2.3 Heavy-Duty Pickup Truck and Van Technologies and Costs................................2-12

2.3.1 Gasoline Engines..............................................................................................2-12

2.3.2 Diesel Engines ..................................................................................................2-15

2.3.3 Drive Train.......................................................................................................2-18

2.3.4 Aerodynamics ..................................................................................................2-21

2.3.5 Tires..................................................................................................................2-21

2.4 Heavy-Duty Engines ..................................................................................................2-21

2.4.1 Spark Ignition Engines....................................................................................2-22

2.4.2 Diesel Engines ..................................................................................................2-26

2.5 Class 7/8 Day Cabs and Sleeper Cabs......................................................................2-35

2.5.1 Aerodynamics ..................................................................................................2-35

2.5.2 Tires..................................................................................................................2-42

2.5.3 Weight Reduction ............................................................................................2-47

2.5.4 Extended Idle ...................................................................................................2-52

2.5.5 Vehicle Speed Limiters....................................................................................2-54

2.5.6 Automated Manual Transmission..................................................................2-56

2.5.7 Class 7-8 Tractor Baseline Assessment..........................................................2-56

2.5.8 Class 7-8 Tractor Standards Derivation........................................................2-57

2.5.9 Class 7-8 Tractor Technology Costs..............................................................2-64

2.6 Class 2b-8 Vocational Vehicles.................................................................................2-64

2.6.1 Tires..................................................................................................................2-64

2.6.2 Other Evaluated Technologies .......................................................................2-65

2.6.2.1 Aerodynamics ..................................................................................................2-65

2.6.2.2 Hybrid Powertrains.........................................................................................2-65

2.6.2.4 Transmission and Driveline............................................................................2-75

2.7 Air Conditioning ........................................................................................................2-75

2.7.1 Refrigerant Leakage........................................................................................2-75

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2.7.2 System Efficiency.............................................................................................2-78

2.8 Trailers and GHG Emission Reduction Opportunities..........................................2-78

2.8.1 Current Trailer Fleet ......................................................................................2-79

2.8.2 Trailer Technologies to Reduce GHG Emissions.........................................2-80

2.9 Other Fuel Consumption and GHG Reducing Strategies......................................2-83

2.9.1 Auxiliaries ........................................................................................................2-83

2.9.2 Driver training .................................................................................................2-85

2.9.3 Automatic Tire inflation and Tire Pressure Monitoring System................2-86

2.9.4 Engine Features...............................................................................................2-87

2.9.5 Logistics............................................................................................................2-87

2.9.6 Longer Combination Vehicles, Weight Increase ..........................................2-88

2.9.7 Traffic Congestion Mitigation........................................................................2-90

2.10 Summary of Technology Costs Used in this Analysis ..........................................2-91

Chapter 2: Technologies, Cost, and Effectiveness

2.1 Overview of Technologies 

In discussing the potential for CO2 emission and fuel consumption reductions, it can 

be helpful to think of the work flow through the system. The initial work input is fuel. Each 

gallon of fuel has the potential to produce some amount of work and will produce a set 

amount of CO2 (about 22 pounds of CO2 per gallon of diesel fuel). The engine converts the 

chemical energy in the fuel to useable work to move the truck. Any reductions in work 

demanded of the engine by the vehicle or improvements in engine fuel conversion efficiency 

will lead directly to CO2

Current diesel engines are 35-38 percent efficient over a range of operating conditions 

with peak efficiency levels between 40 and 45 percent depending on engine sizes and 

applications, while gasoline engines are approximately 30 percent efficient overall. This 

means that approximately one-third of the fuel’s chemical energy is converted to useful work 

and two-thirds is lost to friction, gas exchange, and waste heat in the coolant and exhaust. In 

turn, the truck uses this work delivered by the engine to overcome overall vehicle-related 

losses such as aerodynamic drag, tire rolling resistance, friction in the vehicle driveline, and to 

provide auxiliary power for components such as air conditioning and lights. Lastly, the 

vehicle’s operation, such as vehicle speed and idle time, affects the amount of total energy 

required to complete its activity. While it may be intuitive to look first to the engine for CO

emission and fuel consumption reductions. 

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important to realize that any improvement in vehicle efficiency reduces both the work 

demanded and also the waste energy in proportion. 

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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Technology is one pathway to improve heavy-duty truck GHG emissions and fuel 

consumption. Near-term solutions exist, such as those being deployed by SmartWay partners 

in heavy-duty truck long haul applications. Other solutions are currently underway in the 

Light-Duty vehicle segment, especially in the Large Pickup sector where many of the 

technologies can apply to the heavy-duty pickup trucks covered under this proposal. Longterm solutions are currently under development to improve efficiencies and cost-effectiveness. 

While there is not a “silver bullet” that will significantly eliminate GHG emissions from 

heavy-duty trucks like the catalytic converter has for criteria pollutant emissions, significant 

GHG and fuel consumption reductions can be achieved through a combination of engine, 

vehicle system, and operational technologies. 

The following sections will discuss technologies in relation to each of the proposed 

regulatory categories – Heavy-Duty Pickup Trucks and Vans, Heavy-Duty Engines, Class 7/8 

Sleeper and Day Cabs, Class 2b-8 Vocational Vehicles, and Trailers.

EPA and NHTSA collected information on the cost and effectiveness of fuel 

consumption and CO2 emission reducing technologies from several sources. The primary 

sources of information were the 2010 National Academy of Sciences report of Technologies 

and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles 

(NAS)1, TIAX’s assessment of technologies to support the NAS panel report (TIAX)2, EPA’s 

Heavy-Duty Lumped Parameter Model3, the analysis conducted by NESCCAF, ICCT, 

Southwest Research Institute and TIAX for reducing fuel consumption of heavy-duty long 

haul combination tractors (NESCCAF/ICCT)4

, and the technology cost analysis conducted by 

ICF for EPA (ICF).5 In addition, EPA’s simplified vehicle simulation model plays a key role 

in quantifying the effectiveness of various technologies on CO2

2.2 Overview of Technology Cost Methodology

emission and fuel 

consumption reductions in terms of vehicle performance. The simulation tool is described in 

DRIA Chapter 3 in more details. 

Section 2.2.1 presents the methods used to address indirect costs in this analysis. Section 

2.2.2 presents the learning effects applied throughout this analysis. Section 2.10 presents a 

summary in tabular form of all the technology costs expected to be implemented in response 

to the proposed standards.

2.2.1 Markups to Address Indirect Costs

To produce a unit of output, engine and truck manufacturers incur direct and indirect 

costs. Direct costs include cost of materials and labor costs. Indirect costs may be related to 

production (such as research and development [R&D]), corporate operations (such as salaries, 

pensions, and health care costs for corporate staff), or selling (such as transportation, dealer 

support, and marketing). Similarly to direct costs, indirect costs are generally recovered by 

allocating a share of the costs to each unit of good sold. Although it is possible to account for 

direct costs allocated to each unit of good sold, it is more challenging to account for indirect 

costs allocated to a unit of goods sold. To make a cost analysis process more feasible, markup 

factors, which relate indirect costs to the changes in direct costs, have been developed. These 

factors are often referred to as retail price equivalent (RPE) multipliers.

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Cost analysts and regulatory agencies including the EPA have frequently used these 

multipliers to predict the resultant impact on costs associated with manufacturers’ responses 

to regulatory requirements. Clearly the best approach to determining the impact of changes in 

direct manufacturing costs on a manufacturer’s indirect costs would be to actually estimate 

the cost impact on each indirect cost element. However, doing this within the constraints of 

an agency’s time or budget is not always feasible, or the technical, financial, and accounting 

information to carry out such an analysis may simply be unavailable. 

RPE multipliers provide, at an aggregate level, the relative shares of revenues6

To address this concern, modified multipliers have been developed. These multipliers 

are referred to as indirect cost multipliers (or IC multipliers). In contrast to RPE multipliers, 

IC multipliers assign unique incremental changes to each indirect cost contributor as well as 

net income.

to 

direct manufacturing costs. Using RPE multipliers implicitly assumes that incremental 

changes in direct manufacturing costs produce common incremental changes in all indirect 

cost contributors as well as net income. A concern in using the RPE multiplier in cost 

analysis for new technologies (which result from regulations requiring reductions in 

emissions) is that the indirect costs of vehicle modifications are not likely to be the same for 

different technologies. For example, less complex technologies could require fewer R&D 

efforts or less warranty coverage than more complex technologies. In addition, some simple 

technological adjustments may, for example, have no effect on the number of corporate 

personnel.

IC multiplier = (direct cost + adjusted indirect cost)/(direct cost)

Developing the IC multipliers from the RPE multipliers requires developing 

adjustment factors based on the complexity of the technology and the time frame under 

consideration. This methodology was used in the cost estimation for the recent Light-Duty 

GHG rule. The agency has used ICM adjustment factors developed for light-duty vehicles 

(with the exception that here return on capital has been incorporated into the ICMs, where it 

had not been in the light-duty rule) for the heavy-duty pickup truck and van cost projections 

in this proposal primarily because the manufacturers involved in this segment of the heavyduty market are the same manufacturers which build light-duty trucks.

For the Class 7/8 tractor, vocational vehicles, and heavy-duty engine cost projections 

in this proposal, EPA contracted with RTI International to update EPA’s methodology for 

accounting for indirect costs associated with changes in direct manufacturing costs for heavyduty engine and truck manufacturers.7

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In addition to the indirect cost contributors varying by 

complexity and time frame, there is no reason to expect that the contributors would be the 

same for engine manufacturers as for truck manufacturers. The resulting report from RTI 

provides a description of the methodology, as well as calculations of new indirect cost 

multipliers. These indirect cost multipliers are intended to be used, along with calculations of 

direct manufacturing costs, to provide improved estimates of the full additional costs 

associated with new technologies. 

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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To account for the indirect costs on Class 2b and 3 trucks and on heavy-duty gasoline

engines, the agencies have applied an indirect cost multiplier (ICM) factor to all of the direct 

costs to arrive at the estimated technology cost. The ICM factors used are shown in Table 

2-1. Near term values (2014 through 2021 in this analysis) account for differences in the 

levels of R&D, tooling, and other indirect costs that will be incurred. Once the program has 

been fully implemented, some of the indirect costs will no longer be attributable to the

proposed standards and, as such, a lower ICM factor is applied to direct costs in 2022 and 

later. 

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Regulatory Impact Analysis 

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Table 2-1 Indirect Cost Multipliers Used in this Analysis

CLASS

a

COMPLEXITY NEAR TERM LONG TERM

2b&3 Trucks and Vans Low 1.17 1.13

Medium 1.31 1.19

High1 1.51 1.32

High2 1.70 1.45

Loose diesel engines Low 1.11 1.09

Medium 1.18 1.13

High1 1.28 1.19

High2 1.43 1.29

Loose gasoline engines Low 1.17 1.13

Medium 1.31 1.19

High1 1.51 1.32

High2 1.70 1.45

Vocational/Combination 

Trucks

Low 1.14 1.10

Medium 1.26 1.16

High1 1.42 1.27

High2 1.57 1.36 a

The agencies have also applied ICM factors to Class 2b through 8 vocational vehicle

and tractor technologies along with all heavy-duty diesel engine technologies. The ICMs

used in this analysis include a factor for profit that is a 0.05 share of direct costs, as calculated 

in the RTI report, for the Class 7/8 tractor, vocational vehicles, and heavy-duty engine cost

projections; for the heavy-duty pickup truck and van cost projections, this analysis used a 

profit factor of 0.06 from the RTI LD report. In the long run in a competitive industry, profits 

should equal the return on capital investments necessary to sustain the industry. These capital 

investments represent the fixed costs of the industry. Note that, for heavy-duty diesel engines, 

the agencies have applied these markups to ensure that our estimates are conservative since 

we have estimated fixed costs separately for technologies applied to these categories, 

effectively making the use of markups a double counting of some of the indirect costs. 

Rogozhin, A., et. al., “Using indirect cost multipliers to estimate the total cost of adding new 

technology in the automobile industry,” International Journal of Production Economics (2009); 

“Documentation of the Development of Indirect Cost Multipliers for Three Automotive 

Technologies,” Helfand, G., and Sherwood, T., Memorandum dated August 2009; “Heavy 

Duty Truck Retail Price Equivalent and Indirect Cost Multipliers,” Draft Report prepared by 

RTI International and Transportation Research Institute, University of Michigan, July 2010

For most of the segments in this analysis, the indirect costs are estimated by applying 

indirect cost multipliers (ICM) to direct cost estimates. ICMs were calculated by EPA as a 

basis for estimating the impact on indirect costs of individual vehicle technology changes that 

would result from regulatory actions. Separate ICMs were derived for low, medium, and high 

complexity technologies, thus enabling estimates of indirect costs that reflect the variation in 

research, overhead, and other indirect costs that can occur among different technologies. 

ICMs were also applied in the MY 2012-2016 CAFE rulemaking. 

Deleted: a Reference RTI LD report; Helfand 

update memo; RTI LD report

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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Previous CAFE rulemakings applied a retail price equivalent (RPE) factor to estimate 

indirect costs and mark up direct costs to the retail level. Retail Price Equivalents are 

estimated by dividing the total revenue of a manufacturer by the direct manufacturing costs. 

As such, it includes all forms of indirect costs for a manufacturer and assumes that the ratio 

applies equivalently for all technologies. ICMs are based on RPE estimates that are then 

modified to reflect only those elements of indirect costs that would be expected to change in 

response to a technology change. For example, warranty costs would be reflected in both 

RPE and ICM estimates, while marketing costs might only be reflected in an RPE estimate 

but not an ICM estimate for a particular technology, if the new technology is not one expected 

to be marketed to consumers. Because ICMs calculated by EPA are for individual 

technologies, many of which are small in scale, they often reflect a subset of RPE costs; as a 

result, the RPE is typically higher than an ICM. This is not always the case, as ICM estimates 

for complex technologies may reflect higher than average indirect costs, with the resulting 

ICM larger than the averaged RPE for the industry. 

Precise association of ICM elements with individual technologies based on the varied 

accounting categories in company annual reports is not possible. Hence, there is a degree of 

uncertainty in the ICM estimates. If all indirect costs moved in proportion to changes in 

direct costs the ICM and RPE would be the same. Because most individual technologies are 

smaller scale than many of the activities of auto companies (such as designing and developing 

entirely new vehicles), it would be expected that the RPE estimate would reflect an upper 

bound on the average ICM estimate. The agencies are continuing to study ICMs and the most 

appropriate way to apply them, and it is possible revised ICM values may be used in our final 

rulemaking. With this in mind, the agencies are presenting a sensitivity analysis reflecting 

costs measured using the RPE in place of the ICM and indirect costs estimated independently 

in our primary analysis to examine the potential impact of these two approaches on estimated 

costs. 

While this analysis relies on ICMs to estimate indirect costs, an alternative method of 

estimating indirect costs is the RPE factor. The RPE has been used by NHTSA, EPA and 

other agencies to account for cost factors not included in available direct cost estimates, which 

are derived from cost teardown studies or sometimes provided by manufacturers. The RPE is 

the basis for these markups in all DOT safety regulations and in most previous fuel economy 

rules. The RPE includes all variable and fixed elements of overhead costs, as well as selling 

costs such as vehicle delivery expenses, manufacturer profit, and full dealer markup, and 

assumes that the ratio of indirect costs to direct costs is constant for all vehicle changes. 

Historically, NHTSA has estimated that the RPE has averaged about 1.5 for the light-duty 

motor vehicle industry. The implication of an RPE of 1.5 is that each added $1.00 of variable 

cost in materials, labor, and other direct manufacturing costs results in an increase in 

consumer prices of $1.50 for any change in vehicles. 

NHTSA has estimated the RPE from light-duty vehicle manufacturers’ financial 

statements over nearly 3 decades, and although its estimated value has varied somewhat yearto-year, it has generally hovered around a level of 1.5 throughout most of this period. The

2010 NAS report as well as a study by RTI International found that other estimates of the 

RPE varied from 1.26 to over 2. In a recent report, The National Academy of Sciences 

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Regulatory Impact Analysis 

2-8

(NAS) acknowledged that an ICM approach was preferable but recommended continued use 

of the RPE over ICMs until such time as empirical data derived from rigorous estimation 

methods is available. The 2010 NAS report recommended using an RPE of 1.5 for 

outsourced (supplier manufactured) and 2.0 for in-house (OEM manufactured) technologies 

and an RPE of 1.33 for advanced hybrid and electric vehicle technologies. 

ICMs typically are significantly lower than RPEs, because they measure changes in 

only those elements of overhead and selling-related costs that are directly influenced by 

specific technology changes to vehicles. For example, the number of managers might not be 

directly proportional to the value of direct costs contained in a vehicle, so that if a regulation 

increases the direct costs of manufacturing vehicles, there might be little or no change in the 

number of managers. ICMs would thus assume little or no change in that portion of indirect 

costs associated with the number of managers – these costs would be allocated only to the 

existing base vehicle. By contrast, the RPE reflects the historical overall relationship between 

the direct costs to manufacture vehicles and the prices charged for vehicles, which must 

compensate manufacturers for both their direct and indirect costs for producing and selling 

vehicles. The assumption behind the RPE is that changes in the long-term price of the final 

product that accompany increases in direct costs of vehicle manufacturing will continue to 

reflect this historical relationship. 

Another difference between the RPE and ICM is that ICMs have been derived 

separately for different categories of technologies. A relatively simple technology change, 

such as switching to a different tire with lower rolling resistance characteristics, would not 

influence indirect costs in the same proportion as a more complex change, such as 

development of a full hybrid design. ICMs were developed for 3 broad categories of 

technology complexities, and are applied separately to fuel economy technologies judged to 

fit into each of these categories. This requires determining which of these complexity 

categories each technology should be assigned. 

There is some level of uncertainty surrounding both the ICM and RPE markup factors. 

The ICM estimates used in this proposal group all technologies into three broad categories 

and treat them as if individual technologies within each of the three categories (low, medium, 

and high complexity) would have the same ratio of indirect costs to direct costs. This 

simplification means it is likely that the direct cost for some technologies within a category 

will be higher and some lower than the estimate for the category in general. More 

importantly, the ICM estimates have not been validated through a direct accounting of actual 

indirect costs for individual technologies. Rather, the ICM estimates were developed using 

adjustment factors developed in two separate occasions: the first, a consensus process, was 

reported in the RTI report; the second, a modified Delphi method, was conducted separately 

and reported in an EPA memo. Both these panels were composed of EPA staff members with 

previous background in the automobile industry; the memberships of the two panels 

overlapped but were not the same. The panels evaluated each element of the industry’s RPE 

estimates and estimated the degree to which those elements would be expected to change in 

proportion to changes in direct manufacturing costs. The method and estimates in the RTI 

report were peer reviewed by three industry experts and subsequently by reviewers for the 

International Journal of Production Economics. RPEs themselves are inherently difficult to 

estimate because the accounting statements of manufacturers do not neatly categorize all cost 

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-9

elements as either direct or indirect costs. Hence, each researcher developing an RPE 

estimate must apply a certain amount of judgment to the allocation of the costs. Moreover, 

RPEs for heavy- and medium-duty trucks and for engine manufacturers are not as well 

studied as they are for the light-duty automobile industry. Since empirical estimates of ICMs 

are ultimately derived from the same data used to measure RPEs, this affects both measures. 

However, the value of RPE has not been measured for specific technologies, or for groups of 

specific technologies. Thus applying a single average RPE to any given technology by 

definition overstates costs for very simple technologies, or understates them for advanced 

technologies. 

To highlight the potential differences between the use of ICMs and RPEs to estimate 

indirect costs, the agencies conducted an analysis based on the use of average RPEs for each 

industry in the place of the ICM and direct fixed cost estimates used in our proposal. Since 

most technologies involved in this proposal are low complexity level technologies, the 

estimate based on the use of an average RPE likely overstates the costs. The weighted 

average RPEs for the truck and engine industries are 1.36 and 1.28 respectively. These values 

were substituted for the ICMs and directly estimate indirect costs used in the primary cost 

analysis referenced elsewhere in this document. Using the average RPEs, the five model year 

cost of $7.7B in the primary analysis increases to $9.3B, an increase of 21 percent.

2.2.2 Learning Effects on Technology Costs

For some of the technologies considered in this analysis, manufacturer learning effects 

would be expected to play a role in the actual end costs. The “learning curve” or “experience 

curve” describes the reduction in unit production costs as a function of accumulated 

production volume. In theory, the cost behavior it describes applies to cumulative production 

volume measured at the level of an individual manufacturer, although it is often assumed—as 

both agencies have done in past regulatory analyses—to apply at the industry-wide level, 

particularly in industries that utilize many common technologies and component supply 

sources. Both agencies believe there are indeed many factors that cause costs to decrease 

over time. Research in the costs of manufacturing has consistently shown that, as 

manufacturers gain experience in production, they are able to apply innovations to simplify 

machining and assembly operations, use lower cost materials, and reduce the number or 

complexity of component parts. All of these factors allow manufacturers to lower the per-unit 

cost of production (i.e., the manufacturing learning curve). 

NHTSA and EPA have a detailed description of the learning effect in the 2012-2016 

light-duty rule. Most studies of the effect of experience or learning on production costs 

appear to assume that cost reductions begin only after some initial volume threshold has been 

reached, but not all of these studies specify this threshold volume. The rate at which costs 

decline beyond the initial threshold is usually expressed as the percent reduction in average 

unit cost that results from each successive doubling of cumulative production volume, 

sometimes referred to as the learning rate. Many estimates of experience curves do not 

specify a cumulative production volume beyond which cost reductions would no longer occur, 

instead depending on the asymptotic behavior of the effect for learning rates below 100 

percent to establish a floor on costs. 

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Regulatory Impact Analysis 

2-10

In past rulemaking analyses, as noted above, both agencies have used a learning curve

algorithm that applied a learning factor of 20 percent for each doubling of production volume. 

NHTSA has used this approach in analyses supporting recent CAFE rules. In its analysis, 

EPA has simplified the approach by using an “every two years” based learning progression 

rather than a pure production volume progression (i.e., after two years of production it was 

assumed that production volumes would have doubled and, therefore, costs would be reduced 

by 20 percent). 

In the 2012-2016 light-duty rule, the agencies employed an additional learning 

algorithm to reflect the volume based learning cost reductions that occur further along on the 

learning curve. This additional learning algorithm was termed “time-based” learning simply 

as a means of distinguishing this algorithm from the volume-based algorithm mentioned 

above, although both of the algorithms reflect the volume based learning curve supported in 

the literature.8

Learning effects are applied to most but not all technologies because some of the 

expected technologies are already used rather widely in the industry and, presumably, 

learning impacts have already occurred. The volume-based learning algorithm was applied

for only a handful of technologies that are considered to be new or emerging technologies. 

Most technologies have been considered to be more established given their current use in the 

fleet and, hence, the lower time-based learning algorithm has been applied. The learning 

algorithms applied to each technology are summarized in Table 2-2.

 The agencies have applied the volume-based algorithm for those technologies 

considered to be newer technologies likely to experience rapid cost reductions through 

manufacturer learning and the time-based algorithm for those technologies considered to be 

mature technologies likely to experience minor cost reductions through manufacturer 

learning. As noted above, the volume-based learning algorithm results in 20 percent lower 

costs after two full years of implementation (i.e., the 2016 MY costs are 20 percent lower than 

the 2014 and 2015 model year costs). Once two volume-based learning steps have occurred

(for technologies having the volume-based learning algorithm applied while time-based 

learning would begin in year 2 for technologies having the time-based learning algorithm

applied), time-based learning at 3 percent per year becomes effective for 5 years. Beyond 5 

years of time-based learning at 3 percent per year, 5 years of time-based learning at 2 percent 

per year, then 5 at 1 percent per year become effective. 

Deleted: considered not only this volume-based 

learning as described above, but also “time-based” 

learning. Time-based learning, estimated by 

NHTSA in the 2011 CAFE rule, at three percent per 

year, occurs in years following the volume-based 

learning steps and represents the smaller scale 

learning that occurs as manufacturers continue to 

innovate. The time-based learning is, in effect, 

represented by the flattened out, asymptotic portion 

of the learning curve. ¶

For this analysis, the agencies have employed both 

volume-based and time-based learning effects. In 

the analysis, as noted above, volume-based learning 

is estimated to result

Deleted: Time-based learning is estimated to 

result in 3 percent lower costs in each year following 

first introduction of a given technology.

Deleted: Volume

Deleted: considered

Deleted: effects

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Table 2-2 Learning Effect Algorithms Applied to Technologies Used in this Analysis

TECHNOLOGY APPLIED TO LEARNING 

ALGORITHM

Cylinder head improvements Engines Time

Turbo efficiency improvements Engines Time

EGR cooler efficiency improvements Engines Time

Water pump improvements Engines Time

Oil pump improvements Engines Time

Fuel pump improvements Engines Time

Fuel rail improvements Engines Time

Fuel injector improvements Engines Time

Piston improvements Engines Time

Valve train friction reductions Engines Time

Turbo compounding Engines Time

Engine friction reduction Engines Time

Coupled cam phasing Engines Time

Stoichiometric gasoline direct injection Engines Time

Low rolling resistance tires Vocational vehicles Volume

Low rolling resistance tires Trucks Time

Aero (except Aero SmartWay Advanced) Trucks Time

Aero SmartWay Advanced Trucks Volume

Weight reduction (via single wide tires and/or 

aluminum wheels)

Trucks Time

Auxiliary power unit Trucks Time

Air conditioning leakage Trucks Time

The learning effects discussed here impact the technology costs considered here in that 

those technology costs for which learning effects are considered applicable are changing 

throughout the period of implementation and the period following implementation. For 

example, some of the technology costs considered in this analysis are taken from the 2012-

2016 light-duty rule and scaled appropriately giving consideration to the heavier weights and 

loads in the heavy-duty segment. Many of the costs in the 2012-2016 light-duty rule were 

consider “valid” for the 2012 model year. If time based learning were applied to those 

technologies, the 2013 cost would be 3 percent lower than the 2012 cost, and the 2014 model 

year cost 3 percent lower than the 2013 cost, etc. As a result, the 2014 model year cost 

presented in, for example, Section 2.3 would reflect those two years of time based learning 

and would not be identical to the 2012 model year cost presented in the 2012-2016 light-duty 

rule.

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Formatted Table

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Formatted Table

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2.3 Heavy-Duty Pickup Truck and Van Technologies and Costs 

2.3.1 Gasoline Engines 

The spark ignited engines for Class 2b and 3 vehicles are typically the same as offered 

in the light-duty segment. These engines typically range in displacement between five and 

eight liters and are either V8 or V10 configurations. 

The engine technologies proposed are based on the technologies described in the LightDuty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards Joint Technical Support Document.9

2.3.1.1 Low Friction Lubricants

 Some of the references come from 

Technologies and Approaches to Reducing the Fuel Consumption of Medium and HeavyDuty Vehicles by The National Academies, March, 2010. These technologies include engine 

friction reduction, cam phasing, cylinder deactivation and stoichiometric gas direct injection.

One of the most basic methods of reducing fuel consumption in both gasoline and 

diesel engines is the use of lower viscosity engine lubricants. More advanced multi-viscosity 

engine oils are available today with improved performance in a wider temperature band and 

with better lubricating properties. This can be accomplished by changes to the oil base stock 

(e.g., switching engine lubricants from a Group I base oils to lower-friction, lower viscosity 

Group III synthetic) and through changes to lubricant additive packages (e.g., friction 

modifiers and viscosity improvers). The use of 5W-30 motor oil is now widespread and auto 

manufacturers are introducing the use of even lower viscosity oils, such as 5W-20 and 0W-20, 

to improve cold-flow properties and reduce cold start friction. However, in some cases, 

changes to the crankshaft, rod and main bearings and changes to the mechanical tolerances of 

engine components may be required. In all cases, durability testing would be required to 

ensure that durability is not compromised. The shift to lower viscosity and lower friction 

lubricants will also improve the effectiveness of valvetrain technologies such as cylinder 

deactivation, which rely on a minimum oil temperature (viscosity) for operation.

Based on 2012-2016 Light-duty final rule, and previously-received confidential 

manufacturer data, NHTSA and EPA estimated the effectiveness of low friction lubricants to 

be between 0 to 1 percent.

In the 2012-2016 light-duty FRM, the agencies estimated the cost of moving to low 

friction lubricants at $3 per vehicle (2007$). That estimate included a markup of 1.11 for a 

low complexity technology. For Class 2b and 3, we are using the same base estimate but have 

marked it up to 2008 dollars using the GDP price deflator and have used a markup of 1.17 for 

a low complexity technology to arrive at a value of $4 per vehicle. As in the light-duty rule, 

learning effects are not applied to costs for this technology and, as such, this estimate applies 

to all model years. 10,11

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2.3.1.2 Engine Friction Reduction 

Manufacturers can reduce friction and improve fuel consumption by improving the 

design of engine components and subsystems. Approximately 10 percent of the energy 

consumed by a vehicle is lost to friction, and just over half is due to frictional losses within 

the engine. Examples include improvements in low-tension piston rings, piston skirt design, 

roller cam followers, improved crankshaft design and bearings, material coatings, material 

substitution, more optimal thermal management, and piston and cylinder surface treatments. 

Additionally, as computer-aided modeling software continues to improve, more opportunities 

for evolutionary friction reductions may become available.

All reciprocating and rotating components in the engine are potential candidates for 

friction reduction, and minute improvements in several components can add up to a 

measurable fuel economy improvement. The 2012-2016 LD rule, 2010 NAS, NESCCAF and 

EEA reports as well as confidential manufacturer data suggested a range of effectiveness for 

engine friction reduction to be between 1 to 3 percent. NHTSA and EPA continue to believe 

that this range is accurate.

Consistent with the 2012-2016 light-duty FRM, the agencies estimate the cost of this 

technology at $14 per cylinder compliance cost (2008$), including the low complexity ICM 

markup value of 1.17. Learning impacts are not applied to the costs of this technology and, as 

such, this estimate applies to all model years. This cost is multiplied by the number of engine 

cylinders.

2.3.1.3 Coupled Cam Phasing (CCP)

Valvetrains with coupled (or coordinated) cam phasing can modify the timing of both 

the inlet valves and the exhaust valves an equal amount by phasing the camshaft of an 

overhead valve (OHV) engine. For overhead valve (OHV) engines, which have only one 

camshaft to actuate both inlet and exhaust valves, CCP is the only VVT implementation 

option available and requires only one cam phaser.

Consistent with the 2012-2016 Light-Duty final rule, NHTSA and EPA estimate the 

effectiveness of CCP to be between 1 to 4 percent. 

Consistent with the 2012-2016 Light-Duty final rule, NHTSA and EPA estimate the 

cost of a cam phaser at $46 (2008$) in the 2014MY. This estimate includes a low complexity 

ICM of 1.17 and time based learning. All engines in the Class 2b&3 category use over-head 

valve engines (OHV) and, as such, would require only one cam phaser for coupled cam 

phasing. 

2.3.1.4 Cylinder Deactivation (DEAC)

In conventional spark-ignited engines throttling the airflow controls engine torque 

output. At partial loads, efficiency can be improved by using cylinder deactivation instead of 

throttling. Cylinder deactivation (DEAC) can improve engine efficiency by disabling or 

deactivating (usually) half of the cylinders when the load is less than half of the engine’s total 

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2-14

torque capability – the valves are kept closed, and no fuel is injected – as a result, the trapped 

air within the deactivated cylinders is simply compressed and expanded as an air spring, with 

reduced friction and heat losses. The active cylinders combust at almost double the load 

required if all of the cylinders were operating. Pumping losses are significantly reduced as 

long as the engine is operated in this “part-cylinder” mode.

Cylinder deactivation control strategy relies on setting maximum manifold absolute 

pressures or predicted torque within which it can deactivate the cylinders. Noise and 

vibration issues reduce the operating range to which cylinder deactivation is allowed, 

although manufacturers are exploring vehicle changes that enable increasing the amount of 

time that cylinder deactivation might be suitable. Some manufacturers may choose to adopt 

active engine mounts and/or active noise cancellations systems to address NVH concerns and 

to allow a greater operating range of activation. 

Effectiveness improvements scale roughly with engine displacement-to-vehicle weight 

ratio: the higher displacement-to-weight vehicles, operating at lower relative loads for normal 

driving, have the potential to operate in part-cylinder mode more frequently.

NHTSA and EPA adjusted the 2012-2016 Light-Duty final rule estimates using 

updated power to weight ratings of heavy-duty trucks and confidential business information 

and confirmed a range of 3 to 4 percent for these vehicles.

Consistent with the 2012-2016 light-duty FRM, NHTSA and EPA have estimated the 

cost of cylinder deactivation at $193 for the 2014MY (2008$). This estimate includes a low 

complexity ICM of 1.17 and time based learning. 

2.3.1.5 Stoichiometric Gasoline Direct Injection (SGDI)

Stoichiometric gasoline direct injection (SGDI) engines inject fuel at high pressure 

directly into the combustion chamber (rather than the intake port in port fuel injection). SGDI 

requires changes to the injector design, an additional high pressure fuel pump, new fuel rails 

to handle the higher fuel pressures and changes to the cylinder head and piston crown design. 

Direct injection of the fuel into the cylinder improves cooling of the air/fuel charge within the 

cylinder, which allows for higher compression ratios and increased thermodynamic efficiency 

without the onset of combustion knock. Recent injector design advances, improved electronic 

engine management systems and the introduction of multiple injection events per cylinder 

firing cycle promote better mixing of the air and fuel, enhance combustion rates, increase 

residual exhaust gas tolerance and improve cold start emissions. SGDI engines achieve 

higher power density and match well with other technologies, such as boosting and variable 

valvetrain designs.

Several manufacturers have recently introduced vehicles with SGDI engines, 

including GM and Ford and have announced their plans to increase dramatically the number 

of SGDI engines in their portfolios.

The 2012-2016 Light-Duty rule estimate the range of effectiveness to be from 1 to 2 

percent for SGDI. NHTSA and EPA reviewed this estimate for purposes of the NPRM, and 

continue to find it accurate. 

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The NHTSA and EPA cost estimates for SGDI take into account the changes required 

to the engine hardware, engine electronic controls, ancillary and Noise Vibration and 

Harshness (NVH) mitigation systems. Through contacts with industry NVH suppliers, and 

manufacturer press releases, the agencies believe that the NVH treatments will be limited to 

the mitigation of fuel system noise, specifically from the injectors and the fuel lines. 

Consistent with the 2012-2016 light-duty rule, the agencies estimate the cost of conversion to 

SGDI on a V8 engine at $395 (2008$) for the 2014MY. This estimate includes a low 

complexity ICM of 1.17 and time based learning. 

2.3.2 Diesel Engines 

Diesel engines in this class of vehicle have emissions characteristics that present 

challenges to meeting federal Tier 2 NOx

The engine technologies proposed are based on the technologies described in the LightDuty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards Joint Technical Support Document.

emissions standards. It is a significant systemsengineering challenge to maintain the fuel consumption advantage of the diesel engine while 

meeting U.S. emissions regulations. Fuel consumption can be negatively impacted by 

emissions reduction strategies depending on the combination of strategies employed. 

Emission compliance strategies for diesel vehicles sold in the U.S. are expected to include a 

combination of improvements of combustion, air handling system, aftertreatment, and 

advanced system control optimization. These emission control strategies are being introduced 

on Tier 2 light-duty diesel vehicles today

12

2.3.2.1 Low Friction Lubricants

 Some of reference comes from 

Technologies and Approaches to Reducing the Fuel Consumption of Medium- and HeavyDuty Vehicles by The National Academies, March, 2010. Several key advances in diesel 

technology have made it possible to reduce missions coming from the engine prior to 

aftertreatment. These technologies include, engine friction and parasitic loss reduction, 

improved fuel systems (higher injection pressure and multiple-injection capability), advanced 

controls and sensors to optimize combustion and emissions performance, higher EGR levels 

and EGR cooling to reduce NOx, and advanced turbocharging systems.

Consistent with the discussion above for gasoline engines (see Section 2.3.1.1), the 

agencies are expecting some engine changes to accommodate low friction lubricants. Based 

on 2012-2016 Light-duty final rule, and previously-received confidential manufacturer data, 

NHTSA and EPA estimated the effectiveness of low friction lubricants to be between 0 to 1 

percent.

In the 2012-2016 light-duty FRM, the agencies estimated the cost of moving to low 

friction lubricants at $3 per vehicle (2007$). That estimate included a markup of 1.11 for a 

low complexity technology. For Class 2b and 3, we are using the same base estimate but have 

marked it up to 2008 dollars using the GDP price deflator and have used a markup of 1.17 for 

a low complexity technology to arrive at a value of $4 per vehicle. As in the light-duty rule, 

learning effects are not applied to costs for this technology and, as such, this estimate applies 

to all model years. 13,14

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Deleted: 

Deleted: C,

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2.3.2.2 Engine Friction Reduction

Engine Friction Reduction: Reduced friction in bearings, valve trains, and the pistonto-liner interface will improve efficiency. Friction reduction opportunities in the engine 

valve train and at its roller/tappet interfaces exist for several production engines. In virtually 

all production engines, the piston at its skirt/cylinder wall interface, wrist pin and oil 

ring/cylinder wall interface offer opportunities for friction reduction. Use of more advanced 

oil lubricant that could be available for production in the future can also play a key role in 

reducing friction. Any friction reduction must be carefully developed to avoid issues with 

durability or performance capability. Estimations of fuel consumption improvements due to 

reduced friction range from 0 percent to 2 percent.15

Consistent with the cost estimated for gasoline engines, the agencies estimate the cost 

of engine friction reduction at $14 per cylinder compliance cost (2008$), including the low 

complexity ICM of 1.17, for a MY 2014 vehicle (learning effects are not applied to engine 

friction reduction). This cost is multiplied by the number of engine cylinders.

2.3.2.3 Combustion and Fuel Injection System Optimization

More flexible fuel injection capability with higher injection pressure provides more 

opportunities to improve engine fuel economy, while maintaining the same emission level. 

Combustion system optimization features system level integration and match, which includes 

piston bowl, injector tip and the number of holes, and intake swirl ratio. Cummins reports 9.1 

percent improvement in fuel consumption as opposed to 2007 baseline while meeting Tier2 

Bin 5 emissions when the combustion and fuel injection system are integrated with other 

technologies, such as advanced and integrated aftertreatment technology, and advanced air 

handling system).16

The cost for this technology includes costs associated with low temperature exhaust 

gas recirculation (see Section 

 Translating this improvement with 2010 baseline engine, this could result 

in 4-6 percent improvement assuming that 2010 baseline engine has 3-5 percent advantage in 

fuel economy over 2007 engine baseline.

2.3.2.4), improved turbochargers (see Section 2.3.2.5) and 

improvements to other systems and components. These costs are considered collectively in 

our costing analysis and termed “diesel engine improvements.” The agencies have estimated 

the cost of diesel engine improvements at $147 based on the cost estimates for several 

individual technologies presented in Table 2-8 for light HD engines. Specifically, the direct 

manufacturing costs we have estimated are: improved cylinder head, $9; turbo efficiency 

improvements, $16; EGR cooler improvements, $3; higher pressure fuel rail, $10; improved 

fuel injectors, $13; improved pistons, $2; and reduced valve train friction, $94. All values 

are in 2008 dollars and are applicable in the 2014MY. Applying a low complexity ICM of 

1.17 results in a cost of $172 (2008$) applicable in the 2014MY. We consider time based 

learning to be appropriate for these technologies.

2.3.2.4 Low Temperature Exhaust Gas Recirculation 

Low temperature exhaust gas recirculation could be one of options to improve engine 

performance. Most medium vehicle diesel engines sold in the U.S. market today use cooled 

Deleted: [TIAX, Assessment of Fuel Economy 

Technologies for Medium- and Heavy- Duty 

Vehicles, Final Report, Nov. 19, 2009, pg 4-15].

Deleted: 

Deleted: (D. Stanton, Cummins, August, 2009 

DEER Conference).

Deleted: ) and

Deleted: ).

Deleted: based on the TIAX report which 

estimated the retail price equivalent at $500 using a 2 

times multiplier. Dividing that value gives a direct 

manufacturing cost of $250. Applying a low 

complexity ICM of 1.17 and time based learning 

from 2012 forward results in the agencies’ estimate 

of $275 (2008$) in the 2014MY
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EGR, in which part of the exhaust gas is routed through a cooler (rejecting energy to the 

engine coolant) before being returned to the engine intake manifold. EGR is a technology 

employed to reduce peak combustion temperatures and thus NOx. Low-temperature EGR uses 

a larger or secondary EGR cooler to achieve lower intake charge temperatures, which tend to 

further reduce NOx formation. Low-temperature EGR can allow changes such as more 

advanced injection timing that will increase engine efficiency slightly more than 1 percent 

(NESCCAF/ICCT, 2009, p. 62). Because low-temperature EGR reduces the engine’s exhaust 

temperature, it may not be compatible with exhaust energy recovery systems such as 

turbocompound or a bottoming cycle.

The agencies’ cost estimate for this technology is discussed in Section 2.3.2.3.

2.3.2.5 Turbocharger Technology 

Compact two stage turbochargers can increase the boost level with wider operation 

range, thus improving engine thermal efficiency. Ford’s new developed 6.7L Scorpion engine 

features twin-compressor turbocharger. Cummins is also developing their own two stage 

turbochargers.

17

The agencies’ cost estimate for this technology is discussed in Section 

 It is expected that this type of technology will continue to be improved by 

better matching with system and developing higher compressor and turbine efficiency.

2.3.2.3.

2.3.2.6 Reduction of Parasitic Loads

Accessories that are traditionally gear or belt driven by a vehicle’s engine can be 

optimized and/or converted to electric power. Examples include the engine water pump, oil 

pump, fuel injection pump, air compressor, power-steering pump, cooling fans, and the 

vehicle’s air-conditioning system. Optimization and improved pressure regulation may 

significantly reduce the parasitic load of the water, air and fuel pumps. Electrification may 

result in a reduction in power demand, because electrically powered accessories (such as the 

air compressor or power steering) operate only when needed if they are electrically powered, 

but they impose a parasitic demand all the time if they are engine driven. In other cases, such 

as cooling fans or an engine’s water pump, electric power allows the accessory to run at 

speeds independent of engine speed, which can reduce power consumption. Electrification of 

accessories can individually improve fuel consumption, but as a package on a hybrid vehicle 

it is estimated that 3 to 5 percent fuel consumption reduction is possible.8 The TIAX [2009, 

pg. 3-5] study used 2 to 4 percent fuel consumption improvement for accessory electrification, 

with the understanding that electrification of accessories will have more effect in shorthaul/urban applications and less benefit in line-haul applications.

Consistent with the 2012-2016 light-duty rule (where this technology was referred to 

as improved accessories), the agencies estimate the cost for this technology at $88 (2008$) for 

a 2014MY vehicle. This estimate includes a low complexity ICM of 1.17 and time based 

learning.

Deleted: (D. Stanton, Cummins, August, 2009 

DEER Conference).
Regulatory Impact Analysis 

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2.3.2.7 Improved Aftertreatment Efficiency and Effectiveness

Improved SCR Conversion Efficiency: Selective Catalytic Reduction (SCR) systems 

are used by several manufacturers to control NOx emissions. 2010 fuel consumption was 

reduced 3 to 4 percent when compared to 2009, depending upon the manufacturer [2009, 

TIAX]. Additional improvements of 3 to 5 percent relative to 2010 may be reasonably 

expected as system effectiveness increases and accumulated knowledge is applied in 

calibration. Additionally, as SCR system effectiveness is improved, Diesel particulate filters 

(DPF) may be better optimized to reduced particulate loading (ability to run at higher engine 

out NOx

The agencies have estimated the cost of this technology at $25 for each percentage 

improvement in fuel consumption. This estimate is based on the agencies’ belief that this 

technology is, in fact, a very cost effective approach to improving fuel consumption. As such, 

$25 per percent improvement is considered a reasonable cost. This cost would cover the 

engineering and test cell related costs necessary to develop and implement the improved 

control strategies that would allow for the improvements in fuel consumption. Importantly, 

the engineering work involved would be expected to result in cost savings to the 

aftertreatment and control hardware (lower platinum group metal (PGM) loadings, lower 

reductant dosing rates, etc.). Those savings are considered to be included in the $25 per 

percent estimate described here. Given the average 4 percent expected improvement in fuel 

consumption results in an estimated cost of $110 (2008$) for a 2014MY vehicle. This 

estimate includes a low complexity ICM of 1.17 and time based learning from 2012 forward. 

), reducing the associated pressure drop associated with their presence in the exhaust 

system. Such DPF changes may result in a 1.0 – 1.5 percent fuel consumption reduction 

[TIAX, 2009, pg. 4-10]. 

2.3.3 Drive Train 

NHTSA and EPA have also reviewed the transmission technology estimates used in 

the 2012-2016 light-duty final rule. In doing so, NHTSA and EPA considered or 

reconsidered all available sources and updated the estimates as appropriate. The section 

below describes each of the transmission technologies considered for this rulemaking.

2.3.3.1 Improved Automatic Transmission Control (IATC) (Aggressive Shift Logic and 

Early Torque Converter Lockup)

Calibrating the transmission shift schedule to upshift earlier and quicker, and to lockup or partially lock-up the torque converter under a broader range of operating conditions can 

reduce fuel consumption and CO2

Deleted: 4

emissions. However, this operation can result in a 

perceptible degradation in noise, vibration, and harshness (NVH). The degree to which NVH 

can be degraded before it becomes noticeable to the driver is strongly influenced by 

characteristics of the vehicle, and although it is somewhat subjective, it always places a limit 

on how much fuel consumption can be improved by transmission control changes. Given that 

the Aggressive Shift Logic and Early Torque Converter Lockup are best optimized 

simultaneously due to the fact that adding both of them primarily requires only minor 

modifications to the transmission or calibration software, these two technologies are 

combined in the modeling.

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2.3.3.2 Aggressive Shift Logic

During operation, an automatic transmission’s controller manages the operation of the 

transmission by scheduling the upshift or downshift, and locking or allowing the torque 

converter to slip based on a preprogrammed shift schedule. The shift schedule contains a 

number of lookup table functions, which define the shift points and torque converter lockup 

based on vehicle speed and throttle position, and other parameters such as temperature. 

Aggressive shift logic (ASL) can be employed in such a way as to maximize fuel efficiency 

by modifying the shift schedule to upshift earlier and inhibit downshifts under some 

conditions, which reduces engine pumping losses and engine friction. The application of this 

technology does require a manufacturer to confirm that drivability, durability, and NVH are 

not significantly degraded.

We consider this technology to be present in the baseline, 6-speed automatic 

transmissions in the majority of Class 2b and 3 trucks in the 2010 model year timeframe.

2.3.3.3 Early Torque Converter Lockup

A torque converter is a fluid coupling located between the engine and transmission in 

vehicles with automatic transmissions and continuously-variable transmissions (CVT). This 

fluid coupling allows for slip so the engine can run while the vehicle is idling in gear (as at a 

stop light), provides for smoothness of the powertrain, and also provides for torque 

multiplication during acceleration, and especially launch. During light acceleration and 

cruising, the inherent slip in a torque converter causes increased fuel consumption, so modern 

automatic transmissions utilize a clutch in the torque converter to lock it and prevent this 

slippage. Fuel consumption can be further reduced by locking up the torque converter at 

lower vehicle speeds, provided there is sufficient power to propel the vehicle, and noise and 

vibration are not excessive. If the torque converter cannot be fully locked up for maximum 

efficiency, a partial lockup strategy can be employed to reduce slippage. Early torque 

converter lockup is applicable to all vehicle types with automatic transmissions. Some torque 

converters will require upgraded clutch materials to withstand additional loading and the 

slipping conditions during partial lock-up. As with aggressive shift logic, confirmation of 

acceptable drivability, performance, durability and NVH characteristics is required to 

successfully implement this technology.

We consider this technology to be present in the baseline, 6-speed automatic 

transmissions in the majority of Class 2b and 3 trucks in the 2010 model year timeframe.

2.3.3.4 Automatic 6- and 8-Speed Transmissions

Manufacturers can also choose to replace 4- and 5-speed transmission with 6- or 8-

speed automatic transmissions. Additional ratios allow for further optimization of engine 

operation over a wider range of conditions, but this is subject to diminishing returns as the 

number of speeds increases. As additional planetary gear sets are added (which may be 

necessary in some cases to achieve the higher number of ratios), additional weight and friction 

are introduced. Also, the additional shifting of such a transmission can be perceived as 

bothersome to some consumers, so manufacturers need to develop strategies for smooth 

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shifts. Some manufacturers are replacing 4- and 5-speed automatics with 6-speed automatics, 

and 7- and 8-speed automatics have also entered production, albeit in lower-volume 

applications in luxury and performance oriented cars.

As discussed in the 2012-2016 light-duty final rule, confidential manufacturer data 

projected that 6-speed transmissions could incrementally reduce fuel consumption by 0 to 5 

percent from a baseline 4-speed automatic transmission, while an 8-speed transmission could 

incrementally reduce fuel consumption by up to 6 percent from a baseline 4-speed automatic 

transmission. GM has publicly claimed a fuel economy improvement of up to 4 percent for 

its new 6-speed automatic transmissions. 

NHTSA and EPA reviewed and revised these effectiveness estimates based on usage 

and testing methods for Class 2b and 3 vehicles along with confidential business information. 

When combined with IATC, the agencies estimate the effectiveness for a conversion from a 4 

to a 6-speed transmission to be 5.3 percent and a conversion from a 6 to 8-speed transmission 

to be 1.7 percent for the NPRM.

As for costs, the agencies have considered the recent study conducted by NAS (NAS 

2010) which showed an incremental cost of $210 for an 8 speed automatic transmission 

relative to a 6 speed automatic transmission (the baseline technology for 2010MY Class 2b & 

3 pickups and vans). Considering this to be a valid cost for 2012MY and applying a low 

complexity ICM of 1.17 results in a cost of $246 in 2012. Considering time based learning to 

be appropriate for automatic transmissions and applying two years of time based learning 

results in a 2014MY cost of $231 (2008$). This technology is considered applicable to both 

gasoline and diesel trucks and vans.

2.3.3.5 Electric Power Steering/Electro-hydraulic Power Steering (EPS/EHPS)

Electric power steering (EPS) or Electrohydraulic power steering (EHPS) provides a 

potential reduction in CO2 emissions and fuel consumption over hydraulic power steering 

because of reduced overall accessory loads. This eliminates the parasitic losses associated 

with belt-driven power steering pumps which consistently draw load from the engine to pump 

hydraulic fluid through the steering actuation systems even when the wheels are not being 

turned. EPS is an enabler for all vehicle hybridization technologies since it provides power 

steering when the engine is off. EPS may be implemented on most vehicles with a standard 

12V system. Some heavier vehicles may require a higher voltage system which may add cost 

and complexity.

The 2010 light-duty final rule estimated a 1 to 2 percent effectiveness based on the 

2002 NAS report, a Sierra Research report, and confidential manufacturer data. NHTSA and 

EPA reviewed these effectiveness estimates and found them to be accurate, thus they have 

been retained for this final rule.

NHTSA and EPA adjusted the EPS cost for the current rulemaking based on a review 

of the specification of the system. Adjustments were made to include potentially higher 

voltage or heavier duty system operation for Class 2b and 3. Accordingly, higher costs were 

estimated for systems with higher capability. After accounting for the differences in system 

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capability and applying the ICM markup of low complexity technology of 1.17, the estimated 

costs for this proposal are $108 for a MY 2014 truck or van (2008$). As EPS systems are in 

widespread usage today, time-based learning is deemed applicable. EHPS systems are 

considered to be of equal cost and both are considered applicable to gasoline and diesel 

engines. 

2.3.4 Aerodynamics

Aerodynamic drag is an important aspect of the power requirements for Class 2b and 3 

trucks. Because aerodynamic drag is a function of the cube of vehicle speed, small changes in 

the aerodynamics of a Class 2b and 3 can reduce drag, fuel consumption, and GHG emissions. 

Some of the opportunities to reduce aerodynamic drag in Class 2b and 3 vehicles are similar 

to those in Class 1 and 2 (i.e., light-duty) vehicles. In general, these transferable features make 

the cab shape more aerodynamic by streamlining the airflow over the bumper, grill, 

windshield, sides, and roof. Class 2b and 3 vehicles may also borrow from light-duty vehicles 

certain drag reducing accessories (e.g., streamlined mirrors, operator steps, and sun visors). 

The great variety of applications for Class 2b and 3 trucks result in a wide range of 

operational speed profiles (i.e., in-use drive cycles) and functional requirements (e.g., shuttle 

buses that must be tall enough for standing passengers, trucks that must have racks for 

ladders). This variety makes it challenging to develop aerodynamic solutions that consider 

the entire vehicle.

Consistent with the 2012-2016 light-duty rule, the agencies have estimated the cost for 

this technology at $54 (2008$) including a low complexity ICM of 1.17. This cost is 

applicable in the 2014 model year to both gasoline and diesel trucks and vans.

2.3.5 Tires

Typically, tires used on Class 2b/3 vehicles are not designed specifically for the 

vehicle. These tires are designed for broader use and no single parameter is optimized. 

Similar to vocational vehicles, the market has not demanded tires with improved rolling 

resistance; therefore, manufacturers have not traditionally designed tires with low rolling 

resistance for Class 2b/3 vehicles. EPA believes that a regulatory program that incentivizes 

the optimization of tire rolling resistance, traction and durability can bring about GHG 

emission reductions from this segment.

Based on the 2012-2016 Light-duty final rule and the 2010 NAS report, the agencies 

have estimated the cost for low rolling resistance tires to be $6 per Class 2b truck or van, and 

$9 per Class 3 truck or van. 18

2.4 Heavy-Duty Engines 

 The higher cost for the Class 3 trucks and vans is due to the 

predominant use of dual rear tires and, thus, 6 tires per truck. Due to the commodity-based 

nature of this technology, cost learning is not applied. This technology is considered

applicable to both gasoline and diesel. 

The proposed regulatory structure for heavy-duty engines separates the compression 

ignition (or “diesel”) engines into three regulatory subcategories and from spark ignition (or 

Deleted: 

Deleted: E

Deleted: 

Deleted: 

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Regulatory Impact Analysis 

2-22

“gasoline”) engines into a single regulatory subcategory. Therefore, the subsequent 

discussion will assess each type of engine separately.

The Light- and Heavy-Duty Diesel engines typically range between 4.7 and 6.7 liters 

displacement, the Medium-Heavy-Duty Diesel engines typically have some overlap in 

displacement with the Light-Heavy-Duty Diesel engines and range between 6.7 and 9.3 liters. 

The Heavy-Duty Diesel engines typically are represented by engines between 10.8 and 16 

liters. The heavy-duty gasoline engines have ranged in the past between 4.8 and 8.1 liters.

2.4.1 Spark Ignition Engines 

Spark ignition engines are certified for the heavy-duty market. These engines 

typically range in displacement between five and eight liters and are either V8 or V10 

configurations. As found in the 2010 NAS study, most are either V8 or V10 engines with 

port fuel injection, naturally aspirated with fixed valves. In the recent past, the primary 

producers of the gasoline engines were limited to Ford and General Motors. The engines sold 

separately, which require an engine certificate in lieu of a chassis certificate, are the same as 

or very similar to the engines used in the pickup truck and vans. Therefore, NHTSA and EPA 

developed the baseline, list of engine technologies, and standards to reflect this commonality.

2.4.1.1 Baseline SI Engine CO2

Similar to the gasoline engine used as the baseline in the Light-Duty GHG rule (an 

assumption not questioned in the comments to that rulemaking), the agencies assumed the 

baseline engine in this segment to be a naturally aspirated, single overhead valve V8 engine. 

The following discussion of effectiveness is generally in comparison to 2010 baseline engine 

performance.

and Fuel Consumption

NHTSA and EPA developed the baseline fuel consumption and CO2 emissions for the 

gasoline engines from manufacturer reported CO2 values used in the certification of nonGHG pollutants. The baseline engine for the analysis was developed to represent a 2011 

model year engine, because this is the most current information available. The average CO2

2.4.1.2 Gasoline Engine Technologies

performance of the heavy-duty gasoline engines was 660 g/bhp-hour, which will be used as a 

baseline. 

The engine technologies projected for the gasoline heavy-duty engines are based on 

the technologies used in the Light-Duty Vehicle Greenhouse Gas Emission Standards and 

Corporate Average Fuel Economy Standards Joint Technical Support Document.19 The 

effectiveness of the technology packages were evaluated using the EPA Lumped Parameter 

model HD Version 1.0.0.1.20

Deleted: class

 The HD version of the Lumped Parameter model includes a 

subset of the technologies included in the Large Pickup Truck version of the Light-Duty 

rulemaking to recognize that some technologies will have limited effectiveness due to the 

higher operating weights of these trucks. The HD Lumped Parameter model also has reduced 

the effectiveness of several of the individual technologies again to recognize the higher test 

weights used in regulatory programs.

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2.4.1.2.1 Engine Friction Reduction 

In addition to low friction lubricants, manufacturers can also reduce friction and 

improve fuel consumption by improving the design of engine components and subsystems. 

Examples include improvements in low-tension piston rings, piston skirt design, roller cam 

followers, improved crankshaft design and bearings, material coatings, material substitution, 

more optimal thermal management, and piston and cylinder surface treatments. Additionally, 

as computer-aided modeling software continues to improve, more opportunities for 

evolutionary friction reductions may become available. All reciprocating and rotating 

components in the engine are potential candidates for friction reduction, and minute 

improvements in several components can add up to a measurable fuel economy improvement. 

The 2012-2016 light-duty rule, 2010 NAS, NESCCAF and EEA reports as well as 

confidential manufacturer data suggested a range of effectiveness for engine friction reduction 

to be between 1 to 3 percent. NHTSA and EPA continue to believe that this range is accurate.

NHTSA and EPA believe that the cost estimate is closer to the lower end of the model 

year (MY) 2011 CAFE final rule range and thus for this rulemaking is proposing $9 per 

cylinder compliance cost (2008$), plus a low complexity Indirect Cost Multiplier (ICM) 

markup value of 1.17, for a MY 2016 engine (learning effects are not applied to engine 

friction reduction). This cost is multiplied by the eight cylinders resulting in a cost of $88 

(2008$) per engine for this technology.

2.4.1.2.2 Coupled Cam Phasing

Valvetrains with coupled (or coordinated) cam phasing (CCP) can modify the timing 

of both the inlet valves and the exhaust valves an equal amount by phasing the camshaft of a 

single overhead cam (SOHC) engine or an overhead valve (OHV) engine. For overhead cam 

engines, this requires the addition of a cam phaser on each bank of the engine so SOHC Vengines have two cam phasers. For overhead valve (OHV) engines, which have only one 

camshaft to actuate both inlet and exhaust valves, CCP is the only variable valve timing 

(VVT) implementation option available and requires only one cam phaser. Based on 2010 

Light-Duty final rule, previously-received confidential manufacturer data, and the NESCCAF 

report, NHTSA and EPA estimated the effectiveness of CCP to be between 1 to 4 percent. 

NHTSA and EPA reviewed this estimate for purposes of the NPRM, and continue to find it 

accurate.

Consistent with the 2010 2012-2016 Light-Duty final rule, NHTSA and EPA estimate 

the cost of a cam phaser at $46 (2008$) in the 2014MY. This estimate includes a low 

complexity ICM of 1.17. With two years of time based learning this cost becomes $43 

(2008$) in the 2016MY. All heavy-duty gasoline loose engines are over-head valve engines 

(OHV) and, as such, would require only one cam phaser for coupled cam phasing. 

2.4.1.2.3 Cylinder Deactivation 

Deleted: 

Deleted: 

Deleted: ¶

Deleted: 
Regulatory Impact Analysis 

2-24

In conventional spark-ignited engines throttling the airflow controls engine torque 

output. At partial loads, efficiency can be improved by using cylinder deactivation instead of 

throttling. Cylinder deactivation (DEAC) can improve engine efficiency by disabling or 

deactivating (usually) half of the cylinders when the load is less than half of the engine’s total 

torque capability – the valves are kept closed, and no fuel is injected – as a result, the trapped 

air within the deactivated cylinders is simply compressed and expanded as an air spring, with 

reduced friction and heat losses. The active cylinders combust at almost double the load 

required if all of the cylinders were operating. Pumping losses are significantly reduced as 

long as the engine is operated in this “part cylinder” mode.

Cylinder deactivation control strategy relies on setting maximum manifold absolute 

pressures or predicted torque within which it can deactivate the cylinders. Noise vibration and 

harshness (NVH) issues reduce the operating range to which cylinder deactivation is allowed, 

although manufacturers are exploring vehicle changes that enable increasing the amount of 

time that cylinder deactivation might be suitable. Some manufacturers may choose to adopt 

active engine mounts and/or active noise cancellations systems to address NVH concerns and 

to allow a greater operating range of activation. Cylinder deactivation has seen a recent 

resurgence thanks to better valvetrain designs and engine controls. General Motors and 

Chrysler Group have incorporated cylinder deactivation across a substantial portion of their 

V8-powered lineups. 

Effectiveness improvements scale roughly with engine displacement-to-vehicle weight 

ratio: the higher displacement-to-weight vehicles, operating at lower relative loads for normal 

driving, have the potential to operate in part-cylinder mode more frequently. NHTSA and 

EPA adjusted the 2010 light-duty final rule estimates using updated power to weight ratings 

of heavy-duty trucks and confidential business information and confirmed a range of 3 to 4 

percent for these vehicles.

Consistent with the 2012-2016 light-duty FRM, NHTSA and EPA have estimated the 

cost of cylinder deactivation at $193 for the 2014MY (2008$). This estimate includes a low 

complexity ICM of 1.17. With two years of time based learning, this cost becomes $181 

(2008$) in the 2016MY. This technology was not considered to be a necessary technology to 

achieve the proposed standards and thus has not been included in the package cost.

2.4.1.2.4 Stoichiometric gasoline direct injection

SGDI engines inject fuel at high pressure directly into the combustion chamber 

(rather than the intake port in port fuel injection). SGDI requires changes to the injector 

design, an additional high pressure fuel pump, new fuel rails to handle the higher fuel 

pressures and changes to the cylinder head and piston crown design. Direct injection of the 

fuel into the cylinder improves cooling of the air/fuel charge within the cylinder, which allows 

for higher compression ratios and increased thermodynamic efficiency without the onset of 

combustion knock. Recent injector design advances, improved electronic engine management 

systems and the introduction of multiple injection events per cylinder firing cycle promote 

better mixing of the air and fuel, enhance combustion rates, increase residual exhaust gas 

Deleted: Light Duty

Deleted: 

Deleted: (SIDI),
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-25

tolerance and improve cold start emissions. SGDI engines achieve higher power density and 

match well with other technologies, such as boosting and variable valvetrain designs. NHTSA 

and EPA estimate the range of 1 to 2 percent improvement for SGDI. 

The NHTSA and EPA cost estimates for SGDI take into account the changes required 

to the engine hardware, engine electronic controls, ancillary and NVH mitigation systems. 

Through contacts with industry NVH suppliers, and manufacturer press releases, the agencies 

believe that the NVH treatments will be limited to the mitigation of fuel system noise, 

specifically from the injectors and the fuel lines. 

The NHTSA and EPA cost estimates for SGDI take into account the changes required 

to the engine hardware, engine electronic controls, ancillary and Noise Vibration and 

Harshness (NVH) mitigation systems. Through contacts with industry NVH suppliers, and 

manufacturer press releases, the agencies believe that the NVH treatments will be limited to 

the mitigation of fuel system noise, specifically from the injectors and the fuel lines. 

Consistent with the 2012-2016 light-duty rule, the agencies estimate the cost of conversion to 

SGDI on a V8 engine at $395 (2008$) for the 2014MY. This estimate includes a low 

complexity ICM of 1.17. With two years of time based learning, this cost becomes $372 

(2008$) in the 2016MY.

2.4.1.3 Derivation of Gasoline Engine Standard 

The average CO2 performance of the two heavy-duty gasoline engines certified for 

2010 and 2011 model years was 660 g CO2/bhp-hour. The HD Lumped Parameter model 

analysis projects that the package of the three technologies (friction reduction, closed couple 

cam phasing, and stoichiometric direct injection) could reduce CO2 emissions and fuel 

consumption by 5 percent. Therefore, the agencies are proposing to set the standard in 2016 

model year at 627 g CO2

2.4.1.4 SI Engine Technology Cost

/bhp-hr.

As shown in Table 2-3, the overall projected engine package cost for a 2016 model 

year engine is $504 (2008$).

Table 2-3 Estimated 2016MY Costs for a Spark-Ignition HD Engine (2008 dollars)

DIRECT MFG 

COST

ICM MARKED UP 

COSTS

Engine Friction Reduction $76 1.17 $88

Coupled Cam Phasing $37 1.17 $43

Stoichiometric Gas Direct Injection $318 1.17 $372

Total $431 $504

Deleted: 

Deleted: The

Deleted: in 

Deleted: 474

Formatted Table

Deleted: 2016

Inserted Cells

Inserted Cells

Deleted: 80

Deleted: 41

Deleted: 353

Deleted: 474
Regulatory Impact Analysis 

2-26

2.4.2 Diesel Engines 

2.4.2.1 Baseline Engines

The agencies developed the baseline diesel engine as a 2010 model year engine with 

an aftertreatment system which meets EPA’s 0.2 grams of NOx/bhp-hr standard with a 

selective catalytic reduction (SCR) system along with EGR and meets the PM emissions 

standard with a diesel particulate filter (DPF) with active regeneration. The engine is 

turbocharged with a variable geometry turbocharger. The following discussion of 

technologies describes improvements over the 2010 model year baseline engine performance, 

unless otherwise noted. 

The CO2 performance over the FTP for the baseline engines were developed through 

manufacturer reporting of CO2 in their non-GHG certification applications for 2010 model 

year. This data was carefully considered to insure that the baseline represented an engine 

meeting the 0.2 g/bhp-hr NOx standard. For those engines that were not at this NOx level or 

higher, then the agencies derived a CO2 correction factor to bring them to a 0.2 g/bhp-hr NOx 

emissions. The CO2 correction factor is derived based on available experimental data 

obtained from manufacturers and public literature. The agencies then sales-weighted the CO2

performance to derive a baseline CO2

In order to establish baseline SET performance for the Heavy Heavy-Duty and 

Medium Heavy-Duty Diesel Engines, several sources were considered. Some engine 

manufacturers provided the agencies SET modal results or fuel consumption maps to 

represent their 2009 model year engine fuel consumption performance. As a supplement to 

this, complete engine map CO

performance for each engine subcategory.

2

In summary, the baseline CO

data (including SET modes) acquired in EPA test cells were 

also considered. The pre-2010 maps are subsequently adjusted to represent 2010 model year 

engine maps by using predefined technologies including SCR and other advanced systems 

that are being used in current 2010 production.

2

Table 2-4

performance for each diesel engine category is included 

in .

Table 2-4: Baseline CO2

LHDD - FTP

Performance (g/bhp-hr)

MHDD - FTP HHDD - FTP HHDD - SET

630 630 584 490

The agencies used the baseline engine to assess the potential of each of the following 

technologies.

2.4.2.2 Combustion System Optimization

Continuous improvements on the fuel injection system allows more flexible fuel 

injection capability with higher injection pressure, which can provide more opportunities to 

improve engine fuel economy, while maintaining the same emission level. Combustion 

system optimization, featuring piston bowl, injector tip and the number of holes, in 

conjunction with the advanced fuel injection system, is able to further improve engine 

Deleted: class

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-27

performance and fuel economy. At this point, all engine manufacturers spearhead substantial 

efforts into this direction in the hope that their development efforts would be translated into 

production in the near futures. The examples include the combustion development programs 

conducted by Cummins21 and Detroit Diesel22

The cost for this technology includes costs associated with several individual 

technologies. Specifically, improved cylinder head, turbo efficiency improvements, EGR 

cooler improvements, higher pressure fuel rail, improved fuel injectors and improved pistons. 

The costs estimates for each of these technologies are presented in 

funded by Department of Energy. They both 

claim that 10 percent thermal efficiency improvement at 2010 emission level is achievable. 

While their findings are still more towards research environment, their results do enhance the 

possibility that some of technologies they are developing could be applied to production in the 

time frame of 2017. 

Table 2-6 through Table 

2-8 for heavy HD, medium HD and light HD engines, respectively. The agencies consider a 

low complexity ICM of 1.11 and time based learning from 2014 forward to be appropriate for 

these technologies.

2.4.2.3 Turbochargers

Many advanced turbocharger technologies can be potentially added into production in 

the time frame between 2014 and 2017, and some of them are already in production. 

Mechanical or electric turbocompound, two-stage turbochargers with intercooler, and high 

efficient low speed compressor to just name a few. 

A turbocompound system extracts energy from the exhaust to provide additional 

power. Mechanical turbocompounding includes a power turbine located downstream of the 

turbine which in turn is connected to the crankshaft to supply additional power. As noted in 

the 2010 NAS report, it typically includes a fluid coupling (to allow for speed variation and to 

protect the power turbine from engine torsional vibration) and a gear set to match power 

turbine speed to crankshaft speed. Turbocompound has been used in production by Detroit 

Diesel for their DD15 and DD16 engines and they claim a 3 to 5 percent fuel consumption 

reduction due to the system. The 2010 NAS report23

Electric turbocompound is another potential device, although it is still not as mature in 

terms of production as opposed to mechanical turbocompound. An electric turbocompound 

includes published information from 

four sources on the fuel consumption reduction from mechanical turbocompounding ranging 

from 2.5 to 5 percent. Some of these differences may depend on the operating condition or 

duty cycle that was considered by the different researchers. The performance of a 

turbocompound system tends to be best at full load and much less or even act as an energy 

sink to suck the energy at light loads. Because of that, a clutch that can separate the engine 

crankshaft from turbocompound gear train could be proposed and put into production in order 

to overcome the drawbacks of turbocompound at light loads, thus improving fuel economy 

over the entire speed and load ranges. Incremental cost increases associated with the addition 

of mechanical turbocompounding are significant, due to the complexity of the mechanical 

power transmission system required to connect the power turbine to the drivetrain. Such costs 

are estimated to be $1040 inclusive of an RPE factor of 1.28 (i.e., $813 in direct 

manufacturing costs). 

Deleted: and Detroit Diesel (D. Stanton, 

Cummins, 2009 DOE Semi-Mega Merit Review, 

May 21, 2009, and H. Zhang, 2009 DOE Semi-Mega 

Merit Review, May 21, 2009) ,

Deleted: low temperature exhaust gas recirculation 

(see Section 2.3.2.4)

Deleted: turbochargers (see Section 2.3.2.5). 

These 

Deleted: considered collectively

Deleted: our costing analysis

Deleted: termed “diesel engine improvements.”

Deleted: have estimated the cost of diesel engine 

improvements based on the TIAX report which 

estimated the retail price equivalent at $500 using a 2 

times multiplier. Dividing that value gives a direct 

manufacturing cost of $250. Applying

Deleted: 2012

Deleted: results in the agencies’ estimate of $217

(2008$) in the 2014MY. This cost is applicable only 

Deleted: light-heavy HD diesel engines

Deleted: turbo-compound

Deleted: stages of

Deleted: are

Deleted: names of

Deleted: Turbo-compound has been used in 

production by Detroit Diesel for their DD15 and 

DD16 engines. It is a

Deleted: with

Deleted: that is added to the

Deleted: to extract additional energy from the 

exhaust. The power turbine

Deleted: (NESCCAF/ICCT, 2009, p. 81). 

Typically, the attachment

Deleted: Published

Deleted: varies, as evidenced by the following: 3 -

5 percent, according to the Detroit Diesel 

Corporation5 which has a turbocompound engine in 

production;

Deleted: 3 percent (NESCCAF/ICCT, 2009, p. 

54); 3 percent (K. G. Duleep of Energy and 

Environmental Analysis)6

; 4 to 

Deleted: (R. Kruiswyk, 2008, pp. 212-214); and 

TIAX (2009, pp. 4-17) used 2.5 to 3 percent

Deleted: highest

Deleted: a

Deleted: turbo-compound

Deleted: turbo-compound

Deleted: turbo-compound

Deleted: turbo-compound. This approach is ...

Deleted: , except that the 
Regulatory Impact Analysis 

2-28

system uses a power turbine to drive an electrical generator which is used to power electric

accessories or provide extra power to the engine. As noted in the 2010 NAS report,24 electric

turbocompound is a technology that fits particularly well with a hybrid electric powertrain for 

long-haul applications where regenerative braking opportunities are limited. The benefits of 

electric turbocompound and an electric hybrid powertrain can be additive. . TIAX used a 

range of 4 to 5 percent for its estimates, which included the benefits of electric accessories.25 

The 2010 NAS report includes the benefit projections from three studies, as listed below. 

However, none of these systems have been demonstrated commercially.26

• The NESCCAF/ICCT study modeled an electric turbocompound system and 

estimated benefits at 4.2 percent, including electrification of accessories. 

 

• Caterpillar, Inc., as part of Department of Energy (DOE) funded work, 

modeled a system that showed 3 to 5 percent improvement27

• John Deere investigated a system (off-highway) that offered 10 percent 

improvement.

Two-stage turbocharger technology has been used in production by Navistar and other 

manufacturers. Ford’s new developed 6.7L diesel engine features twin-compressor 

turbocharger. Higher boost with wider range of operations and higher efficiency can further 

enhance engine performance, thus fuel economy. It is expected that this type of technology 

will continue to be improved by better matching with system and developing higher 

compressor and turbine efficiency.

For this analysis, we have estimated the cost of turbocompounding at $823 (2008$). 

This estimate includes a low complexity ICM of 1.11. This cost is applicable in the 2017MY 

when engines being placed in day cab and sleeper cab tractors are expected to add this 

technology. Time based learning is considered applicable to this technology. For the more 

basic technology of improving the turbo efficiency, the agencies have estimated a cost of $17 

(2008$) including a low complexity ICM of 1.11. That estimate would be considered valid in 

the 2014MY and time based learning would be applied going forward.

2.4.2.4 Engine Parasitic and Friction Reduction

Engine parasitic and friction reduction is another key technical areas that can be 

further improved in production moving to 2014 and 2017 time frame. Reduced friction in 

bearings, valve trains, and the piston-to-liner interface will improve efficiency. Friction 

reduction opportunities in the engine valve train and at its roller/tappet interfaces exist for 

several production engines. The piston at its skirt/cylinder wall interface, wrist pin and oil 

ring/cylinder wall interface offers opportunities for friction reduction. Use of more advanced 

oil lubricant that could be available for production in the future can also play a key role in 

reducing friction. Any friction reduction must be carefully developed to avoid issues with 

durability or performance capability. Estimations of fuel consumption improvements due to 

reduced friction range from 0 percent to 2 percent.28

Deleted: drives

 All fuel injection system manufacturers 

are working hard to reduce parasitic loss due to high pressure pumps and common rail flow 

loss in the hope that those development would add up further fuel economy improvement.

Deleted: (NESCCAF/ICCT, 2009, p. 29). The 

electricity produced can be 

Deleted: an electrical motor supplementing the 

engine output, to power electrified

Deleted: ,

Deleted: to charge a hybrid system battery. 

Electric

Deleted: (p. 54)

Deleted: , while John Deere investigated a system 

(off-highway) that offered 10 percent improvement 

(Vuk 2006; TIAX, 2009, p. A-10). None of these 

systems have been demonstrated commercially. 

TIAX (2009, pp. 3-5) used a range of 4 to 5 percent

for its estimates, which included the benefits of 

electric accessories.

Deleted: Scorpion

Deleted: turbo-compounding

Deleted: long-haul (i.e.,

Deleted: ) trucks

Deleted: [TIAX, Assessment of Fuel Economy 

Technologies for Medium- and Heavy- Duty 

Vehicles, Final Report, Nov. 19, 2009, pg 4-15].
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-29

Incremental manufacturing costs increases associated with the reduction of parasitics 

and friction may include those associated with an optimized, electric water pump, replacing a 

mechanically driven water pump ($100). Additionally, an improved mechanical oil pump 

with more efficient relief mechanism and optimized hydrodynamic design may incur costs 

($5). A fuel pump capable of delivering higher pressures and with efficient regulation may 

require improved materials and more elaborate regulating hardware ($5). Improved Pistons 

with less friction generated at the skirt may require incrementally more precision in finish 

machine operations ($3). Finally, a more efficient, reduced friction valve train will require 

more precise machining processes and an increased parts count ($90). All costs presented 

here are considered to include a retail price equivalent factor of 1.28.

Removing the 1.28 RPE factor from the above cost estimates and instead applying a 

low complexity ICM of 1.11 results in the following costs: electric water pump, $87; 

improved mechanical oil pump, $4, improved fuel pump, $4; improved pistons, $3; reduced 

friction valve train, $104 for LHDD engines and $78 for HHDD engines. All costs are in 

2008 dollars and are applicable to the 2014MY. Time based learning is considered applicable 

to all of these costs.

2.4.2.5 Advanced Model Based Control

Significant progresses on advanced model based control have been made in the past 

few years. Detroit Diesel introduced the next generation model based control concept, 

achieving 4 percent thermal efficiency improvement while simultaneously reducing emissions 

in transient operations.

29

2.4.2.6 Integrated Aftertreatment System

 Their model based concept features a series of real time optimizers 

with multiple inputs and multiple outputs. This controller contains many physical based 

models for engine and aftertreatment. It produces fully transient engine performance and 

emissions predictions in a real-time manner. Although this control concept may still not be 

mature in 2014 production, it would be a realistic estimate that this type of real time model 

control could be in production before 2017, thus significantly improving engine fuel 

economy.

All manufacturers use diesel particulate filter (DPF) to reduce particulate matter (PM). 

All except Navistar rely on SCR to reduce NOx emissions. Periodic regeneration to remove 

loaded soot is required for all DPF. One way is to directly inject the fuel into exhaust stream, 

called active regeneration, and a diesel oxidation catalyst (DOC) or other device then oxidizes 

the fuel in the exhaust stream, providing the heat required for DPF regeneration and 

increasing the fuel consumption of the vehicle. The other method is to use NO2

Deleted: 

, called 

passive regeneration, to directly react with soot at much lower exhaust temperature than 

active regeneration. Use of advanced thermal management could be made in production to 

eliminate active regeneration, thus significantly improve fuel economy. Volvo has announced 

in 2009 that their 2010 DPF+SCR system has eliminated active regeneration for on-highway 

vehicles. All other manufacturers are working in the same direction, minimizing or 

eliminating active regeneration, thus improving fuel economy at least by 1 percent, providing 

efficiency improvements in the real world which are not reflected in the proposed HD engine 

test procedure

Deleted: .

Deleted: (H. Zhang etc., DEER conference, 

Dearborn, Michigan, August 6, 2008).

Deleted: . 
Regulatory Impact Analysis 

2-30

Higher SCR NOx conversion efficiency will allow higher engine-out NOx emissions, 

and therefore, will give more room for engine system optimization, while maintaining the 

same or even less diesel engine fluid (DEF) consumption. Advanced model based control on 

DEF usage and slip can further improve DEF consumption, thus fuel economy. For those 

manufacturers that use SCR as their NOx

The agencies have estimated the cost of this technology at $25 for each percentage 

improvement in fuel consumption. This estimate is based on the agencies’ belief that this 

technology is, in fact, a very cost effective approach to improving fuel consumption. As such, 

$25 per percent improvement is considered a reasonable cost. This cost would cover the 

engineering and test cell related costs necessary to develop and implement the improved 

control strategies that would allow for the improvements in fuel consumption. Importantly, 

the engineering work involved would be expected to result in cost savings to the 

aftertreatment and control hardware (lower platinum group metal (PGM) loadings, lower 

reductant dosing rates, etc.). Those savings are considered to be included in the $25 per 

percent estimate described here. Given the 4 percent expected improvement in fuel 

consumption results in an estimated cost of $111 (2008$) for a 2014MY vehicle. This 

estimate includes a low complexity ICM of 1.11 and time based learning from 2014 forward. 

Note that this cost is applied only to light-heavy HD diesel engines. The cost for this 

technology is considered separately for medium and heavy HD diesel engines since the cost is 

considered largely one of research and development which probably results in lower actual 

part cost.

reduction devices, properly integrated DPF and 

SCR system is essential, which is not only able to improve emissions reductions, but also to 

improve fuel economy through more advancing canning design, thus minimizing pressure 

drop across the system. Improvements in aftertreatment system efficiency should be 

technology cost neutral, requiring no increases in precious metal loading or manufacturing 

expense, and only require additional development costs. 

2.4.2.7 Electrification

Many accessories that are traditionally gear or belt driven by a vehicle’s engine can be 

decoupled with the engine speed, so that those accessories can be tailored to a specific engine 

speed, thus better efficiency. Examples include the engine water pump, oil pump, fuel 

injection pump, air compressor, power-steering pump, cooling fans, and the vehicle’s airconditioning system. The most tangible development toward production in 2017 time frame 

would be electric water and oil pumps. It is expected that about 0.5 to 1.0 percent thermal 

efficiency improvement could be achieved with electrification of these two pumps.

Costs for electrification are considered as part of the costs for improved water and oil 

pumps discussed in Section 2.4.2.4.

2.4.2.8 Waste Heat Recovery

Waste heat recovery uses exhaust gas or other heat sources (such as EGR or coolant) 

from the primary engine to develop additional power. Waste heat recovery systems have other 

names such as bottoming cycle or Rankine cycle. As described in the 2010 NAS report, a

typical system consists of the following components: a feed pump to drive the working fluid 

Deleted: 110

Deleted: 2012

Deleted: A bottoming cycle 

Deleted: energy

Deleted: without using additional fuel. A

Deleted: bottoming cycle
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-31

from the condenser to the evaporator (or boiler); the evaporator, which transfers waste heat 

energy from the primary engine to the working fluid; an expander, which takes energy from 

the working fluid to make mechanical power; and a condenser that rejects unused heat energy 

from the bottoming cycle working fluid before starting a new cycle. The costs of 

implementing a Waste Heat Recovery system are significant, estimated at $1700. Such costs 

include necessary power extraction unit and gearbox, heat exchangers and compressor. The 

2010 NAS report cited two studies related to waste heat recovery, as listed below.30

• Cummins has shown a projected increase of thermal efficiency from 49.1 to 

52.9 percent (7.2 percent decrease in fuel consumption) using an organic 

Rankine cycle.31

• The NESCCAF/ICCT report showed the effect of a steam bottoming cycle to 

reduce fuel consumption by up to 10 percent. 

 Cummins reports recovering 2.5 thermal efficiency points 

from the exhaust and 1.3 thermal efficiency points from the coolant and EGR 

stream.

The agencies’ assessment of this technology indicates that it currently exists only in 

the research phase, and therefore should not be included in proposing the standard for 2017 

model year.

2.4.2.9 2014 Model Year HHD Diesel Engine Package

The agencies assessed the impact of technologies over each of the SET modes to 

project an overall improvement in the 2014 model year. The agencies considered 

improvements in parasitic and friction losses through piston designs to reduce friction, 

improved lubrication, and improved water pump and oil pump designs to reduce parasitic 

losses. The aftertreatment improvements are available through lower backpressure of the 

systems and optimization of the engine-out NOx levels. Improvements to the EGR system 

and air flow through the intake and exhaust systems, along with turbochargers can also 

produce engine efficiency improvements. Lastly, an increase in combustion pressures and 

controls can reduce fuel consumption of the engine. The projected impact of each set of these 

technologies is included in Table 2-5. Based on the improvements listed in the table, the 

overall weighted reduction based on the SET mode weightings is projected at 3 percent 

Table 2-5: Projected Percent CO2 Impact for SET Modes in 2014 Model Year

SET 

Mode

Speed, percent Load Parasitic, 

Friction 

Aftertreatment 

Improvement

Air Handling Combustion, 

Control

1 Idle 0.0 0.0 0.0 -0.4

2 A, 100 -0.9 -1.1 -1.1 -0.9

3 B, 50 -0.9 -1.1 -1.1 -1.1

4 B, 75 -1.1 -1.3 -1.3 -1.3

5 A, 50 -0.4 -0.7 -1.1 -0.9

6 A, 75 -0.7 -0.9 -1.3 -1.1

7 A, 25 -0.2 -0.4 -0.9 -0.4

8 B, 100 -1.3 -1.3 -1.3 -0.9

9 B, 25 -0.7 -0.9 -0.9 -0.4

Moved (insertion) [1]

Deleted: While it is still questionable whether 

this technology would be put into production before 

2014 model year, significant progress has been made 

recently. Cummins, Inc.

Deleted: 16 The NESCCAF/ICCT report (2009, 

pp. 55-56) showed the effect of a steam bottoming 

cycle to reduce fuel consumption by up to 10 

percent. 

Moved up [1]: The costs of implementing a 

Waste Heat Recovery system are significant, 

estimated at $1700. Such costs include necessary 

power extraction unit and gearbox, heat exchangers 

and compressor. 

Deleted: HHDD

Deleted: ¶

Deleted: 

Formatted Table

Deleted: percentLoad
Regulatory Impact Analysis 

2-32

10 C, 100 -1.7 -1.5 -1.3 -0.9

11 C, 25 -0.9 -0.9 -0.9 -0.2

12 C, 75 -1.3 -1.3 -1.1 -0.4

13 C, 50 -1.1 -1.1 -0.9 -0.7

The agencies derived the HHD diesel engine FTP technology effectiveness for the 

2014 model year based on a similar approach. Using the same technologies as discussed for 

the HHD diesel engine SET above, the agencies project the reductions at 3 percent. It should 

be pointed out that individual technology improvement is not additive to each other due to the 

interaction of technology to technology.

The cost estimates for the complete HHD diesel engine packages are shown in Table 

2-6.

Table 2-6 Technology and Package Costs for HHD Diesel Engines (2008$)

Technology 2014 2015 2016 2017

Cylinder Head $6 $6 $6 $6

Turbo efficiency $17 $17 $16 $16

EGR cooler $3 $3 $3 $3

Water pump $87 $84 $82 $79

Oil pump $4 $4 $4 $4

Fuel pump $4 $4 $4 $4

Fuel rail $10 $9 $9 $9

Fuel injector $10 $10 $10 $9

Piston $3 $3 $2 $2

Turbo-compounding (engines placed in combination tractors only) $0 $0 $0 $823

HHDD Total (vocational truck engines) $145 $140 $136 $132

HHDD Total (combination tractors) $145 $140 $136 $955

2.4.2.10 2014 Model Year LHD/MHD Diesel Engine Package

The agencies considered the same 2014 model year technology package developed for 

the HHD diesel engines for the LHD diesel and MHD diesel engines. The package includes 

parasitic and friction reduction, improved lubrication, aftertreatment improvements, EGR 

system and air flow improvements, and combustion pressure increase and controls to reduce 

fuel consumption of the engine. The agencies project that these improvements will produce a 

5 percent reduction in fuel consumption and CO2

The cost estimates for the complete MHD diesel engines are shown in 

. 

Table 2-7. The 

cost estimates for the complete LHD diesel engines are shown in Table 2-8. 

Table 2-7 Technology and Package Costs for MHD Diesel Engines (2008$)

Technology 2014 2015 2016 2017

Cylinder Head $6 $6 $6 $6

Turbo efficiency $17 $17 $16 $16

EGR cooler $3 $3 $3 $3

Deleted: HHDD

Deleted: HHDD

Deleted: heavy-HD

Deleted: [need help with this cross ref to table just 

below – cannot fix until accept all track changes].

Deleted: Heavy-HDD

Formatted Table

Deleted: sleeper cabs

Deleted: sleeper cab

Deleted: ¶

Deleted: LHDD/MHDD

Deleted: HHDD

Deleted: LHDD

Deleted: MHDD

Deleted: medium-HD

Deleted: light-HD

Deleted: Medium-HDD
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-33

Water pump $87 $84 $82 $79

Oil pump $4 $4 $4 $4

Fuel pump $4 $4 $4 $4

Fuel rail $10 $9 $9 $9

Fuel injector $10 $10 $10 $9

Piston $3 $3 $2 $2

Valve train friction reduction $78 $76 $73 $71

Turbo-compounding (engines placed in combination tractors only) $0 $0 $0 $823

MHDD Total (vocational truck engines) $223 $216 $210 $203

MHDD Total (combination tractors) $223 $216 $210 $1,027

Table 2-8 Technology and Package Costs for LHD Diesel Engines (2008$)

Technology 2014 2015 2016 2017

Aftertreatment improvements $111 $108 $104 $101

Cylinder Head $10 $10 $10 $9

Turbo efficiency $17 $17 $16 $16

EGR cooler $3 $3 $3 $3

Water pump $87 $84 $82 $79

Oil pump $4 $4 $4 $4

Fuel pump $4 $4 $4 $4

Fuel rail $11 $11 $11 $10

Fuel injector $14 $13 $13 $13

Piston $3 $3 $2 $2

Valve train friction reduction $104 $101 $98 $95

LHDD Total $369 $358 $348 $337

2.4.2.11 2014 Model Year Diesel Engine Standards

The agencies applied the 5 percent reduction for the LHDD/MHDD engines and the 3 

percent reduction for the HHD diesel engines based on the projected technology package 

improvements in 2014 model year to the 2010 model year baseline performance included in 

Table 2-4. The results are the proposed 2014 model year standards, as shown in Table 2-9.

Table 2-9: 2014 Model Year Proposed Standards (g CO2

LHDD - FTP

/bhp-hr)

MHDD - FTP HHDD - FTP MHDD_- SET HHDD - SET

600 600 567 502 475

2.4.2.12 2017 Model Year HHDD Engine Package

The agencies assessed the impact of technologies over each of the SET modes to 

project an overall improvement in the 2017 model year. The agencies considered additional 

improvements in the technologies included in the 2014 model year package in addition to 

Formatted Table

Deleted: Light-HDD

Deleted: Engine improvements

Formatted Table

Deleted: 217

Deleted: 210

Deleted: 204

Deleted: 198

Formatted Table

Deleted: 328

Deleted: 318

Deleted: 308

Deleted: 299

Deleted: HHDD
Regulatory Impact Analysis 

2-34

turbocompounding. The projected impact of each set of these technologies is included 

inTable 2-10. Based on the improvements listed in the table, the overall weighted reduction 

based on the SET mode weightings is projected at 6 percent.

Costs for 2017 are shown in Table 2-6.

Table 2-10: Projected CO2

SET 

Mode

Improvements for SET Modes in 2017 Model Year

Speed, 

Percent 

Load

Turbocompounding Parasitic, 

Friction 

Aftertreatment 

Improvement

Air 

handling

Combustion, 

Control

1 Idle 0.2 0.00 0.00 0.00 -0.50

2 A, 100 -4.50 -1.00 -1.25 -1.25 -1.00

3 B, 50 -2.50 -1.00 -1.25 -1.25 -1.25

4 B, 75 -4.50 -1.25 -1.50 -1.50 -1.50

5 A, 50 -1.50 -0.50 -0.75 -1.25 -1.00

6 A, 75 -4.00 -0.75 -1.00 -1.50 -1.25

7 A, 25 0.20 -0.25 -0.50 -1.00 -0.50

8 B, 100 -5.50 -1.50 -1.50 -1.50 -1.00

9 B, 25 0.30 -0.75 -1.00 -1.00 -0.50

10 C, 100 -5.00 -2.00 -1.75 -1.50 -1.00

11 C, 25 0.50 -1.00 -1.00 -1.00 -0.25

12 C, 75 -3.50 -1.50 -1.50 -1.25 -0.50

13 C, 50 -2.00 -1.25 -1.25 -1.00 -0.75

The agencies derived the HHDD FTP technology package effectiveness for the 2017 

model year based on a similar approach. However, the addition of turbocompounding shows 

a greater effectiveness on the SET cycle than the FTP cycle because of the steady state nature 

and amount of time spent at higher speeds and loads during the SET. Using the same 

technologies as discussed for the HHDD SET above, the agencies project the reductions at 5 

percent for the FTP. It is noticed that there is a small penalty on CO2 using turbocomponding 

at low loads from Table 2-5, since no mechanism to disengage turbocompounding and engine 

crankshaft is proposed in this table. This means that an introduction of a clutch to disengage 

turbocompound and engine whenever the turbocompounding does not provide positive work 

will further improve CO2

2.4.2.13 2017 Model Year LHD/MHD Diesel Engine Package

reduction. Similar to Table 2-3, individual technology in Table 2-5 

is not additive to each other due to the interaction of technology to technology.

The agencies developed the 2017 model year LHD/MHD diesel engine package based 

on additional improvements in the technologies included in the 2014 model year package. 

The projected impact of these technologies provides an overall reduction of 9 percent over the 

2010 model year baseline.

Costs for the 2017 model year are shown in Table 2-7 (MHD) and Table 2-8 (LHD).

Deleted: 

Field Code Changed

Deleted: [help with Cross Ref to table on HeavyHD diesel costs.

Deleted: ¶

Formatted Table

Deleted: tLoad

Deleted: LHDD/MHDD

Deleted: LHDD/MHDD

Deleted: 77

Deleted: medium-HD

Deleted: light-HD
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-35

2.4.2.14 2017 Model Year Diesel Engine Standards

The agencies applied the 8.6 percent reduction for the LHD/MHD diesel engines and 

the 5 percent reduction for the HHD diesel engines using the FTP and a 6.1 percent reduction 

for HHD diesel engines using the SET based on the projected technology package 

improvements in 2017 model year to the 2010 model year baseline performance included in 

Table 2-4. The results are the proposed 2014 model year standards, as shown in Table 2-11.

Table 2-11 2017 Model Year Proposed Standards (g CO2

LHDD - FTP

/bhp-hr)

MHDD - FTP HHDD - FTP MHDD - SET HHDD - SET

576 576 555 487 460

2.5 Class 7/8 Day Cabs and Sleeper Cabs

The proposed regulatory category for Class 7 and 8 day and sleeper cabs involves 

seven regulatory subcategories. 

Class 7 Day Cab with Low Roof

Class 7 Day Cab with High Roof

Class 8 Day Cab with Low Roof

Class 8 Day Cab with High Roof

Class 8 Sleeper Cab with Low Roof

Class 8 Sleeper Cab with Mid Roof

Class 8 Sleeper Cab with High Roof

The regulatory subcategories are being proposed to differentiate between tractor 

usages through using characteristics of the truck. The technologies being proposed to reduce 

fuel consumption and CO2 emissions from tractors can be developed for all seven 

subcategories. However, the typical usage pattern may limit the penetration rate of the 

technology. For example, aerodynamic improvements can reduce the fuel consumption and 

CO2

2.5.1 Aerodynamics

emissions of a tractor at high speeds. However, this technology could be a detriment to 

fuel consumption if applied to a tractor travelling at low speeds. The agencies discuss 

technologies, penetration rates, and costs for each regulatory subcategory in the sections 

below.

Up to 25 percent of the fuel consumed by a line-haul truck traveling at highway speeds 

is used to overcome aerodynamic drag forces, making aerodynamic drag a significant 

contributor to a Class 7 or 8 tractor’s GHG emissions and fuel consumption.32

Deleted: LHDD/MHDD

 Because 

aerodynamic drag varies by the square of the vehicle speed, small changes in the tractor 

Deleted: HHDD

Deleted: HHDD

Deleted: ¶

Deleted: classifications

Deleted: classes

Deleted: classes

Deleted: classes.

Deleted: class
Regulatory Impact Analysis 

2-36

aerodynamics can have significant impacts on GHG emissions and fuel efficiency of that 

vehicle. With much of their driving at highway speed, the benefits of reduced aerodynamic 

drag for Class 7 or 8 tractors are significant.33

The common measure of aerodynamic efficiency is the coefficient of drag (Cd). The 

aerodynamic drag force (i.e., the force the vehicle must overcome due to air) is a function the 

Cd, the area presented to the wind (i.e., the projected area perpendicular to the direction of 

travel or frontal area), and the cube of the vehicle speed. Cds for today’s fleet typically range 

from greater than 0.80 for a “classic” body tractor to approximately 0.58 for tractors that 

incorporate a full package of widely, commercially available aerodynamic features.

2.5.1.1 Challenges of Tractor Aerodynamics

The aerodynamic efficiency of heavy-duty vehicles has gained increasing interest in 

recent years as fuel prices, competitive freight markets, and overall environmental awareness 

has focused owners and operators on getting as much useful work out of every gallon of 

diesel fuel as possible. While designers of heavy-duty vehicles and aftermarket products try 

to aerodynamically streamline heavy-duty vehicles, there are some challenges. Foremost is 

balancing the need to maximize the amount of freight that can be transported. For a tractor, 

this often means pulling a trailer that is as tall and as wide as motor safety laws permit, 

thereby presenting a large, drag-inducing area perpendicular to the wind (i.e., projected 

frontal area). As a result, the tractor must also present a relatively large projected frontal area 

to smoothly manage the flow of air along the cab and transition it to trailer. In instances 

where the height of the cab is not properly matched with that of trailer, aerodynamic drag can 

be significantly increased by creating large wakes (when the trailer is much shorter than the 

cab) or presenting a large non-aerodynamic surface (when the trailer is taller than the cab). 

Aerodynamic design must also meet practical and safety needs such as providing for physical 

access and visual inspections of vehicle equipment. Because weight added to the vehicle 

impacts its overall fuel efficiency and GHG emissions and, in some circumstances the amount 

of freight the vehicle can carry, aerodynamic design and devices will sacrifice some benefit to 

overcoming their contribution to the vehicle weight. 

2.5.1.2 Technology to Reduce Aerodynamic Drag

Aerodynamic designs and devices also 

must balance being as light and streamlined as possible with being durable enough to 

withstand the rigors a working, freight vehicle encounters while traveling or loading and 

unloading. Durability can be a significant concern for cabs designed for specialty 

applications, such as “severe duty” cabs that may operate on unimproved roads. In addition, 

absent mandatory requirements, aerodynamic features for heavy-duty vehicles must appeal to 

the owners and operators. Finally, because the behavior of airflow across the cab (and cab 

and trailer combination) is dependent upon the entire system, it isn’t possible to make 

inferences about the vehicles aerodynamic performance based upon the performance of 

individual components. This can make it difficult to assess the benefit of adding (or 

subtracting) individual aerodynamic features and can discourage owners and operators from 

adopting aerodynamic technologies. 

Addressing aerodynamic drag in Class 7 and tractors requires considering the entire 

vehicle as a system to include the tractor and trailer. The overall shape can be optimized to 

Deleted: tractor aerodynamics

Deleted: 34

Deleted: 35

Deleted: reduce aerodynamic drag
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-37

minimize aerodynamic drag and, in fact, the tractor body must have at least a moderately 

aerodynamic shape (and its relatively smooth flow) to benefit from add-on aerodynamic 

components. Whether integrated into the shape of the tractor body or as an add-on 

component to a generally aerodynamic tractor, there is a wide range of technologies available 

for Class 7 and 8 tractors. Table 2-12 describes several of these potential aerodynamic 

features and components. 

Table 2-12: Technologies to Address Aerodynamic Drag

LOCATION 

ON CAB

TECHNOLOGY 

TYPE

DESIGNED EFFECT

Front Bumper, grill, hood, 

windshield

Minimize pressure created by front of vehicle moving 

ambient air to make way for truck 

Side Fuel tank fairings Reduce surface area perpendicular to wind, minimize 

opportunity to trap airflow, and smooth surface

Top Roof fairings 

(integrated) and wind 

visors (attached)

Transition air to flow smoothly over trailer and 

minimize surface area perpendicular to the wind (for 

tractor and trailer)

Rear Side extending gap 

reducers

Transition air to flow smoothly over trailer and reduce 

entrapment of air in gap between tractor and trailer

Undercarriage Underbelly treatment Manage flow of air underneath tractor to reduce 

eddies and smoothly transition flow to trailer

Accessories Mirrors, signal horns, 

exhaust

Reducing surface area perpendicular to travel and 

minimizing complex shapes that may induce drag

General Active air management Manage airflow by actively directing or blowing air 

into reduce pressure drag

General Advanced, passive air 

management

Manage airflow through passive aerodynamic shapes 

or devices that keep flow attached to the vehicle 

(tractor and trailer)

2.5.1.3 Aerodynamics in the Current Fleet

Aerodynamics in the Class 7 and 8 tractors fleet currently on the road ranges from 

trucks with few modern aerodynamic features to those that address the major areas of 

aerodynamic drag to tractors applying more advanced techniques. Because they operate at 

highway speeds less of the time, Class 7 and 8 tractors configured as day cabs (i.e., dedicated 

to regional routes) tend to have fewer aerodynamic features than cabs designed for line-haul 

applications. For tractors, it’s useful to consider aerodynamics in the current fleet as in three 

packages: the “classic” truck body; the “conventional” truck body; and the “SmartWay” truck 

body. 

“Classic” truck body: At the lower end of aerodynamic performance are tractors that 

have a “classic” truck body. These truck bodies prioritize looks or special duty capabilities 

(e.g., clearance, durability on unimproved roads, visual access to key vehicle components) 

and have remained relatively unchanged since the 1970’s. Typical applications are logging, 

waste hauling, and some agricultural related uses. These trucks incorporate few, if any, 

Deleted: Table 2-12

Deleted: ¶

¶

Deleted: ¶

Deleted: current fleet
Regulatory Impact Analysis 

2-38

aerodynamic features and several that detract from aerodynamics including equipment such as 

bug deflectors, custom sunshades, air cleaners, b-pillar exhaust stacks, additional horns, lights 

and mirrors may constitute a conventional vehicle. 

“Conventional” truck body: The conventional, modern truck capitalizes on a 

generally aerodynamic shape and avoids classic features that increase drag. The conventional, 

modern truck body has removed extra equipment (e.g., bug deflectors, custom sunshades, 

additional signal horns, decorative lights), moved essential equipment out of the airflow (e.g., 

b-pillar exhaust stacks and air cleaners), and streamlined fixed-position, essential equipment 

(e.g., mirrors, steps, and safety lights).

“SmartWay” truck body: The SmartWay aerodynamic package builds off of the 

aerodynamic package required for a Class 8 sleeper cab high roof tractor to meet the 

SmartWay design specifications and represents the top aerodynamic package widely, 

commercially available. The SmartWay package is a fully aerodynamic truck package which 

has an overall streamlined shape, removes drag inducing features (i.e., those removed or 

moved in conventional, modern truck body), and adds components to reduce drag in the most 

significant areas on the tractor. This includes aerodynamic features at the front to the tractor 

(e.g., streamlined bumper, grill, and hood), sides (i.e., fuel tank fairings and streamlined 

mirrors), top (i.e., roof fairings), and rear (i.e., side extending gap reducers). Regional and 

line-haul applications often employ different approaches, such as removable, rooftop wind 

visors and fully integrated, enclosed roof fairings, respectively, based upon their intended 

operation. 

More advanced aerodynamic features are possible and are the focus of product 

development, pilot and testing projects, and, in some cases, product lines that have seen 

limited fleet adoption. Advanced aerodynamic designs can further optimize the overall shape 

of the tractor and may add other advanced aerodynamic features (e.g., underbody airflow 

treatment, down exhaust, and lowered ride height). Some advanced aerodynamic features, 

including those listed above, show promise but will likely need ongoing refinement as these 

technologies are tailored to specific applications and payback periods are reduced. Fleets 

with whose line-haul operations permit are currently testing and using some advanced 

aerodynamic technologies.

2.5.1.4 Aerodynamic Bins

The agencies have characterized the typical aerodynamic performance (expressed as 

Cd) and cost for select applications. To do so, it was necessary to represent the wide variety 

of tractor aerodynamic shapes – which are a collection of the shapes of the multitude of 

component parts – by developing aerodynamic packages. These are the “classic,” 

“conventional,” “SmartWay,” “Advanced SmartWay,” and the “Advanced SmartWay II.” 

“Classic” aerodynamic package: As described in section 2.4.1.3, these trucks 

incorporate few, if any, aerodynamic features and several that detract from aerodynamics 

including equipment such as bug deflectors, custom sunshades, air cleaners, b-pillar exhaust 

stacks, additional horns, lights and mirrors may constitute a conventional vehicle. No cost for 

aerodynamics is assumed for the classic package.

Deleted: 36
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-39

“Conventional” package: As described in section 2.4.1.3, the conventional, modern 

truck capitalizes on a generally aerodynamic shape and avoids classic features that increase 

drag. No cost for aerodynamics is assumed for the conventional package since there has been 

no addition of additional body work and these moderate modifications to the tractor shape 

would not likely require the redesign of other components.

“SmartWay” package: Based upon the design requirements of EPA’s SmartWay 

Certified Tractors, this package has an overall streamlined shape, removes drag inducing 

features, and adds components (i.e., aerodynamic mirrors, side fairings, aerodynamic 

bumpers, and side extending gap reducers) to reduce drag in the most significant areas on the 

tractor. The SmartWay aerodynamics package does add some incremental cost above the 

classic and conventional packages.

 “Advanced SmartWay” and “Advanced SmartWay II” packages: These packages 

include components similar to that found in the SmartWay package but with additional 

aerodynamic refinement. This can be a combination of more sophisticated shape and 

increased coverage of drag inducing elements. Where the Advanced SmartWay package 

represents a tractor using the most advanced aerodynamics available today, the Advanced 

SmartWay II package is designed to represent aerodynamics expected to be available in the 

near future. With more attention paid to aerodynamic performance than the conventional 

package, the Advanced SmartWay package is estimated to be slightly more expensive. As a 

representation of the future aerodynamics, the Advanced SmartWay II package is estimated as 

being 50 percent more expensive than the Advanced SmartWay package.

The agencies developed the typical coefficient of drag (Cd) values for the truck 

categories based on coastdown testing conducted by EPA and from literature surveys. If the 

Cd values found in literature were described with a frontal area, then they were converted to a 

Cd value that represents the frontal area being proposed by the agencies for each subcategory. 

In addition to the absolute values, the agencies used the results of a wind tunnel evaluation of 

aerodynamic components. SAE 2006-01-3456 evaluated aerodynamic components on a Class 

8 high roof tractor and found that side extenders provide a Cd reduction of 0.04 and tank and 

cab skirts provide a Cd reduction of 0.03. 38

Deleted: coast down

Deleted: 37
Regulatory Impact Analysis 

2-40

Table 2-13: Tractor Cd Values 

Truck Expected Bin Source Frontal 

Area (m2 Cd)

Class 8 Sleeper Cab High Roof

International ProStar SmartWay –

Adv. 

SmartWay

ATDS39 9.8 0.54-0.56

NAS – Improved Tractor Adv. 

SmartWay

2010 NAS Report unknown 0.55-0.56

SmartWay Tractor SmartWay 2010 NAS Report unknown 0.59-0.60

Best Aero Truck SmartWay DDC Spec Manager 9.8 0.61

Full Aero SmartWay EPA PERE & 

MOVES Model

9.8 0.59

Roof Deflector Conventional EPA PERE & 

MOVES Model

9.8 0.65

International 9200i #1 Conventional TRC 9.8 0.71

International 9200i #2 Conventional NVFEL 9.8 0.70

CE-CERT Conventional EPA PERE & 

MOVES Model

9.8 0.74

No Aero Feature Classic DDC Spec Manager 9.8 0.77

Baseline Truck Classic McCallen, 1999 9.8 0.77

Class 8 Day Cab High Roof

International ProStar SmartWay ATDS 9.8 0.58

Aero Features SmartWay SAE 2005-01-3512 9.8 0.61

Roof Fairing Only Conventional SAE 2005-01-3512 9.8 0.66

Class 8 Day Cab Low Roof

International ProStar Conventional 

- SmartWay

ATDS 6.0 0.78

Based on the testing and literature information, the agencies developed the Cd value 

for each aerodynamic bin and tractor subcategory, as shown in Table 2-14.

Table 2-14: Coefficient of Drag Performance of the Aerodynamic Bins 

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low 

Roof

High 

Roof

Low Roof High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics (Cd)

Frontal Area (m2) 6.0 9.8 6.0 9.8 6.0 7.7 9.8

Classic 0.85 0.75 0.85 0.75 0.85 0.80 0.75

Conventional 0.80 0.68 0.80 0.68 0.80 0.75 0.68

SmartWay 0.75 0.60 0.75 0.60 0.75 0.70 0.60

Advanced SmartWay 0.70 0.55 0.70 0.55 0.70 0.65 0.55

Advanced SmartWay 

II

0.65 0.50 0.65 0.50 0.65 0.60 0.50

The agencies estimated the cost of the aerodynamic packages based on ICF’s price 

estimates.41

Deleted: 6.6

 The agencies applied a 15 percent reduction to the prices to reflect a large Deleted: 40
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-41

volume discount which would be applicable to the tractor manufacturers. Although 

technologies such as roof fairings may already be in widespread use today, the ICF study 

researched retail prices that a consumer would pay for the purchase of a single item in 

addition to researching possible discounts based on a large volume sale, therefore this 15 

percent discount was applied to reflect bulk purchases on these items. In addition, the 

agencies removed an RPE of 1.36 to obtain the direct manufacturer cost and then applied a 

low complexity ICM of 1.14 or a medium complexity ICM of 1.26 (for Advanced SmartWay

II) to obtain the overall technology costs included in Table 2-15 and Table 2-16. In Table 

2-17 and Table 2-18 the costs are shown including the expected penetration rates which range 

between 20 percent and 50 percent for most technologies shown.

Table 2-15 Estimated Aerodynamic Technology Costs for Class 7 & 8 Day Cabs for the 2014MY (2008$)

CLASS 7 DAYCAB CLASS 8 DAYCAB

Low Roof High Roof Low Roof High Roof

Classic $0 $0 $0 $0

Conventional $0 $0 $0 $0

SmartWay $1,079 $1,107 $1,079 $1,107

Advanced SmartWay $2,179 $2,207 $2,179 $2,207

Advanced SmartWay II $3,070 $3,111 $3,070 $3,111

Table 2-16 Estimated Aerodynamic Technology Costs for Class 8 Sleeper Cabs for the 2014My (2008$)

LOW ROOF MID ROOF HIGH ROOF

Classic $0 $0 $0

Conventional $0 $0 $0

SmartWay $1,317 $1,345 $1,495

Advanced SmartWay $2,492 $2,492 $2,564

Advanced SmartWay II $3,512 $3,512 $3,613

Table 2-17 Estimated Aerodynamic Technology Costs for Class 7 & 8 Day Cabs for the 2014MY Inclusive 

of Penetration Rates (2008$)

CLASS 7 DAYCAB CLASS 8 DAYCAB

Low Roof High Roof Low Roof High Roof

SmartWay $539 $775 $647 $332

Advanced SmartWay $436 $441 $0 $883

Table 2-18 Estimated Aerodynamic Technology Costs for Class 8 Sleeper Cabs for the 2014MY Inclusive 

of Penetration Rates (2008$)

LOW ROOF MID ROOF HIGH ROOF

SmartWay $527 $404 $1,271

Advanced SmartWay $498 $748 $256

Deleted: SmartWayII

Field Code Changed

Field Code Changed

Field Code Changed

Field Code Changed

Deleted: DayCabs

Deleted: Aeordynamic

Deleted: ¶

Deleted: DayCabs

Deleted: Aeordynamic
Regulatory Impact Analysis 

2-42

2.5.2 Tires 

Tire rolling resistance is defined as the energy consumed by the tire per unit of 

distance traveled. Energy is consumed mainly by the deformation of the tires, known as 

hysteresis, but smaller losses are due to aerodynamic drag and other friction forces between 

the tire and road surface and tire and wheel rim. About 90 percent of a tire’s rolling resistance 

comes from hysteresis. Collectively the forces that result in energy loss from the tires are 

referred to as rolling resistance. The share of truck energy required to overcome rolling 

resistance is estimated at nearly 13 percent for Class 8 trucks42. Reducing a tire’s rolling 

resistance will reduce fuel consumption and lower emissions of CO2

To measure a tire’s efficiency the vertical load supported by the tire must be factored 

because rolling resistance is a function of the load on a tire. EPA uses a tire’s rolling 

resistance coefficient (RR

and other greenhouse

gases. Low rolling resistance tires are commercially available from most tire manufacturers. 

The EPA SmartWay program identified test methods and established criteria to designate 

certain tires as “low rolling resistance” for use in the program’s emissions tracking system, 

verification program, and SmartWay vehicle specifications. Below is a discussion of EPA’s 

approach to quantifying tire rolling resistance and the emission reductions associated with 

reduced rolling resistance, and a discussion of single wide tires, retread tires, and replacement 

tires. 

c), which is measured as the rolling resistance force over vertical 

load (kg/metric ton). The RRc

Beginning in 2007, EPA began designating certain Class 8 sleeper-cab configurations 

as Certified SmartWay Tractors. In order for a tractor to be designated as Certified 

SmartWay, the tractor must be equipped with verified low rolling resistance tires (either dual 

or single wide), among other criteria. In order to be verified as a low rolling resistance tire, a 

steer tire must have a RR

baseline for today’s fleet is 7.8 kg/metric ton for the steer tire 

and 8.2 kg/metric ton for the drive tire, based on sales weighting of the top three 

manufacturers based on market share. These values are based on new tires, since rolling 

resistance decreases as the tread wears. 

c less than 6.6 kg/metric ton and a drive tire must have a RRc

Research indicates the contribution to overall vehicle fuel efficiency by tires is 

approximately equal to the proportion of the vehicle weight on them

less 

than 7.0 kg/metric ton. SmartWay-verified low rolling resistance tires are the best performing 

tires available based on fuel efficiency. The SmartWay program expects to decrease the 

maximum allowable rolling resistance coefficient by 10 percent between 2010 and 2014. As 

more low rolling resistance tires are sold, the baseline rolling resistance coefficient value will 

improve. 

43

A tire’s rolling resistance is a factor considered in the design of the tire. It is a result 

of the tread compound material, the architect of the casing, tread design and the tire 

manufacturing process. Differences in rolling resistance of up to 50 percent have been 

. On a fully loaded 

typical Class 8 long-haul truck (tractor and trailer), about 12.5 percent of the total tire energy 

loss attributed to rolling resistance is from the steer tires and about 42.5 percent is from the 

drive tires. When evaluating just the tractor, the proportionate amount of energy loss would 

be about 24 percent from the steer tires and 76 percent from the drive tires. 
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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identified for tires designed to equip the same vehicle44

43

. It is estimated that 35 percent to 50 

percent of a tire’s rolling resistance is from the tread and the other 50 to 65 percent is from the 

casing . Tires with increased RRc

Research and testing have shown a 5 percent reduction of rolling resistance provides a 

fuel consumption reduction of 1 percent while maintaining similar traction and handling 

characteristics. Bridgestone found a 5 percent improvement in rolling resistance will produce 

a 1.3 to 1.7 percent improvement in fuel economy

values are likely designed for treadwear and not fuel 

efficiency.

43. Assuming a truck achieves 6 miles per 

gallon and is driven 100,000 miles annually, a 1.5 percent improvement in fuel economy 

results in a fuel consumption reduction of 1.48 percent, which is in line with EPA’s study. 

According to Bridgestone43, use of a fuel-efficient tire will result in approximately a 12 

percent improvement in fuel economy compared to a non-fuel efficient tire at 55 mph, and 9 

percent improvement in fuel economy at 65 mph. 

To further demonstrate the correlation between rolling resistance and fuel economy, 

Michelin modeled vehicle fuel consumption using two drive cycles and various rolling 

resistance values. One drive cycle incorporated several instances of stop and start that 

replicated driving a vehicle on a secondary road; the other drive cycle replicated driving on a 

highway at nearly uniform speed but with several elevation changes. Simulations were 

performed using a base case and for rolling resistance reductions of 10 percent and 20 percent 

for both the secondary roadway and highway drive cycles. The simulation modeling for the 

secondary road drive cycle predicts a 1.8 percent and a 3.6 percent improvement in fuel 

economy as a result of the 10 percent and 20 percent reduction in rolling resistance, 

respectively45

45

. The simulation modeling for the highway drive cycle predicts a 2.6 percent 

and a 4.9 percent improvement in fuel economy as a result of the 10 percent and 20 percent 

reduction in rolling resistance, respectively . The modeling demonstrates less of a benefit 

from reduced rolling resistance when a vehicle is operated on secondary roadways. The 

modeling predicts an improvement in fuel economy from a reduction in rolling resistance 

comparable to what Bridgestone demonstrated. A 5 percent reduction in rolling resistance 

results in a 1 percent improvement in fuel economy. 

Proper tire inflation is critical to maintaining proper stress distribution in the tire, 

which reduces heat loss and rolling resistance. Tires with reduced inflation pressure exhibit 

more sidewall bending and tread shearing, therefore, have greater rolling resistance than a tire 

operating at its optimal inflation pressure. Bridgestone tested the effect of inflation pressure 

and found a 2 percent variation in fuel consumption over a 40 psi range.43 Generally, a 10 psi 

reduction in overall tire inflation results in about a 1 percent reduction in fuel economy46

Tire rolling resistance is only one of several performance criteria that affect tire 

selection. The characteristics of a tire also influence durability, traction control, vehicle 

handling and comfort. A single performance parameter can easily be enhanced, but an 

optimal balance of all the criteria must be maintained. Tire design requires balancing 

performance, since changes in design may change different performance characteristics in 

opposing direction

. To 

achieve the intended fuel economy benefits of low rolling resistance tires, it is critical that 

tires are properly maintained. 

47. Truck tires are most often axle-specific in relation to these different 
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performance criteria48

The Center for Transportation Research at Argonne National Laboratory analyzed 

technology options to support energy use projections. The Center estimated the incremental 

cost of low rolling resistance tires of $15 - $20 per tire

. The same tire on different axles or used in different applications can a 

have different rolling resistance value. Any changes to a tire would generally be accompanied 

with additional changes to suspension tuning and/or suspension design. 

61. The ICF report estimated the cost of 

low rolling resistance steer and drive tires to be $20 and $43 per tire, respectively. The NAS 

panel estimated $30 per tire. EPA and NHTSA project a cost of $65 (2008$) for low rolling 

resistance steer tires (2 per truck) for both Class 7 and 8 tractors including a low complexity 

ICM of 1.14. For low rolling resistance drive tires, the agencies estimate truck-based costs of 

$60 (2008$) and $121(2008$) for Class 7 and 8 tractors, respectively, including a low 

complexity ICM of 1.14. The higher Class 8 reflects the assumption of one drive axle for 

Class 7 tractors and two drive axles for Class 8 tractors. All costs are considered valid for the 

2014MY and time based learning would be considered appropriate for this technology.

2.5.2.1 Single Wide Tires 

Low rolling resistance tires are offered for dual assembly and as single wide tires. 

They are typically only used on the drive axle of a tractor. A single wide tire is a larger tire 

with a lower profile. The common single wide sizes include: 385/65R22.5, 425/65R22.5, 

445/65R22.5, 435/50R22.5 and 445/50R22.5. Generally, a single wide tire has less sidewall 

flexing compared to a dual assembly and therefore less hysteresis occurs. Compared to a dual 

tire assembly, single wide tires also produce less aerodynamic resistance or drag. Single wide 

tires can contribute to improving a vehicle’s fuel efficiency through design as a low rolling 

resistance tire and/or through vehicle weight reduction. 

The use of fuel efficient single wide tires can reduce rolling resistance by 3.7 to 4.9 

percent compared to the most equivalent dual tire49. An EPA study demonstrated an 

improvement in fuel economy of 6 percent at 55 mph on the highway, 13 percent at 65 mph 

on the highway and 10 percent on a suburban loop50 using single wide tires on the drive and 

trailer axles. EPA attributed the fuel economy improvement to the reduction in rolling 

resistance and vehicle weight reduction from using single wide tires. In 2008 the Department 

of Energy (DOE) compared the effect of different combinations of tires on the fuel efficiency 

of Class-8 trucks. The data collected based on field testing indicates that trucks with tractors 

equipped with single wide tires on the drive axle experience better fuel economy than trucks 

with tractors equipped with dual tires, independent of the type of tire on the trailer51

There is also a weight savings associated with single wide tires compared to dual tires. 

Single wide tires can reduce a tractor and trailer’s weight by as much as 1,000 lbs. when 

combined with aluminum wheels. Bulk haulers of gasoline and other liquids recognize the 

immediate advantage in carrying capacity provided by the reduction in the weight of tires and 

have led the transportation industry in retrofitting their tractors and trailers

. This 

study in particular indicated a 6.2 percent improvement in fuel economy from single wide 

tires. 

52

Deleted: xx

.

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New generation single wide tires, which were first introduced in 2000, are designed to 

replace a set of dual tires on the drive and/or trailer positions. They are designed to be 

interchangeable with the dual tires without any change to the vehicle53

52

. If the vehicle does 

not have hub-piloted wheels, there may be a need to retrofit axle components . In addition to 

consideration of hub / bearing / axle, other axle-end components may be affected by use of 

single wide tires. To assure successful operation, suitable components should be fitted as 

recommended by the vehicle manufacturer54

Current, single wide tires are wider than earlier models and legal in all 50 states for a 

5-axle, 80,000 GVW truck

. 

49. Single wide tires meet the “inch-width” requirements 

nationwide, but are restricted in certain states up to 17,500 lbs. on a single axle at 500 lbs/inch 

width limit, and are not allowed on single axle positions on certain double and triple 

combination vehicles53. An inch-width law regulates the maximum load that a tire can carry 

as a function of the tire width. Typically single wide tires are optimized for highway 

operation and not city or on/off highway operation. However, newer single wide tires are 

being designed for better scrub resistance, which will allow an expansion of their use. The 

current market share of single wide tires in combination tractor applications is 5 percent and 

the potential market is all combination tractors.49. New generation single wide tires represent 

an estimated 0.5 percent of the 17.5 million tires sold each year in the U.S.53. 

The Center for Transportation Research at Argonne National Laboratory estimated 

incremental capital cost of single wide tires is $30 - $40 per tire61. ICF estimates the 

incremental price of low rolling resistance tires at $20 for drive tires and $43 for steer tires.55

2.5.2.2 Replacement Tires

 

With 4 single wide tires replacing 8 dual tires on the drive axle of a tractor, the incremental 

cost would be between $120 and $160.

Original equipment (OE) tires are designed and marketed for specific applications and 

vehicles. Their characteristics are optimized for the specific application and vehicle. Because 

they are not sold as OE, replacement tires are generally designed for a variety of applications 

and vehicle types that require different handling characteristics. The tires marketed to the 

replacement tire market tend to place greater emphasis on tread wear, and therefore often have 

higher rolling resistance than OE tires. 

The market for replacement tires is individual vehicle owners and fleet owners and not 

the vehicle manufacturers. Many fleets report that the cost of fuel as opposed to driver pay is 

its number one cost. This has resulted in a greater demand for low rolling resistance 

replacement tires. Both heavy-duty and medium-duty truck fleets are looking for ways to 

reduce operational costs. 

In 2007, EPA’s SmartWay Transport Partnership introduced a means to distinguish 

tires based on their rolling resistance. Since 2007 the number of low rolling resistance tires 

available to vehicle owners and vehicle fleets has increased greatly, which is an indicator of 

an increase in demand. EPA expects this trend to continue. In addition, effective January 1, 

2010, California Air Resource Board requires that all tractor-trailers hauling dry van trailers 

on any California road be equipped with SmartWay verified low rolling resistance tires; other 

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states may adopt this requirement. EPA expects this requirement will drive the demand for 

low rolling resistance tires even further. 

2.5.2.3 Retreaded Tires

The tread life of a tire is a measure of durability and some tires are designed 

specifically for greater durability. Commercial truck tires are designed to be retreaded, a 

process in which a new tread compound is adhered to the tire casing. The original tread of a 

tire will last anywhere from 100,000 miles to over 300,000 miles, depending on vehicle 

operation, original tread depth, tire axle position, and proper tire maintenance. Retreading can 

extend the tire’s useful life by 100,000 miles or more.56 In 2005, the Tire Industry 

Association estimated that approximately 17.6 million retreaded truck tires were sold in North 

America57

To maintain the quality of the casing and increase the likelihood of retreading, a tire 

should be retreaded before the tread depth is reduced to its legal limit. At any time, a steer 

tire must have a tread depth of at least 4/32 of an inch and a drive tire must have a tread depth 

of at least 2/32 of an inch (49 CFR. § 393.75). To protect the casing, a steer tire is generally 

retreaded once the tread is worn down to 6/32 of an inch and a drive tire is retreaded once the 

tread is worn down to 8/32 of an inch.

.

58

Both the casing and the tread contribute to a tire’s rolling resistance. It is estimated 

that 35 percent to 50 percent of a tire’s rolling resistance is the result of the tread.

 Tires used on Class 8 vehicles are retreaded as many 

as three times. 

43 

Differences in drive tire rolling resistance of up to 50 percent for the same casing with various 

tread compounds have been demonstrated. For example, a fuel efficient tread compound (as 

defined by the manufacturer) was added to two different casings resulting in an average 

increase in rolling resistance of 48 percent. When a nonfuel efficient tread compound (also 

defined by the manufacturer) was added to the same casings, the rolling resistance increased 

by 125 percent on average. This characterizes the effect of the tread on the rolling resistance 

of a tire. 

Because tires can be retreaded multiple times, changes in the casing due to wear, 

damage and material aging may impact rolling resistance to a greater degree than would occur 

in an original tire. Additionally, as evidenced above, if a tread compound different than the 

original tread is used, a retreaded tire can have higher or lower rolling resistance than the 

original tire. 

There is a cost savings associated with retread tires. A new retread costs between 

$150 and $200, compared to a new tire which costs typically around $400. Since retreads are 

not typically used on the steer axle position, this represents a savings of $1,600 to $2,000 per 

tractor. 

2.5.2.4 Tire Rolling Resistance 

The agencies are projecting the following tire rolling resistance performance for 

setting the proposed tractor standards, as shown in Table 2-19. 
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Table 2-19 Tire Rolling Resistance

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/

Mid

Roof

High 

Roof

Low/Mid

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Steer Tires (Crr kg/metric ton)

Baseline 7.8 7.8 7.8 7.8 7.8 7.8 7.8

SmartWay 6.6 6.6 6.6 6.6 6.6 6.6 6.6

Advanced SmartWay 5.7 5.7 5.7 5.7 5.7 5.7 5.7

Drive Tires (Crr kg/metric ton)

Baseline 8.2 8.2 8.2 8.2 8.2 8.2 8.2

SmartWay 7.0 7.0 7.0 7.0 7.0 7.0 7.0

Advanced SmartWay 6.0 6.0 6.0 6.0 6.0 6.0 6.0

2.5.3 Weight Reduction 

Mass reduction encompasses a variety of techniques ranging from improved design 

and better component integration to application of lighter and higher-strength materials. Mass 

reduction can be further compounded by reductions in engine power and ancillary systems 

(transmission, steering, brakes, suspension, etc.). Although common on light-duty passenger 

vehicles for fuel economy and performance increases, mass reduction on heavy-duty vehicles 

is more complex due to the size and duty cycle of the vehicles.

Reducing a vehicle’s mass decreases fuel consumption and GHG output by reducing 

the energy demand needed to overcome forces resisting motion, and rolling resistance. 

Passenger vehicle manufacturers employ a systematic approach to mass reduction, where the 

net mass reduction is the addition of a direct component or system mass reduction plus the 

additional mass reduction taken from indirect ancillary systems and components, effectively 

compounding or obtaining a secondary mass reduction from a primary mass reduction. For 

example, use of a smaller, lighter engine with lower torque-output subsequently allows the 

use of a smaller, lighter-weight transmission and drive line components. Likewise, the 

compounded weight reductions of the body, engine and drivetrain reduce stresses on the 

suspension components, steering components, wheels, tires and brakes, allowing further 

reductions in the mass of these subsystems. The reductions in unsprung masses such as 

brakes, control arms, wheels and tires further reduce stresses in the suspension mounting 

points. This produces a compounding effect of ripple effect of possible mass reductions.

A fully loaded tractor-trailer combination can weigh up to 80,000 pounds. Reduction 

in overall vehicle weight could enable an increase in freight delivered on a ton-mile basis. 

Practically, this enables more freight to be delivered per truck and improves freight 

transportation efficiency. In certain applications, heavy trucks are weight-limited (i.e. bulk 

cargo carriers), and reduced tractor and trailer weight allows direct increases in the quantity of 

material that can be carried. 

Mass reduction can be accomplished by proven methods such as:

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2-48

• Smart Design: Computer aided engineering (CAE) tools can be used to better 

optimize load paths within structures by reducing stresses and bending moments 

applied to structures. This allows better optimization of the sectional thicknesses of 

structural components to reduce mass while maintaining or improving the function of 

the component. Smart designs also integrate separate parts in a manner that reduces 

mass by combining functions or the reduced use of separate fasteners. 

• Material Substitution: Substitution of lower density and/or higher strength materials 

into a design in a manner that preserves or improves the function of the component. 

This includes substitution of high-strength steels, aluminum, magnesium or composite 

materials for components currently fabricated from mild steel. Mass reduction 

through material substitution is currently broadly applied across in both light and 

heavy-duty applications in all vehicle subsystems such as aluminum engine block, 

aluminum transmission housing, high-strength steel body structure, etc. 

• Reduced Powertrain Requirements: Reducing vehicle weight sufficiently can allows 

for the use of a smaller, lighter and more efficient engine while maintaining or 

increasing work or cargo requirements. The subsequent reduced rotating mass (e.g., 

transmission, driveshafts/halfshafts, wheels and tires) via weight and/or size reduction 

of components are made possible by reduced torque output requirements.

Reduced mass in heavy-duty vehicles can benefit fuel efficiency and CO2 

Mass reduction can be achieved by making components with lighter materials (high 

strength steel, aluminum, composites) or by eliminating components from the truck. A 

common component-elimination example is to use single wide tires and aluminum rims to 

replace traditional dual tires and rims, eliminating eight steel rims and eight tires. Although 

many gains have been made to reduce truck mass, many of the features being added to 

modern trucks to benefit fuel economy, such as additional aerodynamic features or idle 

reduction systems, have the effect of increasing truck weight causing mass to stay relatively 

constant. Material and manufacturing technologies can also play a significant role in vehicle 

safety by reducing vehicle weight, and in the improved performance of vehicle passive and 

active safety systems. Although new vehicle systems, such as hybrid power trains, fuel cells 

and auxiliary power will present complex packaging and weight issues, this will further 

increase the need for reductions in the weight of the body, chassis, and power train 

components in order to maintain vehicle functionality.

emissions in 

two ways. If a truck is running at its gross vehicle weight limit with high density freight, more 

freight can be carried on each trip, increasing the trucks ton-miles per gallon. If the truck is 

carrying lower density freight and is below the GVW limit, the total vehicle mass is 

decreased, reducing rolling resistance and the power required to accelerate or climb grades.

EPA’s SmartWay transport web page discusses how the truck fuel consumption 

increases with the weight of the vehicle. Many truck components are typically made of 

heavier material, such as steel. Heavier trucks require more fuel to accelerate and to climb 

hills, and may reduce the amount of cargo that can be carried.59

Deleted: 

 Every 10 percent drop in 

truck weight reduces fuel use about 5 percent. Generally, an empty truck makes up about onethird of the total weight of the truck. Using aluminum, metal alloys, metal matrix composites, 

Deleted: 
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-49

and other lightweight components where appropriate can reduce empty truck weight (known 

as “tare weight”), improve fuel efficiency, and reduce greenhouse gas emissions. As an 

example, trimming 3,000 pounds from a heavy truck (about 4 percent of its loaded weight) 

with lighter-weight components could improve fuel economy by up to 3 percent and trucks 

that employ more weight saving options would save more. In addition, in weight-sensitive 

applications, lightweight components can allow more cargo and increased productivity. 

Another report by the National Commission on Energy Policy estimates that a fuel economy 

gain of 5.0 percent on certain applications could be achieved by vehicle mass reduction 

further illustrating the fuel economy gains possible on heavy-duty applications60

In support of the overall goal to cost-effectively enable trucks and other heavy 

vehicles to be more energy efficient and to use alternative fuels while reducing emissions, the 

21st Century Truck Partnership seeks to reduce parasitic energy losses due to the weight of 

heavy vehicles without reducing vehicle functionality, durability, reliability, or safety, and to 

do so cost-effectively. Aggressive weight reduction goals vary according to the weight class 

of the vehicle with targets between 10 and 33 percent. The weight targets for each vehicle 

class depend on the performance requirements and duty cycle. It is important to note that 

materials or technologies developed for a particular vehicle class are not necessarily limited to 

that class. For example, materials developed for lightweight frames for pickup trucks, vans, or 

SUVs will eventually be used in Class 3-5 vehicles, and materials developed to meet the 

demanding performance requirements for Class 7 and 8 trucks will find application in smaller 

vehicles. Weight reduction must not in any way sacrifice the durability, reliability, and 

performance of the vehicle. Attaining these goals by reducing inertial loading will yield 

substantial benefits such as increased fuel efficiency with concomitant reductions in 

emissions, increased available payload capacity for some vehicles, reduced rolling resistance, 

and optimized safety structures and aerodynamic drag reduction systems. 

. A third 

report, estimated potential reductions in modal GHG emissions are 4.6 percent, however also 

states current light-weight materials are costly and are application and vehicle specific with 

further research and development for advanced materials are needed.

A 2009 NESCAFF report evaluated the potential to reduce fuel consumption and CO2 

emissions by reducing weight from the baseline weight of 80,000 pounds. For the purpose of 

this calculation, the weight reduction could come either from carrying lighter freight or from a 

reduction in the empty weight of the truck. If the vehicle mass is reduced to 65,000 pounds, 

the fuel economy improves to 5.9 MPG from 5.4 MPG. The fuel savings and CO2 

Argonne has also attempted to simulate the effect of mass reduction on the fuel 

economy of heavy trucks through the National Renewable Energy Laboratory’s Advanced 

Vehicle Simulator Model, ADVISOR. The Argonne simulations relied on a few driving 

schedules developed by the West Virginia University (WVU) because there are no established 

driving schedules for heavy trucks,. While simulating a Class 8 truck on the WVU Intercity 

Driving Schedule, a fuel economy gain of 0.6 percent was observed for each 1 percent mass 

reduction from 65,000 lb to 58,000 lb

reduction on 

the baseline vehicle amount to about 0.5 percent per 1,000 pounds of mass reduction. This 

result suggests that efforts to reduce the empty vehicle mass will have only a modest benefit 

on fuel economy, for long haul routes. 

61

Deleted: 

. The maximum speed during the simulation was 61 

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Regulatory Impact Analysis 

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mph, and the average running speed (excluding stops) was 37.5 mph although most intercity 

Class 8 trucks average a much higher speed than 37.5 mph. Argonne assumed a 0.66 percent 

increase in fuel economy for each 1 percent weight reduction and total possible estimated fuel 

economy increases of 5–10 percent. While simulating a Class 6 truck on a WVU Suburban 

Driving Schedule, a fuel economy gain of 0.48 percent was observed for each 1 percent mass 

reduction from 22,600 lb to 21,800 lb. The maximum speed during the simulation was 44.8 

mph, and the average running speed was 21.5 mph. The potential fuel economy gains for 

medium trucks, both heavy- and light-, were capped at 5 percent since they are less likely to 

be weight or volume limited, and so the use of expensive lightweight material would not be 

cost-effective.

The principal barriers to overcome in reducing the weight of heavy vehicles are 

associated with the cost of lightweight materials, the difficulties in forming and 

manufacturing lightweight materials and structures, the cost of tooling for use in the 

manufacture of relatively low-volume vehicles (when compared to automotive production 

volumes), and ultimately, the extreme durability requirements of heavy vehicles. While lightduty vehicles may have a life span requirement of several hundred thousand miles, typical 

heavy-duty commercial vehicles must last over 1 million miles with minimum maintenance, 

and often are used in secondary applications for many more years. This requires high strength, 

lightweight materials that provide resistance to fatigue, corrosion, and can be economically 

repaired. Additionally, because of the limited production volumes and the high levels of 

customization in the heavy-duty market, tooling and manufacturing technologies that are used 

by the automotive industry are often uneconomical for heavy vehicle manufacturers. 

Lightweight materials such as aluminum, titanium and carbon fiber composites provide the 

opportunity for significant weight reductions, but their material cost and difficult forming and 

manufacturing requirements make it difficult for them to compete with low-cost steels. In 

addition, although mass reduction is currently occurring on both vocational and line haul 

trucks, the addition of other systems for fuel economy, performance or comfort increases the 

truck mass offsetting the mass reduction that has already occurred, thus is not captured in the 

overall truck mass measurement.

Most truck manufacturers offer lightweight tractor models that are 1,000 or more pounds 

lighter than comparable models. Lighter-weight models combine different weight-saving options that 

may include: 62

• Cast aluminum alloy wheels can save 40 pounds each for total savings of 400 pounds

• Aluminum axle hubs can save over 120 pounds compared to ductile iron or steel

• Centrifuse brake drums can save nearly 100 pounds compared to standard brake drums

• Aluminum clutch housing can save 50 pounds compared to iron clutch housing

• Composite front axle leaf springs can save 70 pounds compared to steel springs

• Aluminum cab frames can save hundreds of pounds compared to standard steel frames

• Downsizing to a smaller, lighter-weight engine can save over 700 pounds63

2.5.3.1 Derivation of Weight Technology Packages

The agencies see many opportunities for weight reduction in tractors. However, the 

empty curb weight of tractors varies significantly today. Items as common as fuel tanks can 

vary between 50 and 300 gallons each for a given truck model. Information provided by truck 
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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manufacturers indicates that there may be as much as a 5,000 to 17,000 pound difference in 

curb weight between the lightest and heaviest tractors within a regulatory subcategory (such 

as Class 8 sleeper cab with a high roof). Because there is such a large variation in the 

baseline weight among trucks that perform roughly similar functions with roughly similar 

configurations, there is not an effective way to quantify the exact CO2 and fuel consumption 

benefit of mass reduction using GEM because of the difficulty in establishing a baseline. 

However, if the weight reduction is limited to tires and wheels, then both the baseline and 

weight differentials for these are readily quantifiable and well-understood. Therefore, the 

agencies are proposing that the mass reduction that would be simulated be limited only to 

reductions in wheel and tire weight. The agencies still encourage each OEM to reduce tractor 

curb weight in as many other ways as possible, which would reduce emission and fuel 

consumption independent of the degree to which such improvements are recognized for fuel 

consumption and CO2

EPA and NHTSA are proposing to specify the baseline vehicle weight for each 

regulatory category (including the tires and wheels), but allow manufacturers to quantify 

weight reductions based on the wheel material selection and single wide versus dual tires per 

compliance purposes. In the context of this heavy-duty vehicle 

program with only changes to tires and wheels, the agencies do not foresee any related impact 

on safety. 

Table 2-20. The agencies assume the baseline wheel and tire configuration contains dual tires 

with steel wheels. The proposed weight reduction due to the wheels and tires would be 

reflected in the payload tons by increasing the specified payload by the weight reduction 

amount discounted by two thirds to recognize that approximately one third of the truck miles 

are travelled at maximum payload. 

Deleted: [TEST]

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Table 2-20: Proposed Weight Reductions

Weight Reduction (lb)

Single Wide Tire (per tire) 57

High strength steel dual wheel (per wheel) 8

Aluminum dual wheel (per wheel) 21

Light weight aluminum dual wheel (per wheel) 30

Steel single wide wheel (per wheel) 27

Aluminum single wide wheel (per wheel) 82

Light weight aluminum single wide wheel (per wheel) 90

The agencies have estimated costs for these technologies. Those costs are shown in 

Table 2-21. The costs shown include a low complexity ICM of 1.14 and time based learning 

would be considered appropriate for these technologies.

Table 2-21 Estimated Weight Reduction Technology Costs for Class 7 & 8 Tractors for the 2014MY 

(2008$)

CLASS 7 TRACTORS CLASS 8 TRACTORS

Single Wide Tire (per tire) $322 $644

Aluminum Steer Wheel $523 $523

Aluminum Wheels - dual $1,569 $2,615

Aluminum Wheel – Single wide $627 $1,254

2.5.4 Extended Idle 

Class 8 heavy-duty diesel truck extended engine idling wastes significant amounts of 

fuel in the United States. Department of Transportation regulations require a certain amount 

of rest for a corresponding period of driving hours. Extended idle occurs when Class 8 long 

haul drivers rest in the sleeper/cab compartment during rest periods as drivers find it more 

convenient and economical to rest in the truck cab itself. In many cases it is the only option 

available. During this rest period a driver will idle the truck in order to provide heating or 

cooling or run on-board appliances. During rest periods the truck’s main propulsion engine is 

running but not engaged in gear and it remains in a stationary position. In some cases the 

engine can idle in excess of 10 hours. During this period of time, fuel consumption will 

generally average 0.8 gallons per hour. Average overnight fuel usage would exceed 8 gallons 

in this example. When multiplied by the number of long haul trucks without idle control 

technology that operate on national highways on a daily basis the number of gallons 

consumed by extended idling would exceed 3 million gallons per day. Fortunately, a number 

of alternatives (idling reduction technologies) are available to alleviate this situation. 

2.5.4.1 Idle Control Technologies

Idle reduction technologies in general utilize an alternative energy source in place of 

operating the main engine. By using these devices the truck driver can obtain needed power 

for services and appliances without running the engine. A number of these devices attach to 

the truck providing heat, air conditioning, or electrical power for microwave oven, televisions, 

etc. 

Deleted: 
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-53

The idle control technologies available today include the following:64

• Auxiliary Power Unit (APU) which powers the truck’s heating, cooling, and 

electrical system. The fuel use of an APU is typically 0.2 gallons per hour

• Fuel Operated Heater (FOH) provides heating services to the truck through 

small diesel fired heaters. The fuel use is typically 0.04 gallons per hour.

• Battery Air Conditioning Systems (BAC) provides cooling to the truck.

• Thermal Storage Systems provide cooling to trucks.

Another alternative involves electrified parking spaces (EPS) with or without 

modification to the truck. An EPS system operates independently of the truck’s engine and 

allows the truck engine to be turned off as the EPS system supplies heating, cooling, and 

electrical power. The EPS system provides off-board electrical power to operate either:

1. A single system electrification requires no on-board equipment by providing an 

independent heating, cooling, and electrical power system, or 

2. A dual system which allows driver to plug in on-board equipment 

In the first case power is provided to stationary equipment that is temporarily attached 

to the truck. In the second, the truck is modified to accept power from the electrical grid to 

operate on board truck equipment. The retail price of idle reduction systems varies depending 

on the level of sophistication, for example, on-board technologies such as APUs can retail for 

over $7,000 while options such as EPS require negligible up-front costs for equipment for the 

truck itself, but will accrue fees with usage.

2.5.4.2 CO2

CO

g/ton-mile Idle Reduction Benefit 

2 emissions during extended idling are a significant contributor to Class 8 sleeper 

cabs. The federal test procedure does evaluate idle emissions as part of the drive cycle and 

related emissions measurement. However, long duration extended idle emissions are not fully 

represented during the prescribed test cycle. Consequently, there is an opportunity to 

recognize the CO2 reductions attributed to idle control systems by employing a credit 

mechanism for manufacturers who provide for idle control devices in the original truck/ 

tractor build or in the case of EPS provide a pre-purchase plan for EPS facility use and install 

all necessary equipment on the tractor. The credit would allow truck manufacturers additional 

flexibility in product design and performance capabilities as the CO2

Truck owners can obtain verified idle reduction technologies on a new truck at the 

time of purchase from the manufacturer or retrofit with verified technology after purchase 

provided a retrofit agreement is in place prior to introduction into commerce. For a 

requirements are put in 

place. 
Regulatory Impact Analysis 

2-54

manufacturer to qualify for the reduction, the agencies are proposing that a truck have an 

automatic engine shut-off system that shuts off the engine after five minutes of idling when it 

is in a parked position. This approach allows for operational strategies such as electrified 

parking spaces, team drivers, and overnights spent in hotels to achieve and idle reduction 

while still being tied back to a verifiable technology (i.e., engine shutoff).

Idle reduction credits would be based on the GHG emission and fuel consumption 

reduction from the technology when compared to main engine idling, as shown in Table 2-22. 

The main engine consumes approximately 0.8 gallons per hour during idling.65 Using a factor 

of 10,180 grams of CO2 per gallon of diesel fuel, the CO2 emissions from the main engine at 

idle is 8,144 g per hour. The agencies assumed the average Class 8 sleeper cab spends 1,800 

hours in extended idle per year to determine the idling emissions per year.66 The agencies 

then assumed the average Class 8 sleeper cab travels 125,000 miles per year (500 miles per 

day and 250 days per year) and carries 19 tons of payload (the standardized payload proposed 

for Class 8 tractors) to calculate the baseline emissions as 6.2 grams of CO2

The engine used to power the APU consumes an approximately 0.2 gallons of diesel 

fuel per hour.

per ton-mile. 

67 The CO2 emissions from the APU equate to 1.5 grams per ton-mile. 

Therefore, the agencies are proposing an idle reduction credit 5 g CO2

Table 2-22: Idle Credit Calculation

per ton-mile which 

represents the difference in emissions between the main engine idling and idling with an 

APU. Credits as proposed are based on the requirement that all Class 8 sleeper cabs shall be 

equipped with and automatic engine shut-off. The credit reflects a technology’s fuel 

consumption in conjunction with a shut-off. 

2.5.5 Vehicle Speed Limiters 

As discussed above, the power required to move a vehicle increases as the vehicle 

speed increases. Travelling at lower speeds provides additional efficiency to the vehicle 

performance. Most vehicles today have the ability to electronically control the maximum 

vehicle speed through the engine controller. This feature is used today by fleets and owners 

to provide increased safety and fuel economy. Currently, these features are able to be 

changed by the owner and/or dealer. 

Idle Fuel 

Consumption 

(gal/hour)

Idle CO2 

emissions 

per hour

Idle 

Hours 

per 

Year

Idle CO2 

Emission 

per year 

(grams)

Miles 

Per 

Year

Payload 

(tons)

GHG 

Emissions 

due to Idling 

(g/ton-mile)

GHG 

Reduction 

(g/tonmile)

Fuel 

Consumption 

Reduction 

(gal/100 tonmile)

Baseline 0.8 8,144 1,800 14,659,20

0 125,000 19 6.2

Idle 

Reduction 

Technology

0.2 2,036 1,800 3,664,800 125,000 19 1.5 5 0.05

Deleted: Individual 

Deleted: reduction associated with the technology 

employed. For example, in the case of an APU, both 

air conditioning

Deleted: heating are provided resulting in year 

round CO2 reduction opportunity. Therefore, an 

APU’s reductions could apply to the full 1800 hours 

of extended idle. However, the engine used to power 

the APU consumes an assumed 0.2 gallons of diesel 

fuel per hour. Consequently, 

Deleted: would be reduced by 0.6 gallons per hour 

for 1800 hours annually resulting in 1080 gallons of 

fuel saved per year.

Deleted: this would result in 10,994,400 grams of 

CO2 reduced (24,238 lbs. or 10.99 metric tons 

equivalent). 

Deleted: Based on

Deleted: of

Deleted: idling

Deleted: truck;

Deleted: truck;

Deleted: pay load this equates

Deleted: 6.2 g/

Deleted: After taking into account the fuel burned 

by the APU device of

Deleted: , the 

Deleted: would be 

Deleted: long haul trucks

Deleted: –

Deleted: credits reflect

Deleted: technologies’

Deleted: ¶

Formatted Table

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 0005
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-55

The impact of this feature is dependent on the difference between the governed speed 

and the speed that would have been travelled, which is dependent on road type, state speed 

limits, traffic congestion, and other factors. EPA will be assessing the benefit of a vehicle 

speed limiter by reducing the maximum drive cycle speed on the 65 mph Cruise mode of the 

cycle. The maximum speed of the drive cycle is 65 mph, therefore any vehicle speed limit 

with a setting greater than this will show no benefit for regulations, but may still show benefit 

in the real world in states where the interstate truck speed limit is greater than the national 

average of 65.5 mph.

The benefits of this simple technology are widely recognized. The American 

Trucking Association (ATA) developed six recommendations to reduce carbon emissions 

from trucks in the United States. Their first recommendation is to enact a national truck speed 

limit of 65 mph and require that trucks manufactured after 1992 have speed governors set at 

not greater than 65 mph.68 The SmartWay program includes speed management as one of 

their key Clean Freight Strategies and provides information to the public regarding the benefit 

of lower highway speeds.69

Some countries have enacted regulations to reduce truck speeds. For example, the 

United Kingdom introduced regulations in 2005 which require new trucks used for goods 

movement to have a vehicle speed limiter not to exceed 90 kph (56 mph).70 The Canadian 

Provinces of Ontario and Quebec developed regulations which took effect in January 2009 

that requires on-highway commercial heavy-duty trucks to have speed limiters which limit the 

truck’s speed to 105 km/h.71

Many truck fleets consider speed limiter application a good business practice in their 

operations. A Canadian assessment of heavy-duty truck speed limiters estimated that 60 

percent of heavy truck fleets in North America use speed limiters.72 Con Way Freight, Con 

Way Truckload, and Wal-Mart currently govern the speeds of their fleets between 62 and 65 

mph.73

A potential disbenefit of this technology is the additional time required for goods 

movement, or loss of productivity. The elasticity between speed reduction and productivity 

loss has not been well defined in industry. The Canadian assessment of speed limiters found 

that the fuel savings due to the lower operating speeds outweigh any productivity losses. A 

general consensus among the OEMs is that a one percent decrease in speed might lower 

productivity by approximately 0.2 percent.74

There is no additional capital cost associated with a vehicle speed limiter. There are 

no hardware requirements for this feature, only software control strategies. Nearly all heavyduty engines today are electronically controlled and are capable of being programmed for a 

maximum vehicle speed. The only new requirement for truck manufacturers is to offer a 

vehicle speed limiter which is protected from tampering and cannot be changed by the fleet or 

truck owner. This technology is required to be used for the full useful life of the vehicle to 

obtain the GHG emissions reduction.

The vehicle speed limiter is applicable to all truck classes which operate at high 

speeds. However, due to the structure of the first phase of the Heavy-Duty truck program, it 

Deleted: 

Deleted: 

Deleted: 

Deleted: 
Regulatory Impact Analysis 

2-56

is only applicable to the Class 7-8 tractors. The benefits of the vehicle speed limiter are 

assessed through the use of alternate High Speed Cruise cycles. The baseline cycle contains a 

constant 65 mph cruise. 

2.5.6 Automated Manual Transmission

Most heavy-duty trucks use manual transmissions with 8 to 18 ratios available. The 

most common transmissions for line haul applications have 10 ratios with an overdrive top 

gear. Torque-converter automatic transmissions, similar to those used in passenger cars, are 

used in some stop/go truck applications but are more expensive do not have an efficiency 

advantage in line-haul applications. Automated manual transmissions have been available on 

the market for over 10 years now and are increasing in market share. Automated manuals 

have a computer to decide when to shift and use pneumatic or hydraulic mechanisms to 

actuate the clutch and hidden shift levers. An automated manual can shift as quickly as the 

best driver, and the shift schedule can be tailored to match the characteristics of the engine 

and vehicle. This reduces variability of fuel consumption and CO2 emissions between drivers, 

with all drivers achieving results closer to those of the best drivers. In application, there 

would be a fuel economy improvement proportional to the number of non-fuel-conscious 

drivers in a fleet. [Reducing Heavy-Duty Long Haul Combination Truck Fuel Consumption 

and CO2

2.5.7 Class 7-8 Tractor Baseline Assessment

Emissions, NESCCAF/ICCT Final Report, October, 2009]

The agencies developed the baseline tractor for each subcategory to represent an 

average 2010 model year tractor. The approach taken by the agencies was to define the 

individual inputs to GEM. For example, the agencies evaluated the industry’s tractor 

offerings and conclude that the average tractor contains a generally aerodynamic shape (such 

as roof fairings) and avoid classic features such as exhaust stacks at the b-pillar which 

increase drag. The agencies consider a baseline truck as having “conventional” 

aerodynamics. The baseline rolling resistance coefficient for today’s fleet is 7.8 kg/metric ton 

for the steer tire and 8.2 kg/metric ton for the drive tire, based on sales weighting of the top 

three manufacturers based on market share.75

Deleted: [TEST].

 However, today there is a large spread in 

aerodynamics in the new tractor fleet. Trucks are sold that reflect classic styling, or are sold 

with conventional or SmartWay aerodynamic packages.
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-57

Table 2-23 Class 7 and 9 Baseline Attributes

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid

Roof

High Roof Low/Mid

Roof

High Roof Low Roof Mid Roof High Roof

Aerodynamics (Cd)

Frontal Area (m2) 6.0 9.8 6.0 9.8 6.0 7.7 9.8

Baseline 0.81 0.69 0.81 0.69 0.81 0.76 0.69

Steer Tires (Crr kg/metric ton)

Baseline 7.8 7.8 7.8 7.8 7.8 7.8 7.8

Drive Tires (Crr kg/metric ton)

Baseline 8.2 8.2 8.2 8.2 8.2 8.2 8.2

Weight Reduction (lbs.)

Baseline 0 0 0 0 0 0 0

Extended Idle Reduction (gram CO2

Baseline

/ton-mile reduction)

N/A N/A N/A N/A 0 0 0

Vehicle Speed Limiter

Baseline -- -- -- -- -- -- --

2.5.8 Class 7-8 Tractor Standards Derivation

EPA and NHTSA project that CO2

The agencies started with a goal of essentially forcing SmartWay technologies 

(aerodynamics, tires, and extended idle) into 100 percent of Class 7 and Class 8 tractors. 

However, as discussed below, the agencies realize that there are some restrictions which 

prevent 100 percent penetration. Therefore, the agencies took the approach of evaluating each 

technology and proposing what we deem as the maximum feasible penetration into each 

tractor regulatory category. The next sections describe the effectiveness of the individual 

technologies, the costs of the technologies, the proposed penetration rates of the technologies 

into the regulatory categories, and finally the derivation of the proposed standards.

emissions and fuel consumption reductions can be 

achieved through the increased penetration of aerodynamic technologies, low rolling 

resistance tires, weight reduction, extended idle reduction technologies, and vehicle speed 

limiters. The agencies believe that hybrid powertrains in line haul applications will not be 

cost effective in the time frame of the rule. The agencies also are proposing to not include 

drivetrain technologies in the standard setting process, as discussed in Section II, instead are 

choosing to allow the continuation of the current truck specifying process that is working well 

today.

2.5.8.1 Technology Effectiveness

The agencies’ assessment of the proposed technology effectiveness was developed 

through the use of the GEM Model in coordination with chassis testing of three SmartWay 

certified Class 8 sleeper cabs. The agencies are projecting the following tire rolling resistance 

Deleted: 6.6

Deleted: class

Deleted: classes

Deleted: [TEST]

Deleted: 
Regulatory Impact Analysis 

2-58

performance for setting the proposed tractor standards, as shows in Table 2-19. Table 2-24

describes the proposed model inputs for the range of Class 7 and 8 tractor technologies. 

Table 2-24: GEM Inputs 

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low Roof High Roof Low Roof High Roof Low Roof Mid Roof High Roof

Aerodynamics (Cd)

Frontal Area (m2) 6.0 9.8 6.0 9.8 6.0 7.7 9.8

Classic 0.85 0.75 0.85 0.75 0.85 0.80 0.75

Conventional 0.80 0.68 0.80 0.68 0.80 0.75 0.68

SmartWay 0.75 0.60 0.75 0.60 0.75 0.70 0.60

Advanced SmartWay 0.70 0.55 0.70 0.55 0.70 0.65 0.55

Advanced SmartWay II 0.65 0.50 0.65 0.50 0.65 0.60 0.50

Steer Tires (Crr kg/metric ton)

Baseline 7.8 7.8 7.8 7.8 7.8 7.8 7.8

SmartWay 6.6 6.6 6.6 6.6 6.6 6.6 6.6

Advanced SmartWay 5.7 5.7 5.7 5.7 5.7 5.7 5.7

Drive Tires (Crr kg/metric ton)

Baseline 8.2 8.2 8.2 8.2 8.2 8.2 8.2

SmartWay 7.0 7.0 7.0 7.0 7.0 7.0 7.0

Advanced SmartWay 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Weight Reduction (lbs.)

Control 400 400 400 400 400 400 400

Extended Idle Reduction (gram CO2

Control

/ton-mile reduction)

N/A N/A N/A N/A 5 5 5

Vehicle Speed Limiter

Control N/A N/A N/A N/A N/A N/A N/A

2.5.8.2 Class 7-8 Tractor Application Rates

Vehicle manufacturers often introduce major product changes together, as a package. 

In this manner the manufacturers can optimize their available resources, including 

engineering, development, manufacturing and marketing activities to create a product with 

multiple new features. In addition, manufacturers recognize that an engine and truck will 

need to remain competitive over its intended life and meet future regulatory requirements. In 

some limited cases, manufacturers may implement an individual technology outside of a 

vehicle’s redesign cycle. In following with these industry practices, the agencies have created 

a set of vehicle technology packages for each regulatory subcategory.

With respect to the level of technology required to meet the standards, NHTSA and 

EPA established technology application caps. The first type of cap was established based on 

the application of common fuel consumption and CO2

Deleted: The agencies are projecting the following 

tire rolling resistance performance for setting the 

proposed tractor standards, as shown in Table 

2-192-112-11Table 2-11. ¶

emission reduction technologies into 

the different types of tractors. For example, idle reduction technologies are limited to Class 8 

Field Code Changed

Deleted: TEST

Deleted: 6.6

Deleted: Baseline ...

Deleted: Baseline ...

Deleted: Baseline ...

Deleted: class
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-59

sleeper cabs using the assumption that day cabs are not used for overnight hoteling. A second 

type of constraint was applied to most other technologies and limited their penetration based 

on factors such as market demands.

The impact of aerodynamics on a truck’s efficiency increases with vehicle speed. 

Therefore, the usage pattern of the truck will determine the benefit of various aerodynamic 

technologies. Sleeper cabs are often used in line haul applications and drive the majority of 

their miles on the highway travelling at speeds greater than 55 mph. The industry has focused 

aerodynamic technology development, including SmartWay certified tractors, on these types 

of trucks. Therefore the agencies are proposing the most aggressive aerodynamic technology 

penetration in this regulatory subcategory. All of the major manufacturers today offer at least 

one truck model that is SmartWay certified. The National Academy of Sciences report on 

heavy-duty truck found that manufacturers indicated that aerodynamic improvements which 

yield 3 to 4 percent fuel consumption reduction or 6 to 8 percent reduction in Cd values, 

beyond technologies used in today’s SmartWay trucks are achievable.76

The aerodynamic penetration for the other tractor regulatory subcategories is less 

aggressive than for the Class 8 sleeper cab high roof. The agencies acknowledge that there 

are truck applications which require on/off-road capability and other truck functions which 

restrict the type of aerodynamic equipment applicable. We also recognize that these types of 

trucks spend less time at highway speeds where aerodynamics have the greatest benefit. The 

2002 Vehicle Inventory and Use Survey (VIUS) data ranks trucks by major use.

 EPA and NHTSA 

are proposing that the aerodynamic penetration rate for Class 8 sleeper cab high roof cabs to 

consist of 20 percent of advanced SmartWay, 70 percent SmartWay, and 10 percent 

conventional. The small percentage of conventional truck aerodynamics is for applications 

such as refuse haulers which spend a portion of their time off-road at the land fill. Features 

such as chassis skirts are prone to damage in off-road applications; therefore we are not 

proposing to require that all trucks have chassis skirts.

77

Trucks designed for on/off-road application may be restricted in the ability to improve 

the aerodynamic design of the bumper, chassis skirts, air cleaners, and other aspects of the 

truck. First, off-road applications may require the use of steel bumpers which tend to be less 

aerodynamic than plastic designs. Second, ground clearance may be an issue for some off 

road applications due to poor road surface quality. This may pose a greater likelihood those 

items such as chassis skirts incur damage in use and therefore would not be a technology 

desirable in these applications. Third, the trucks used in off-road applications may also 

experience dust which requires an additional air cleaner to manage the dirt. Fourth, some 

trucks are used in applications which require heavier load capacity, such as those with gross 

combined weights of greater than 80,000 pounds, which is today’s federal highway limit. 

Often these trucks are configured with different axle combinations than those traditionally 

used on-road. These trucks may contain either a lift axle or spread axle which allows for 

 The heavy 

trucks usage indicates that up to 35 percent of the trucks may be used in on/off-road 

applications or heavier applications. The uses include construction (16 percent), agriculture 

(12 percent), waste management (5 percent), and mining (2 percent). Therefore the agencies 

analyzed the technologies to evaluate the potential restrictions that would prevent 100 percent 

penetration of SmartWay technologies for all of the tractor regulatory subcategories.

Deleted: class

Deleted: 

Deleted: classes

Deleted: classes
Regulatory Impact Analysis 

2-60

greater carrying capability. Both of these configurations limit the design and effectiveness of 

chassis skirts. Lastly, some work trucks require the use of power take off (PTO) operation or 

access to equipment which may limit the application of side extenders and chassis skirts.

NHTSA and EPA have considered these potential restrictions while developing the 

proposed maximum penetration rate of each of the aerodynamic bins for the Class 7 and 8 

tractors. The high roof applications are designed for more highway driving and pulling box 

trailers. Therefore, they have the greatest penetration rates. However, truck buyers will 

typically purchase low roof cabs to handle the on/off-road or heavier applications. Therefore, 

the penetration rates are lower for these segments.

Tire rolling resistance is only one of several performance criteria that affect tire 

selection. The characteristics of a tire also influence durability, traction control, vehicle 

handling and comfort. A single performance parameter can easily be enhanced, but

Weight reductions can be achieved through single wide tires replacing dual tires and 

lighter weight wheel material. Single wide tires can reduce weight by over 160 pounds per 

axle. Aluminum wheels used in lieu of steel wheels will reduce weight by over 80 pounds for 

a dual wheel axle. Light weight aluminum steer wheels and aluminum single wide drive 

wheels and tires package will provide a 670 pound weight reduction over the baseline steel 

steer and dual drive wheels. The agencies are proposing 100 percent penetration of a 

technology package which reduces vehicle weight by 400 pounds. 

an 

optimal balance of all the criteria must be maintained. Tire design requires balancing 

performance, since changes in design may change different performance characteristics in 

opposing direction. Similar to the discussion regarding lesser aerodynamic technology 

penetration in tractor segments other than sleeper cab high roof, the agencies believe that low 

rolling resistance tires should not be applied to 100 percent of all tractor segments. The 

agencies are proposing application rates that vary by subcategory to reflect the on/off-road 

application of some tractors which require a different balancing of traction versus rolling 

resistance.

Idle reduction technologies provide significant reductions in fuel consumption and 

CO2 emissions. There are several different technologies available to reduce idling. Auxiliary 

power units, diesel fired heaters, and battery powered units. Each of these technologies has a 

different level of fuel consumption and CO2

Vehicle speed limiters will be used as a technology to meet the standard, but was not 

used to set the standard. The agencies do not want to create the perception of setting a 

emissions. Therefore, the emissions reduction 

value varies by technology. Also, our discussions with manufacturers indicate that idle 

technologies are sometimes installed in the factory, but it is also a common practice to have 

the units installed after the sale of the truck. Therefore, we would like to continue to 

incentivize this practice while providing some certainty that the overnight idle operations will 

be eliminated. Therefore, we are allowing the installation of only an automatic engine 

shutoff, without override capability, to qualify for idle emission reductions. We are proposing 

a 100 percent penetration rate for this technology and have estimated that 30 percent of the 

current fleet already employs this technology meaning that 70 percent are estimated to add 

this technology.

Deleted: The agencies welcome comment on our 

assessment of penetration rates and are interested in 

data which provides estimates on truck sales to the 

various applications where aerodynamics are less 

effective or restricted.

Deleted: EPA and NHSTA in developing the 

proposal have received comment from manufacturers 

and owners that trucks sometimes have very limited 

on-road usage. These trucks by definition of Title 

40, Part 85.1703 are motor vehicles, but will spend 

the majority of the life off-road. Trucks, such as 

those used in oil fields, will experience little benefit 

from improved aerodynamics. The agencies are 

therefore proposing to allow a narrow range of these 

off-road trucks to be excluded from the vehicle 

requirements because the trucks do not travel at 

speeds high enough to realize aerodynamic 

improvements and require special off-road tires such 

as lug tires. The trucks must still use a certified 

engine, which will provide fuel consumption and 

CO2 emission reductions to the truck in all 

applications. The trucks must meet the following 

requirements to qualify for an exemption:¶

<#>Installed tires which are lug tires or contain a 

speed rating of less than or equal to 60 mph; and¶

<#>Contain PTO controls, or have axle 

configurations other than 4x2, 6x2, or 6x4 and have 

GVW greater than 57,000 pounds; and¶

<#>Include a vehicle speed limiter governed to 55 

mph, and¶

<#>Has a frame Resisting Bending Moment (RBM) 

greater than 2,000,000 lb. in.¶

EPA and NHTSA have determined that the 

restrictions and the additional cost to develop a truck 

which meets these specifications will limit the 

exemption to trucks built for the desired purposes.

Deleted: 78¶

Deleted: class

Deleted: We are seeking comment on our 

assessment.
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-61

national speed limit for trucks. While we believe this is a simple, easy to implement, and 

inexpensive technology, we want to leave the use up to the truck purchaser. Since truck fleets 

purchase trucks today with this option, we believe the trend will continue. However, we 

cannot predict the impact of this technology on the resale value of the truck and the decreased 

productivity, therefore we leave it to the purchasers to optimize the use of speed limiters 

based on the fuel savings relative to impact on business operations and resale value.

Table 2-25 provides the proposed application rates for each technology by regulatory 

subcategory.

Table 2-25: Proposed Application Rates

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid

Roof

High Roof Low/Mid

Roof

High Roof Low Roof Mid Roof High Roof

Aerodynamics (Cd)

Classic 0% 0% 0% 0% 0% 10% 0%

Conventional 40% 30% 40% 30% 30% 20% 10%

SmartWay 50% 60% 50% 60% 60% 60% 70%

Advanced 

SmartWay

10% 10% 10% 10% 10% 10% 20%

Advanced 

SmartWay II

0% 0% 0% 0% 0% 0% 0%

Steer Tires (Crr kg/metric ton)

Baseline 40% 30% 40% 30% 30% 30% 10%

SmartWay 50% 60% 50% 60% 60% 60% 70%

Advanced 

SmartWay

10% 10% 10% 10% 10% 10% 20%

Drive Tires (Crr kg/metric ton)

Baseline 40% 30% 40% 30% 30% 30% 10%

SmartWay 50% 60% 50% 60% 60% 60% 70%

Advanced 

SmartWay

10% 10% 10% 10% 10% 10% 20%

Weight Reduction (lbs.)

Control 100% 100% 100% 100% 100% 100% 100%

Extended Idle Reduction (gram CO2

Control

/ton-mile reduction)

Not 

Applicable

Not 

Applicable

Not 

Applicable

Not 

Applicable

100% 100% 100%

Vehicle Speed Limiter

Control -- -- -- -- -- -- --

The agencies used the technology inputs and proposed technology application rates in 

GEM to develop the fuel consumption and CO2

Table 2-24

emissions standards for each subcategory of 

Class 7/8 combination tractors. The agencies derived a scenario truck for each subcategory 

by weighting the individual GEM input parameters included in by the application 

rates in Table 2-25. For example, the Cd value for a Class 8 Sleeper Cab High Roof scenario 

Deleted: Baseline ...

Deleted: Baseline ...

Deleted: Baseline ...
Regulatory Impact Analysis 

2-62

case was derived as 10 percent times 0.68 plus 70 percent times 0.60 plus 20 percent times 

0.55, which is equal to a Cd of 0.60. Similar calculations were done for tire rolling resistance, 

weight reduction, idle reduction, and vehicle speed limiters. To account for the two proposed 

engine standards, EPA is proposing the use of a 2014 model year fuel consumption map in 

GEM to derive the 2014 model year tractor standard and a 2017 model year fuel consumption 

map to derive the 2017 model year tractor standard.79

Table 2-26

 The agencies then ran GEM with a 

single set of vehicle inputs, as shown in , to derive the proposed standards for each 

subcategory. The proposed standards and percent reductions are included in Table 2-27.
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-63

Table 2-26 Inputs to the GEM model for Class 7/8 Standard Setting

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid 

Roof

High Roof Low/Mid 

Roof

High Roof Low Roof Mid Roof High Roof

Aerodynamics (Cd) 0.77 0.62 0.77 0.62 0.76 0.72 0.60

Steer Tire CRR 

(kg/metric ton)

6.99 6.87 6.99 6.87 6.87 6.87 6.54

Drive Tire CRR 

(kg/metric ton)

7.38 7.26 7.38 7.26 7.26 7.26 6.92

Weight Reduction (lbs.) 400 400 400 400 400 400 400

Extended Idle Reduction 

(g/ton-mile)

-- -- -- -- 5 5 5

Vehicle Speed Limiter -- -- -- -- -- -- --

2014 MY Proposed Standard

Engine 2014 MY 

11L

2014 MY 

11L

2014 MY 

15L

2014 MY 

15L

2014 MY 

15L

2014 MY 

15L

2014 MY 

15L

2017 MY Proposed Standard

Engine 2017 MY 

11L

2017 MY 

11L

2017 MY 

15L

2017 MY 

15L

2017 MY 

15L

2017 MY 

15L

2017 MY 

15L

Table 2-27 Proposed Tractor Standards and Percent Reductions

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid 

Roof

High Roof Low/Mid 

Roof

High Roof Low Roof Mid Roof High Roof

2014 Model Year

2014 MY Voluntary Fuel 

Consumption Standard 

(gallon/1000 ton-mile)

10.3 11.6 7.8 8.6 6.3 6.9 7.1

2014 MY CO2 Standard 

(grams CO2

104

/ton-mile)

118 79 87 65 70 73

Percent Reduction 6% 9% 6% 9% 15% 14% 18%

2017 Model Year

2017 MY Fuel 

Consumption Standard 

(gallon/1000 ton-mile)

10.1 11.4 7.7 8.5 6.3 6.8 7.0

2017 MY CO2 Standard 

(grams CO2

103

/ton-mile)

116 78 86 64 69 71

Percent Reduction 7% 11% 7% 10% 16% 15% 20%
Regulatory Impact Analysis 

2-64

2.5.9 Class 7-8 Tractor Technology Costs

The technology costs associated with the tractor defined in Table 2-26 for each of the 

tractor subcategories are listed in Table 2-28.

Table 2-28 Estimated Class 7-8 Tractor Technology Costs, Inclusive of Markups and Penetration Rates, 

Applicable in the 2014MY (2008 dollars)

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low Roof High Roof Low Roof High Roof Low Roof Mid Roof High Roof

Aerodynamics 

SmartWay & Advanced 

SmartWay $975 $1,216 $647 $1,215 $1,025 $1,152 $1,527

Steer Tires 

Low Rolling Resistance $65 $65 $65 $65 $65 $65 $65

Drive Tires 

Low Rolling Resistance $60 $60 $121 $121 $121 $121 $121

Weight Reduction 

Control $1,472 $1,472 $2,421 $2,421 $2,421 $2,421 $2,421

Extended Idle Reduction

Auxiliary Power Unit N/A N/A N/A N/A $3,660 $3,660 $3,660

Vehicle Speed Limiter

Control N/A N/A N/A N/A N/A N/A N/A

2.6 Class 2b-8 Vocational Vehicles

2.6.1 Tires 

The range of rolling resistance of tires used on vocational vehicles (Class 2b – 8) 

today is large. The competitive pressure to improve rolling resistance of these tires has been 

less than that found in the Class 8 line haul tire market. Due to the drive cycles typical for 

these applications, tire traction and durability are weighed more heavily in a purchaser’s 

decision than rolling resistance. Therefore, EPA believes that a regulatory program that 

incentivizes the optimization of tire rolling resistance, traction and durability can bring about 

GHG emission reductions from this segment. It is estimated that low rolling resistance tires 

used on Class 3 – 6 trucks would improve fuel economy by 2.5 percent61

Tires used on vocational vehicles (Class 2b – 8) typically carry less load than a Class 8

line haul vehicle. They are also designed for instances of high scrubbing. Because they carry 

less load and high scrubbing, tires used on vocational vehicles are can retreaded as many as 

five times. 

relative to tires not 

designed for fuel efficiency.

Deleted: Table 2-26¶

Deleted: Classic ...

Formatted Table

Deleted: 539

Deleted: 775

Deleted: 332

Deleted: 527

Deleted: 404

Deleted: 271

Deleted: Advanced SmartWay ...

Deleted: 5,228

Deleted: 5,228

Deleted: 5,228

Deleted: Trucks

Deleted: trucks

Deleted: class
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-65

The baseline tire rolling resistance for this segment of vehicles was derived for the 

proposal based on the current baseline tractor80 and passenger car tires.81

The agencies have estimated the costs of low rolling resistance tires as shown in 

 The baseline tractor 

drive tire has a rolling resistance of 8.2 kg/metric ton. The average passenger car has a tire 

rolling resistance of 9.75 kg/metric ton. EPA and NHTSA derived the vocational vehicle tire 

baseline rolling resistance from the average of these two values. EPA is conducting an 

extensive tire rolling resistance evaluation during 2010 and anticipates that the baseline value 

will be updated for the final rulemaking based on the results.

Table 

2-29. These costs include a low complexity ICM of 1.14 and time based learning would be 

considered appropriate for these technologies.

Table 2-29 Estimated Costs for Low Rolling Resistance Tires on Vocational Vehicles in the 2014MY 

(2008$)

LIGHT-HEAVY & 

MEDIUM-HEAVY HEAVY-HEAVY

Low rolling resistance steer tires $65 $65

Low rolling resistance drive tires $91 $121

2.6.2 Other Evaluated Technologies

2.6.2.1 Aerodynamics 

Aerodynamic drag is an important aspect of the power requirements for Class 2b 

through 8 vocational vehicles. Because aerodynamic drag is a function of the cube of vehicle 

speed, small changes in the aerodynamics of a vocational vehicle reduces drag, fuel 

consumption, and GHG emissions. The great variety of applications for vocational vehicles

result in a wide range of operational speed profiles (i.e., in-use drive cycles) with many 

weighted toward lower speeds where aerodynamic improvement benefits are less pronounced. 

In addition, vocational vehicles have a wide variety of configurations (e.g., utility trucks with 

aerial devices, transit buses, and pick-up and delivery trucks) and functional needs (e.g., 

ground clearance, towing, and all weather capability). This specialization can make the 

implementation of aerodynamic features impractical and, where specialty markets are limited, 

make it unlikely that per-unit costs will lower with sales volume.

This technology is not expected as a result of the proposed standards.

2.6.2.2 Hybrid Powertrains

A hybrid electric vehicle (HEV) is a vehicle that combines two or more sources of 

propulsion energy, where one uses a consumable fuel (i.e. gasoline or diesel), and one is 

rechargeable (during operation, or by another energy source). Hybrid technology is 

established in the U.S. market and more manufacturers are adding hybrid models to their 

lineups. Hybrids reduce fuel consumption through three major mechanisms:

Deleted: truck

Deleted: 28

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Deleted: trucks

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Regulatory Impact Analysis 

2-66

• Powertrain control strategy can be developed to operate the engine at or near its 

most efficient point most of the time.

• The internal combustion engine can be optimized through downsizing or

modifying the operating cycle. Power loss from engine downsizing can be 

mitigated by employing power assist from the secondary power source.

• Some of the energy normally lost as heat while braking can be captured and stored 

in the energy storage system for later use.

• The engine is turned off when it is not needed, such as when the vehicle is coasting 

or stopped, such as extending idle conditions.

Hybrid vehicles utilize some combination of the three above mechanisms to reduce 

fuel consumption and CO2

The effectiveness of fuel consumption and CO

emissions. A fourth mechanism to reduce fuel consumption, 

available only to plug-in hybrids, is by substituting the petroleum fuel energy with energy 

from another source, such as the electric grid. Plug-in hybrids may be suitable for some

applications which travel short distances such as local pickup and delivery. 

2

In addition to the purely hybrid technologies, which decreases the proportion of 

propulsion energy coming from the fuel by increasing the proportion of that energy coming 

from electricity, there are other steps that can be taken to improve the efficiency of auxiliary 

functions (e.g., power-assisted steering or air-conditioning) which also reduce CO

reduction depends on the utilization of 

the above mechanisms and how aggressively they are pursued. One area where this variation 

is particularly prevalent is in the choice of engine size and its effect on balancing fuel 

economy and performance. Some manufacturers choose not to downsize the engine when 

applying hybrid technologies depending on the power from the hybrid system components. In 

these cases, performance is improved, while fuel efficiency improves significantly less than if 

the engine was downsized to maintain the same performance as the conventional version. 

While this approach has been used in passenger cars it is more likely to be used for trucks 

where towing, hauling and/or cargo capacity is an integral part of their performance 

requirements. In these cases, if the engine is downsized, the battery can be quickly drained 

during a long hill climb with a heavy load, leaving only a downsized engine to carry the entire 

load. Because cargo capability is critical truck attribute, manufacturers are hesitant to offer a 

truck with downsized engine which can lead to a significantly diminished towing performance 

with a low battery, and therefore engines are traditionally not significantly downsized for 

these vehicles.

2

A hybrid drive unit is complex and consists of discrete components such as the electric 

traction motor, transmission, generator, inverter, controller and cooling devices. Certain types 

emissions 

and fuel consumption. Optimization of the auxiliary functions, together with the hybrid 

technologies, is collectively referred to as vehicle or accessory load electrification because 

they generally use electricity instead of engine power. Fuel efficiency gains achieved only 

electrification is considered in a separate section although may be combined with the hybrid 

system.

Deleted: (

Deleted: ,

Deleted: , or other control techniques) to operate at

or near its most efficient point more of the time. 

Deleted: Although plug

Deleted: are not considered feasible

Deleted: truck

Deleted: for propulsion power, this mechanism is 

explored further for trucks in a separate section 

discussing extended idle
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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of drive units may work better than others for specific vehicle applications or performance 

requirements. Several types of motors and generators have been proposed for hybrid-electric 

drive systems, many of which merit further evaluation and development on specific 

applications. Series HEVs typically have larger motors with higher power ratings because the 

motor alone propels the vehicle, which may be applicable to Class 3-5 applications. In parallel 

hybrids, the power plant and the motor combine to propel the vehicle. Motor and engine 

torque are usually blended through couplings, planetary gear sets and clutch/brake units. The 

same mechanical components that make parallel heavy-duty hybrid drive units possible can 

be designed into series hybrid drive units to decrease the size of the electric motor(s) and 

power electronics. 

An electrical energy storage system is needed to capture energy from the generator, to 

store energy captured during vehicle braking events, and to return energy when the driver 

demands power. This technology has seen a tremendous amount of improvement over the last 

decade and recent years. Advanced battery technologies and other types of energy storage are 

emerging to give the vehicle its needed performance and efficiency gains while still providing 

a product with long life. The focus on the more promising energy storage technologies such as 

nickel metal-hydride (NiMH) and lithium technology batteries along with ultra capacitors for 

the heavy-duty fleet should yield interesting results after further research and applications in 

the light-duty fleet.

Heavy-duty hybrid vehicles also use regenerative braking for improved fuel economy, 

emissions, brake heat, and wear. A conventional heavy vehicle relies on friction brakes at the 

wheels, sometimes combined with an optional engine retarder or driveline retarder to reduce 

vehicle speed. During normal braking, the vehicle’s kinetic energy is wasted when it is 

converted to heat by the friction brakes. The conventional brake configuration has large 

components, heavy brake heat sinks, and high temperatures at the wheels during braking, 

audible brake squeal, and consumable components requiring maintenance and replacement. 

Hybrid electric systems recover some of the vehicle’s kinetic energy through regenerative 

braking, where kinetic energy is captured and directed to the energy storage system. The 

remaining kinetic energy is dissipated through conventional wheel brakes or in a driveline or 

transmission retarder. Regenerative braking in a hybrid electric vehicle can require integration 

with the vehicle’s foundation (friction) braking system to maximize performance and safety. 

Today’s systems function by simultaneously using the regenerative features and the friction 

braking system, allowing only some of the kinetic energy to be saved for later use. Optimizing 

the integration of the regenerative braking system with the foundation brakes will increase the 

benefits and is a focus for continued work. This type of hybrid regenerative braking system 

improves fuel economy, GHG emissions, brake heat, and wear.

In addition to electric hybrid systems, EPA is experimenting with a Class 6 hydraulic 

hybrid that achieves a fuel economy increase superior to that of an electric hybrid.

82

Deleted: 

 In this 

type of system, deceleration energy is taken from the drivetrain by an inline hydraulic 

pump/motor unit by pumping hydraulic fluid into high pressure cylinders. The fluid, while not 

compressible, pushes against a membrane in the cylinder that compresses an inert gas to 5,000 

PSI or more when fully charged. Upon acceleration, the energy stored in the pressurized tank 

pushes hydraulic fluid back into the drivetrain pump/motor unit, allowing it to motor into the 

Deleted: 

Deleted: 

Deleted: 

Deleted: similar

Deleted: gains and given high manufacturing 

volumes at with similar electric hybrid costs.
Regulatory Impact Analysis 

2-68

drivetrain and assist the vehicle’s engine with the acceleration event. This heavy-duty truck 

hybrid approach has been demonstrated successfully, producing good results on a number of 

commercial and military trucks. 

Considering the diversity of the heavy-duty fleet along with the various types of 

hybridization, the results are diverse as well. The percentage savings that can be expected 

from hybridization is very sensitive to duty cycle. For this reason, analyses and efforts to 

promote hybrids often focus on narrow categories of vehicles. For vocational vehicles other 

than tractor-trailers, hybrid technologies are promising, because a large fraction of miles 

driven by these trucks are local and under stop-and-go conditions. One study claims 

hybridization could almost double fuel economy for Class 3-5 trucks and raise Class 6-7 fuel

economy by 71 percent in city driving, at costs that will decline rapidly in the coming years 

with the incremental cost of the hybrid vehicles depending on the choice of technology and 

the year, the later being a surrogate for progress towards economies of scale and experience 

with the technology60. Another Argonne National Lab study considering only truck Classes 2 

and 3 indicates possible fuel efficiency gains of 40 percent61. The Hybrid Truck Users Forum 

has published a selection of four types as good candidates for hybridization; Class 4-8 

Specialty Trucks, including utility and fire trucks; Class 4-6 urban delivery trucks, including 

package and beverage delivery; Class 7 and 8 refuse collection; and Class 7 and 8 less-thanload urban delivery trucks. The average fuel economy increase over the five cycles is 93 

percent for the Class 3-4 truck and 71 percent for the Class 6-7 vehicle. 

Stop-and-go truck driving includes a fraction of idling conditions during which the 

truck base engine consumes fuel but produces no economically useful output (e.g., movement 

of goods, or repositioning of the truck to a new location). Hybrid propulsion systems, shut off 

the engine under idling conditions or situations of low engine power demand. Trucks that 

have high fractions of stop-and-go freight transport activities within their driving cycles, such 

as medium-duty package and beverage delivery trucks, are appropriate candidates for 

hybridization. Long-haul trucks have a lower proportion of short-term idling or low engine 

power demand in their duty cycles because of traffic conditions or frequency stops compared 

to medium-duty trucks in local services. Based on the results of hybridization effects 

modeling, medium-duty trucks in local service (e.g., delivery) can reduce energy use by 41.5 

percent83. Another 2009 report states that a 10 percent fuel consumption decrease could be 

achieved if idle reduction benefits were realized and a 5 percent improvement considering for 

on-road only 84

In heavy-duty hybrid research, the industry role will be represented by the heavyhybrid team members (e.g. Allison Transmission, Arvin-Meritor, BAE Systems, and Eaton 

Corporation). The Department of Energy is pursuing heavy hybrid research through the 

Freedom CAR and Vehicle Technologies Program. The Department of Transportation 

(Federal Transit Administration) is playing a role in demonstration of these vehicles for the 

transit bus market. The Department of Defense is working with heavy hybrid equipment 

suppliers to develop and demonstrate hybrid vehicles for military applications, and has 

already made significant investments in hybrid technology to reduce fuel consumption and 

improve their ability to travel silently in combat situations. The Environmental Protection 

Agency has participated in the heavy hybrid arena through its work on mechanical hybrids for 

certain applications as discussed previously. The U.S. Department of Energy’s 21st Century 

. 

Deleted: 

Deleted: 

Deleted: trucks
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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Truck Partnership (21CTP) has established challenging goals for improving fuel economy and 

pollutant emissions from heavy-duty vehicles including a diverse set of vehicles ranging from 

approximately 8,500 lb GVW to 100,000+ lb GVW42. 

In summary, many technologies that apply to cars do not apply to heavy-duty trucks 

and there is a common perception that investments in passenger car (light-duty vehicle) 

technology can easily benefit heavy-duty trucks. This group of vehicles is very diverse and 

includes tractor-trailers, refuse and dump trucks, package delivery vehicles and buses. The 

life expectancy and duty cycles for heavy-duty vehicles are about ten times more demanding 

than those for light-duty vehicles, technologies and solutions for the fleet must be more 

durable and reliable. Although a new generation of components is being developed for 

commercial and military HEVs, more research and testing are required.

There are no simple solutions applicable for each heavy-duty hybrid application due to 

the large fleet variation. A choice must be made relative to the requirements and priorities for 

the application. Challenges in motor subsystems such as gear reductions and cooling systems 

must be considered when comparing the specific power, power density, and cost of the motor 

assemblies. High speed motors can significantly reduce weight and size, but they require 

speed reduction gear sets that can offset some of the weight savings, reduce reliability and add 

cost and complexity. Air-cooled motors are simpler and generally less expensive than liquidcooled motors, but they will be larger and heavier, and they require access to ambient air, 

which can carry dirt, water, and other contaminants. Liquid-cooled motors are generally 

smaller and lighter for a given power rating, but they may require more complex cooling 

systems that can be avoided with air-cooled versions. Various coolant options, including 

water, water-glycol, and oil, are available for liquid-cooled motors but must be further 

researched for long term durability. Electric motors, power electronics, electrical safety, 

regenerative braking, and power-plant control optimization have been identified as the most 

critical technologies requiring further research to enable the development of higher efficiency 

hybrid electric propulsion systems.

In addition, because manufacturers will incur expenses in bringing hybrids to market, 

and because buyers do not purchase vehicles on the basis of net lifetime savings, the costeffectiveness of hybrids may not in itself translate into market success, and measures to 

promote hybrids are needed until costs come down. Vocational vehicles have diverse duty 

cycles, and they are used to a far greater extent for local trips. Some of the technologies are 

much less effective for trucks that generally drive at low speeds and therefore have limited 

applicability. Conversely, these trucks are the best candidates for hybrid technology, because 

local trips typically involve a large amount of stop-and-go driving, which permits extensive 

capture of braking and deceleration energy.

Due to the complexity of the heavy-duty fleet, the variation of hybrid system reported 

fuel efficiency gains and the growing research and testing – vehicle hybridization is not 

mandated nor included in the model for calculation of truck fuel efficiency and GHG output. 

Vehicle hybridization is feasible on both tractor and vocational applications but must be tested 

on an individual basis to an applicable baseline to realize the system benefits and net fuel 

usage and GHG reductions.

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: 

Deleted: trucks

Deleted: 
Regulatory Impact Analysis 

2-70

2.6.2.3 EPA Testing of a Hybrid Transit Bus

EPA conducted a hybrid transit bus test to gather experience in testing hybrids and 

evaluate the GHG emissions and fuel consumption benefits. This section provides an 

overview of the study and its results. 

Following coastdown testing, in-use emissions testing was conducted on each bus 

using portable emissions measurement systems meeting subpart J of 40 CFR 1065. Each bus 

was operated over two routes, which were meant to simulate normal transit bus operation. The 

first route was comprised entirely of typical urban stop/go driving, with a number of bus stops 

along the 4.75 mile route. The second route was comprised of roughly half urban driving and 

half highway operation, reaching a maximum speed of approximately 60 MPH. This route 

was approximately 5.75 miles in length.

Fuel economy could be calculated using two methods: through integration of the 

instantaneous fuel rate broadcast by the ECU (ECU method) or through a carbon balance of 

the exhaust gases (Carbon Balance Method). Both methods provided repeatable results, 

however the ECU method tended to consistently yield approximately 5 percent lower fuel 

consumption on both vehicles. This bias appears to be due to small differences in predicted 

fuel flow versus measured exhaust carbon, particularly during deceleration where the ECU 

predicts a complete fuel cut-off. Since the carbon balance method yields more conservative 

results, all fuel consumption data presented has been calculating using this method.

Figure 2-1 presents a comparison of the fuel economy of both buses over the two test 

routes. Each vehicle was tested at least 3 times over each route, and in several cases up to 10 

repeats of each route were conducted. The error bars represent the standard deviation over the 

replicates of each route. Over both routes, the hybrid showed a significant fuel economy 

benefit over the conventional bus. Over route 1 (urban only), this benefit was greatest and 

approached 37 percent. Over route 2 (mixed urban/highway), fuel economy was still 

improved by over 25 percent. Much of this benefit is likely attributable to the regenerative 

braking and launch assist capability of the hybrid system since there is no idle shut-off of the 

engine. A secondary benefit to the regenerative braking system is a significant increase in 

brake service intervals, which was highlighted in discussions with a bus fleet operator.

Deleted: coast down

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Figure 2-1 Hybrid and Conventional Bus Fuel Economy (mpg)

Fuel Economy vs Route

5.52 5.15

6.95 7.04

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Route 1 Route 2

Fuel Economy (mpg)

Conventional

Hybrid

Figure 2-2 presents the CO2 

Figure 2-3

emissions over each route on a work-specific basis. For 

comparison, , presents CO2 normalized by the mileage travelled. Characterizing the 

CO2

Deleted: 

reduction due to the hybrid system, both methods show significant decreases in 

emissions. The work-specific basis may provide a more accurate comparison in this case, 

since environmental effects are better accounted for (i.e. driver aggressiveness, traffic, etc). 

This is evident when comparing the variation over the course of testing, represented by the 

standard deviation. The variability on a work-specific basis is nearly half that of using the 

distance-based metric.

Fue 

5.15

7.04

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Route 1

Fuel Economy (mpg)

Field Code Changed

Field Code Changed
Regulatory Impact Analysis 

2-72

Figure 2-2 Hybrid and Conventional Bus CO2

CO2 Emissions vs Route

624 602

410 396

0

100

200

300

400

500

600

700

Route 1 Route 2

CO2 (g/bhp-hr)

Conventional

Hybrid

Emission Rates (g/bhp-hr)

Figure 2-3 Hybrid and Conventional Bus CO2

CO2 Emissions vs Route

1859

1995

1442 1467

0

500

1000

1500

2000

2500

Route 1 Route 2

CO2 (g/mile)

Conventional

Hybrid

Emission Rates (g/mile)

Figure 2-4 (a-d) compares the CO2 emissions rate (in g/s) during typical launch 

(starting from a stop) events in both buses. Both vehicles showed a spike in CO2 emissions 

when starting from a stop. However, this spike was much more attenuated with the hybrid 

bus, which demonstrates the ability of the launch assist system to reduce CO2

Figure 2-4

emissions. The 

magnitude of this attenuation varied depending on the exact event, however reductions of 

over 50 percent were not uncommon. Also worth noting is that near the 0.35 mile mark on 

-d (lower-right), the CO2

Deleted: 

emissions are near zero, suggesting that the vehicle is 

maintaining a speed of approximately 15 MPH solely on electric power.

CO2 

624

396

0

100

200

300

400

500

600

700

Route 1

CO2 (g/bhp-hr)

Field Code Changed

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Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

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2-73

Figure 2-4 Hybrid and Conventional Bus CO2

0

5

10

15

20

25

30

35

40

45

50

0 0.1 0.2

Distance (miles)

Speed (MPH) or CO2 (g/s)

Conv-MPH

Hybrid-MPH

Conv - CO2

Hybrid-CO2

Emission Rates (g/s)

0

5

10

15

20

25

30

35

40

45

50

0.1 0.2 0.3

Distance (miles)

Speed (MPH) or CO2 (g/s)

Conv-MPH

Hybrid-MPH

Conv - CO2

Hybrid-CO2

a b

0

5

10

15

20

25

30

35

40

45

50

0 0.1 0.2

Distance (miles)

Speed (MPH) or CO2 (g/s)

Conv-MPH

Hybrid-MPH

Conv - CO2

Hybrid-CO2

0

5

10

15

20

25

30

35

40

45

50

0.2 0.3 0.4

Distance (miles)

Speed (MPH) or CO2 (g/s)

Conv-MPH

Hybrid-MPH

Conv - CO2

Hybrid-CO2

c d

Other observations through this testing suggest significant complexity in the 

calibration of the hybrid powertrain, presumably with the intent of reducing fuel consumption. 

One example is the set of engine speed-torque points over a give route (see Figure 2-5). The 

calibration of the hybrid powertrain (red) shows distinct patterns for where the engine 

operates. First, the engine is less frequently loaded at, or near idle speed. Second, the engine 

frequently operates at 1200 RPM, which is the lowest speed at which peak torque is available. 

Third, when more power is required (beyond 100 percent torque at 1200 RPM), the engine 

tends to operate along the maximum torque curve as RPM is increased. Keeping engine 

speed as low as possible reduces frictional losses, thus increasing efficiency. In contrast, the 

speed-torque points of the conventional bus show a much more random distribution and 

propensity for operating at lower engine loads. 

Deleted: 

0

5

10

15

20

25

30

35

40

45

50

0 0.1

Distance (miles)

Speed (MPH) or CO2 (g/s)

 

0

5

10

15

20

25

30

35

40

45

50

0.1 0.2

Distance (miles)

Speed (MPH) or CO2 (g/s)

Conv-MPH

Hybrid-MPH

Conv - CO2

Hybrid-CO2

0

5

10

15

20

25

30

35

40

45

50

0 0.1

Distance (miles)

Speed (MPH) or CO2 (g/s)

 

0

5

10

15

20

25

30

35

40

45

50

0.2 0.3

Distance (miles)

Speed (MPH) or CO2 (g/s)

Conv

Hybr

Conv 

Hybr

Deleted: (

Field Code Changed
Regulatory Impact Analysis 

2-74

Figure 2-5 Hybrid and Conventional Bus Operating Map Comparison

0

20

40

60

80

100

120

500 1000 1500 2000 2500

Engine Speed (RPM)

Engine Load (%)

Conventional

Hybrid

In summary, the hybrid powertrain has demonstrated significant opportunity for 

reduction of fuel consumption and CO2 emissions in transit bus applications. Testing over 

typical bus routes showed up to a 37 percent reduction in both fuel consumption and CO2

emissions. A summary of these finding is presented in Table 2-30. These reductions can be 

attributed to three features of the hybrid powertrain. First, electric launch assist facilitated 

through regenerative braking. Second, calibration of the engine to operate in the most efficient 

regions of the speed-torque map. Third, electric-only drive at lower speeds was witnessed 

occasionally. 

Table 2-30 Hybrid Powertrain Benefit

Conventional Hybrid Benefit

Avg CoV Avg CoV mpg or 

g/mile

percent

Route 1 MPG 5.15 8.2% 7.04 5.5% 1.89 37%

CO2 (g/mile) 1995 8.0% 1442 5.5% 553 28%

CO2 (g/bhp-hr) 624 3.7% 396 5.3% 228 37%

Route 2 MPG 5.52 8.0% 6.95 5.3% 1.43 26%

CO2 (g/mile) 1859 7.9% 1467 5.5% 392 21%

CO2 (g/bhp-hr) 602 4.0% 410 1.7% 192 32%

Deleted: 

0

20

40

60

80

100

120

500 1000

E 

Engine Load (%)

Field Code Changed

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2-75

2.6.2.4 Transmission and Driveline 

This technology is not expected to change as a result of the proposed standards.

2.7 Air Conditioning

Air conditioning (A/C) systems contribute to GHG emissions in two ways – direct 

emissions through refrigerant leakage and indirect exhaust emissions due to the extra load on 

the vehicle’s engine to provide power to the air conditioning system. Hydrofluorocarbon 

(HFC) refrigerants, which are powerful GHG pollutants, can leak from the A/C system. This 

includes the direct leakage of refrigerant as well as the subsequent leakage associate with 

maintenance and servicing, and with disposal at the end of the vehicle’s life. No other vehicle 

system has associated GHG leakage.85 The current refrigerant – R134a, has a high global 

warming potential (GWP) of 1430. 86 Due to the high GWP of this HFC, a small leakage of 

the refrigerant has a much greater global warming impact than a similar amount of emissions 

of CO2

Heavy-duty air conditioning systems today are similar to those used in light-duty 

applications. However, differences may exist in terms of cooling capacity (such as sleeper 

cabs have larger cabin volumes than day cabs), system layout (such as the number of 

evaporators), and the durability requirements due to longer truck life. However, the 

component technologies and costs to reduce direct HFC emissions are similar between the 

two types of vehicles. 

or other mobile source GHGs. 

The quantity of indirect GHG emissions from A/C use in heavy-duty trucks relative to 

the CO2

2.7.1 Refrigerant Leakage

emissions from driving the vehicle and moving freight is very small. Therefore, a 

credit approach for improved A/C system efficiency is not appropriate for this segment of 

vehicles because the value of the credit is too small to provide sufficient incentive to utilize 

feasible and cost-effective air conditioning leakage improvements. For the same reason, 

including air conditioning leakage improvements within the main standard would in many 

instances result in lost control opportunities. Therefore, EPA is proposing that truck 

manufacturers be required to meet a low leakage requirement for all air conditioning systems 

installed in 2014 model year and later trucks, with one exception. The agencies are not 

proposing leakage standards for Class 2b-8 Vocational Vehicles at this time due to the 

complexity in the build process and the potential for different entities besides the chassis 

manufacturer to be involved in the air conditioning system production and installation, with 

consequent difficulties in developing a regulatory system. 

Based on measurements from 300 European light-duty vehicles (collected in 2002 and 

2003), Schwarz and Harnisch estimate that the average HFC direct leakage rate from modern 

A/C systems was estimated to be 53 g/yr.87

Deleted: 

 This corresponds to a leakage rate of 6.9 percent 

per year. This was estimated by extracting the refrigerant from recruited vehicles and 

comparing the amount extracted to the amount originally filled (as per the vehicle 

specifications). The fleet and size of vehicles differs from Europe and the United States, 

therefore it is conceivable that vehicles in the United States could have a different leakage 

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rate. The authors measured the average charge of refrigerant at initial fill to be about 747 

grams (it is somewhat higher in the U.S. at 770g), and that the smaller cars (684 gram charge) 

emitted less than the higher charge vehicles (883 gram charge). Moreover, due to the climate 

differences, the A/C usage patterns also vary between the two continents, which may 

influence leakage rates. 

Vincent et al., from the California Air Resources Board estimated the in-use 

refrigerant leakage rate to be 80 g/yr.88

Since the A/C systems are similar in design and operation between light- and heavyduty vehicles, and emissions due to direct refrigerant leakage are significant in all vehicle 

types, EPA is proposing a leakage standard which is a “percent refrigerant leakage per year” 

to assure that high-quality, low-leakage components are used in each air conditioning system 

design. The agency believes that a single “gram of refrigerant leakage per year” would not 

fairly address the variety of air conditioning system designs and layouts found in the heavyduty truck sector. EPA is proposing a standard of 1.50 percent leakage per year for HeavyDuty Pickup Trucks and Vans and Class 7/8 Tractors. The proposed standard was derived 

from the vehicles with the largest system refrigerant capacity based on the Minnesota GHG 

Reporting database.

 This is based on consumption of refrigerant in 

commercial fleets, surveys of vehicle owners and technicians. The study assumed an average 

A/C charge size of 950 grams and a recharge rate of 1 in 16 years (lifetime). The recharges 

occurred when the system was 52 percent empty and the fraction recovered at end-of-life was 

8.5 percent.

89 As shown in Figure 2-6, the average percent leakage per year of the 

2010 model year vehicles in the upper quartile in terms of refrigerant capacity was 1.60 

percent (for reference, in the 2010 Light-Duty GHG rule, the average was estimated to be 2.7 

percent, based on a leakage rate of 20.7 g/yr and a system capacity of 770 g). 

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0.0000

0.0200

0.0400

0.0600

0.0800

0.1000

0.1200

0.1400

0.1600

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00 2.10 2.20 2.30 2.40 2.50 2.60 2.70 2.80 2.90 3.00

Frequency

Annual Percentage Refrigerant Loss (%/yr)

-Annual Percentage Loss = Yearly Leak Rate / Refrigerant Capacity

-53 vehicles in data set (2010 model year only)

- System refrigerant capacity ranges from 810 g (Chevrolet Express)

to 1531 g (Ford E-Series w/dual evaporators)

- Yearly % leak rate ranges from 0.78%/yr (Chevrolet Express) to

2.77%/yr (Toyota Land Cruiser w/dual evaporator and coolbox)

Median = 1.44 %/yr

Average = 1.60 %/yr

Figure 2-6 Distribution of Percentage Refrigerant Loss Per Year - Vehicles in Upper Quartile of A/C 

System Refrigerant Capacity (from 2010 Minnesota Reporting Data).

By requiring that all heavy-duty trucks achieve the proposed leakage level of 1.50 

percent per year, roughly half of the vehicles in the 2010 data sample would need to reduce 

their leakage rates, and an emissions reduction roughly comparable to that necessary to 

generate direct emission credits under the light-duty vehicle program would result. See 75 FR 

at 25426-247. We believe that a yearly system leakage approach will assure that high-quality, 

low-leakage, components are used in each A/C system design, and we expect that 

manufacturers will reduce A/C leakage emissions by utilizing improved, leak-tight 

components. Some of the improved components available to manufacturers are lowpermeation flexible hoses, multiple o-ring or seal washer connections, and multiple-lip 

compressor shaft seals. The availability of low leakage components is being driven by the air 

conditioning credit program in the light-duty GHG rule (which applies to 2012 model year 

and later vehicles). EPA believes that reducing A/C system leakage is both highly costeffective and technologically feasible. The cooperative industry and government Improved 

Mobile Air Conditioning (IMAC) program has demonstrated that new-vehicle leakage 

emissions can be reduced by 50 percent by reducing the number and improving the quality of 

the components, fittings, seals, and hoses of the A/C system.90

 

 All of these technologies are 

already in commercial use and exist on some of today’s systems.

Deleted: While use of alternative refrigerants with 

a lower GWP is encouraged, we are proposing that 

the same leakage standard will apply to all A/C 

systems, regardless of the type of refrigerant used. 

For A/C systems to maintain their efficiency, the 

refrigerant charge must be preserved. Systems which 

lose significant amounts of refrigerant, the cooling 

capacity is diminished, possibly requiring increased 

operating duty cycle to achieve a desired cabin 

comfort level, which will increase indirect CO2 

emissions. In addition, as refrigerant levels in the 

system drop below a critical level, the ability of the 

refrigerant to move lubrication oil through the 

system (necessary for compressor durability) is 

diminished, resulting in deterioration of the 

compressor, and ultimately, replacement of system 

components, which will result in service-related 

direct emissions. Also, even refrigerants with low 

GWP may not be desirable in the atmosphere, as 

they are potential VOCs, and the products of their 

chemical breakdown (e.g. hydrogen fluoride or triflouroacetic acid) can affect human health.
Regulatory Impact Analysis 

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EPA proposes that manufacturers demonstrate improvements in their A/C system 

designs and components through a design-based method. The proposed method for 

calculating A/C Leakage is based closely on an industry-consensus leakage scoring method, 

described below. This leakage scoring method is correlated to experimentally-measured 

leakage rates from a number of vehicles using the different available A/C components. Under 

the proposed approach, manufacturers would choose from a menu of A/C equipment and 

components used in their vehicles in order to establish leakage scores, which would 

characterize their A/C system leakage performance and calculate the percent leakage per year 

as this score divided by the system refrigerant capacity. 

Consistent with the Light-Duty Vehicle Greenhouse Gas Emissions rulemaking, EPA 

is proposing that a manufacturer would compare the components of its A/C system with a set 

of leakage-reduction technologies and actions that is based closely on that being developed 

through IMAC and the Society of Automotive Engineers (as SAE Surface Vehicle Standard 

J2727, August 2008 version).91

2.7.2 System Efficiency

 See generally 75 FR at 25426. The SAE J2727 approach was 

developed from laboratory testing of a variety of A/C related components, and EPA believes 

that the J2727 leakage scoring system generally represents a reasonable correlation with 

average real-world leakage in new vehicles. Like the IMAC approach, our proposed approach 

would associate each component with a specific leakage rate in grams per year identical to the 

values in J2727 and then sum together the component leakage values to develop the total A/C 

system leakage. However, in the heavy-duty truck program, the total A/C leakage score is 

then divided the value by the total refrigerant system capacity to develop a percent leakage 

per year value.

The agencies can also develop a program that includes efficiency improvements. 

CO2-equivalent emissions are also associated with air conditioner efficiency, since air 

conditioners create load on the engine. See 74 FR at 49529. However, EPA is not proposing 

to set air conditioning efficiency standards for heavy-duty trucks, as the CO2 emissions due to 

air conditioning systems in heavy-duty trucks are minimal (compared to their overall 

emissions of CO2). For example, EPA conducted modeling of a Class 8 sleeper cab using 

GEM to evaluate the impact of air conditioning and found that it leads to approximately 1 

gram of CO2/ton- mile. Therefore, a projected 24 percent improvement of the air 

conditioning system (the level projected in the light-duty GHG rulemaking), would only 

reduce CO2 emissions by less than 0.3 g CO2/ton-mile, or approximately 0.3 percent of the 

baseline Class 8 sleeper cab CO2

2.8 Trailers and GHG Emission Reduction Opportunities

emissions.

Trailers for use with HD tractors are an important aspect of the GHG emission 

performance of combination tractors and are estimated to be responsible for 11 to 12 percent

of fuel consumed by Class 8 combination tractors. Optimizing the tractor and trailer as a 

system allows designers to take full advantage of the GHG emission reduction opportunities 

and, in some cases (e.g., aerodynamic drag reduction), the performance of emission reduction 

approach is dependent upon the tractor and trailer working in concert. For example, when 

designing a tractor’s roofline it is important to understand the type and physical characteristics 

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of the trailer for which it is intended for use. If the roofline of the tractor and trailer are 

mismatched, it can result in a large, post-tractor wake (i.e., the tractors roofline is taller than 

that of the trailer) or present a large, drag inducing surface (i.e., the trailer front is taller than 

the top of the tractor). Even though trailers are an integral part of a combination tractor’s

ultimate GHG emissions and fuel consumption, trailer design has remained relatively 

unchanged when compared to the progress made in tractors. The impacts of incorporating 

improved GHG emission and fuel saving performance into trailers can have long lasting 

impacts since trailers are often kept in service for longer periods than tractors.

2.8.1 Current Trailer Fleet

There are approximately 5.6 million HD trailers on the roads today92

Table 2-31

. In general, it is 

common to have roughly 3 trailers for every tractor to facilitate efficiency in loading and 

unloading operations. Serving a wide range of needs, this trailer fleet is necessarily 

comprised of a wide range of trailer types including box van (including refrigerated units), 

shipping container (e.g., 20 and 40 foot ocean-going container) chassis, flat bed (including 

drop deck units), dump, tanker, and specialty (e.g., grain, livestock, auto-carriers). Types of 

trailers can be further subdivided by their length and height. The vast majority of HD trailers 

on the road are box van trailers that are 53 feet long. presents the current market 

share of major types of trailers.93

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Table 2-31: Composition of Current Heavy-Duty Trailer Fleet

TRAILER TYPE MARKET SHARE1

Box, van (53’)

(PERCENT)

45

Box, van (40 – 52’) 6

Box, van (24 – 39’) 9

Box, van (refrigerated) 5

Container chassis 7

Dump 3

Flatbed 8

Flatbed (drop deck) 2

Grain 2

Tagalong 4

Tagalong (enclosed) 2

Other 9

Diversity in the trailer fleet is not limited to the types of trailers on the road but also 

extends to the owners and operators of trailers. Trailers are owned and operated by individual 

fleets, logistics companies that move goods for others, and government entities. 

While approximately 10 companies manufacture approximately 80 percent of the 

trailers sold, the entire trailer market includes a large number of trailer producers. 94

2.8.2 Trailer Technologies to Reduce GHG Emissions

 Only 14 

manufacturers have an annual sales volume of greater than 3,000 trailers with many 

specializing in a type of trailer (e.g., grain, dump, tanker). 

Technologies for use on trailers that reduce GHG emissions and fuel consumption are 

commercially available. These include aerodynamic devices, low rolling resistance tires, and 

weight reduction. Trailer systems that allow a tractor to move more goods such as double 

trailer configurations (e.g., Rocky Mountain Doubles with 28 or 48 foot trailers) can also be 

considered as trailer strategies to reduce GHG emissions. Of these technologies, trailer 

aerodynamics and low rolling resistance tires have gained wide acceptance and are discussed 

in detail below. 

2.8.2.1 Trailer Aerodynamics 

Trailer aerodynamic technologies have focused on the box, van trailers – the largest 

segment of the trailer fleet. This focus on box, van trailers may also be partially attributed to 

the complexity of the shape of the non-box, van trailers which, in many cases, transport cargo 

that is in the windstream (e.g., flatbeds that carry heavy equipment, car carriers, and loggers). 

For non-box, van trailers you could have a different aerodynamic shape with every load. 

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While some technologies exist to address aerodynamic drag for non-box, van trailers, it has 

been either experimental or not widely commercially available. 

Current trailer aerodynamic technologies for box, van trailers are estimated to provide 

approximately 7 percent GHG emission reductions when used as a package. For box, van 

trailers, trailer aerodynamic technologies have addressed drag at the front of the trailer (i.e., 

vortex traps, leading edge fairings), underneath the trailer (i.e., side skirts, wheel fairings) and 

the trailer rear (i.e., afterbodies). These technologies are commercially available and have 

seen moderate adoption rates. Table 2-32 shows technologies that have generally been 

accepted for use on box, van trailers. In general, the performance of these technologies is 

dependent upon the smooth transition of airflow from the tractor to the trailer. True for both 

tractor and trailer aerodynamic drag reduction, the overall shape can be optimized to 

minimize aerodynamic drag and, in fact, the trailer body must have at least a moderately 

aerodynamic shape (and its relatively smooth flow) to benefit from add-on aerodynamic 

components. 

Table 2-32: Trailer Technologies to Address Aerodynamic Drag

LOCATION ON 

TRAILER

TECHNOLOGY TYPE DESIGNED EFFECT

Front Vortex trap Reduce drag induced by cross-flow through 

gap between tractor and trailer

Front Front fairings Smoothly transition air to flow from tractor 

to the trailer

Rear Afterbody (boat tail and 

rear fairings)

Reduce pressure drag induced by the trailer 

wake

Undercarriage Side skirts Manage flow of air underneath tractor to 

reduce eddies and wake

Undercarriage Underbelly treatment Manage flow of air underneath tractor to 

reduce eddies and wake

Accessories General Reducing surface area perpendicular to 

travel and minimizing complex shapes that 

may induce drag

General Advanced, passive air 

management

Manage airflow through passive 

aerodynamic shapes or devices that keep 

flow attached to the vehicle (tractor and 

trailer)

Table 2-33 Trailer Technologies Incremental Costs

TECHNOLOGY COST ESTIMATE

Trailer Side Skirts $1300 – 1600

Gap Fairing $850

Trailer Aerocone $1000

Boat Tails $1960

Air Tabs $180

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2.8.2.2 Tires – Single Wide and Low Rolling Resistance

Beginning in 2007, EPA began designating certain new dry freight box van trailers for 

on the road use of 53 feet or greater length Certified SmartWay Trailers. Older or pre-owned 

trailers could also be certified if properly retrofitted. In order for a trailer to be designated as 

Certified SmartWay, the trailer must be equipped with verified low rolling resistance trailer 

tires (either dual or single-wide), among other things. 

The RRc baseline for today’s fleet is 6.5 kg/metric ton for the trailer tire, based on 

sales weighting of the top three manufacturers based on market share. This value is based on 

new trailer tires, since rolling resistance decreases as the tread wears. To achieve the intended 

emissions benefit, SmartWay established the maximum allowable RRc

Research indicates the contribution to overall vehicle fuel efficiency by tires is 

approximately equal to the proportion of the vehicle weight on them

for the trailer tire 15

percent below the baseline or 5.5 kg/metric ton. 

43. On a fully loaded 

typical Class 8 long-haul tractor and trailer, 42.5 percent of the total tire energy loss attributed 

to rolling resistance is from the trailer tires. 

The Center for Transportation Research at Argonne National Laboratory analyzed 

technology options to support energy use projections. EPA agrees with their assumed 

incremental cost of low rolling resistance tires of $15 - $20 per tire61. With 8 tires replaced on 

a trailer, the incremental cost would be between $120 and $160. Often the steer tire is 

retreaded and placed on the trailer axle. There is a cost savings associated with retread tires. 

A new retread costs between $150 and $200, compared to a new tire which costs typically 

around $400. This represents a savings of $1,200 to $1,600 per trailer. 

Single wide tires are also used on trailers. The Center for Transportation Research 

estimated incremental capital cost of single wide tires is $30 - $40 per tire61. With 4 single 

wide tires replacing 8 dual tires on the trailer, the incremental cost would be between $120 

and $160.

Based on the ICF report,95

2.8.2.3 Trailer Weight Reduction

EPA and NHTSA estimate the incremental retail cost for 

low rolling resistance tires as $78 per tire. The agencies also estimate that the incremental 

cost to replace a pair of dual tires with a single wide based tire is $216, however, the cost can 

be reduced when the wheel replacement cost is considered.

Weight reduction opportunities in trailers exist in both the structural components and 

in the wheels and tires. Material substitution (replacing steel with aluminum) is feasible for 

components such as roof posts, bows, side posts, cross members, floor joists, and floors. 

Similar material substitution is feasible for wheels. Weight reduction opportunities also exist 

through the use of single wide based tires replacing two dual tires.

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The agencies’ assessment of the ICF report indicates that the expected incremental 

retail prices of the lightweighted components are as included in Table 2-34 Trailer 

Lightweighting Incremental Costs.

Table 2-34 Trailer Lightweighting Incremental Costs

COMPONENT COST

Roof Posts/Bows $120

Side Posts $525

Cross Members/Floor Joists $400

Floor $1,500

Wheels $1,500

2.8.2.4 Opportunities in Refrigerated Trailers 

Refrigeration units are used in van trailers to transport temperature sensitive products. 

A traditional trailer refrigeration unit (TRU) is powered by a nonroad diesel engine. There 

are GHG reduction opportunities in refrigerated trailers through the use of electrical trailer 

refrigeration units and highly reflective trailer coatings. 

Highly reflective materials, such as reflective paints or translucent white fiberglass 

roofs, can reflect the solar radiation and decrease the cooling demands on the trailer’s 

refrigeration unit. A reflective composite roof can cost approximately $800, the addition of 

reflective tape to a trailer roof would cost approximately $450.

Hybrid TRUs utilize a diesel engine which drives a generator which in turn powers the 

compressor and fans. The cost of this unit is approximately $4,000.

All-electric TRUs, needing no diesel engine to power the unit, are being tested in U.S. 

refrigerated fleets. There is no market price for these units at this time.

2.9 Other Fuel Consumption and GHG Reducing Strategies

There are several other types of strategies available to reduce fuel consumption and 

GHG emissions from trucks. EPA and NHTSA identify several of these technologies and 

strategies below, but acknowledge that they are outside the proposed regulatory framework 

currently identified. 

2.9.1 Auxiliaries 

The accessories on a truck engine, including the alternator, coolant and oil pumps are 

traditionally mechanically gear or belt driven by the base engine. In general, the effect of 

accessory power consumption in trucks is much less than in cars but the mechanical 

auxiliaries operate whenever base engines are running, which can waste energy when the 

auxiliaries are not needed. The replacement of mechanical auxiliaries by electrically driven 

systems can decouple mechanical loads from the base engine and reduce energy use. Since 

the average engine loads from mechanical auxiliaries are higher than those from a small 

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generator that supplies electricity to electric auxiliaries, base engine fuel can be reduced. A 

reduction in CO2

• Air compressor,

emissions and fuel consumption can be realized by driving them electrically 

and only when needed (“on-demand”). The heavy and medium trucks have several auxiliary 

systems:

• Hydraulic pumps,

• Coolant pump,

• Engine oil and fuel pumps,

• Fans, and

• Air conditioning compressor.

The systems listed above, although not inclusive, can be optimized by various 

methods reducing fuel consumption and GHG emissions;

• Electric power steering (EPS) – is an electrically-assisted steering system that has 

advantages over traditional hydraulic power steering because it replaces a 

continuously operated hydraulic pump, thereby reducing parasitic losses from the 

accessory drive.

• Electric water pumps and electric fans - can provide better control of engine cooling. 

For example, coolant flow from an electric water pump can be reduced and the 

radiator fan can be shut off during engine warm-up or cold ambient temperature 

conditions which will reduce warm-up time, reduce warm-up fuel enrichment, and 

reduce parasitic losses. Indirect benefit may be obtained by reducing the flow from the 

water pump electrically during the engine warm-up period, allowing the engine to heat 

more rapidly and thereby reducing the fuel enrichment needed during cold starting of 

the engine.

• High efficiency alternators - provide greater electrical power and efficiency at road 

speed or at idle than conventional original equipment replacement alternators that 

typically operate at 55 percent efficiency. 

• If electric power is not available - there are still some technologies that can be applied 

to reduce the parasitic power consumption of accessories. Increased component 

efficiency is one approach, and clutches can be used to disengage the alternator and air 

compressor when they are not required. Many MD/HD engines incorporate clutched 

cooling fans which can be shut off during engine warm-up thereby not requiring 

electric cooling fans. Air compressors that are rotating but not creating pressure 

absorb about half the power of a pumping compressor, and compressors normally only 

pump a small percentage of the time in long-haul trucks.

Several studies have documented the GHG reductions from electrification and/or 

optimization of truck auxiliaries. One study, based on a full-scaled test of a prototype truck 

that used a small generator to produce electricity, full electrification of auxiliaries reduces fuel 

use by 2 percent including extended idle and estimated potential reductions in modal GHG 

emissions are 1.4 percent. Another study recently completed by Ricardo discussed the Deleted: 54.
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advantages of electrification of engine accessories along with the potential to increase fuel 

economy citing examples such as variable flow water pumps and oil pumps96

Accurate data providing power consumption values for each discrete accessory over a 

range of operating conditions was not available due to the variation of the truck fleet. Based 

on research and industry feedback, a simplified assumption for modeling was made that the 

average power demand for mechanically driven accessories is 5 kW, and the average power 

demand for electrically driven accessories is 3 kW. This provides a 2 kW advantage for the 

electrically driven accessories over the entire drive cycle represent and is estimated to provide 

a 1.5 percent improvement in efficiency and reduction in CO

. Potential gains 

may be realized in the range of 1 to 3 percent but are highly dependent on truck type, size and 

duty cycle. In a NESCAFF study, the accessory power demand of a baseline truck was 

modeled as a steady state power draw of 5 kW, and 3 kW for more electrical accessories in 

individual vehicle configurations that included electric turbo compounding. The 2 kW savings 

versus average engine power of 100 to 200kW over a drive cycle nets roughly 1 to 2 percent

savings compared to a baseline vehicle.

2 

2.9.2 Driver training 

emissions. As a comparison, 

the average load on a car engine over a drive cycle may be in the 10 to 20 kW range. At this 

level, a 2 kW reduction in accessory loads of a passenger vehicle makes a significant 

difference (approximately 10 percent). Given the higher loads experienced by truck engines, 

accessory demand is a much smaller share of overall fuel consumption. Accessory power 

demand determined by discrete components will be not be included in the model at this time 

and a power draw of 5 kW for standard accessories and 3 kW for electrical accessories will be 

used. There is opportunity for additional research to improve upon this simple modeling 

approach by using actual measured data to improve the modeling assumptions.

Driver training that targets fuel efficiency can help drivers recognize and change 

driving habits that waste fuel and increase harmful emissions. Even highly experienced truck 

drivers can boost their skills and enhance driving performance through driver training 

programs.97

Driving habits that commonly waste fuel are high speed driving, driving at 

unnecessarily high rpm, excessive idling, improper shifting, too-rapid acceleration, 

unnecessarily frequent stops and starts, and poor route planning. Well-trained drivers can 

reduce fuel consumption by applying simple techniques to address vehicle and engine speed, 

shifting patterns, acceleration and braking habits, idling, and use of accessories.98 Some 

techniques include starting out in a gear that does not require using the throttle when releasing 

the clutch, progressive shifting (upshifting at the lowest possible rpm), anticipating traffic 

flow to reduce starts and stops, use of block shifting where possible (e.g., shifting from 2nd to 

5th

As discussed elsewhere in this chapter, idling can be eliminated by the use of auxiliary 

power units or other idle reduction solutions that provide power or heating and cooling to the 

cab at a much lower rate of energy consumption.

gear), using cruise control as appropriate, and coasting down or using the engine brake to 

slow the vehicle, instead of gearing down or using the brake pedal.

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Better route planning that reduces unnecessary mileage and the frequency of empty 

backhauls, and takes into account factors like daily congestion patterns is another facet of a 

comprehensive driver training program. Such planning can be assisted through the use of 

logistics companies, which specialize in such efficiencies.

In its report, Technologies and Approaches to Reducing the Fuel Consumption of 

Medium and Heavy-Duty Vehicles, the National Research Council cited studies that found, on 

average, a five percent improvement in vehicle fuel efficiency due to driver training.99 EPA’s 

SmartWay Transport Partnership has documented the success of dozens of trucking 

companies’ use of driver training programs. One company reported saving an average of 42 

gallons per student, or 335,000 gallons of fuel per year; and, saving 837,000 gallons of fuel in 

the four years it has had its training program in place.

100

While EPA and NHTSA recognize the potential opportunity to reduce fuel 

consumption and greenhouse gas emissions by encouraging fuel-efficient driver habits, 

mandating driver training for all of the nation’s truck drivers is beyond the scope of this 

proposed regulation. However, in developing this proposal, the agencies did consider 

technologies that can provide some of the benefits typically addressed through driver training. 

Examples include automatic engine shutdown to reduce idling, automated or automated 

manual transmissions to optimize shifting, and speed limiters to reduce high speed operation. 

EPA will continue to promote fuel-efficient driving through its SmartWay program. In 

addition to providing fact sheets on fuel efficient driving,

 Trucking fleets can provide 

additional motivation to reward drivers for improved performance with incentive programs, 

which may be monetary or provide other forms of benefits and recognition. Sometimes 

negative measures are employed to urge compliance with company expectations, up to and 

including termination of employment. Successful programs are those that perform ongoing 

reviews of driver techniques, and provide assistance to improve and/or retrain drivers. 

101

2.9.3 Automatic Tire inflation and Tire Pressure Monitoring System

SmartWay is collaborating with 

Natural Resources Canada’s FleetSmart program to develop a web-enabled “fuel efficient 

driver” training course for commercial truck drivers. Once the course is developed, it will 

complement the agencies regulatory program by making fuel efficient driver training 

strategies available to any commercial truck driver.

Underinflation of tires has the potential to reduce fuel economy by as much as two to 

three percent102. Although most truck fleets understand the importance of keeping tires 

properly inflated, it is likely that a substantial proportion of trucks on the road have one or 

more underinflated tires. An industry survey conducted in 2002 at two truck stops found that 

fewer than half of the tires checked were within five pounds of their recommended inflation 

pressure. Twenty-two percent of the vehicles checked had at least one tire underinflated by at 

least twenty pounds per square inch (psi), and four percent of the vehicles were running with 

at least one flat tire, defined as a tire underinflated by fifty psi or more. The survey also found 

mismatches in tire pressure exceeding five percent for dual tires on axle ends.103

Proper tire inflation pressure can be maintained with a rigorous tire inspection and 

maintenance program or with the use of tire pressure and inflation systems. These systems 

monitor tire pressure; some also automatically keep tires inflated to a specific level. 

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However, while the agencies recognize that such devices could have a beneficial effect on 

fuel economy, their use is not included in the regulatory framework. Notwithstanding the 

cited survey, the level of underinflation of tires in the American truck fleet is not known,104

which means that neither a baseline value nor an estimate of the fuel savings from the use of 

automatic tire inflation systems can be quantified with certainty. Through its SmartWay 

program, however, EPA does provide information on proper tire inflation pressure and on tire 

inflation and tire inflation pressure monitoring systems.105

2.9.4 Engine Features 

Previous sections 2.3.2.2 through 2.3.2.8 describe the technologies that can be tested 

in an engine test cell for certification purpose and could be potentially implemented in 

production before the time frame of 2017. Some other technologies that cannot be easily

tested in an engine test cell, but can improve engine fuel economy, should be worthwhile 

mentioning. Examples include these technologies, such as driver rewards, load based speed 

control, gear down protection, and fan control offered by Cummins’s PowerSpec. 

The driver reward developed by Cummins monitors and averages the driver trip fuel 

economy and trip idle percent time at regular intervals, seeking to modify driver behavior by 

offering incentives to use less fuel. Desirable driving habits, such as low percentage of idle 

time, and high MPG, are rewarded with higher limits on the road speed governor, cruise 

control or both. The load based speed control or other similar programs are designed to 

improve fuel economy, lower vehicle noise, and improve driver satisfaction by managing 

engine speed (rpm) based on real time operating conditions. During high power requirements, 

this type of technology enhances engine performance by providing the driver with an 

extended operating range. In addition to the fuel economy benefits from operating the engine 

at lower speeds, vehicle noise is lowered. 

Gear down protection offered by Cummins is to promote increased fuel economy by 

encouraging the vehicle driver to operate as much as effectively possible in top gear where 

fuel consumption is lower. This can be done by limiting vehicle speed in lower gears. 

Maximizing time in top gear means the engine runs in a lower rpm range, where fuel 

economy is best with improved durability and without compromising performance. Difference 

between top gear and one gear down can be as much as 16 percent in fuel economy. More 

detailed descriptions of many technologies including those mentioned here can be viewed at 

Cummins’s website of http://www.powerspec.cummins.com/site/home/index.html. 

Although these technologies mentioned in this section are not able to be tested in an 

engine test cell environment, thus being unable to be directly used for benefits of certification 

purpose, the agency encourages manufacturers to continue improving the current and 

developing new technologies, thereby reducing green house gases in a broader way.

2.9.5 Logistics

Logistics encompasses a number of interrelated, mostly operational factors that affect 

how efficiently the overall freight transport system works. These factors include choice of 

mode, carrier and equipment; packaging type and amount; delivery time; points of origin and 
Regulatory Impact Analysis 

2-88

destination; route choice, including locations of ports and distribution hubs; and transportation 

tracking systems. These factors are controlled by the organizations that ship and receive 

goods. Due to the specialized nature of logistics management, organizations increasingly rely 

upon internal or outsourced business units to handle this function; many transportation 

providers offer logistics management services to their freight customers. 

Because optimizing logistics is specific to each individual freight move, neither EPA 

nor NHTSA believed it is feasible to manage logistics through this proposed regulation. 

However, implementing certain system-wide logistics enhancements on a national level could 

provide benefits. As described in the National Research Council’s recent report,106 a broader 

national approach could include enhanced telematics and intelligent transportation systems; 

changes to existing infrastructure to optimize modal choice; and increased truck capacity 

through changes to current truck weight and size limits. While such a broad transformation of 

our freight system is worthwhile to consider, implementing such system-wide changes falls 

outside the scope of this proposed regulation. As the National Research Council noted,107

2.9.6 Longer Combination Vehicles, Weight Increase

due 

to its complex nature, logistics management is not readily or effectively addressed through 

any single approach or regulation; a number of complementary measures and alternatives are 

needed. Such measures can include initiatives that enable companies to better understand, 

measure and track the benefits of logistics optimization from an environmental and economic 

standpoint. The SmartWay program provides uniform tools and methodologies that 

companies can use to assess and optimize transportation supply chains, and can complement 

any future regulatory and nonregulatory approaches. 

Longer combination vehicles (LCVs) are tractor-trailer combinations that tow more 

than one trailer, where at least one of the trailers exceeds the “pup” size (typically 24-28 feet). 

Because LCVs are capable of hauling more freight than a typical tractor-trailer combination, 

using LCVs reduces the number of truck trips needed to carry the same amount of freight. On 

a fleetwide basis, this saves fuel, reduces greenhouse gas emissions, and reduces per-fleet 

shipping costs. A typical non-LCV may tow a single trailer up to 53 feet in length, or tow two 

pup trailers, or even be a straight truck with a pup trailer connected via a draw bar. In 

contrast, the typical LCV may consist of a tractor towing two trailers of 45-48 feet, and 

occasionally 53 feet in length (a “turnpike double”), or one of that size and one pup (a “Rocky 

Mountain double”), or may tow three pups (a “triple”). 

Trucks consisting of a two-axle tractor combined with two one-axle trailers up to 28.5 

feet are permitted on all highways in the U.S. National Network, which consists of the 

interstate highway system and certain other roads. Individual states may permit longer LCVs 

to operate on roads that are not part of the National Network. They are allowed in 16 western 

states, but only on turnpikes in the five states east of the Mississippi that allow them; no new 

states were granted permitting authority for LCVs after 1991.

108

Deleted: combination vehicles, weight increase

 Regulations vary among 

states; some allow LCVs with more than three trailers, but only by permit. Longer length 

turnpike doubles are typically restricted to tolled turnpikes. Such restrictions are based on 

considerations of the difficulty of operation and on expected weather conditions. Other 

regulations on the types of LCVs allowed are seen in other countries; in Australia, “road 

trains” of up to four trailers, usually with three axles per trailer, are permitted. 

Deleted: combination trucks

Deleted: truck
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-89

Some proponents of liberalized size and weight regulations project substantial 

benefits, estimating that highway freight productivity could be doubled and costs reduced. 

Despite the potential benefits of LCVs, as the National Research Council noted in its recent 

report, there are considerations that may make LCVs less cost effective and less safe. For 

example, if infrastructure (e.g., bridges with sufficient capacity; roadways with adequate lane 

width and curb radii for turning to accommodate an LCV safely) are not available without 

traveling far from a more efficient route, or if there is insufficient opportunity for the LCV to 

make the most of the available volume in multiple trailers, then LCVs would not be cost 

effective. 

The increased vehicular weight of LCVs is both a safety issue and a road maintenance 

issue (see discussion below on increasing vehicle weight and legal load limits). The 

additional weight of extra trailers increases braking and stopping distance, and adds difficulty 

in maintaining speed in grade situations.

With additional regard to safety, LCVs might have trouble with offtracking (when the 

truck’s front and rear wheels do not follow the same path, which can result in departing the 

lane boundaries—a particular problem with longer LCVs), and could increase the challenge of 

merging with and maneuvering in traffic. Lateral stability is a greater problem in LCVs, and 

leads to a greater chance of rollover, particularly when the individual trailers are shorter. 

Also, when a vehicle is passing a LCV on a two-lane road, the period of time spent in the 

opposing lane (up to 2-3 seconds) poses another safety problem.109

Moves to increase commercial vehicle weight limits concern not only relaxing 

limitations on the use of LCVs, but also increasing gross vehicle weight limits for single unit 

trucks and conventional tractor-trailer combinations, as well as increasing axle load limits and 

trailer lengths. Some analysts cite scenarios in which such relaxations result in increased 

highway freight productivity, while yielding significant reductions in shipping costs, 

congestion, and total vehicle miles traveled. Increasing the weight limits allows commercial 

freight vehicles to carry heavier loads, reducing the number of trucks required to transport 

freight, potentially resulting in overall emissions reductions.

 Such safety 

considerations impact decisions regarding restrictions on the use of LCVs, even when they 

may otherwise be a cost effective freight choice.

Federal law limits gross vehicle weight for commercial vehicles operating in the 

Interstate Highway System to a maximum of 80,000 lbs. (maximum 20,000 lbs. per single 

axle, 34,000 lbs. per tandem axle), with permits available for certain oversize or overweight 

loads and exceptions allowing 400 lbs. more for tractors with idle reduction devices. 

Additional vehicle weight limitations have been set by state and local regulations. These 

limitations arise from considerations of infrastructure characteristics, traffic densities, 

economic activities, freight movement, mode options, and approach to transportation design. 

In some cases, state limits are higher than federal limits.

110 While these parameters are 

changeable, federal weight limits on vehicles have not changed since 1982, and limits set by 

states have been frozen since 1991.
Regulatory Impact Analysis 

2-90

In response to input from the freight transportation sector and other interested 

parties, the Department of Transportation, the Transportation Research Board, the General 

Accounting Office, and others have conducted studies examining the impacts of proposals 

related to liberalized weight limits. However, regardless of the potential benefits of such 

action, the analyses predict premature degradation of infrastructure (e.g., bridges, pavement, 

grades) as a consequence. Increased costs required to maintain and upgrade the highway 

system would impose high burdens on already-strained public resources, raising serious 

questions on the desirability of relaxing weight limits, and on whether such expenditures 

provide adequate public good to justify them. Safety issues similar to those cited for LCVs 

enter into this debate, as do concerns with the effect on the efficiency of automotive travel, 

impacts on and net productivity of other shipping modes (particularly rail), and potential 

environmental and social costs.

The National Research Council in its recent report111

2.9.7 Traffic Congestion Mitigation

recognized the complexities 

and potential trade-offs involved in increasing vehicle size and weight limits. While is worthy 

to discuss the potential emission and energy benefits of heavier and longer trucks, the farreaching policy ramifications extend far beyond the scope of this proposal.

There are a wide range of strategies to reduce traffic congestion. Many of them are 

aimed at eliminating light-duty vehicle trips such as mass transit improvements, commute trip 

reduction programs, ridesharing programs, implementation of high occupancy vehicle lanes, 

parking pricing, and parking management programs. While focused on reducing light-duty 

vehicle trips, these types of strategies would allow heavy- and medium-duty vehicles to travel 

on less congested roads and thereby use less fuel and emit less CO2

A second group of strategies would directly impact CO

. 

2

Some strategies would be designed to effect trips made by heavy- and medium-duty 

trucks. These would include programs to shift deliveries in congested areas to off-peak hours. 

Another example is to modify land use so that common destinations are closer together, which 

reduces the amount of travel required for goods distribution. 

emissions and fuel 

consumption from all types of vehicles. One example of these strategies is road pricing 

including increasing the price of driving on certain roads or in certain areas during the most 

congested periods of the day. A second example is reducing the speed limits on roads and 

implementing measures to ensure that drivers obey the lower speed limits such as increased 

enforcement or adding design features that discourage excessive speeds. 

These types of congestion relief strategies have been implemented in a number of 

areas around the country. They are typically implemented either by state or local 

governments or in some cases strategies to reduce commuting trips and scheduling off-peak 

deliveries have been implemented by private companies or groups of companies. 

Deleted: congestion mitigation
Heavy Duty GHG and Fuel Efficiency Standards NPRM: Technologies, Cost, and 

Effectiveness

2-91

2.10 Summary of Technology Costs Used in this Analysis

Table 2-35 shows the technology costs used throughout this analysis for heavy-duty 

engines, vocational vehicles and combination tractors for the years 2014-2020. Table 2-36

shows the technology costs used throughout this analysis for Class 2b and 3 diesel and 

gasoline trucks for the years 2014-2020. These tables reflect the impact of learning effects on 

estimated technology costs. Refer to Table 2-1 for details on the ICMs applied to each 

technology and Table 2-2 for the type of learning applied to each technology. The costs 

shown in the tables do not include the penetration rates so do not always reflect the 

technology’s contribution to the resultant package costs. One final note of clarification is that 

the terms “MHDDcomb” and “HHDDcomb” in the “Class” column refer specifically to 

engines placed in combination tractors (Class 7 and 8 day cabs and sleeper cabs).

Deleted: 33

Deleted: This table reflects

Deleted: Table 

Field Code Changed

Deleted: table 

Deleted: true cost of 

Deleted: technology if, for example, the expected 

penetration rate for that technology is less than 100 

percent or, as is the case for turbo compounding, the 

technology is not expected until the 2017 model year 

(cost for this technology are shown as $0 in years 

prior to 2017).

Deleted: term “HHDD8

Deleted: refers specially

Deleted: .
Deleted: Regulatory Impact Analysis 

Deleted: 2-94

Table 2-35 Technology Effectiveness and Costs, Inclusive of Markups, by Year for Heavy-duty DieselG

and Gasoline Engines, Vocational Vehicles, and Combination Tractors (2008$)

Technology Applie

d to Truck type Class

CO2

2014

eq 

Effectivenes

s

2015 2016 2017 2018 2019 2020

Aftertreatment 

improvements Engine LHDD 1-4% $111 $108 $104 $101 $98 $96 $94

Turbo efficiency 

improvements Engine LHDD 1-2% $17 $17 $16 $16 $17 $17 $16

Piston improvements Engine LHDD

0.5-2%

$3 $3 $2 $2 $2 $2 $2

Optimized water pump Engine LHDD $87 $84 $82 $79 $77 $75 $74

Optimized oil pump Engine LHDD $4 $4 $4 $4 $4 $4 $4

Optimized fuel pump Engine LHDD $4 $4 $4 $4 $4 $4 $4

Valve train friction 

reductions Engine LHDD $104 $101 $98 $95 $92 $90 $88

Optimized fuel rail Engine LHDD

2-7%

$11 $11 $11 $10 $10 $10 $10

Optimized fuel injector Engine LHDD $14 $13 $13 $13 $12 $12 $12

EGR cooler

improvements Engine LHDD $3 $3 $3 $3 $3 $3 $3

Cylinder head 

improvements Engine LHDD $10 $10 $10 $9 $9 $9 $9

2014 MY LHDD 

Engine Package Engine LHDD 5% $369 $358 $348

2017 MY LHDD 

Engine Package Engine LHDD 9% $337 $327 $321 $314

Aftertreatment 

Improvements Engine MHDD 1-4% In R&D

In 

R&D

In 

R&D

In 

R&D In R&D In R&D In R&D

Turbo efficiency 

improvements Engine MHDD 1-2% $17 $17 $16 $16 $15 $15 $15

Piston improvements Engine MHDD 0.5-2% $3 $3 $2 $2 $2 $2 $2

 

G The costs included in the table represent technology costs. The engineering costs of $6,750,000 per 

diesel engine manufacturer per year for a five year period are not included in the table.

Deleted: used in this Analysis

Deleted: ¶ ...

Deleted: ¶ ...

Deleted: ¶ ...

Deleted: ¶ ...

Deleted: ¶ ...

Deleted: ¶ ...

Deleted: ¶

TruckClass _DayCa
Deleted: Heavy Duty GHG and Fuel Efficiency 

Standards NPRM: Technologies, Cost, and 

Effectiveness

Deleted: 2-93

Optimized water pump Engine MHDD $87 $84 $82 $79 $77 $75 $74

Optimized oil pump Engine MHDD $4 $4 $4 $4 $4 $4 $4

Optimized fuel pump Engine MHDD $4 $4 $4 $4 $4 $4 $4

Valve train friction 

reductions Engine MHDD $78 $76 $73 $71 $69 $68 $66

Optimized fuel rail Engine MHDD

2-7%

$10 $9 $9 $9 $8 $8 $8

Optimized fuel injector Engine MHDD $10 $10 $10 $9 $9 $9 $9

EGR cooler

improvements Engine MHDD $3 $3 $3 $3 $3 $3 $3

Cylinder head 

improvements Engine MHDD $6 $6 $6 $6 $5 $5 $5

2014 MY MHDD 

Engine Package Engine MHDD 5% $223 $216 $210

2017 MY MHDD 

Engine Package Engine MHDD 9% $203 $197 $193 $189

Aftertreatment 

Improvements Engine MHDDcomb

1-4% In 

R&D

In 

R&D

In 

R&D

In 

R&D In R&D In R&D In R&D

Turboefficiency 

improvements Engine MHDDcomb

1-2% $17 $17 $16 $16 $15 $15 $15

Piston improvements Engine MHDDcomb

0.5-2%

$3 $3 $2 $2 $2 $2 $2

Optimized water pump Engine MHDDcomb $87 $84 $82 $79 $77 $75 $74

Optimized oil pump Engine MHDDcomb $4 $4 $4 $4 $4 $4 $4

Optimized fuel pump Engine MHDDcomb $4 $4 $4 $4 $4 $4 $4

Valve train friction 

reductions Engine MHDDcomb $78 $76 $73 $71 $69 $68 $66

Optimized fuel rail Engine MHDDcomb

2-7%

$10 $9 $9 $9 $8 $8 $8

Optimized fuel injector Engine MHDDcomb $10 $10 $10 $9 $9 $9 $9

EGR cooler

improvements Engine MHDDcomb $3 $3 $3 $3 $3 $3 $3

Cylinder head 

improvements Engine MHDDcomb $6 $6 $6 $6 $5 $5 $5

Turbomechanical-

compounding Engine MHDDcomb 2.5

-5% -- -- -- $823 $798 $782 $767

2014 MY MHDD 

Engine Package Engine MHDDcomb 3% $223 $216 $210

2017 MY MHDD 

Engine Package Engine MHDDcomb 5% $1,027 $996 $976 $956

Aftertreatment 

Improvements Engine HHDD

1-4% In 

R&D

In 

R&D

In 

R&D

In 

R&D In R&D In R&D In R&D

Turboefficiency 

improvements Engine HHDD

1-2% $17 $17 $16 $16 $15 $15 $15

Piston improvements Engine HHDD

0.5-2%

$3 $3 $2 $2 $2 $2 $2

Optimized water pump Engine HHDD $87 $84 $82 $79 $77 $75 $74

Optimized oil pump Engine HHDD $4 $4 $4 $4 $4 $4 $4

Optimized fuel pump Engine HHDD $4 $4 $4 $4 $4 $4 $4

Optimized fuel rail Engine HHDD

2-7%

$10 $9 $9 $9 $8 $8 $8

Optimized fuel injector Engine HHDD $10 $10 $10 $9 $9 $9 $9

Cylinder head 

improvements Engine HHDD $6 $6 $6 $6 $5 $5 $5

EGR cooler

improvements Engine HHDD $3 $3 $3 $3 $3 $3 $3

2014 MY HHDD 

Engine Package Engine HHDD 5% $145 $140 $136

2017 MY HHDD 

Engine Package Engine HHDD 9% $132 $128 $126 $123

Aftertreatment Engine HHDDcomb1-4% In In In In In R&D In R&D In R&D
Deleted: Regulatory Impact Analysis 

Deleted: 2-94

Improvements R&D R&D R&D R&D

Turbo efficiency 

improvements Engine HHDDcomb 1-2% $17 $17 $16 $16 $15 $15 $15

Piston improvements Engine HHDDcomb

0.5-2%

$3 $3 $2 $2 $2 $2 $2

Optimized water pump Engine HHDDcomb $87 $84 $82 $79 $77 $75 $74

Optimized oil pump Engine HHDDcomb $4 $4 $4 $4 $4 $4 $4

Optimized fuel pump Engine HHDDcomb $4 $4 $4 $4 $4 $4 $4

Optimized fuel rail Engine HHDDcomb

2-7%

$10 $9 $9 $9 $8 $8 $8

Optimized fuel injector Engine HHDDcomb $10 $10 $10 $9 $9 $9 $9

Cylinder head 

improvements Engine HHDDcomb $6 $6 $6 $6 $5 $5 $5

EGR cooler

improvements Engine HHDD $3 $3 $3 $3 $3 $3 $3

Turbo mechanicalcompounding Engine HHDDcomb 2.5-5% -- -- -- $823 $798 $782 $767

2014 MY HHDD 

Engine Package Engine HHDDcomb 3% $145 $140 $136

2017 MY HHDD 

Engine Package Engine HHDDcomb 5% $955 $927 $908 $890

Engine friction 

reduction Engine HDG 1-3% -- -- $88 $88 $88 $88 $88

Coupled valve timing Engine HDG 1-4% -- -- $43 $42 $40 $40 $39

Stoich GDI-V8 Engine HDG 1-2% -- -- $372 $361 $350 $343 $336

HD Gasoline Engine 

Package – 2016 MY Engine HDG 5% -- -- $504 $491 $479 $471 $464

LRR steer tire 5.7 Truck Vocational LH 2-3% $65 $65 $52 $52 $42 $40 $39

LRR drive tire 7.0 Truck Vocational LH $91 $91 $72 $72 $58 $56 $55

2014MY Vehicle 

Package Truck Vocational LH 3% $155 $155 $124 $124 $99 $96 $94

LRR steer tire 5.7 Truck Vocational MH 2-3% $65 $65 $52 $52 $42 $40 $39

LRR drive tire 7.0 Truck Vocational MH $91 $91 $72 $72 $58 $56 $55

2014MY Vehicle 

Package Truck Vocational MH 3% $155 $155 $124 $124 $99 $96 $94

LRR steer tire 5.7 Truck Vocational HH 2-3% $65 $65 $52 $52 $42 $40 $39

LRR drive tire 7.0 Truck Vocational HH $121 $121 $97 $97 $77 $75 $73

2014MY Vehicle 

Package Truck Vocational HH 2% $186 $186 $148 $148 $119 $115 $112

Aero-SmartWay Truck Class7_DayCa

b LowRoof 1-2% $1,079 $1,046 $1,015 $985 $955 $936 $917

Aero-SmartWay 

Advance Truck Class7_DayCab LowRoof 2-3% $2,179 $2,179 $1,743 $1,743 $1,394 $1,353 $1,312

LRR steer tire Truck Class7_DayCa

b LowRoof

1-3%

$65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class7_DayCa

b LowRoof $60 $59 $57 $55 $53 $52 $51

Weight reduction: 

Single-wide tire Truck Class7_DayCab LowRoof

<1%

$322 $312 $303 $294 $285 $279 $274

Weight reduction: 

Aluminum steer wheel Truck Class7_DayCab LowRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class7_DayCa

b LowRoof $627 $608 $590 $572 $555 $544 $533

Air Conditioning 

Leakage Truck Class7_DayCab LowRoof <1% $21 $20 $20 $19 $19 $18 $18
Deleted: Heavy Duty GHG and Fuel Efficiency 

Standards NPRM: Technologies, Cost, and 

Effectiveness

Deleted: 2-93

2014MY Vehicle 

PackageH Truck Class7_DayCab LowRoof 3-4% $2,593 $2,529 $2,379 $2,318 $2,189 $2,142 $2,097

Aero-SmartWay Truck Class7_DayCa

b HighRoof 2-4% $1,107 $1,074 $1,042 $1,011 $980 $961 $941

Aero-SmartWay 

Advance Truck Class7_DayCab HighRoof 3-5% $2,207 $2,207 $1,766 $1,766 $1,413 $1,370 $1,329

LRR steer tire Truck Class7_DayCa

b HighRoof

1-3%

$65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class7_DayCa

b HighRoof $60 $59 $57 $55 $53 $52 $51

Weight reduction: 

Single-wide tire Truck Class7_DayCab HighRoof

<1%

$322 $312 $303 $294 $285 $279 $274

Weight reduction: 

Aluminum steer wheel Truck Class7_DayCab HighRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class7_DayCa

b HighRoof $627 $608 $590 $572 $555 $544 $533

Air Conditioning 

Leakage Truck Class7_DayCab HighRoof <1% $21 $20 $20 $19 $19 $18 $18

2014MY Vehicle 

Package Truck Class7_DayCab HighRoof 6-7% $2,835 $2,763 $2,605 $2,537 $2,401 $2,350 $2,301

Aero-SmartWay Truck Class8_DayCa

b LowRoof 1-2% $1,079 $1,046 $1,015 $985 $955 $936 $917

Aero-SmartWay 

Advance Truck Class 8_DayCab LowRoof 2-3% $2,179 $2,179 $1,743 $1,743 $1,394 $1,353 $1,312

LRR steer tire Truck Class8_DayCa

b LowRoof

1-3%

$65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class8_DayCa

b LowRoof $121 $117 $114 $110 $107 $105 $103

Weight reduction: 

Single-wide tire Truck Class8_DayCab LowRoof

<1%

$644 $624 $606 $588 $570 $559 $547

Weight reduction: 

Aluminum steer wheel Truck Class8_DayCab LowRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class8_DayCa

b LowRoof $1,254 $1,216 $1,180 $1,144 $1,110 $1,088 $1,066

Air Conditioning

Leakage Truck Class8_DayCab LowRoof <1% $21 $20 $20 $19 $19 $18 $18

2014MY Vehicle 

Package Truck Class8_DayCab LowRoof 3-4% $3,275 $3,17

6

$3,08

1

$2,98

9 $2,899 $2,841 $2,784

Aero-SmartWay Truck Class8_DayCa

b HighRoof 2-4% $1,107 $1,074 $1,042 $1,011 $980 $961 $941

Aero-SmartWay 

Advance Truck Class8_DayCab HighRoof 3-5% $2,207 $2,207 $1,766 $1,766 $1,413 $1,370 $1,329

LRR steer tire Truck Class8_DayCa

b HighRoof

1-3%

$65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class8_DayCa

b HighRoof $121 $117 $114 $110 $107 $105 $103

Weight reduction: Truck Class8_DayCa HighRoof <1% $644 $624 $606 $588 $570 $559 $547

 

H All vehicle package costs in the table include the proposed application rates of the individual 

technologies used to establish the proposed standards. 
Deleted: Regulatory Impact Analysis 

Deleted: 2-94

Single-wide tire b

Weight reduction: 

Aluminum steer wheel Truck Class8_DayCab HighRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class8_DayCa

b HighRoof $1,254 $1,216 $1,180 $1,144 $1,110 $1,088 $1,066

Air Conditioning 

Leakage Truck Class8_DayCab HighRoof <1% $21 $20 $20 $19 $19 $18 $18

2014MY Vehicle 

Package Truck Class8_DayCab HighRoof

6-7% $3,842 $3,75

4

$3,49

1

$3,40

7 $3,185 $3,116 $3,048

Aero-SmartWay Truck Class8_Sleeper

Cab LowRoof 3-5% $1,317 $1,277 $1,239 $1,202 $1,166 $1,142 $1,120

Aero-SmartWay 

Advance Truck Class8_SleeperCab LowRoof 4-7% $2,492 $2,492 $1,994 $1,994 $1,595 $1,547 $1,501

LRR steer tire Truck Class8_Sleeper

Cab LowRoof 1-3% $65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class8_Sleeper

Cab LowRoof $121 $117 $114 $110 $107 $105 $103

Weight reduction: 

Single-wide tire Truck Class8_SleeperCab LowRoof <1% $644 $624 $606 $588 $570 $559 $547

Weight reduction: 

Aluminum steer wheel Truck Class8_SleeperCab LowRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class8_Sleeper

Cab LowRoof $1,254 $1,216 $1,180 $1,144 $1,110 $1,088 $1,066

Aux power unit (APU) Truck Class8_Sleeper

Cab LowRoof 5-6% $5,228 $5,071 $4,919 $4,772 $4,628 $4,536 $4,445

Air Conditioning 

Leakage Truck Class8_SleeperCab LowRoof <1% $21 $20 $20 $19 $19 $18 $18

2014MY Vehicle 

Package Truck Class8_SleeperCab LowRoof

12-13% $7,312 $7,10

8

$6,81

0

$6,61

7 $6,351 $6,221 $6,093

Aero-SmartWay Truck Class8_Sleeper

Cab MidRoof 3-5% $1,345 $1,305 $1,266 $1,228 $1,191 $1,167 $1,144

Aero-SmartWay 

Advance Truck Class8_SleeperCab MidRoof 4-7% $2,492 $2,492 $1,994 $1,994 $1,595 $1,547 $1,501

LRR steer tire Truck Class8_Sleeper

Cab MidRoof 1-3% $65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class8_Sleeper

Cab MidRoof $121 $117 $114 $110 $107 $105 $103

Weight reduction: 

Single-wide tire Truck Class8_SleeperCab MidRoof <1% $644 $624 $606 $588 $570 $559 $547

Weight reduction: 

Aluminum steer wheel Truck Class8_SleeperCab MidRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class8_Sleeper

Cab MidRoof $1,254 $1,216 $1,180 $1,144 $1,110 $1,088 $1,066

Aux power unit (APU) Truck Class8_Sleeper

Cab MidRoof 5-6% $5,228 $5,071 $4,919 $4,772 $4,628 $4,536 $4,445

Air Conditioning 

Leakage Truck Class8_SleeperCab MidRoof <1% $21 $20 $20 $19 $19 $18 $18

2014MY Vehicle 

Package Truck Class8_SleeperCab MidRoof

11-12% $7,438 $7,23

8

$6,89

3

$6,70

4 $6,402 $6,269 $6,139

Aero-SmartWay Truck Class8_Sleeper

Cab HighRoof 3-5% $1,495 $1,450 $1,406 $1,364 $1,323 $1,297 $1,271

Aero-SmartWay 

Advance Truck Class8_SleeperCab HighRoof 4-7% $2,564 $2,564 $2,051 $2,051 $1,641 $1,591 $1,544
Deleted: Heavy Duty GHG and Fuel Efficiency 

Standards NPRM: Technologies, Cost, and 

Effectiveness

Deleted: 2-93

LRR steer tire Truck Class8_Sleeper

Cab HighRoof 1-3% $65 $63 $61 $59 $57 $56 $55

LRR drive tire Truck Class8_Sleeper

Cab HighRoof $121 $117 $114 $110 $107 $105 $103

Weight reduction: 

Single-wide tire Truck Class8_SleeperCab HighRoof <1% $644 $624 $606 $588 $570 $559 $547

Weight reduction: 

Aluminum steer wheel Truck Class8_SleeperCab HighRoof $523 $507 $492 $477 $463 $454 $445

Weight reduction: 

Aluminum single-wide 

wheel

Truck Class8_Sleeper

Cab HighRoof $1,254 $1,216 $1,180 $1,144 $1,110 $1,088 $1,066

Aux power unit (APU) Truck Class8_Sleeper

Cab HighRoof 5-6% $5,228 $5,071 $4,919 $4,772 $4,628 $4,536 $4,445

Air Conditioning 

Leakage Truck Class8_SleeperCab HighRoof <1% $21 $20 $20 $19 $19 $18 $18

2014MY Vehicle 

Package Truck Class8_SleeperCab HighRoof 15-16% $7,814 $7,58

7

$7,31

6

$7,10

3 $6,855 $6,716 $6,580

Deleted: Page Break

¶
Deleted: Regulatory Impact Analysis 

Deleted: 2-94

Table 2-36 Technology Effectiveness and Costs, Inclusive of Markups, by Year for HD Diesel and 

Gasoline Pickup Trucks & Vans (2008$)

Technology Applied to CO2eq 

Effectiveness 2014 2015 2016 2017 2018 2019 2020

Low friction 

lubricants All 0-1% $4 $4 $4 $4 $4 $4 $4

Engine friction 

reduction

HD

Gasoline 1-3% $108 $108 $108 $108 $108 $108 $108

Coupled cam 

phasing

HD 

Gasoline 1-4% $46 $44 $43 $43 $43 $43 $43

Cylinder 

deactivation

HD

Gasoline 3-4% $193 $187 $182 $182 $182 $182 $182

Stoich GDI V8 HD

Gasoline 1-2% $395 $384 $372 $372 $372 $372 $372

8sp AT (relative 

to 6sp AT) All 1.7% $231 $224 $218 $218 $218 $218 $218

Low RR Tires All 1-2% $6 $6 $6 $6 $6 $6 $6

Aero1 All 1-2% $54 $53 $51 $51 $51 $51 $51

Electric/Electrohydraulic Power 

steering

All 1-2% $108 $104 $101 $101 $101 $101 $101

DSL engine 

improvements HD Diesel 4-6% $172 $167 $162 $157 $152 $148 $145

DSL 

aftertreatment 

improvements

HD Diesel 3-5% $110 $107 $104 $104 $104 $104 $104

Improved 

accessories HD Diesel 1-2% $88 $85 $82 $82 $82 $82 $82

Mass Reduction 

(5%)

2b 

HDGasoline 1.6% $462 $448 $435 $435 $435 $435 $435

Mass Reduction 

(5%)

2b 

HDDiesel 1.6% $544 $527 $511 $511 $511 $511 $511

Mass Reduction 

(5%)

3 

HDGasoline 1.6% $513 $498 $483 $483 $483 $483 $483

Mass Reduction 

(5%) 3 HDDiesel 1.6% $576 $559 $542 $542 $542 $542 $542

Air 

Conditioning

Leakage

All 2% $21 $20 $20 $19 $19 $18 $18

Overall 2018 

MY Package 12-17% $1,411 $1,406 $1,350
Deleted: Heavy Duty GHG and Fuel Efficiency 

Standards NPRM: Technologies, Cost, and 

Effectiveness

Deleted: 2-93

References

1 National Academy of Science. Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles. March 2010.

2 TIAX, LLC. Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles. November 

2009.

3 U.S. EPA. EPA Lumped Parameter Model HD Version 1.0.0.5, 2010. Docket #EPA-HQ-OAR-2010-0162.

4 NESCCAF, ICCT, Southwest Research Institute, and TIAX. Reducing Heavy-Duty Long Haul Combination 

Truck Fuel Consumption and CO2 Emissions. October 2009.

5 ICF International. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for Heavy-Duty 

On-Road Vehicles. July 2010. Docket Identification Number EPA-HQ-OAR-2010-0162-0044.

6 Revenue = Direct Costs + Indirect Costs + Net Income

7 RTI International. Heavy Duty Truck Retail Price Equivalent and Indirect Cost Multipliers. July 2010.

8 See “Learning Curves in Manufacturing”, L. Argote and D. Epple, Science, Volume 247; “Toward Cost Buy 

down Via Learning-by-Doing for Environmental Energy Technologies, R. Williams, Princeton University, 

Workshop on Learning-by-Doing in Energy Technologies, June 2003; “Industry Learning Environments and the 

Heterogeneity of Firm Performance, N. Balasubramanian and M. Lieberman, UCLA Anderson School of 

Management, December 2006, Discussion Papers, Center for Economic Studies, Washington DC.

9 U.S. EPA and NHTSA, “Final Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission 

Standards and Corporate Average Fuel Economy Standards – Joint Technical Support Document,” 2010. Last 

viewed on June 3, 2010 at http://www.epa.gov/otaq/climate/regulations/420r10901.pdf

10 Note that throughout the cost estimates for this HD analysis, the agencies have used slightly higher markups 

than those used in the 2010-2016 light-duty FRM. The new, slightly higher ICMs include return on capital of 

roughly 6 percent, a factor that was not included in the light-duty analysis. 11 Note that the costs developed for low friction lubes for this analysis reflect the costs associated with any 

engine changes that would be required as well as any durability testing that may be required.

12 U.S. EPA and NHTSA, “Final Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission 

Standards and Corporate Average Fuel Economy Standards – Joint Technical Support Document,” 2010. Last 

viewed on June 3, 2010 at http://www.epa.gov/otaq/climate/regulations/420r10901.pdf

13 Note that throughout the cost estimates for this HD analysis, the agencies have used slightly higher markups 

than those used in the 2010-2016 light-duty FRM. The new, slightly higher ICMs include return on capital of 

roughly 6 percent, a factor that was not included in the light-duty analysis. 14 Note that the costs developed for low friction lubes for this analysis reflect the costs associated with any 

engine changes that would be required as well as any durability testing that may be required.

15 TIAX. Assessment of Fuel Economy Technologies for Medium- and Heavy- Duty Vehicles, Final Report, 

Nov. 19, 2009, pg 4-15.

16 Stanton, Donald. “Enabling High Efficiency Clean Combustion.” 2009 Semi-Mega Merit Review of the 

Department of Energy. May 21, 2009. Last accessed on August 25, 2010 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2009/advanced_combustion/ace_40_stanton.p

df.

17 Stanton, Donald. “Enabling High Efficiency Clean Combustion.” 2009 Semi-Mega Merit Review of the 

Department of Energy. May 21, 2009. Last accessed on August 25, 2010 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2009/advanced_combustion/ace_40_stanton.p

df.

Deleted: Heavy Duty

Deleted: . NEED DOCKET #.

Deleted: June 2010.
Deleted: Regulatory Impact Analysis 

Deleted: 2-94

 

18 “Tires and Passenger Vehicle Fuel Economy,” Transportation Research Board Special Report 286, National 

Research Council of the National Academies, 2006, Docket EPA-HQ-OAR-2009-0472-0146.

19 U.S. EPA and NHTSA, “Final Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission 

Standards and Corporate Average Fuel Economy Standards – Joint Technical Support Document,” 2010. Last 

viewed on June 3, 2010 at http://www.epa.gov/otaq/climate/regulations/420r10901.pdf

20 U.S.EPA, EPA Lumped Parameter Model HD Version 1.0.0.5, 2010. Docket #EPA-HQ-OAR-2010-0162.

21 Stanton, Donald. “Enabling High Efficiency Clean Combustion.” 2009 Semi-Mega Merit Review of the 

Department of Energy. May 21, 2009. Last accessed on August 25, 2010 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2009/advanced_combustion/ace_40_stanton.p

df.

22 Zhang, H. Heavy Truck Engine Development & HECC. 2009 DOE Semi-Mega Merit Review, May 21, 2009. 

Last accessed on August 25, 2010 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2009/advanced_combustion/ace_42_zhang.pd

f

23 NAS Report. 2010. Pages 53-54.

24 NAS Report. 2010. Page 54.

25 TIAX Report. 2009. Page 3-5.

26 NAS Report. 2010. Page 54.

27 Vuk, C. “Electric Turbo Compounding...A Technology Who’s Time Has Come.” 2006 DEER Conference. 

Last accessed on August 25, 2010 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2006/session6/2006_deer_vuk.pdf

28 TIAX, Nov. 19, 2009, page 4-15.

29 Zhang, H. “High Efficiency Clean Combustion for Heavy-Duty Engine.” August 6, 2008 presentation to 

DEER Conference. Last accessed on August 25, 2010 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2008/session5/deer08_zhang.pdf

30 NAS Report. 2010. Page 57.

31 NAS Report. 2010. Page 57.

32 Assumes travel on level road at 65 MPH. (21st Century Truck Partnership Roadmap and Technical White 

Papers, December 2006. U.S. Department of Energy, Energy Efficiency and Renewable Energy Program. 

21CTP-003. p. 36.)

33 Reducing Heavy-Duty Long Haul Combination Truck Fuel Consumption and CO2 Emissions, ICCT, October 

2009

38 SAE 2006-01-3456

39 U.S. EPA. Heavy-Duty Coastdown Test Procedure Development. Docket # EPA-HQ-OAR-2010-0162-0144.

41 ICF. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions fro Heavy-Duty On-Road 

Vehicles. July 2010. Docket Identification Number EPA-HQ-OAR-2010-0162-0044.

42 21st Century Truck Partnership, “Roadmap and technical White Papers”, U.S. Department of Energy, 

Technical paper: 21CTP-0003, December 2006.

Deleted: “

Deleted: 1,”

Deleted: 

Deleted: 33 Class 8, line-haul tractors typically 

operate for extended periods of time at highway 

speeds. (

Deleted: ). Class 7 and 8 day cabs with “regional” 

routes are expected to travel at highway speeds for 

portions of their operation but also include 

significant time operating at slower speeds that are 

influenced by urban congestion. (CITATION! 

FIRM-UP. sjw)

Deleted: 39 Memo to Docket. Summary of EPA 

testing with ATDS on vehicle coastdown.
Deleted: Heavy Duty GHG and Fuel Efficiency 

Standards NPRM: Technologies, Cost, and 

Effectiveness

Deleted: 2-93

 

43 “Tires & Truck Fuel Economy,” A New Perspective. Bridgestone Firestone, North American Tire, LLC, 

Special Edition Four, 2008. 

44 “Michelin’s Green Meters,” Press Kit, October, 30, 2007. http://www.michelin-greenmeter.com/main.php?cLang=en (Complete Press File, Viewed March 6, 2010)

45 “Modeling of Fuel Consumption for Heavy-Duty Trucks and the Impact of Tire Rolling Resistance,” Tim J. 

LaClair, Russell Truemner, SAE International, 2005-01-3550, 2005. 

46 “Factors Affecting Truck Fuel Economy,” Goodyear, Radial Truck and Retread Service Manual. Accessed 

February 16, 2010 at http://www.goodyear.com/truck/pdf/radialretserv/Retread_S9_V.pdf. 

47 “Tire Rolling Resistance, Its Impact on Fuel Economy, and Measurement Standards,” Presentation by Tim J. 

LaClair of Michelin Americas Research & Development Corp. to the California Energy Commission, 2002.

48 “Technology Roadmap for the 21st Century Truck Program. A Government-Industry Partnership,” U.S. 

Department of Energy, 21CT-001, December 2000. 

49 “Energy Efficiency Strategies for Freight Trucking: Potential Impact on Fuel Use and Greenhouse Gas 

Emissions,” J. Ang-Olson, W. Schroer, Transportation Research Record: Journal of the Transportation Research 

Board, 2002(1815):11-18. 

50 “Effect of Single Wide Tires and Trailer Aerodynamics on Fuel Economy and NOx Emissions of Class 8 

Line-Haul Tractor-Trailer,” J. Bachman, A. Erb, C. Bynum, U.S. Environmental Protection Agency, SAE 

International, Paper Number 05CV-45, 2005. 

51 “Class 8 Heavy Truck Duty Cycle Project Final Report,” U.S. Department of Energy, Oak Ridge National 

Laboratory, ORNL/TM-2008/122, p. 21, December 2008. Accessed January 19, 2010 at 

http://cta.ornl.gov/cta/Publications/Reports/ORNL_TM_2008-122.pdf. 

52 “Are Ultra-Wide, Ultra-Low Aspect Ratio Tires the Next Big Thing?” K. Rohlwing, Today’s Tire Industry, 

Vol. 1, Issue 1, July/August, July 2003.

53 “New Generation Wide Base Single Tires,” American Trucking Association, White paper presented at the 

International Workshop on the use of wide tires sponsored by Federal Highway Administration, Turner-Fairbank 

Highway Research Center, October 25-26, 2007, Revision 9, December 21, 2007, Accessed on February 3, 2010 

at http://www.arc.unr.edu/Workshops/Wide_Tires/Wide_Base_Summary-v9-ATA-whitepaper.pdf

54 “Recommended Practice: Guidelines for Outset Wide Base Wheels for Drive, Trailer and Auxiliary Axle 

Applications (Draft),” Technology and Maintenance Council, Council of American Trucking Associations, 

circulated September 28, 2009. 

55 ICF. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions fro Heavy-Duty On-Road 

Vehicles. July 2010. Docket Identification Number EPA-HQ-OAR-2010-0162-0044.

56 “Buses & Retread Tires,” The Tire Retread & Repair Information Bureau, Pacific Grove, Ca., Accessed on 

January 27, 2010 at http://www.retread.org/packet/index.cfm/ID/284.htm. 

57 “What are Retreaders Doing to Improve Fuel Efficiency?” H. Inman, Tire Review, December 11, 2006, 

Accessed on February 18, 2010 at 

http://www.tirereview.com/Article/59777/what_are_retreaders_doing_to_improve_fuel_efficiency.aspx. 

58 “Better Fuel Economy? Start with a Strong Tire Program,” H. Inman, Fleet & Tire 2006, Tire Review, 

December 11, 2006, Accessed on February 18, 2010 at 

http://www.tirereview.com/Article/59776/better_fuel_economy_start_with_a_strong_tire_program.aspx. 

59 “SmartWay Transport Partnership: Innovative Carrier Strategies”, February 2004, EPA420-F-04-005, 

Accessed on the Internet on January 18, 2010 at: http://www.epa.gov/smartway/transport/what-smartway/carrierstrategies.htm#weight.

Deleted: June 2010.
Deleted: Regulatory Impact Analysis 

Deleted: 2-94

 

60 “Energy Savings through Increased Fuel Economy for Heavy Duty Trucks”, Therese Langer, American 

Council for an Energy-Efficient Economy prepared for the National Commission on Energy Policy, February 11, 

2004.

61 “The Potential Effect of Future Energy-Efficiency and Emissions-Improving Technologies on Fuel 

Consumption of Heavy Trucks”, Argonne National Laboratory, Technical Report ANL/ESD/02-4, August 2002.

62 U.S. EPA. http://www.epa.gov/smartway/documents/weightreduction.pdf

63 U.S. EPA. http://www.epa.gov/smartway/documents/weightreduction.pdf

64 Gaines, L. and D. Santini. Argonne National Laboratory, Economic Analysis of Commercial Idling Reduction 

Technologies

65 Gaines, L., A. Vyas, J. Anderson. Estimation of Fuel Use by Idling Commercial Trucks. 2006. Page 9. 66 Gaines, L., A. Vyas, J. Anderson. Estimation of Fuel Use by Idling Commercial Trucks. 2006. Page 7. 67 NAS Study. 2010. Page 122 says the best in class APU consumes 0.18 gallon per hour.

68 American Trucking Association. Last viewed on January 29, 2010 at 

http://www.trucksdeliver.org/recommendations/speed-limits.html

69 U.S. EPA SmartWay Transport Partnership. Last viewed on January 28, 2010 at 

http://www.epa.gov/smartway/transport/documents/tech/reducedspeed.pdf

70 Department for Transport, Vehicle and Operator Services Agency. Last viewed on January 6, 2010 at 

http://www.dft.gov.uk/vosa/newsandevents/pressreleases/2006pressreleases/28-12-06speedlimiterlegislation.htm

71 Transport Canada. Summary Report – Assessment of a Heavy Truck Speed Limiter Requirement in Canada. 

Last viewed on January 6, 2010 at http://www.tc.gc.ca/eng/roadsafety/tp-tp14808-menu-370.htm

72 Transport Canada. Summary Report – Assessment of a Heavy-Truck Speed Limiter Requirement in Canada.

73 “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles”, TIAX LLC, November 

19, 2009. Page 4-98.

74 “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles”, TIAX LLC, November 

19, 2009. Page 4-98.

75 US Environmental Protection Agency's SmartWay Transport Partnership July 2010 e-update accessed July 

16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf

76 TIAX. Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles. November 2009. 

Page 4-40.

77 U.S. Department of Energy. Transportation Energy Data Book, Edition 28-2009. Table 5.7.

79 As explained further in Section V below, EPA would use these inputs in GEM even for engines electing to use 

the alternative engine standard.

80

81 Rubber Manufacturers Association. Presentation to California Air Resource Board. June 2009. Last viewed 

at 

http://www.rma.org/rma_resources/government_affairs/federal_issues/RMA%20COMMENTS%20APPENDIX

%201%20-%20ENVIRON%20Report%20-%20Data%20Analysis.pdf

82 Kargul, J. J., 2010, "Clean Automotive Technology. Cost-Effective Solutions for a Petroleum and Carbon 

Constrained World," Presentation made to National Academy of Sciences, Review of 21st Century Truck 

Program, September 8, 2010
Deleted: Heavy Duty GHG and Fuel Efficiency 

Standards NPRM: Technologies, Cost, and 

Effectiveness

Deleted: 2-93

 

83 “Best practices Guidebook for Greenhouse Gas Reductions in Freight Transportation”, H. Christopher Fey, 

Po-Yao Kuo, North Carolina State University prepared for the U.S. Department of Transportation, October 4, 

2007.

84 “Reducing Heavy-Duty long haul Combination Truck Fuel Consumption and CO2 Emissions”, NESCCAF, 

ICCT, SwRI, TIAX LLC, October 2009.

85 The U.S. EPA has reclamation requirements for refrigerants in place under Title VI of the Clean Air Act.

86 The global warming potentials (GWP) used in the NPRM analysis are consistent with Intergovernmental Panel 

on Climate Change (IPCC) Fourth Assessment Report (AR4). At this time, the IPCC Second Assessment Report 

(SAR) global warming potential values have been agreed upon as the official U.S. framework for addressing 

climate change. The IPCC SAR GWP values are used in the official U.S. greenhouse gas inventory submission 

to the climate change framework. When inventories are recalculated for the final rule, changes in GWP used 

may lead to adjustments. 

87 Schwarz, W., Harnisch, J. 2003. “Establishing Leakage Rates of Mobile Air Conditioners.” Prepared for the 

European Commission (DG Environment), Doc B4-3040/2002/337136/MAR/C1. 

88 Vincent, R., Cleary, K., Ayala, A., Corey, R. 2004. “Emissions of HFC-134a from Light-Duty Vehicles in 

California.” SAE 2004-01-2256. 

89 The Minnesota refrigerant leakage data can be found at 

http://www.pca.state.mn.us/climatechange/mobileair.html#leakdata.

90 Society of Automotive Engineers, “IMAC Team 1 – Refrigerant Leakage Reduction, Final Report to 

Sponsors,” 2006.

91 Society of Automotive Engineers Surface Vehicle Standard J2727, issued August 2008, http://www.sae.org.

92 U.S. Department of Transportation, Federal Highway Administration. Federal Highway Statistics. “Trailer 

and Semitrailer Registrations – 2008” Table MV-11 located at 

www.fhwa.dot.gov/policyinformation/statistics/2008/mv11.cfm

93 The International Council on Clean Transportation. Heavy Duty Vehicle Market Analysis. May 2009. Table

94Trailer Body Builders. Last viewed on August 18, 2010 at http://trailer-bodybuilders.com/traileroutput/output/2008_trailer_output_table/

95 ICF. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions fro Heavy-Duty On-Road 

Vehicles. July 2010. Docket Identification Number EPA-HQ-OAR-2010-0162-0044.

96 “Review of Low Carbon Technologies for Heavy Goods Vehicles – Annex 1”, Ricardo prepared for 

Department of Transport, Technology Paper RD.09/182601.7, Jun 2009

97 U.S. Environmental Protection Agency Office of Transportation and Air Quality SmartWay Transport 

Partnership, A Glance at Clean Freight Strategies: Drivers Training EPA 420-F-04-008; February 2004.

98 Ibid.

99 National Research Council, Technologies and Approaches to Reducing the Fuel Consumption of Medium- and 

Heavy-Duty Vehicles, Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty 

Vehicles; Washington, DC, National Academies Press, 2010.

100 Information from US EPA review of 2009 SmartWay Excellence Awards applications.

101 U.S. Environmental Protection Agency Office of Transportation and Air Quality SmartWay Transport 

Partnership, A Glance at Clean Freight Strategies: Drivers Training EPA 420-F-04-008; February 2004. 

Deleted: 92 2008 FHWA – NEED COMPLETE 

CITATION.

Deleted: June 2010.
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Deleted: 2-94

 

102 National Research Council, Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles, Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty 

Vehicles; Washington, DC, National Academies Press, 2010.

103 Technology and Maintenance Council of the American Trucking Associations, Tire Air Pressure Study, Tire 

Debris Prevention Task Force S.2 Tire & Wheel Study Group; May 2002.

104 National Research Council, Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles, Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty 

Vehicles; Washington, DC, National Academies Press, 2010.

105 U.S. Environmental Protection Agency Office of Transportation and Air Quality SmartWay Transport 

Partnership, A Glance at Clean Freight Strategies: Automatic Tire Inflation Systems EPA 420-F-04-0010; 

February 2004. 

106 National Research Council, Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles, Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty 

Vehicles; Washington, DC, National Academies Press, 2010.

107 Ibid.

108 “Comprehensive Truck Weight and Size Study: Summary Report,” U.S. DOT Federal Highway Traffic 

Administration, August 2000.

109 “Comprehensive Truck Weight and Size Study: Summary Report,” U.S. DOT Federal Highway Traffic 

Administration, August 2000.

110 “Comprehensive Truck Weight and Size Study: Summary Report,” U.S. DOT Federal Highway Traffic 

Administration, August 2000.

111 National Research Council, Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles, Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty 

Vehicles; Washington, DC, National Academies Press, 2010.
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-1

CHAPTER 3: TEST PROCEDURES................................................................. 3-2

3.1 Heavy-Duty Engine Test Procedure ............................................................................... 3-2

3.1.1 Existing Regulation Reference.............................................................................. 3-2

3.1.2 Engine Dynamometer Test Procedure Modifications ........................................ 3-3

3.1.3 Engine Family Definition and Test Engine Selection ......................................... 3-5

3.2 Aerodynamic Assessment ................................................................................................ 3-6

3.2.1 Standardized Trailer Definition ........................................................................... 3-6

3.2.2 Aerodynamic Assessment...................................................................................... 3-7

3.3 Tire Rolling Resistance .................................................................................................. 3-21

3.3.1 Reason for Using ISO 28580 ............................................................................... 3-21

3.3.2 Measurement Method and Results..................................................................... 3-22

3.3.3 Sample Size........................................................................................................... 3-22

3.4 Drive Cycle...................................................................................................................... 3-23

3.4.1 Drive Cycles Considered ..................................................................................... 3-23

3.4.2 Proposed Drive Cycles......................................................................................... 3-25

3.4.3 Weightings of Each Cycle per Regulatory Subcategory .................................. 3-25

3.5 Tare Weights and Payload ............................................................................................ 3-27

3.5.1 Truck Tare Weights............................................................................................. 3-27

3.5.2 Trailer Tare Weights........................................................................................... 3-28

3.5.3 Payload.................................................................................................................. 3-28

3.5.4 Total Weight......................................................................................................... 3-29

3.6 Heavy-Duty Chassis Test Procedure ............................................................................ 3-30

3.7 Hybrid Powertrain Test Procedures............................................................................. 3-31

3.7.1 Chassis Dynamometer Evaluation...................................................................... 3-34

3.7.2 Engine Dynamometer Evaluation ...................................................................... 3-40

3.8 HD Pickup Truck and Van Chassis Test Procedure................................................... 3-42

3.8.1 LHD UDDS and HWFE Testing......................................................................... 3-42

3.8.2 LHD UDDS and HWFE Hybrid Testing ........................................................... 3-43

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Draft Regulatory Impact Analysis 

3-2

Chapter 3: Test Procedures

Test procedures are a crucial aspect of the proposed heavy-duty vehicle GHG and fuel 

consumption program. The proposed rulemaking is establishing several new test procedures for 

both engine and vehicle compliance. This chapter will describe the development process for the 

test procedures being proposed, including the assessment of engines, aerodynamics, rolling 

resistance, chassis dynamometer testing, and drive cycles.

3.1 Heavy-Duty Engine Test Procedure 

The agencies are proposing to control heavy-duty engine fuel consumption and 

greenhouse gas emissions through the use of engine certification. The proposed program will 

mirror existing engine regulations for the control of non-GHG pollutants in many aspects. The 

following sections provide an overview of the proposed test procedures.

3.1.1 Existing Regulation Reference

Heavy-duty engines currently are certified for non-GHG pollutants using test procedures 

developed by EPA. The Heavy-Duty Federal Test Procedure is a transient test consisting of 

second-by-second sequences of engine speed and torque pairs with values given in normalized 

percent of maximum form. The cycle was computer generated from a dataset of 88 heavy-duty

trucks in urban operation in New York and Los Angeles. These procedures are well-defined and 

we believe appropriate also for the assessment of GHG emissions. EPA is concerned that we 

maintain a regulatory relationship between the non-GHG emissions and GHG emissions, 

especially for control of CO2 and NOx

For 2007 and later Heavy-Duty engines, Parts 86 – “Control of Emissions from New and 

In-Use Highway Vehicles and Engines” and 1065 – “Engine Testing Procedures” detail the 

certification process. Part 86.007-11 defines the standard settings of Oxides of Nitrogen, NonMethane Hydrocarbons, Carbon Monoxide, and Particulate. The duty cycles are defined in Part 

86. The Federal Test Procedure engine test cycle is defined in Part 86 Appendix I. The 

Supplemental Emissions Test engine cycle is defined in §86.1360-2007(b). All emission 

measurements and calculations are defined in Part 1065, with exceptions as noted in §86.007-11. 

The data requirements are defined in § 86.001-23 and 1065.695.

. Therefore, we are proposing to use the same test 

procedures. 

The procedure for CO2 measurement is presented in §1065.250. For measurement of 

CH4 refer to §1065.260. For measurement of N2O refer to §1065.275. We recommend that you 

use an analyzer that meets performance specifications shown in Table 1 of §1065.205. Note that 

your system must meet the linearity verification of §1065.307. To calculate the brake specific 

mass emissions for CO2, CH4 and N2O refer to §1065.650. For CH4

Deleted: 

refer to §1065.660(a) to 

calculate the contamination correction. 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-3

3.1.2 Engine Dynamometer Test Procedure Modifications 

3.1.2.1 Fuel Consumption Calculation

EPA and NHTSA propose to calculate fuel consumption, as defined as gallons per brake 

horsepower-hour, from the CO2 measurement. The agencies are proposing that manufacturers 

use 8,887 gram of CO2 per gallon of gasoline and 10,180 g CO2 per gallon of diesel fuel.

3.1.2.2 N2

EPA proposes that manufacturers would need to submit measurements of N

O Measurement

2O to be able 

to apply for a certificate of conformity with the N2O standard. Engine emissions regulations do 

not currently require testing for N2O, and most test facilities do not have equipment for its 

measurement. Manufacturers without this capability would need to acquire and install 

appropriate measurement equipment. For use commencing with MY 2015 engines and vehicles, 

EPA is proposing four N2

3.1.2.3 CO

O measurement methods, all of which are commercially available 

today. EPA expects that most manufacturers would use photo-acoustic measurement equipment, 

which the Agency estimates would result in a one-time cost of about $50,000 for each test cell 

that would need to be upgraded. 

2

EPA and NHTSA evaluated two means to handle the CO

Measurement Variability

2

The agencies are proposing to take an approach where manufacturers are allowed to 

determine their own compliance margin, but it must be at least two percent to account for the 

test-to-test variation. The agencies developed the two percent threshold based on CO

and fuel consumption 

measurement variability. The first is to use an approach similar to the LD GHG and Fuel 

Economy program where the agencies adopted a compliance factor that is applied to the 

measured value. The second is an approach where the standard is set as a not to exceed standard. 

Manufacturers set a design target set sufficiently below the standard to account for production 

variability and deterioration.

2

measurement variability from several test programs. The programs include internal EPA roundrobin testing, ACES2

, and the Gaseous MA program.3 Table 3-1 summarizes the results from 

each of these programs.

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Draft Regulatory Impact Analysis 

3-4

Table 3-1: Summary of CO2

ENGINE

Measurement Variability

AFTERTREATMENT TEST SITE TEST

# 

OF 

TESTS

CoV (%)

Same Engine – Same Test Cell – Different Days

11L DPF EPA HD05 Hot Transient 10 0.22%

11L DPF EPA HD05 RMC 7 0.12%

11L DPF EPA HD05 Cold/Soak/Hot 3 0.02%

9L No DPF EPA HD05 8 Mode 7 0.44%

12L No DPF EPA HD01 Hot Transient 8 0.09%

12L No DPF EPA HD05 Hot Transient 31 1.37%

6.7L No DPF EPA HD02 FTP 12 0.67%

13L DPF EPA HD05 FTP 11 0.37%

14L DPF SwRI NTE 9 0.2%

14L DPF SwRI 13 Mode SET 6 0.2%

14L DPF CE-CERT NTE 9 0.5%

14L DPF CE-CERT 13 Mode SET 6 0.5%

Engine A DPF SwRI (ACES) FTP 3 0.1%

Engine B DPF SwRI (ACES) FTP 3 0.4%

Engine C DPF SwRI (ACES) FTP 3 0.6%

Engine D DPF SwRI (ACES) FTP 3 0.5%

Same Engine – Different Test Cells – Different Days

12L No DPF EPA HD01 & 

HD05

Hot Transient 39 1.58%

14L DPF SwRI & CECERTNTE 18 1.4%

14L DPF SwRI & CECERT13 Mode SET 12 1.2%

3.1.2.4 Regeneration Impact on CO2

The current engine test procedures also require the development of regeneration emission 

rate and frequency factors to account for the emission changes during a regeneration event.4 We 

are proposing to exclude the CO2 emissions due to regeneration. Our assessment of the current 

non-GHG regulatory program indicates that engine manufacturers are already highly motivated 

to reduce the frequency of regeneration events due to the significant impact on NOx emissions. 

In addition, market forces already exist which create incentives to reduce fuel consumption 

during regeneration. EPA is proposing the exclusion of CO2

As described in §86.001-24(i), emission results from heavy-duty engines equipped with 

aftertreatment systems may need to be adjusted to account for regeneration events. This is 

particularly true if these regenerations are expected to occur on a frequency of less than once per 

transient test cycle. Regeneration of exhaust aftertreatment devices commonly involves increases 

in fueling rate to raise exhaust temperature or lower exhaust oxygen content. While the impact of 

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emissions during regeneration; 

however, we consider the existing regulations, as described below, as a potential alternative.

Deleted: impact

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-5

a regeneration event on criteria pollutant emissions (i.e. CO, NOx, PM, HC) varies, regeneration 

is more likely to increase CO2

The current regulations outline a method of accounting for changes in emissions due to 

regeneration events (§86.001-24(i)(1)-(i)(5)). This method involves developing downward and 

upward adjustment factors (D/UAFs) meant to characterize emissions with and without 

(respectively) a regeneration event. Combined with a frequency factor (F), characterizing the 

frequency at which regeneration occurs, these adjustments are applied to the final emission test 

results. Use of this procedure to account for changes in CO

emissions and therefore must be considered.

2 emissions during regeneration 

appears to be a practical, well accepted, and accurate method for certification. Any increases (or 

decreases) in CO2

3.1.2.5 Fuel Heating Value Correction

due to regeneration would be captured in the adjustment factors and final 

emission results could be corrected accordingly.

The agencies collected baseline CO2

The existing regulations correct for gasoline fuel properties, as described in Part 86. The 

same correction can be used for the testing of complete pickup trucks and vans with gasoline 

fueled engines.

performance of diesel engines from testing which 

used fuels with similar properties. The agencies are proposing a fuel-specific correction factor 

for the fuel’s energy content in case this changes in the future. The agencies found the average 

energy content of the diesel fuel used at EPA’s National Vehicle Fuel and Emissions Laboratory 

was 21,200 BTU per pound of carbon. This value is determined by dividing the Net Heating 

Value (BTU per pound) by the carbon weight fraction of the fuel used in testing. 

The agencies are not proposing fuel corrections for alcohols because the fuel chemistry is 

homogeneous. The agencies are proposing a fuel correction for natural gas.

3.1.2.6 Multiple Fuel Maps

Modern heavy-duty engines may have multiple fuel maps, commonly meant to improve 

performance or fuel economy under certain operating conditions. CO2 emissions can also be 

different depending on which map is tested, so it is important to specify a procedure to properly 

deal with engines with multiple fuel maps. Consistent with criteria-pollutant emissions 

certification, engine manufacturers should submit CO2

3.1.3 Engine Family Definition and Test Engine Selection

data from all fuel maps on a given test 

engine. This includes fuel map information as well as the conditions under which a given fuel 

map is used (i.e. transmission gear, vehicle speed, etc).

3.1.3.1 Criteria for Engine Families

The current regulations outline the criteria for grouping engine models into engine 

families sharing similar emission characteristics. A few of these defining criteria include borecenter dimensions, cylinder block configuration, valve configuration, and combustion cycle; a 

comprehensive list can be found in §86.096-24(a)(2). While this set of criteria was developed 

Deleted: upward and 

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Draft Regulatory Impact Analysis 

3-6

with criteria pollutant emissions in mind, similar effects on CO2 emissions can be expected. For 

this reason, this methodology should continue to be followed when considering CO2

3.1.3.2 Emissions Test Engine

emissions.

Manufacturers must select at least one engine per engine family for emission testing. The 

methodology for selecting the test engine(s) should be consistent with §86.096-24(b)(2) (for 

heavy-duty Otto cycle engines) and §86.096-24(b)(3) (for heavy-duty diesel engines). An 

inherent characteristic of these methodologies is selecting the engine with the highest fuel feed 

per stroke (primarily at the speed of maximum rated torque and secondarily at rated speed) as the 

test engine, as this is expected to produce the worst-case criteria pollutant emissions. CO2

emissions are expected to scale well with fuel feed in a given engine family and therefore workbased CO2

3.2 Aerodynamic Assessment

measurements are expected to be less sensitive to the specific engine model selected 

than criteria pollutant emissions. To be consistent however, it is recommended that the same 

methodology continue to be used for selecting test engines. 

The aerodynamics of a Class 7/8 combination tractor is dependent on many factors, 

including the tractor design, trailer design, gap between the tractor and trailer, vehicle speed, 

wind speed, and many others. We believe that to fairly assess the aerodynamics of combination

tractors certain aspects of the truck need to be defined, including the trailer, location of payload, 

and tractor-trailer gap.

3.2.1 Standardized Trailer Definition

We are proposing to use a model input reflecting a standardized trailer for each

subcategory of the Class 7/8 tractor subcategories based on tractor roof height. High roof 

tractors are designed to optimally pull box trailers. The height of the roof fairing is designed to 

minimize the height differential between the tractor and typical trailer to reduce the air flow 

disruption. Low roof tractors are designed to carry flatbed or low-boy trailers. Mid roof tractors 

are designed to carry tanker and bulk carrier trailers. High roof tractors are designed to 

optimally pull box trailers. However, we recognize that during actual operation tractors 

sometimes pull trailers that do not provide the optimal roof height that matches the tractor. In 

order to assess how often truck and trailer mismatches are found in operation, EPA conducted a 

study based on observations of traffic across the U.S.

5

Deleted: test engine

 Data was gathered on over 4,000 tractortrailer combinations using 33 live traffic cameras in 22 states across the United States. 

Approximately 95% of trucks were “matched” per our definition (e.g. box trailers were pulled by 

high roof tractors and flatbed trailers were pulled with low roof tractors). The amount of 

mismatch varied depending on the type of location. Over 99% of the tractors were observed to 

be in matched configuration in Indiana at the I-80/I-94/I-65 interchange, which is representative 

of long-haul operation. On the other hand, only about 90% of the tractors were matched with the 

appropriate trailer in metro New York City, where all mismatches consisted of a day cab and a 

tall container trailer. The study also found that approximately 3% of the tractors were traveling 

without a trailer or with an empty flatbed. The agencies therefore conclude that given this very 

limited degree of mismatch, we can use a standardized definition which optimizes tractor-trailer 

matching.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-7

Section 1037.510 prescribes the proposed standardized trailer for each tractor 

subcategory (low, mid, and high roof) including trailer dimensions and tractor-trailer gap.

3.2.2 Aerodynamic Assessment

The aerodynamic drag of a vehicle is determined by the vehicle’s coefficient of drag 

(Cd), frontal area, air density and speed. The agencies are proposing to define the input 

parameters to GEM which represent the frontal area and air density, while the speed of the 

vehicle would be determined in GEM through the proposed drive cycles. The agencies are 

proposing that the manufacturer would determine a truck’s Cd, a dimensionless measure of a 

vehicle’s aerodynamics, through testing which then would be input into the GEM model. 

Quantifying truck aerodynamics as an input to the GEM presents technical challenges because of 

the proliferation of truck configurations and the lack of a common industry-standard test method. 

Class 7/8 tractor aerodynamics are currently developed by manufacturers using coastdown 

testing, wind tunnel testing and computational fluid dynamics. The agencies are proposing to 

allow manufacturers to use any of these three aerodynamic evaluation methods.

3.2.2.1 Coastdown Testing

For several decades, light-duty vehicle manufacturers have performed coastdown tests 

prior to vehicle certification. However, this practice is less common with heavy-duty vehicles, 

since the current heavy-duty certification process focuses on engine and not vehicle exhaust 

emissions, i.e., NOx, PM, NMHC, CO. In recent years, growing concerns over energy security, 

fuel efficiency and carbon footprint have prompted efforts to develop and improve design 

features or technologies related to the aerodynamic and mechanical components of heavy-duty 

(HD) vehicles. Lowering tire rolling resistance, aerodynamic drag, and driveline parasitic losses 

on HD vehicles could translate into significant long-term fuel savings as well as HD greenhouse 

gas emissions reductions, since vehicles with enhanced aerodynamic or mechanical features 

encounter lower road load force during transport, and thereby consume less fuel. The road load 

force can be captured by coasting a vehicle along a flat straightaway under a set of prescribed 

conditions. Such coastdown tests produce vehicle specific coastdown coefficients describing the 

road load as a function of vehicle speed. 

The coefficients obtained are essential parameters for conducting chassis dynamometer 

tests as well as for assessing GHG and fuel consumption performance for Class 7/8 combination 

tractors via modeling. Because the existing coastdown test protocols, i.e., SAE J1263and SAE 

J2263, were established primarily from the light-duty perspective, the agencies realize that some 

aspects of this methodology might not be applicable or directly transferable to heavy-duty tractor 

applications. 6,7

3.2.2.1.1 Overview of SAE J2263 

 Therefore, it appears that some modifications to existing light-duty vehiclefocused coastdown protocols are necessary. Sections 3.2.2.1.1 and 3.2.2.2.2 describe the 

existing protocols and our proposed modifications to the protocols, respectively.

The Society of Automotive Engineers (SAE) publishes voluntary reports to advance the 

technical and engineering sciences. The SAE Technical Standards Board, in the J2263 DEC2008 

Deleted: [TEST]

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Draft Regulatory Impact Analysis 

3-8

Surface Vehicle Recommended Practice publication, established a procedure for determination 

of vehicle road load force using onboard anemometry and coastdown techniques.

The coastdown runs need to be conducted on a dry and level road, under no rain or fog 

conditions, at an ambient temperature between 5 to 35o

C (41 to 95o

The vehicle and tires should have a preferable break-in of 6500 km (4039 mi) prior to 

testing, and a minimum of 3500 km (2175 mi). The tire pressure must be set and recorded before 

moving the vehicle. The vehicle and tires require preconditioning for a minimum of 30 minutes 

running at 80 km/h (49.7 mi/h). Calibration of the instrumentation can be done during 

preconditioning.

F), and average wind speed 

less than 35 km/h (21.7 mi/h) with wind gusts less than 15 km/h (31.3 mi/h) and average cross 

winds less than 15 km/h (9.3 mi/h).

The vehicle’s windows and vents must be closed and the use of any accessory that can 

affect the engine speed shall be noted and duplicated during any subsequent dynamometer 

adjustments.

The recommended relative wind speed and direction measurement location is at the 

approximate mid-point of the vehicle’s frontal cross section and about 2 meters in front of it.

A minimum of 10 valid runs, 5 in each alternating direction, must be made. For each run 

the vehicle is accelerated to a speed of 125 km/h (77.7 mi/h) for heavy-duty vehicles, the 

transmission is shift into neutral gear, and measurements are taken until the vehicle speed 

reaches 15 km/h (9.3 mi/h). Engage the transmission and accelerate for the next run; try to 

minimize the time between runs to avoid vehicle and ambient variations. 

Lane changes should be avoided, and the run should be voided if a passing vehicle in the 

same direction comes within 200 meters from the leading or trailing end of the vehicle. Traffic 

moving in the adjacent lane in opposite direction is fine. For tracks that are too short, “split” 

coastdown runs are allowed to form a complete run.

Data from the “split” runs should be knitted by taking the information recorded for the 

coastdown from the 100 km/h (62.2 mi/h) speed to speed X, and the information recorded from 

speed X to the 15 km/h (9.3 mi/h) speed. 

The mass of the vehicle is recorded at the end of the test; including instrumentation, 

driver and any passengers.

The road load force model is a function of vehicle speed, relative wind speed and yaw 

angle. The model will calculate road force for vehicle speeds between 100 km/h (62.2 mi/h) and 

15 km/h (9.3 mi/h).

The mechanical drag is modeled as a three-term polynomial with respect to speed (V): 

Dmech = A + B*V + C*V2

Deleted: 

 

Deleted: of 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-9

Where A, B, and C coefficients are determined by fitting the data into the polynomial 

curve.

The aerodynamic drag is modeled as a five-term polynomial with respect to the yaw 

angle (Y) in degrees:

Daero = 1⁄2 * ρ * A * Vr

2 * (a + b*Y + c*Y2 + d*Y3 + e*Y4

Where ρ is the air density (kg/m

)

3

), A is the vehicle’s frontal area (m2), Vr

The test asks for a level surface, but if the track is not level, the force contribution due to 

gravity is:

is the relative 

wind velocity (km/h), and a, b, c, d, and e coefficients are determined by fitting the data into the 

polynomial curve.

Dgrav

Where the plus sign is up and minus is down, M is the mass of the vehicle, g is gravity, 

and (dh/ds) is the change in elevation per distance along the track.

= + M*g*(dh/ds)

The equation of motion is:

-Me*(dV/dt) = Dmech + Daero +D

Where M

grav

e

The road load force equation used by EPA is:

is the effective vehicle mass, and (dV/dt) is the vehicle velocity as a function 

of time.

Road Load Force = Amech + Bmech*V+ Ctotl*V

Where A

2

mech, Bmech and Ctotl

3.2.2.1.2 Proposed Modifications to SAE J2263 

are values obtained from the analysis of the data done by 

SAE program and V is the vehicle speed.

The agencies have assessed the feasibility of performing coastdown testing on heavyduty trucks, primarily on Class 7/8 combination tractors. EPA, through its contractor Southwest 

Research Institute, conducted coastdown tests using SAE test methods J1263 and J2263 on three 

SmartWay-certified Class 8 tractor-trailers equipped with sleeper cabs during the period October 

2008 through November 2009. Also, other contractors, Transportation Research Center in Ohio 

and Automotive Testing and Development Inc. in California performed coastdown testing for the 

agencies on up to two dozen Class 2b-8 truck configurations in 2009-2010. EPA also gained 

firsthand experience of such testing by performing its own coastdown testing on one Class 6 and 

multiple Class 8 truck configurations at nearby locations using both SAE test methods. Details 

regarding these tests can be found in “Heavy-Duty Coastdown Test Procedure Development”

Docket Number EPA-HQ-OAR-2010-0162-0144.

8

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Draft Regulatory Impact Analysis 

3-10

Based on our ongoing experiences with Class 7/8 combination tractor coastdown testing 

and our consultation with light-duty coastdown expert Peter Janosi, we propose the following for 

a heavy-duty coastdown test procedure; details on how we reached our determination through 

coastdown data analysis are presented below. 

• Vehicle Testing

o Conduct SAE J2263 with more runs. EPA recommends that 10 pairs be run for a 

total of 20 tests. Since heavy-duty coastdowns involve more uncertainty, more 

tests are required to achieve and acceptable certainty in the mean of the resulting 

coefficients. Abide all road and weather restrictions given in the SAE J2263 

standard.

o For safety reasons, because EPA was conducting its coastdown on roadways, 

EPA modified the high speed procedure running at vehicle speeds between 100

km/h (62.2 mi/h) and 15 km/h (9.3 mi/h). 

o Calibration runs can be conducted at constant 50 mi/h in each road direction, 

immediately back-to-back so as to minimize changes in weather/average wind 

speed

o Split runs can be used, but whole runs are preferred.

o J2263 states that consecutive runs shall be made in opposite directions; however, 

to reduce our presence on state and county roads and run more tests during core 

testing hours, EPA ran two to four consecutive tests (depending on the vehicle 

class) in the same direction and accounted for this in the analysis; we are 

proposing this modification to J2263 as an option. 

• Data Analysis

o Use Equation 2 for yaw angle correction

o Use Equation 1 for wind speed correction

o Use MM5 for road load mean and uncertainty determination. If E is not 

statistically significant, then use MM6.

o Correct regression coefficients for ambient temperature and ambient pressure as 

per SAE J2263

o Use Equation 12 to determine rolling resistance coefficient 

3.2.2.1.3 Mixed Model Analysis with SAS

As already mentioned, the agencies conducted several coastdown testing programs to 

evaluate the feasibility of Class 7/8 combination tractor coastdown testing. This section details 

the process which we undertook upon generating or receiving coastdown data files. First, we 

determined which runs were valid, based on instrument readings, weather, and other criteria. 

During travel, air will “pile up” near the front of the tractor. This causes our anemometer wind 

speed readings to be offset from actual wind speed. To correct for this, we calculated the ratio 

between the vehicle speed and measured wind speed at each time interval. We then averaged the 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-11

ratio by run direction. We then averaged each run direction’s ratio for each date and applied this 

ratio back to the measured wind speed to estimate actual wind speed.

Equation 1 ∑ ∑ 





























 = dir i r meas dir i

dir i

i dir

r i r meas dir i V

V

n V V

, , ,

,

,

, , , ,

1

2

1

We observed an offset to the anemometer’s wind direction measurements. We corrected 

this by assuming that at high speeds, wind direction is head-on (zero degrees). For each date, we 

averaged the first five seconds (25 measurements for 5-hz data) of wind direction for each run 

direction. We then averaged the two directions’ average. We then subtracted the resulting value 

from all of the measured wind direction values to get our correct wind direction.

Equation 2 ∑ ∑ 













 = − dir i=

meas dir i

i dir

i meas i Y n Y Y

25

1

, ,

,

,

1

2

1

In general, the J2263 analysis method and equations were used as a foundation for this analysis:

Equation 3

ds

dh A B V C V DV a a Y a Y a Y a Y Mg dt

dV − Me = m + m + m + r ( + + + + ) ± 4

4

3

3

2

0 1 2

2 2

We used a mixed model (through SAS® software) to describe our 5-hz data with the 

above equation. A mixed model allows us to accurately predict the mean coefficients for each 

vehicle, while accounting for the scatter within each run and also the run-to-run variability when 

determining the standard error of the coefficient estimates. This takes into account that 

measurements are not independent within each run, but each run is independent from all other 

runs.

The equations below represent the versions of Equation 3 we modeled to determine 

means and significances of each of the variables. As an initial simplification, a1, a3, and a4 were 

eliminated in all iterations since we determined that yaw angle did not vary enough during 

testing to warrant such a complex polynomial characterization. We also set a0=1 so that the 

drag coefficient could be characterized by the D term. Since our elevation change was negligible 

in the stretch of road on which we conducted coastdowns, the grade term was also eliminated for 

all runs. The following mixed models were run:

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Draft Regulatory Impact Analysis 

3-12

Equation 4

Equation 5

(1 )

2

2

2 2 A B V C V DV a Y

dt

dV − Me = m + m + m + r + , rewritten as

2 2 2 2 A B V C V DV EV Y

dt

dV − Me = m + m + m + r + r , where D a = E 2

MM1

Equation 6 2 2

e Am BmV CmV DVr dt

dV − M = + + + MM2

Equation 7 2 2 2 A B V DV EV Y

dt

dV − Me = m + m + r + r MM3

Equation 8 2

e Am BmV DVr dt

dV − M = + + MM4

Equation 9 2 2 2 A DV EV Y

dt

dV − Me = m + r + r MM5

Equation 10 2

e Am DVr dt

dV − M = + MM6

Based on statistical significance of the various effects, one of the mixed models was 

chosen as the model to appropriately determine the road load coefficients. For heavy-duty

trucks, this was usually MM6.

3.2.2.1.4 Use of the Data for Modeling 

In each mixed model (MM1-MM6), we found that the Bm, Cm

In MM4, the results consistently show that B

, and E were not 

consistently significant from zero. As examples, models MM4 and MM6 are described below.

m is not significant from zero. Table 3-2

summarizes these results. The inclusion of Bm often causes the estimates and uncertainties of the 

other terms to vary.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

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Table 3-2 – Mixed Model MM4 Shows No Significant Road Load Linear with Vehicle Speed.

Date Truck configuration

(tractor_trailer_payload) Am

% Std 

err [lb]

Sig 

from 

zero?

Bm Std err [lb/mph]

Sig 

from 

zero?

D 

[lb/mph2

% 

Std 

err ]

Sig 

from 

zero?

5-Aug-09 FL60_N/A_full 153.8 7.75% Yes 0.165 497.00% No 0.143 9.64

% Yes

6-Aug-09 FL60_N/A_full 137.7 5.24% Yes 1.105 41.42% Yes 0.127 5.86

% Yes

1-Sep-09 Int’l_flatbed_full 490.5 10.94% Yes -2.070 -177.70% No 0.233 25.8

7% Yes

2-Sep-09 Int’l_flatbed_full 483.3 7.69% Yes -2.065 -122.70% No 0.237 17.9

9% Yes

3-Sep-09 Int’l_flatbed_full 551.5 7.76% Yes -6.123 -47.40% No 0.291 16.5

5% Yes

18-Sep-09 Int’l_flatbed_half 372.2 9.72% Yes -1.979 -127.80% No 0.244 17.3

8% Yes

23-Sep-09 Int’l_flatbed_empty 226.3 9.38% Yes 1.153 119.90% No 0.174 12.2

7% Yes

24-Sep-09 Int’l_box_full 521.5 6.51% Yes -3.480 -63.15% No 0.248 14.1

1% Yes

25-Sep-09 Int’l_box_full 495.7 8.47% Yes -1.149 -238.00% No 0.208 21.0

4% Yes

In MM6, the elimination of Bm shows confident and stable estimates of Am and D, with 

lower relative standard errors. This indicates that the road load curve is best described by just 

Am and D.

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Draft Regulatory Impact Analysis 

3-14

Table 3-3 – Mixed Model MM6 Shows the Most Confident Estimates of A and D.

Date Truck configuration Am [N] Am [lb] % Std error D [N/(m/s)2] D [lb/mph2] % Std error

5-Aug-09 FL60_N/A_full 693.9 156.0 3.81% 3.24 0.145 2.05%

6-Aug-09 FL60_N/A_full 676.8 152.2 2.63% 3.23 0.145 1.13%

1-Sep-09 Int’l_flatbed_full 2060.3 463.2 4.85% 4.45 0.200 6.08%

2-Sep-09 Int’l_flatbed_full 2030.6 456.5 3.71% 4.51 0.203 4.59%

3-Sep-09 Int’l_flatbed_full 2093.6 470.7 3.89% 4.25 0.191 5.55%

18-Sep-09 Int’l_flatbed_half 1539.8 346.2 3.92% 4.71 0.212 4.09%

23-Sep-09 Int’l_flatbed_empty 1076.2 242.0 4.53% 4.27 0.192 2.39%

24-Sep-09 Int’l_box_full 2119.1 476.4 3.87% 4.32 0.194 4.06%

25-Sep-09 Int’l_box_full 2136.5 480.3 4.12% 4.23 0.190 4.88%

Compared to the MM4, MM6 produces more confident mean coefficient values. Also, 

for the same configurations, the MM6 shows better day-to-day variability, confirming that the 

coastdown procedure is repeatable from one day to the next. Often, the MM6 model is used to 

simplify the road load versus speed curve through rolling resistance and aerodynamic drag 

coefficients. The EPA MOVES heavy-duty inventory model and the CRC E-55/59 chassis 

dynamometer emissions test program are two examples of this. In general, the equation 

implemented during a coastdown is:

Equation 11 2

2

1 Mg Ac V

dt

dV − Me = μ + ρ D

Therefore, 

Equation 12

Mg

Am μ = and 

A

D cD 2ρ = Equation 13

Equation 11 and Equation 12 assume that the rolling resistance coefficient μ is wholly 

contained in the Am coefficient and the drag coefficient cd is wholly contained in the D

coefficient. The equations also imply that any values of Bm and Cm

Deleted: model

that would be used in the 

other mixed models are mechanical drag forces, other than rolling resistance, that are dependent 

on vehicle speed. To check the reasonability of our results and feasibility of using our 

Deleted: shows

Deleted: most confident estimates

Formatted Table
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-15

coefficients to accurately determine μ and Cd

Rolling Resistance Coefficient

, we can compare our results to realistic values of 

rolling resistance and drag coefficients. 

For the International truck, we recorded the tire model and obtained different laboratory 

results of tire rolling resistance coefficients. These values were determined through the SAE 

J1269 standard. This standard does not contain a provision that lets a laboratory result be 

corrected against a reference laboratory result. As a result, each laboratory has its own bias for 

any given tire. When we weighed the truck, we recorded the weight measured over each axle: 

steer, drive, and trailer. Since we had no more than one tire model on any one axle, we can 

weight-average the laboratory rolling resistance coefficients to estimate the truck’s overall 

rolling resistance coefficient.

Equation 14 ( ) steerM steer driveMdrive trailerMtrailer M μ = μ + μ + μ

1

Figure 3-1 below compares our coastdown rolling resistance results with those from three 

different tire labs. We are not naming the tire models or the laboratories to protect confidential 

business information. The dimensionless rolling resistance coefficient is multiplied by 1000 for 

convenience (resulting “unit” is often referred to as kg/metric ton).

Figure 3-1 – Coastdown-Determined and Independent Lab Rolling Resistance Coefficients Match Reasonably 

Well. 

 

0

1

2

3

4

5

6

7

8

9

FL60_N/A_fullFL60_N/A_full

Int'l_flatbed_fullInt'l_flatbed_fullInt'l_flatbed_full

Int'l_flatbed_half

Int'l_flatbed_empty

Int'l_box_fullInt'l_box_full

5-Aug-09 6-Aug-09 1-Sep-09 2-Sep-09 3-Sep-09 18-Sep-09 23-Sep-09 24-Sep-09 25-Sep-09

Rolling resistance coefficient [kg/metric ton]

Coastdown RR

Lab A

Lab B

Lab C

3 Lab avg

There are only three different labs, with four unique weightings (flatbed full, flatbed half, 

flatbed empty, and box full) for each lab. Lab results were only available for the tires used on 

the International truck. Our coastdown results show reliable day-to-day repeatability for the 

same truck configuration (Sep 1-3, Sep 24-25). Also, when we reduced the weight on the flatbed 

Deleted: resistance coefficient

Formatted: Space Before: 6 pt, After: 6 pt

Formatted: Space Before: 6 pt, After: 6 pt

Deleted: 

 

 

0

1

2

3

4

5

6

7

8

9

FL60_N/A_fullFL60_N/A_full

Int'l_flatbed_full

5-Aug-09 6-Aug-09 1-Sep-09 2-Se

Rolling resistance coefficient [kg/metric ton]

Deleted: determined

Deleted: independent lab rolling resistance 

coefficients match reasonably well
Draft Regulatory Impact Analysis 

3-16

trailer, we found that our coastdowns produced a higher theoretical tire rolling resistance. This is 

most likely due to the fact that reducing weight from full payload increases the relative weight 

over the drive axle. Since the tires on the drive axle have a higher rolling resistance coefficient 

(inverse relation with grip for a given tire material and surface), the overall rolling resistance 

coefficient increased. This is confirmed by the lab tests, which showed higher rolling resistance 

coefficients for the drive and steer axles tire models. Our coastdown results do, however, show a 

larger increase in coefficient due to complete payload removal compared to the lab results. 

The agencies are not proposing to use coastdown testing to determine the tire rolling 

resistance. The proposed tire test procedures are discussed in Section 3.3. 

Drag Coefficient

We estimated frontal area of the International truck to be 99 ft2 (9.2 m2

Equation 13

) by measuring the 

various dimensions of the tractor cab and other equipment such as exterior mirrors and tires. We 

used this value as a placeholder estimate for the FL60 vehicle also. Using these frontal area 

estimates and , Figure 3-2 shows our coastdown-estimated drag coefficients for each 

date and truck configuration.

Figure 3-2 – Drag Coefficient Calculated from D from Mixed Model

0.0

0.2

0.4

0.6

0.8

1.0

1.2

FL60_N/A_fullFL60_N/A_full

Int'l_flatbed_fullInt'l_flatbed_fullInt'l_flatbed_full

Int'l_flatbed_half

Int'l_flatbed_empty

Int'l_box_fullInt'l_box_full

5-Aug-09 6-Aug-09 1-Sep-09 2-Sep-09 3-Sep-09 18-Sep-09 23-Sep-09 24-Sep-09 25-Sep-09

Unlike rolling resistance, we do not expect our drag coefficient to change with payload 

removal because the physical configuration of the tractor-trailer is not significantly altered, 

which is reflected in Figure 3-2. Also, while we are using a frontal area of 9.2 m2

Deleted: coefficient

specific to the 

International tractor, a uniform frontal area, such as an average box trailer frontal area or typical 

tractor frontal area, may be used for all trucks of a certain class when determining drag 

coefficient as an input to the compliance model.

Deleted: coefficient calculated

Deleted: mixed model

Formatted: Indent: First line: 0"
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-17

3.2.2.2 Wind Tunnel Testing

A wind tunnel provides a stable environment yielding a more repeatable test than 

coastdown. This allows the manufacturer to run multiple baseline vehicle tests and explore 

configuration modifications for nearly the same effort (e.g., time and cost) as conducting the 

coastdown procedure. In addition, wind tunnels provide testers with the ability to yaw the 

vehicle at positive and negative angles relative to the original centerline of the vehicle to 

accurately capture the influence of non-uniform wind direction on the Cd (e.g., wind averaged 

Cd). 

However, there are challenges with the use of wind tunnels in a regulatory program that 

would need to be addressed in order for manufacturers to use this method. There are several 

different configurations and types of wind tunnels. There are wind tunnels that use forced air 

(fan upstream pushing air through the wind tunnel) versus suction (fan downstream and pulling 

air through the wind tunnel). There are wind tunnels with open or semi-open jet, closed jet, and 

slotted or adaptive wall test sections. There are wind tunnels with static floors versus moving 

floors or suction that compensate for the boundary layer of air that builds up at the ground level. 

Finally, there are full scale wind tunnels (e.g., dimensions as large as 80 feet times 120 feet in the 

test section) that can accommodate a full-size vehicle or clay model versus reduced scale wind 

tunnels (e.g., dimensions as small as 3 feet by 4.5 feet) that require the vehicle to be scaled down 

in model form. In addition, regardless of wind tunnel type there are several factors that would 

need to be minimized or addressed by applying correction factors to maintain flow quality 

including but not limited to ground boundary layer thickness and location; flow uniformity, 

angularity and fluctuation; turbulence and wall interference, and environmental conditions (e.g., 

temperature, humidity, air/fluid density) in the tunnel. 

As a result of the wind tunnel testing issues and configuration complexities, it would be 

difficult to develop a new, uniform wind tunnel testing standard for this rulemaking. Therefore, 

the agencies propose to use the established SAE standards for wind tunnel testing (such as SAE 

J1252) and recommended practices, with some modifications and exceptions, for aerodynamic 

assessment.

3.2.2.3 Computational Fluid Dynamics

Computational Fluid Dynamics, or CFD, capitalizes on today’s computing power by 

modeling a full size vehicle and simulating the flows around this model to examine the fluid 

dynamic properties, in a virtual environment. CFD tools are used to solve either the NavierStokes equations that relate the physical law of conservation of momentum to the flow 

relationship around a body in motion or a static body with fluid in motion around it, or the 

Boltzman equation that examines fluid mechanics and determines the characteristics of discreet, 

individual particles within a fluid and relates this behavior to the overall dynamics and behavior 

of the fluid. CFD analysis involves several steps: defining the model structure or geometry 

based on provided specifications to define the basic model shape; applying a closed surface 

around the structure to define the external model shape (wrapping or surface meshing); dividing 

the control volume, including the model and the surrounding environment, up into smaller, 

discreet shapes (gridding); defining the flow conditions in and out of the control volume and the 

Deleted: follow

Deleted: and govern fluid dynamics and 

Deleted: ,

Deleted: ),

Deleted: ),
Draft Regulatory Impact Analysis 

3-18

flow relationships within the grid (including eddies and turbulence); and solving the flow 

equations based on the prescribed flow conditions and relationships.

This approach can be beneficial to manufacturers since they can rapidly prototype (e.g., 

design, research, and model) an entire vehicle without investing in material costs; they can 

modify and investigate changes easily; and the data files can be re-used and shared within the 

company or with corporate partners. 

As with the two aerodynamic assessment methods mentioned above, CFD has challenges 

that must be addressed. Although it can save on material cost, it can be time consuming 

(manpower cost) and requires significant computing power depending on the model detail 

(information technology costs). As described above, a considerable amount of time goes into 

defining the shape, meshing or gridding the shape and the environment, and solving all of the 

associated flow equations. Meshes/grids in CFD can contain anywhere from 1 million to 100 

million individual cells depending on the modeler’s criteria. Consequently, run times needed to 

solve all of the flow relationships can be extremely long.

The accuracy of the outputs from CFD analysis can be highly dependent on the inputs. 

The CFD modeler decides what method to use for wrapping, how fine the mesh cell and grid size 

should be, and the physical and flow relationships within the environment. A balance must be 

achieved between the number of cells, which defines how fine the mesh is, and the 

computational times for a result (i.e., solution-time-efficiency). All of these decisions affect the 

results of the CFD aerodynamic assessment.

In addition, CFD software tools have difficulty solving for complex turbulent flows and 

the spatial interaction that occurs in real-world aerodynamics. This source can lead to large 

errors between the actual and predicted aerodynamic characteristics. Therefore, care must be 

taken to ensure that the various turbulent flows and ground/wall interference affects are 

accounted for.

As with any software tool, the CFD software marketplace is vast and ever-evolving at an 

astonishing pace. There are commercially-available CFD software tools and publicly-available 

customized CFD software tools used by academia and government agencies. Any attempt to 

require one particular CFD software tool in a rulemaking would nearly guarantee its 

obsolescence by the time the rule was published. In addition, no two CFD software tools are 

alike and there are currently no established SAE standards or recommended practices, that we 

are aware of, governing the use of CFD. As a result, it is difficult propose a particular CFD 

software tool or approach in a regulatory arena.

Much of the recent research has examined the correlation of CFD to experimental results 

and to determine the sensitivity of the results to certain aspects of CFD (e.g., varying cell size 

and shape, grid size and meshing technique). This research can aid in defining boundaries for 

the use of CFD in aerodynamic assessment. In addition, the available research has demonstrated 

correlation of CFD predictions within one to five percent of experimental results. 9

Deleted: ),

Thus, CFD 

does have some ability to accurately model aerodynamic assessments, if conditions for 

performing the analysis are appropriately defined.

Deleted: is
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-19

To address these considerations, the agencies propose a minimum set of criteria 

applicable to using CFD for aerodynamic assessment (should a manufacturer choose to use this 

means of aerodynamic assessment). This will allow the use of CFD and the design freedom that 

it offers while ensuring that, regardless of the decisions made during the process, the CFD 

aerodynamic assessment accurately simulates real-world aerodynamics.

3.2.2.4 Aerodynamic Assessment Proposal

The agencies are proposing that the coefficient of drag assessment be a product of test 

data and modeling using good engineering judgment. This is a similar approach that EPA has 

provided as an option in testing light-duty vehicles where the manufacturers supply 

representative road load forces for the vehicle.10

The agencies are also interested in developing an acceptance demonstration process for 

aerodynamic testing in the final rulemaking. As part of the process, the manufacturer would 

have to demonstrate that the methodology used for aerodynamic assessment is acceptable prior 

to using it for aerodynamic assessment. In addition to the acceptance demonstration, alternative 

methods would also require correlation testing to the coastdown procedure using a reference 

vehicle. This process would provide confidence in the use of the alternative method once this 

rule is implemented. We are requesting comment on the proposed requirements for each allowed 

method, standards and practices that should be used and any unique criteria that we are 

proposing.

In addition, EPA and NHTSA recognize that wind conditions have a greater impact on 

real world CO2 emissions and fuel consumption of heavy-duty trucks than occur with light-duty

vehicles. As stated in the NAS report11

NHTSA and EPA are proposing that manufacturers take the aerodynamic test result from 

a truck and determine the appropriate bin (e.g., Classic, Conventional, SmartWay, etc.), as 

defined in 

, the wind average drag coefficient is about 15 percent 

higher than the zero degree coefficient of drag (Cd). The large ratio of the side area of a 

combination tractor and trailer to the frontal area illustrates that winds will have a significant 

impact on the drag. One disadvantage of the agencies’ proposed approach to aerodynamic 

assessment is that the test methods have varying degrees of ability to assess wind conditions. 

Wind tunnels are currently the only demonstrated tool to accurately assess the influence of wind 

speed and direction on a truck’s aerodynamic performance. Both the coastdown tests and 

computational fluid dynamics modeling have limited ability in assessing yaw conditions. To 

address this issue, the agencies are proposing to use coefficient of drag values which represent 

zero yaw (i.e., representing wind from directly in front of the vehicle, not from the side). The 

agencies recognize that the results of using the zero yaw approach will produce fuel consumption 

results in the regulatory program which are slightly lower than in-use but we believe this 

approach is appropriate since not all manufacturers will use wind tunnels for the aerodynamic 

assessment. 

Table 3-4. The agencies are proposing aerodynamic technology categories which 

divide the wide spectrum of tractor aerodynamics into five categories. The first category, 

“Classic,” represents tractor bodies which prioritize appearance or special duty capabilities over 

aerodynamics. The Classic trucks incorporate few, if any, aerodynamic features and may have 

several which detract from aerodynamics, such as bug deflectors, custom sunshades, b-pillar 

Deleted: . Further, we are proposing a 

requirement to correlate CFD aerodynamic 

assessments with experimental results from either or 

both the coastdown procedure and wind tunnel 

testing, within a certain tolerance level.

Deleted: 

Deleted: 

Deleted: 
Draft Regulatory Impact Analysis 

3-20

exhaust stacks, and others. The second category for aerodynamics is the “Conventional” tractor 

body. The agencies consider Conventional tractors to be the average new tractor today which 

capitalizes on a generally aerodynamic shape and avoids classic features which increase drag. 

Tractors within the “SmartWay” category build on Conventional tractors with added components 

to reduce drag in the most significant areas on the tractor, such as fully enclosed roof fairings, 

side extending gap reducers, fuel tank fairings, and streamlined grill/hood/mirrors/bumpers. The 

“Advanced SmartWay” aerodynamic category builds upon the SmartWay tractor body with 

additional aerodynamic treatments such as underbody airflow treatment, down exhaust, and 

lowered ride height. “Advanced SmartWay II” tractors incorporate advanced technologies which 

are currently in the prototype stage of development, such as advanced gap reduction, rearview 

cameras to replace mirrors, wheel system streamlining, and advanced body designs.

Under this proposal, the manufacturer would then input into GEM the Cd value specified 

for each bin as also defined in Table 3-4. For example, if a manufacturer tests a Class 8 sleeper 

cab high roof tractor with features which are similar to a SmartWay tractor and the test produces 

a Cd value of 0.59, then the manufacturer would assign this tractor to the Class 8 Sleeper Cab 

High Roof SmartWay bin. The manufacturer would then use the Cd value of 0.60 as the input to 

GEM. The agencies are proposing the aerodynamic bin approach to address the variability in the 

proposed testing methods.

Table 3-4: Aerodynamic Input Definitions to GEM

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid

Roof

High 

Roof

Low/Mid

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics Test Results (Cd)

Classic ≥0.83 ≥0.73 ≥0.83 ≥0.73 ≥0.83 ≥0.78 ≥0.73

Conventional 0.78-0.82 0.63-

0.72

0.78-0.82 0.63-

0.72

0.78-

0.82

0.73-

0.77

0.63-

0.72

SmartWay 0.73-0.77 0.58-

0.62

0.73-0.77 0.58-

0.62

0.73-

0.77

0.68-

0.72

0.58-

0.62

Advanced SmartWay 0.68-0.72 0.53-

0.57

0.68-0.72 0.53-

0.57

0.68-

0.72

0.63-

0.67

0.53-

0.57

Advanced SmartWay 

II

≤0.67 ≤0.52 ≤0.67 ≤0.52 ≤0.67 ≤0.62 ≤0.52

Aerodynamic Input to GEM (Cd)

Frontal Area (m2) 6.0 9.8 6.0 9.8 6.0 7.7 9.8

Classic 0.85 0.75 0.85 0.75 0.85 0.80 0.75

Conventional 0.80 0.65 0.80 0.65 0.80 0.75 0.65

SmartWay 0.75 0.60 0.75 0.60 0.75 0.70 0.60

Advanced SmartWay 0.70 0.55 0.70 0.55 0.70 0.65 0.55

Advanced SmartWay 

II

0.65 0.50 0.65 0.50 0.65 0.60 0.50

Deleted: [TEST]

Deleted: [TEST].

Deleted: [TEST]

Formatted Table

Deleted: >

Deleted: >

Deleted: >

Deleted: >

Deleted: >

Deleted: >

Deleted: 77

Deleted: >

Deleted: 67

Deleted: 67

Deleted: 68

Deleted: 72

Deleted: 67

Deleted: 63

Deleted: 67

Deleted: 58

Deleted: 62

Deleted: <

Deleted: 68

Deleted: <

Deleted: 53

Deleted: <

Deleted: 68

Deleted: <

Deleted: 53

Deleted: <

Deleted: 68

Deleted: <

Deleted: 58

Deleted: <

Deleted: 53

Deleted: [TEST]

Deleted: 6.6
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-21

Coefficient of drag (Cd

Table 3-4

) and frontal area of the tractor-trailer combination go hand-inhand to determine the force required to overcome aerodynamic drag. As explained above, the 

agencies are proposing that the Cd value is one of the GEM inputs which will be derived by the 

manufacturer. However, the agencies are proposing to specify the truck’s frontal area for each 

regulatory subcategory (i.e. each of the seven subcategories which are proposed). The frontal 

area of a high roof tractor pulling a box trailer will be determined primarily by the box trailer’s 

dimensions and the ground clearance of the tractor. The frontal area of low and mid roof tractors 

will be determined by the tractor itself. An alternate approach to the proposed frontal area 

specification is to create the aerodynamic input table (as discussed in ) with values that 

represent the Cd multiplied by the frontal area. This approach will provide the same 

aerodynamic load, but it will not allow the comparison of aerodynamic efficiency across 

regulatory subcategories that can be done with the Cd

The agencies recognize that wind conditions have a greater impact on real world GHG 

emissions from heavy-duty trucks than occur with light-duty vehicles. The ratio of the side area 

of a combination tractor and trailer to the frontal area illustrates that winds will have a significant 

impact on the drag. A disadvantage of the proposed approach to aerodynamic assessment is that 

the test methods have varying degrees of ability to assess wind conditions. Wind tunnels are 

currently the only tool which has demonstrated the ability to accurately assess the influence of 

wind speed and direction on a truck’s aerodynamic performance. Therefore, we are proposing to 

use coefficient of drag values which represent zero yaw. 

values alone. 

3.3 Tire Rolling Resistance

EPA is proposing that the ISO 28580 test method be used to determine rolling resistance 

and the coefficient of rolling resistance. A copy of the test method can be obtained through the 

American National Standards Institute 

(http://webstore.ansi.org/RecordDetail.aspx?sku=ISO+28580%3a2009).

3.3.1 Reason for Using ISO 28580

The EPA SmartWay Partnership Program started to identify equipment and feature 

requirements for SmartWay-designated Class 8 over-the-road tractors and trailers in 2006. In 

order to develop a tire rolling resistance specification for SmartWay-designated commercial 

trucks, EPA researched different test methods used to evaluate tire rolling resistance, reviewing 

data and information from tire manufacturers, testing laboratories, the State of California, the 

Department of Transportation, truck manufacturers, and various technical organizations. After 

assessing this information, EPA determined that its SmartWay program would use the SAE 

J126912 tire rolling resistance method until the ISO 2858013

During this same time period, the National Highway Traffic Safety Administration 

(NHTSA) conducted an evaluation of passenger vehicle tire rolling resistance test methods and 

their variability

method (at that time under 

development) was finalized, at which time the Agency would consider moving to this method for 

its SmartWay program. 

14

Deleted: [TEST]

. Five different laboratory test methods at two separate labs were evaluated. 

The NHTSA study focused on passenger tires; however, three of the four test methods evaluated 

can be used for medium-duty and heavy-duty truck tires. The methods evaluated were SAE 

Deleted: class

Deleted: classes

Deleted: EPA recognizes

Deleted: 

Deleted: 

Deleted: EPA’s

Deleted: 

Deleted: 
Draft Regulatory Impact Analysis 

3-22

J1269, SAE J245215 (not applicable for medium-duty or heavy-duty truck tires), ISO 1816416

The reason that ISO 28580 is preferred is that the test involves a laboratory alignment is 

between a “reference laboratory” and a “candidate laboratory.” The ISO technical committee 

involved in developing this test method also has the responsibility for determining the laboratory 

that will serve as the reference laboratory. The reference laboratory will make available an 

alignment tire that can be purchased by candidate laboratories. The candidate laboratory shall 

identify its reference machine. However, at this time, the reference laboratory and alignment 

tires have not been identified. 

and ISO 28580. The NHTSA study showed significant lab to lab variability between the labs 

used. The variability was not consistent between tests or types of tire within the same test. The 

study concluded that a method to account for this variability is necessary if the rolling resistance 

value of tires is to be compared (NHTSA, 2009). Because of laboratory variability, NHTSA 

recommended that the use of ISO 28580 is preferred over the other test methods referenced. 

3.3.2 Measurement Method and Results

The ISO 28580 test method includes a specific methodology for “light truck, commercial 

truck and bus” tires, and it has 4 measurement methods, force, torque, deceleration, and power, 

all of which appear to be suitable for use.

The results of the ISO 28580 test are intended for use in vehicle simulation modeling, 

such as the model used to assess the effects of various technology options for national 

greenhouse gas and fuel economy requirements for commercial trucks (see chapter 4). The 

results are usually expressed as a rolling resistance coefficient and measured as kilogram per 

metric ton (kg/metric ton) or as dimensionless units. (1 kg/metric ton is the same as the 

dimensionless unit 0.001) The results are corrected for ambient temperature drum surface and 

drum diameter as specified in the test method. 

3.3.3 Sample Size

The rolling resistance of tires within the same model and construction are expected to be 

relatively uniform. In the study conducted by NHTSA, only one individual tire had a rolling 

resistance value that was significantly different from the other tires of the same model. This 

means that only one tire within a model needs to be tested to obtain a representative value of 

rolling resistance for the model. The effect of test-to-test variability can be further reduced by 

conducting three replicate tests and using the average as the value for the rolling resistance 

coefficient. Tire models available in multiple diameters may have different values of rolling 

resistance for each diameter because larger diameter tires produce lower rolling resistance than 

smaller diameters under the same load and inflation conditions. If the size range within a tire 

model becomes large enough that a given tire size is no longer “substantially similar” in rolling 

resistance performance to all other tire sizes of that model, then good engineering judgment 

should be exercised as to whether the differently-sized tire shall be treated, for testing and 

vehicle simulation purposes, as a distinct tire model. For Class 8 tractors that typically use tires 

that fit on 22.5” or 24.5” wheels, this situation might occur with 17.5” tires, more commonly

used on moving vans and other applications that require a low floor.

Deleted: 

Deleted: 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-23

3.4 Drive Cycle

Drive cycles have a significant impact on the GHG emissions from a truck and how 

technologies are assessed. Every truck has a different drive cycle in-use. Therefore, it is very 

challenging to develop a uniform drive cycle which accurately assesses GHG improvements 

from technologies relative to their performance in the real world. 

The drive cycle attributes that impact a vehicle’s performance include average speed, 

maximum speed, acceleration rates, deceleration rates, number of stops, road grade, and idling 

time. Average and maximum speeds are the attributes which have the greatest impact on 

aerodynamic technologies. Vehicle speed also impacts the effect of low rolling resistance tires. 

The effectiveness of extended idle reduction measures is determined by the amount of time spent 

idling. Lastly, hybrid technologies demonstrate the greatest improvement on cycles which 

include a significant amount of stop-and-go driving due to the opportunities to recover braking 

energy. In addition, the amount of power take-off operation will impact the effectiveness of 

some vocational hybrid applications.

The ideal drive cycle for a line-haul truck would account for significant amount of time 

spent cruising at high speeds. A pickup and delivery truck would contain a combination of urban 

driving, some number of stops, and limited highway driving. If EPA proposes an ill-suited drive 

cycle for a regulatory subcategory, it may drive technologies where they may not see the in-use 

benefits. For example, requiring all trucks to use a constant speed highway drive cycle will drive 

significant aerodynamic improvements. However, in the real world a pickup and delivery truck 

may spend too little time on the highway to realize the benefits of aerodynamic enhancements. 

In addition, the extra weight of the aerodynamic fairings will actually penalize the GHG 

performance of that truck in urban driving and may reduce its freight carrying capability. 

3.4.1 Drive Cycles Considered

The agencies carefully considered which drive cycles are appropriate for the different 

proposed regulatory subcategories. We considered several drive cycles in the development of 

the proposal including EPA’s MOVES model; the Light-Duty FTP75 and HWFEC; Heavy-Duty 

UDDS; World Wide Transient Vehicle Cycle (WTVC); Highway Line Haul; Hybrid Truck User 

Forum (HTUF) cycles; and California ARB’s Heavy-Heavy-Duty Truck 5 Mode Cycle.

MOVES Medium-Duty and Heavy-Duty schedules were developed based on three 

studies. Eastern Research Group (ERG) instrumented 150 medium and heavy-duty vehicles, 

Battelle instrumented 120 vehicles instrumented with GPS, and Faucett instrumented 30 trucks

to characterize their in-use operation.17

Deleted: cycle

 ERG then segregated the driving into freeway and nonfreeway driving for medium and heavy-duty vehicles, and then further stratified vehicles trips 

according the predefined ranges of average speed covering the range of vehicle operation. 

Driving schedules were then developed for each speed bin by creating combinations of idle-toidle “microtrips” until the representative target metrics were achieved. The schedules developed 

by ERG are not contiguous schedules which would be run on a chassis dynamometer, but are 

made up of non-continguous “snippets” of driving meant to represent target distributions. This 

gives MOVES the versatility to handle smaller scale inventories, such as intersections or sections 

of interstate highway, independently. 

Deleted: class

Deleted: EPA

Deleted: 

Deleted: 

Deleted: 

Deleted: 
Draft Regulatory Impact Analysis 

3-24

The FTP75 and HWFEC drive cycles are used extensively for Light-Duty emissions and 

CAFE programs. Our assessment is that these cycles are not appropriate for HD trucks for two 

primary reasons. First, the FTP has 24 accelerations during the cycle which are too steep for a 

Class 8 combination tractor to follow. Second, the maximum speed is 60 mph during the 

HWFEC, while the national average truck highway speed is 65 mph. 

The Heavy-Duty Urban Dynamometer Driving Cycle was developed to determine the 

Heavy-Duty Engine FTP cycle. The cycle was developed from CAPE-21 survey data which 

included information from 44 trucks and 3 buses in Los Angeles and 44 trucks and 4 buses in 

New York in 1977. The cycle was computer generated and weighted to represent New York 

non-freeway (254 sec), Los Angeles non-freeway (285 sec), Los Angeles freeway (267 sec), 

New York non-freeway (254 sec) to produce a nearly 50/50 weighting of highway cruise and 

urban transient. We believe this cycle is not appropriate for our program for several reasons. 

The maximum speed on the UDDS is 58 mph which is low relative to the truck speed limits in 

effect today. The 50/50 weighting of cruise to transient is too low for combination tractors and 

too high for vocational vehicles and the single cycle does not provide flexibility to change the

weightings. Lastly, the acceleration rates are low for today’s higher power trucks.

The World Harmonized WTVC was developed by the UN ECE GRPE group. It represents 

urban, rural, and motorway operation. The cycle was developed based on data from 20 straight 

trucks, 18 combination tractors, and 11 buses total from Australia, Europe, Japan, and US. EPA 

has a desire to harmonize internationally, however, we believe this single cycle does not 

optimally cover the different types of truck operation in the United States and does not provide 

the flexibility to vary the weightings of a single cycle.

The Highway Line Haul schedule was created by Southwest Research Institute, using input 

from a group of stakeholders, including EPA, Northeastern States for Coordinated Air Use 

Management (NESCAUM), several truck and engine manufacturers, state organizations, and 

others, for a NESCAUM heavy truck fuel efficiency modeling and simulation project. The cycle 

is 103 miles long and incorporates grade and altitude. This cycle is a good representation of line 

haul operation. However, the grade and altitude changes cannot be incorporated into a chassis 

dynamometer or track test. The cycle is also too long for a typical chassis dynamometer test. 

The Calstart-Weststart Hybrid Truck Users Forum is developing cycles to match the 

characteristics of trucks applications which are expected to be first to market for hybrids. The 

cycles include the Manhattan Bus Cycle, Orange County Bus Cycle, Class 4 Parcel Delivery, 

Class 6 Parcel Delivery, Combined International Local and Commuter Cycle (CILCC), 

Neighborhood Refuse, Utility Service, and Intermodal Drayage cycles. The cycles are very 

application-specific and appropriately evaluate each vocation. However, the use of these type of 

application specific cycles in a regulatory scheme will lead to a proliferation of cycles for every 

application, an outcome that is not desirable.

The ARB 5 Mode cycle was developed from data gathered by the University of California

Riverside in collaboration with California ARB from 270 1993 through 2001 MY trucks and 

over 1 million miles of activity. The cycles were developed to reflect typical in-use behavior as 

demonstrated from the data collected. The four modes (idle, creep, transient, and cruise) were 

determined as distinct operating patterns, which then led to the four drive schedules. The cycle 

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is well accepted in the heavy-duty industry. It was used in the CRC E55/59 Study which is the

largest HD chassis dynamometer study to date and used in MOVES and EMFAC to determine 

emission rate inputs; the EPA biodiesel study which used engine dynamometer schedules created 

from ARB cruise cycle; the HEI ACES Study: WVU developed engine cycles from ARB 4-

mode chassis cycles; CE/CERT test; and by WVU to predict fuel efficiency performance on any 

drive cycle from ARB 5 mode results. The modal approach to the cycles provides flexibility in 

cycle weightings to accommodate a variety of truck applications. A downside of the cycle is that 

it was developed from truck activity in California only.

3.4.2 Proposed Drive Cycles

The drive cycle we are proposing is a modified version of the California Air Resource 

Board (CARB) Heavy Heavy-Duty Truck 5 Mode Cycle. We are proposing the use of the 

Transient mode, as defined by CARB. The cycle is 668 seconds long and travels 2.84 miles. 

The cycle contains 5 stops and contains 112 seconds idling. The maximum speed of the cycle is 

47.5 mph with an average speed of 15.3 mph. 

We are also proposing to alter the High Speed Cruise and Low Speed Cruise modes to 

reflect only constant speed cycles at 65 mph and 55 mph respectively. Based on input from 

trucking fleets and truck manufacturers, we believe the latter is representative of in-use 

operation, wherein truck drivers use cruise control whenever the possible during periods of 

sustained higher speed driving. 

3.4.3 Weightings of Each Cycle per Regulatory Subcategory

As mentioned above, the advantage of using a modal approach to drive cycles is that the 

standardized modes can be weighted differently to reflect the difference in operating conditions 

of various truck applications.

The development of the Class 8 sleeper cab cycle weightings is based on studies 

developed to characterize the operation of line haul trucks. The EPA MOVES model, a study 

conducted by University of California Riverside, an estimation of commercial truck idling 

conducted by Argonne National Lab, and a tire test on line haul trucks conducted by Oak Ridge 

National Lab were used in the weighting analysis.

The distribution of vehicle miles travelled (VMT) among different speed bins was 

developed for the EPA MOVES model from analysis of the Federal Highway Administration 

data. The data is based on highway vehicle monitoring data from FHWA used to develop the 

distribution of VMT among road types from 1999. The information on speed distributions on the 

different type of roads at different times of day came from traffic modeling of urban locations 

and chase car data in rural California. This data was used to characterize the fraction of VMT 

spent in high speed cruise versus transient operation. 

The University of California Riverside and California Air Resource Board evaluated 

engine control module data from 270 trucks which travelled over one million miles to develop 

the heavy-duty diesel truck activity report in 2006.18

Deleted: 

 The study found that line haul trucks spend 

approximately 50% of the time cruising at speeds greater than 45 mph, 10% of time in transient 

stop-and-go driving, and 40% in extended idle operation. After removing the idle portion to 

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3-26

establish weightings of only the motive operation, the breakdown looks like 82% of the time 

cruising at speeds greater than 45 mph and 18% in transient operation.

Argonne National Lab estimated the percentage of fuel consumed while idling for various 

combinations of trucks, such as sleeper cabs.19

Oak Ridge National Laboratory evaluated the fuel efficiency effect of tires on Class 8 

heavy trucks.

 The estimation is based on FHWA’s Highway 

Statistics and the Census Bureau’s Vehicle In-Use Survey (VIUS). The study found that Class 8 

sleeper cabs use an average of 6.8% of their fuel idling.

20 The study collected fleet data related to real-world highway environments over a 

period of two years. The fleet consisted of six trucks which operate widely across the United 

States. In the Transportation Energy Data Book (2009)21

Table 3-5: Combination Tractor Drive Cycle Weighting

Table 5.11 was analyzed and found on 

average that the line haul trucks spent 5% of the miles at speeds less than 50 mph, 17% between 

50 and 60 mph, and 78% of the time at speeds greater than 60 mph.

and Table 3-6: Vocational 

Vehicle Drive Cycle Weighting summarize the studies and the agencies’ proposal for drive cycle 

weightings.

Table 3-5: Combination Tractor Drive Cycle Weighting

MOVES UCR Proposal

All Restricted 

Access

Short 

Haul

Long 

Haul

Sleeper Cab 

Proposal

Day Cab 

Proposal

> 60 mph 64% 86%

47%

> 45 mph

81%

> 45 mph

86%

65 mph Cruise

64%

65 mph 

Cruise

50-60 mph 17% 9% 9%

55 mph Cruise

17%

55 mph 

Cruise

< 50 mph 19% 5% 53% 5% 5%

Transient

19%

Transient

Table 3-6: Vocational Vehicle Drive Cycle Weighting

MOVES

Single Unit

UCR

Medium-Duty

Proposal

> 60 mph 37%

16%

> 45 mph

37%

65 mph Cruise

50-60 mph 21% 21%

55 mph Cruise

< 50 mph 42% 84% 42%

Transient

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The proposed drive cycle weightings for each regulatory category are included in Table 

3-7: Drive Cycle Mode Weightings.

Table 3-7: Drive Cycle Mode Weightings

VOCATIONAL 

VEHICLES

DAY CABS SLEEPER CABS

Transient 42% 19% 5%

55 mph Cruise 21% 17% 9%

65 mph Cruise 37% 64% 86%

3.5 Tare Weights and Payload

The total weight of a truck is the combination of the truck’s tare weight, a trailer’s tare 

weight (if applicable), and the payload. The total weight of a truck is important because it in part 

determines the impact of technologies, such as rolling resistance, on GHG emissions and fuel 

consumptions. As the HD program is proposed, it is important that the agencies define weights 

which are representative of the fleet while recognizing that the proposed weights are not 

representative of a specific vehicle. The sections below describe the agencies’ approach to 

defining each of these weights.

3.5.1 Truck Tare Weights

The tare weight of a truck will vary depending on many factors, including the choices 

made by the manufacturer in designing the truck (such as the use of lightweight materials, the 

cab configuration (such as day or sleeper cab), whether it has aerodynamic fairing (such as a roof 

fairing), and the specific options on the truck. 

The proposed Class 8 combination tractor tare weights were developed based on the 

weights of actual tractors tested in the EPA coastdown program. The empty weight of the Class 

8 sleeper cabs with a high roof tested ranged between 19,000 and 20,260 pounds. The empty 

weight of the Class 8 day cab with a high roof tested was 17,840 pounds. The agencies derived 

the tare weight of the Class 7 day cabs based on the guidance of truck manufacturer. The 

agencies then assumed that a roof fairing weighs approximately 500 pounds. Based on this, the 

agencies are proposing the tractor tare weights as shown in Table 3-8.

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3-28

Table 3-8: Tractor Tare Weights

MODEL TYPE CLASS 8 CLASS 8 CLASS 8 CLASS 8 CLASS 8 CLASS 7 CLASS 7

Regulatory 

Subcategory

Sleeper Cab 

High Roof

Sleeper Cab 

Mid Roof

Sleeper Cab 

Low Roof

Day Cab 

High Roof

Day Cab 

Low Roof

Day Cab 

High Roof

Day Cab 

Low Roof

Tractor Tare 

Weight (lbs) 19,000 18,750 18,500 17,500 17,000 11,500 11,000

The agencies developed the empty tare weights of the vocational vehicles based on the 

EDF report22

• Light Heavy (Class 2b-5) = 10,300 pounds

on GHG management for Medium-Duty Fleets. The EDF report found that the 

average tare weight of a Class 4 truck is 10,343 pounds, of a Class 6 trucks is 13,942 pounds, 

and a Class 8 as 28,979 pounds. The agencies are proposing the following tare weights:

• Medium Heavy (Class 6-7) = 13,950 pounds

• Heavy Heavy (Class 8) = 29,000 pounds

3.5.2 Trailer Tare Weights

The proposed trailer tare weights are based on measurements conducted during EPA’s 

coastdown testing and information gathered by ICF in the cost report to EPA.23

A typical 53 foot box (or van) trailer has an empty weight ranging between 13,500 and 

14,000 pounds per ICF’s findings. The box trailer tested by EPA in the coastdown testing 

weighed 13,660 pounds. Therefore, the agencies are proposing to define the empty box trailer 

weight as 13,500 pounds.

 

A typical flatbed trailer weighs between 9,760 and 10,760 per the survey conducted by 

ICF. EPA’s coastdown work utilized a flatbed trailer which weighed 10,480 pounds. Based on 

this, the agencies are proposing a defined flatbed trailer weight of 10,500 pounds.

Lastly, a tanker trailer weight typically ranges between 9,010 and 10,500 pounds based 

on ICF findings. The tanker trailer used in the coastdown testing weighed 9,840 pounds. The 

agencies are proposing an empty tanker trailer weight of 10,000 pounds.

3.5.3 Payload

The amount of payload by weight that a tractor can carry depends on the class (or 

GVWR) of the vehicle. For example, a typical Class 7 tractor can carry fewer tons of payload 

than a Class 8 tractor. Payload impacts both the overall test weight of the truck and is used to 

assess the “per ton-mile” fuel consumption and GHG emissions. The “tons” represent the 

payload measured in tons. 

M.J. Bradley analyzed the Truck Inventory and Use Survey and found that approximately 

9 percent of combination tractor miles travelled empty, 61 percent are “cubed-out” (the trailer is 

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full before the weight limit is reached), and 30 percent are “weighed out” (operating weight 

equal 80,000 pounds which is the gross vehicle weight limit on the Federal Interstate Highway 

System or greater than 80,000 pounds for vehicles traveling on roads outside of the interstate 

system).24

Table 

3-9

 The Federal Highway Administration developed Truck Payload Equivalent Factors 

to inform the development of highway system strategies using Vehicle Inventory and Use Survey 

(VIUS) and Vehicle Travel Information System (VTRIS) data. Their results, as shown in 

, found that the average payload of a Class 8 truck ranged from 29,628 to 40,243 pounds, 

depending on the average distance travelled per day.25

Table 3-9: National Average Payload (lbs.) per Distance Travelled and Gross Vehicle Weight Group (VIUS)

The same results found that Class 7 

trucks carried between 18,674 and 34,210 pounds of payload also depending on average distance 

travelled per day. 

26

CLASS 3 CLASS 4 CLASS 5 CLASS 6 CLASS 7 CLASS 8

< 50 miles 3,706 4,550 8,023 10,310 18,674 29,628

51 to100 miles 3,585 4,913 6,436 10,628 23,270 36,247

101 to 200 

miles 4,189 6,628 8,491 12,747 30,180 39,743

201 to 500 

miles 4,273 7,029 6,360 10,301 25,379 40,243

> 500 mile 3,216 8,052 6,545 12,031 34,210 40,089

Average 3,794 6,234 7,171 11,203 26,343 37,190

The agencies are proposing to prescribe a fixed payload of 25,000 pounds for Class 7 

tractors and 38,000 pounds for Class 8 tractors for their respective test procedures. These 

payload values represent a heavily loaded trailer, but not maximum GVWR, since as described 

above the majority of tractors "cube-out" rather than "weigh-out.” 

NHTSA and EPA are also proposing payload requirements for each regulatory 

subcategory in the vocational vehicle category. The payloads were developed from Federal

Highway statistics based on the averaging the payloads for the weight classes of represented 

within each vehicle category.27

Table 3-9

The proposed payload requirement is 5,700 pounds for the Light 

Heavy trucks based on the average payload of Class 3, 4, and 5 trucks from . The 

proposed payload for Medium Heavy trucks is 11,200 pounds per the average payload of Class 6 

trucks as shown in Table 3-9. Lastly the agencies are proposing 38,000 pounds payload for the 

Heavy Heavy trucks based on the average Class 8 payload in Table 3-9. 

3.5.4 Total Weight

In summary, the total weights of the combination tractors are shown in Table 3-10.

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3-30

Table 3-10: Combination Tractor Total weight

MODEL TYPE CLASS 8 CLASS 8 CLASS 8 CLASS 8 CLASS 8 CLASS 7 CLASS 7

Regulatory 

Subcategory

Sleeper Cab 

High Roof

Sleeper Cab 

Mid Roof

Sleeper Cab 

Low Roof

Day Cab 

High Roof

Day Cab 

Low Roof

Day Cab 

High Roof

Day Cab 

Low Roof

Tractor Tare 

Weight (lbs) 19,000 18,750 18,500 17,500 17,000 11,500 11,000

Trailer Weight 

(lbs) 13,500 10,000 10,500 13,500 10,500 13,500 10,500

Payload (lbs) 38,000 38,000 38,000 38,000 38,000 25,000 25,000

Total Weight (lbs) 70,500 66,750 67,000 69,000 65,500 50,000 46,500

The proposed total weights of the vocational vehicles are as shown in Table 3-11.

Table 3-11: Vocational Vehicle Total Weights

REGULATORY 

SUBCATEGORY

LIGHT 

HEAVY

MEDIUM 

HEAVY

HEAVY

HEAVY

Truck Tare 

Weight (lbs) 10,300 13,950 29,000

Payload (lbs) 5,700 11,200 38,000

Total Weight (lbs) 16,000 25,150 67,000

3.6 Heavy-Duty Chassis Test Procedure

The agencies are proposing a chassis test procedure for heavy-duty trucks (with GVWR 

greater than 14,000 pounds) in Code of Federal Regulations (CFR), title 40, part 1066. The 

chassis test procedure is one of the options being proposed for manufacturers to demonstrate 

hybrid powertrain credits. The proposed procedures are adapted from the optional complete 

federal vehicle emissions certification for light heavy-duty vehicles (i.e., those with a GVWR of 

8,500-14,000 pounds). Details of the light heavy-duty vehicle procedure are found in the Code 

of Federal Regulations (CFR), title 40, part 86.1816-05 through part 86.1816-07. Additional test 

procedures are described in 40 CFR §86.1863. The proposed test method was further developed 

from the draft SmartWay test protocol28, which includes a description of the procedures for 

determining the state of charge and net energy change for hybrid vehicles based on SAE test 

method 2711.

30

EPA, under the SmartWay program, conducted feasibility testing for the proposed test 

method on Class 8 tractors. The testing evaluated track tests against chassis dynamometer tests, 

and measurement of CO2

Table 3-12

emissions by use of a standard test cell, a portable emissions 

monitoring system (PEMS), and calculation from gravimetric measurement of fuel consumption. 

Testing issues involving highly variable ambient conditions (i.e. wind speed, temperature, etc.) 

suggested that chassis dynamometer tests were preferable for obtaining consistent test results. 

Replicate results of the chassis dynamometer procedure demonstrate that the test precision is 

typically less than 5%, which is comparable to that of the similar light-duty chassis dynamometer 

test procedure, as shown in .

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3-31

Table 3-12 Coefficients of Variation Reported for Chassis Dynamometer Tests Conducted Using the 

SmartWay Test Procedure.

METHOD OF 

EMISSIONS 

MEASUREMENT

TEST CELL PEMS GRAVIMETRIC

Truck number 29 555 598 29 555 598 29 555 598

UCT 12.7% 6.2% 1.6% 1.8% 0.8% 2.2% 3.9% 2.2% 2.0%

LSC 2.0% 3.9% 1.4% 1.2% 0.3% 0.7% 2.1% 3.7% 0.7%

HSC 1.3% 4.5% 1.0% 0.6% 0.5% 0.5% 1.7% 0.6% 1.2%

Coefficient of variation is the standard deviation of the test replicates divided by the mean of the test replicates.

UCT – Urban Creep and Transient duty cycle

LSC -- Low Speed Cruise duty cycle

HSC -- High Speed Cruise duty cycle

The number of heavy-duty chassis dynamometers in the United States is limited. EPA’s 

investigation found 11 chassis dynamometer sites in North America, including the following:

• Air Resources Board Heavy-Duty Emissions Testing Laboratory in Los Angeles,

California

• California Truck Testing Services in Richmond, California

• Colorado School of Mines, Colorado Institute for Fuels and Research in Golden,

Colorado

• Environment Canada in Ottawa, Ontario, Canada

• Southwest Research Institute in San Antonio, Texas

• West Virginia University Transportable Heavy-Duty Vehicle Emissions Testing 

Laboratory 

• National Renewable Energy Lab in Golden, Colorado

• University of Houston in Houston, Texas

• US EPA in Research Triangle Park (not in operation yet)

• Argonne National Lab (up to 14,000 lb.)

• National Vehicle Fuel and Emissions Lab in Ann Arbor, Michigan (up to 14,000 lb.)

3.7 Hybrid Powertrain Test Procedures

As discussed in Section II, the agencies see an opportunity to create incentives for use of

hybrid powertrains in this proposal, to help drive the technology’s advancement. EPA and 

NHTSA are proposing two methods to demonstrate benefits of a hybrid powertrain – chassis and 

engine testing, and thereby generate credits through the use of such technology. The reduction in 

CO2

Deleted: variation reported

emissions and fuel consumption demonstrated would be available to use as credits in any 

vehicle or engine subcategory. That is, unlike ABT credits, credits generated by use of this 

technology would be available for use anywhere in the heavy-duty vehicle and engine sector. 

We are proposing the greater portability for these credits in order to create incentives to use this 

promising technology and thereby further its acceptance in the heavy-duty sector, with attendant 

GHG and fuel consumption reduction benefits.

Deleted: chassis dynamometer tests conducted 

using

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3-32

The purpose of this testing provision is to allow for evaluation of greenhouse gas and fuel 

consumption reducing technologies that are available, but may lack broad market penetration 

beyond niche sectors. To effectively incentivize the introduction of this technology, as well as to 

accurately characterize its effectiveness, it is important to develop a standardized protocol as a 

basis for comparison. As described in the preamble for this rulemaking, the benefit of the 

hybridized version of the will be assessed based on a comparison to the conventional version. 

The basic methods considered for evaluation include full vehicle chassis testing of the hybrid 

system and powertrain evaluation in a configuration that does not include the full vehicle. The 

powertrain or “powerpack” testing may be undertaken in one of two ways. A powertrain test cell 

capable of accommodating the engine, complete hybrid system (including motor, power 

electronics, battery(ies), electronic control system, etc.), and the transmission may be used to 

evaluate post-transmission power pack systems. Engine dynamometer test cells may be used to 

assess the performance of the engine and hybrid power system with the control volume 

extending to just prior to the transmission. The distinction largely being the type of operation the 

engine – hybrid system can accommodate. When considering performance of any hybrid 

system, the durability of various emissions related system components will need to be included 

over the full regulatory useful life. While the industry and component manufacturers may be in 

the process of addressing battery technology and lifetime performance, any benefit associated 

with the hybrid system will be based on how this performance changes over the life of the hybrid 

system and vehicle. 

Vehicle Chassis Dynamometer Testing

As a straightforward basis for addressing performance of hybrid systems for greenhouse 

gas emissions / fuel consumption reduction potential, the vehicle chassis dynamometer involves 

exercising the complete powertrain system within the vehicle for both conventional and hybrid 

systems. In this way, actual vehicle performance may be measured using prescribed duty cycles 

that have a real-world basis. The certification duty cycles considered for conventional heavyduty vehicle certification may be applied to the hybrid vehicle system based on the proposed

chassis testing protocols. The A to B testing would be conducted as described in Figure 3-3

Example of A to B Testing for Chassis or Powertrain Dynamometers below.

Figure 3-3 Example of A to B Testing for Chassis or Powertrain Dynamometers

Conventional Vehicle Hybrid Vehicle

Curb wt: 21k lbs

Payload: 1k lbs

Test wt: 22k lbs

Coastdown Wt: 22k lbs

GVWR: 33k lbs

Curb wt: 22k lbs

Payload: 1k lbs

Test wt: 23k lbs

Coastdown Wt: 23k lbs

GVWR: 33k lbs

A Test B Test

Deleted: established

Deleted: <sp>¶

¶

¶

¶

¶

¶

¶

¶
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-33

This approach is meant to account for the differences in vehicle weight expected for 

vehicles equipped with hybrid power systems. In so doing, the capability (e.g. payload, etc.) is 

not diminished for testing purposes. The expectation is that the benefit associated with the use of 

hybrid system may be characterized by the tractive operation duty cycles and / or the PowerTake Off duty cycle meant to better reflect the idle work and emissions saved through the use of 

a hybrid energy system. Chassis dynamometer testing for hybrid vehicles will be conducted 

using standard test protocols as described in SAE J1711 and 2711. To address the use of the 

power-take off and the GHG emissions related improvements associated with hybrid power 

systems, a separate duty as described in Table 3-14is provided. To address improvements for the 

purposes of credit generation, a weighted composite emission level will be used. 

Powertrain / Powerpack Evaluation

To address hybrid power system performance for pre-vehicle testing configurations, this 

may be accomplished in a powertrain test cell or converted engine dynamometer test cell. There 

are various hardware-in-the-loop simulations being contemplated and implemented today, 

however the focus of this discussion will be on basic powertrain / powerpack evaluation. Any 

pre-vehicle testing provision that incorporates the benefits of hybrid power systems, would need 

to address several factors including durability of those components, kinetic energy recovery, 

design variety that could be captured using a chassis dynamometer test, and the drive cycle to 

appropriately characterize the vehicle activity. The testing methodologies for pre-vehicle hybrid 

evaluation currently consist of two equally viable strategies with different implications with 

respect to how emissions improvements are characterized. The first system to be discussed is the 

pre-transmission powerpack evaluation which incorporates all of the hybrid system components 

that exist prior to the transmission in the vehicle. The control volume is drawn so as to include 

the battery, battery support and control systems, power electronics, the engine, and motor 

generator and hybrid control module. The performance of this system is largely an engine based 

evaluation in which emission rates are determined on a brake-specific work basis. As such, the 

duty cycles being considered to assess this system performance are engine speed and torque 

command cycles. The emissions results associated with the system performance for GHG 

pollutants may be measured on brake-specific basis as an absolute test result. This differs from 

the approach used for post-transmission testing methods which may be conducted in a 

powertrain test cell or using a chassis dynamometer. As this rulemaking does not contemplate 

changes to criteria pollutant standards, the duty cycles and measurement methods may be similar 

to the criteria pollutants, however the emission results for GHG may be based on this full system 

consideration, which is not the case for criteria pollutants. Engine certification for criteria 

pollutant standards remain unchanged. It is expected that pre-transmission, parallel hybrids 

would be the most likely choice for engine-based hybrid certification. 

For powertrain testing to determine hybrid benefit, the components mentioned for 

powerpack testing would be included for powertrain testing, as well as the transmission 

integrated with the hybrid power system. It is expected that testing could be conducted in a 

powertrain test cell which would differ from the traditional engine test cell in that it would need 

to accommodate the additional rotational inertia and speeds associated with inclusion of the 

vehicle / hybrid transmission with an electric, alternating current dynamometer. Additionally, 

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Draft Regulatory Impact Analysis 

3-34

test cell control systems will need to address all relevant control factors including ways to 

integrate vehicle command data into the control strategy for the engine and hybrid transmission 

system. This could eventually include the need for vehicle and driver model inclusions into the 

control schema for test cell and test article. 

Emissions testing for vehicles and hybrid powertrains will require A to B testing to 

determine the improvement factor as described in Preamble Section IV using the GEM result for 

the base vehicle model as the basis for assessing the CO2 performance improvement versus the 

appropriate vocational vehicle standard. Engine performance which includes the pretransmission approach for hybrid certification will generate grams per brake-horsepower hour 

emissions result that should demonstrate improvement versus the base standard. 

3.7.1 Chassis Dynamometer Evaluation

We are proposing that heavy-duty hybrid vehicles be certified using an A to B test 

method using a chassis dynamometer for testing vehicles. This concept allows the hybrid 

manufacturer to directly quantify the benefit associated with use of their hybrid system on an 

application specific basis. The concept would entail exercising the conventional vehicle, 

identified as “A”, tested over the defined cycles. The “B” vehicle would be the hybrid version of 

vehicle “A”. To be considered an appropriate “B” vehicle it must be the same exact vehicle 

model as the “A” vehicle. As an alternative, if no specific “A” vehicle exists for the hybrid 

vehicle that is the exact vehicle model, the most similar vehicle model must be used for 

certification. The most similar vehicle is defined as a vehicle with the same footprint, same 

payload, same intended service class, and the same coefficient of drag. 

To determine the benefit associated with the hybrid system for greenhouse gas (GHG) 

performance, the weighted CO2

1. (CO

emissions results from the chassis test of each vehicle would 

define the benefit as described below:

2_A – CO2_B)/ (CO2_A

2. Improvement Factor x Applicable Standard = ___ (g/ton mile benefit)

) = ______ (Improvement Factor)

Similarly, the benefit associated with the hybrid system for fuel consumption would be 

determined from the weighted fuel consumption results from the chassis tests of each vehicle as 

described below:

3. (Fuel ConsumptionA – Fuel ConsumptionB)/ (Fuel ConsumptionA

4. Improvement Factor x Fuel Consumption Standard = ___ (gallon/ton mile 

benefit)

)= ______ 

(Improvement Factor)

3.7.1.1 Chassis Dynamometer Drive Cycles

The agencies are proposing two sets of duty cycles to evaluate the benefit depending on 

the vehicle application (such as delivery truck, bucket truck, or refuse truck). The key difference 

between these two sets of vehicles is that one does not operate a power take-off (PTO) unit while 

the other does. 

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A power take off (PTO) is a system on a vehicle that allows energy to be drawn from the 

vehicle’s drive system and used to power an attachment or a separate machine. Typically in a 

heavy-duty truck, a shaft runs from the transmission of the truck and operates a hydraulic pump. 

The operator of the truck can select to engage the PTO shaft in order for it to do work, or 

disengage the PTO shaft when the PTO is not required to do work. The pressure and flow from 

this hydraulic fluid can be used to do work in implements attached to the truck. Common 

examples of this are utility trucks that have a lift boom on them, refuse trucks that pick up and 

compact trash, and cement trucks that have a rotating barrel. In each case the auxiliary 

implement is typically powered by a PTO that uses energy from the truck’s primary drive engine.

In most PTO equipped trucks, it is necessary to run the primary drive engine at all times 

when the PTO might be needed. This is less efficient than an optimal system. Typical PTO 

systems require no more than 19 kW at any time, which is far below the optimal operation range 

of the primary drive engine of most trucks. Furthermore, in intermittent operations, the primary 

drive engine is kept running at all times in order to ensure that the PTO can operate 

instantaneously. This results in excess GHG emissions and fuel consumption due to idle time. 

Additionally, idling a truck engine for prolonged periods while operating auxiliary equipment 

like a PTO could cause the engine to cycle into a higher idle speed, wasting even more fuel. It 

would be possible to hybridize or change the operation of a conventional PTO equipped truck to 

lower the GHG emissions and fuel consumption in the real world. However, there is currently no 

method for an equipment manufacturer to demonstrate fuel consumption and GHG emissions 

reductions due to the application of advanced PTO technology. The proposed drive cycles do not 

allow for PTO operation to be included in the test protocol. We are proposing to add a new 

optional PTO test to the standard set of test cycles in order for manufacturers of advanced PTO 

systems to demonstrate in the laboratory environment fuel consumption and GHG reductions that 

would be realized from their systems in the real world. For this reason, the EPA contracted 

Southwest Research Institute (SwRI) to study PTO systems on heavy-duty trucks with a goal of 

determining an appropriate test cycle.

We worked with SwRI to review the heavy-duty truck market to determine what types of 

trucks used PTO’s and if the manufacturers thought that there was any possibility of commercial 

hybrid PTO applications. In some segments, manufacturers did not think a hybrid PTO was 

feasible. On the other hand, there are already utility and refuse trucks in existence that feature 

hybrid PTO units. We chose to study the behavior of conventional versions of these trucks in 

order to understand their typical operation.

We categorized the trucks based on the PTO opportunity. Trucks where limited PTO 

operation makes them infeasible due to low rates of return include dump trucks. Trucks where 

PTO operation is infeasible due to high power requirements include blower trucks, 

fire/emergency trucks, and concrete mixer trucks. Trucks where there is the possibility of PTO 

operation but there was no commercial interest include tow trucks, grapple trucks, and snowplow 

trucks.

We selected one utility truck that was in a rental fleet. Over the course of several weeks 

this truck was rented to two different customers and used in two different environments. The first 

time the truck was rented it was used in a rural setting outside of San Antonio, Texas. The 

following week the truck was used in a more urban setting in Fort Worth, Texas. Data was taken 

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Draft Regulatory Impact Analysis 

3-36

from the truck as follows: - Engine Speed, Engine Fuel Rate, Vehicle Speed, PTO Pressure, and 

PTO Flow Rate.

From this data we were able to determine how often the truck’s engine was running, how 

often the PTO was engaged, and how often the boom of the utility truck was being manipulated 

by the user. The field data showed that when the truck was operated in the rural setting it had a 

much lower rate of utilization that when it was operated in the urban setting. Table 3-13 shows a 

breakdown of the operation of the truck in each setting.

Table 3-13 Utility Truck PTO Operation

RURAL SETTING URBAN SETTING

% Time PTO at “Idle” 90% 50%

% Time PTO working 10% 50%

In order to better understand the field operation of refuse trucks, EPA commissioned 

SwRI to study the operation of a refuse hauling truck. SwRI worked with Waste Management in 

Conroe Texas to instrument a typical PTO equipped neighborhood pickup refuse hauler. The 

truck that we instrumented was equipped with a side-load-arm (SLA). Southwest’s research 

revealed that approximately 20 percent of the trucks in the industry include an SLA, and the 

percentage of trucks with an SLA is increasing. Also, a truck with an SLA is able to service more 

homes per day than a standard truck, so as more SLA equipped trucks are added to the fleet, the 

total number of trucks will decrease.

The refuse truck was driven on its various routes over the course of a week and the data 

recorded. Though the truck operated on different streets and areas within the city of Conroe each 

day, the operation characteristics of the truck were uniform day-to-day. 

Once the data was collected, definitions of power take-off (PTO) operations were 

identified as (1) pump “on” and idle (utility truck), and (2) compactor only, loader only, both 

compactor and loader, and idle (refuse truck). Steady-state pressure modes were identified by a 

statistical disjoint cluster analysis. Statistical frequency analyses of the in-field data were used to 

determine the relative proportion of time allocated to each steady-state mode. The loader and 

compactor pressure data from the refuse truck demonstrated cyclical behavior, therefore, a 

discrete Fourier transform using the fast Fourier transform (FFT) algorithm was performed on 

the loader and compactor data independently. The results of the FFT were used to determine the 

frequency of the modes in the test cycle. Information collected on population usage was used to 

weight different portions of the composite duty cycle (utility and refuse truck cycles) to reflect 

actual field PTO operations. 

Based upon the results of the data collection, we decided that a representative duty cycle 

for PTO operation would not begin until the engine was fully warmed up. In all cases the trucks 

were warmed up before driving, then driven some distance to a location where the PTO was 

engaged. Thus, the traction engine was always fully warm before PTO operation commenced.

Based upon the data collection we believe that a representative PTO cycle should test a 

PTO that is at operating temperature. In the case of the utility truck, most of the operation is in 

an urban environment and about one-half of the operation time is loaded. Thus, the PTO would 

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only operate in a “cold” state for less than 2% of a typical day. The refuse truck showed similar 

operation, the PTO was run continuously throughout the eight hour work day resulting in cold 

operation of the PTO for less than 2% of the typical day.

EPA and NHTSA are proposing that truck manufacturers be able to test their PTO system 

and compare it to a baseline system to generate GHG emissions and fuel consumption credits. 

The manufacturer will need to test their system in an emissions cell capable of measuring GHG 

emissions. The PTO would be exercised by an auxiliary test bench and commanded to follow a 

prescribed cycle. The cycle will be determined by the type of PTO system that is under 

consideration. At this time, PTO cycles have been developed for utility trucks and refuse hauling 

trucks.

The agencies are proposing a composite PTO cycle to allow PTO manufacturers to earn 

credits for GHG emissions. The cycle we are proposing has been weighted based on the utility 

truck and refuse truck data in the SwRI report. It was determined that utility truck usage was 

approximately 20 percent rural and 80 percent urban. Furthermore, based on the field data 

obtained from the test trucks, the utility trucks are expected to use the PTO when performing 

boom operations 10 percent of the time in rural settings and 50 percent of the time in urban 

settings. The data from the refuse truck in the SwRI report was used to complete the refuse 

portion of the cycle. Because the refuse truck used in the data collection had two hydraulic 

circuits, one for the load arm and one for the compactor, there are two pressure traces, one for 

each circuit. Thus, the PTO test cycle described in Table 3-14 reflects this.

Field Code Changed

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0

10

20

30

40

50

60

70

80

90

0 100

Normalized Pressure

Figure
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3-38

Table 3-14: Proposed PTO Cycle

Cycle 

Simulation

Mode Time Normalized Pressure, 

Circuit 1 (%)

Normalized Pressure, 

Circuit 2 (%)

Utility 0 0 0.0 0.0

Utility 1 33 80.5 0.0

Utility 2 40 0.0 0.0

Utility 3 145 83.5 0.0

Utility 4 289 0.0 0.0

Refuse 5 361 0.0 13.0

Refuse 6 363 0.0 38.0

Refuse 7 373 0.0 53.0

Refuse 8 384 0.0 73.0

Refuse 9 388 0.0 0.0

Refuse 10 401 0.0 13.0

Refuse 11 403 0.0 38.0

Refuse 12 413 0.0 53.0

Refuse 13 424 0.0 73.0

Refuse 14 442 11.2 0.0

Refuse 15 468 29.3 0.0

Refuse 16 473 0.0 0.0

Refuse 17 486 11.2 0.0

Refuse 18 512 29.3 0.0

Refuse 19 517 0.0 0.0

Refuse 20 530 12.8 11.1

Refuse 21 532 12.8 38.2

Refuse 22 541 12.8 53.4

Refuse 23 550 12.8 73.5

Refuse 24 553 0.0 0.0

Refuse 25 566 12.8 11.1

Refuse 26 568 12.8 38.2

Refuse 27 577 12.8 53.4

Refuse 28 586 12.8 73.5

Refuse 29 589 0.0 0.0

Refuse 30 600 0.0 0.0

The protocol for testing the PTO system will be similar to chassis testing. The vehicle 

will be positioned such that the exhaust system can be attached to exhaust emission analyzers. 

This can be done using, but does not necessarily require, a chassis dynamometer. The PTO 

system will be disconnected from the truck’s work absorbing apparatus and connected to a bench 

Field Code Changed

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-39

that will provide energy absorption to the PTO system. For trucks with one hydraulic circuit in 

the PTO system, they will be hooked up to the utility/compactor side of the PTO bench. Trucks 

with two hydraulic circuits will be hooked up to both circuits on the PTO bench. A schematic of 

this bench can be seen in Appendix I. The vehicle will be pre-conditioned at ambient conditions 

and then the engine will be run until it is at operating temperature. The PTO will then be 

exercised until the working fluid and or driving mechanism of the PTO is up to operating 

temperature. The fully warmed up operating temperature may be defined by the manufacturer or 

may be assumed to be 150°C. The test will then commence. We believe that a “hot-start” test is 

appropriate because our data analysis found that trucks equipped with PTO’s are nearly always 

warmed up before the PTO is used, and that cold PTO operation makes up less than 2% of a 

PTO’s typical daily usage.

The PTO would be manipulated by the operator to the prescribed duty cycle. GHG 

emissions and fuel consumption will be measured as well as criteria pollutants. GHG emissions 

and fuel consumption would be reported to determine credits; criteria pollutants will simply be 

reported.

In order to gain credits the manufacturer would have to demonstrate how a truck with a 

conventional PTO system would perform over the same duty cycle. Both sets of data will need to 

be measured and reported to EPA and NHTSA in order to claim GHG emission and fuel 

consumption credits.

The first set of proposed duty cycles would apply to the hybrid powertrains used to 

improve the motive performance of the vehicle (such as pickup and delivery trucks). The typical 

operation of these vehicles is very similar to the proposed drive cycles. Therefore, the agencies 

are proposing to use the vocational vehicle weightings for these vehicles, as shown in Table 3-

12. We are using the proposed regulatory vocational vehicle classifications for the ABT 

vocational vehicle classification. Hybrid vehicles used in applications such as utility and refuse 

trucks tend to have additional benefit associated with use of stored energy, which avoids main 

engine operation and related CO2 emissions and fuel consumption. To appropriately address 

these alternative sources for benefits, exercising the conventional and hybrid vehicles using their 

PTO would help to quantify the benefit to GHG emissions and fuel consumption reductions. The 

duty cycle proposed to quantify the hybrid CO2

Table 3-15

and fuel consumption impact over this broader 

set of operation would be the three primary cycles plus a PTO duty cycle. The proposed 

weighting for the cycle is based on data gathered during the SwRI study. Based on fleet owner 

information, the agencies estimate that the utility trucks are used 20 percent of the time in rural 

operations and 80 percent of the time in urban operations. The SwRI study found that utility 

trucks spent 5.5 percent of the time operating the PTO in rural settings and 34.4 percent of the 

time on in urban settings. This produces an overall percent PTO on time for utility trucks of 28.6 

percent. The study found that the refuse trucks have the PTO on 26.7 percent of the time. The 

agencies weighted each truck type’s percent on time based on 40 percent refuse trucks and 60 

percent utility trucks to establish an overall 28 percent on-time. Therefore, the agencies are 

proposing that the PTO cycle be weighted at 28 percent and weight the other three cycles for the 

remaining 72 percent. The proposed weightings for the hybrids with and without PTO are 

included in .

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3-40

Table 3-15: Proposed Drive Cycle Weightings for Hybrid Vehicles

Transient 55 mph 65 mph PTO

Vocational Vehicles without PTO 42% 21% 37% 0%

Vocational Vehicles with PTO 30% 15% 27% 28%

3.7.2 Engine Dynamometer Evaluation

The engine test procedure we are proposing for hybrid evaluation involves exercising the 

conventional engine and hybrid-engine system based on an engine testing strategy. The basis for 

the system control volume, which serves to determine the valid test article, will need to be the 

most accurate representation of real world functionality. An engine test methodology would be 

considered valid to the extent the test is performed on a test article that does not mischaracterize 

criteria pollutant performance or actual system performance. Energy inputs should not be based 

on simulation data which is not an accurate reflection of actual real world operation. It is clearly 

important to be sure credits are generated based on known physical systems. This includes 

testing using recovered vehicle kinetic energy. Additionally, the duty cycle over which this 

engine-hybrid system will be exercised must reflect the use of the application, while not 

promoting a proliferation of duty cycles which prevent a standardized basis for comparing hybrid 

system performance. The agencies are proposing the use of the Heavy-Duty Engine FTP cycle 

for evaluation of hybrid vehicles, which is the same test cycle proposed for engines used in 

vocational vehicles. It is important that introduction of clean technology be incentivized without 

compromising the program intent of real world improvements in GHG and fuel consumption 

performance.

Pre-transmission power-pack testing would involve the power system components 

included in the engine test cell up to the transmission (pre-gearbox) as the valid test article. The 

engine power would serve as the basis for assessing brake specific emissions performance for 

criteria pollutants as the agencies are not proposing changes to the criteria pollutant standards. 

For GHG pollutant performance, the entire power system pre-gearbox can serve as the basis for 

the brake-specific emissions performance as seen in 

Pre-Transmission Power-Pack Testing

Figure 3-4 Pre-Transmission Parallel 

Hybrid Power Pack Test Configuration. Testing using this method, as described previously, 

could utilize existing engine certification duty cycles. The applicability to the broader set of 

applications could be based largely on the approach taken with today’s engine certification. 

Changes to how the engine certification would be conducted to address energy capture and idle 

operation will need to be evaluated as a complete protocol is developed. In conducting hybrid 

testing it is important for the RESS to have a state of charge at the end of the certification test to 

have a net change in the state of charge of less than 1%. It has been suggested to the agencies 

that energy capture for pre-transmission, parallel hybrid, power-pack testing could be based on 

one of the following three approaches: allow capture up to capability of system, place upper 

limit on energy captured over cycle based on available brake energy in real world cycles, or 

calculate second-by-second available regeneration torque based on FTP31

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. 

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3-41

Figure 3-4 Pre-Transmission Parallel Hybrid Power Pack Test Configuration

 

 Source: Cummins Incorporated’s White Paper: Regulation of emissions from commercial hybrid vehicles, August 9, 2010

Post-transmission power-pack testing would involve the power system components 

included in the engine test cell up to and including the transmission (potentially still pre-gearbox) 

as the valid test article. The inclusion of the transmission in the hybrid system for certification 

potentially introduced a new entity to the certification and a new aspect to of test article control. 

With the additional components, the traditional FTP is not viable, in its current form for 

exercising a more complete powertrain. A vehicle-like duty cycle which provides the 

appropriate speeds and torques to more appropriately match field operation would be needed. 

The test article anticipated for this configuration, would more closely match complete hardware 

in the loop evaluation methods contemplated in other testing regimes. The ability to obtain 

actual performance results versus simulations of actual results in a test environment largely 

center on evaluating components with native intelligence rather than simulating their control 

system.

Post-Transmission Power-Pack Testing
Draft Regulatory Impact Analysis 

3-42

Figure 3-5 Hardware-in-the-Loop Post-Transmission Powerpack Test Configuration

Source: Eaton Presentation to EPA, September 15, 2010

3.8 HD Pickup Truck and Van Chassis Test Procedure

The agencies are proposing that HD pickup trucks and vans demonstrate compliance 

using a chassis test procedure. For each test vehicle from a family required to comply with the 

proposed GHG and fuel consumption requirements, the manufacturer would supply 

representative road load forces for the vehicle at speeds between 15 km/hr (9.3 mph) and 115 

km/hr (71.5 mph). The road load force would represent vehicle operation on a smooth level road, 

during calm winds, with no precipitation, at an ambient temperature of 20 [deg]C (68 [deg]F), 

and atmospheric pressure of 98.21 kPa. Road load force for low speed may be extrapolated. 

The dynamometer's power absorption would be set for each vehicle's emission test 

sequence such that the force imposed during dynamometer operation matches actual road load 

force at all speeds. Required test dynamometer inertia weight class selections are determined by 

the test vehicle test weight basis and corresponding equivalent weight.

3.8.1 LHD UDDS and HWFE Testing

The UDDS dynamometer run consists of two tests, a “cold” start test after a minimum 

12-hour and a maximum 36-hour soak according to the provisions of Sec. Sec. 86.132 and 

86.133, and a “hot” start test following the “cold” start by 10 minutes. Engine startup (with all 

accessories turned off), operation over the UDDS, and engine shutdown constitutes a complete 

cold start test. Engine startup and operation over the first 505 seconds of the driving schedule 

complete the hot start test. The driving schedule for the EPA Urban Dynamometer Driving 

Schedule is contained in Appendix I of 40 CFR part 86. The driving schedule is defined by a 

smooth trace drawn through the specified speed vs. time relationship. The schedule consists of a 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

3-43

distinct non-repetitive series of idle, acceleration, cruise, and deceleration modes of various time 

sequences and rates.

The Highway Fuel Economy Dynamometer Procedure (HFET) consists of 

preconditioning highway driving sequence and a measured highway driving sequence. The 

HFET is designated to simulate non-metropolitan driving with an average speed of 48.6 mph and 

a maximum speed of 60 mph. The cycle is 10.2 miles long with 0.2 stop per mile and consists of 

warmed-up vehicle operation on a chassis dynamometer through a specified driving cycle. The 

Highway Fuel Economy Driving Schedule is set forth in Appendix I of 40 CFR Part 600. The 

driving schedule is defined by a smooth trace drawn through the specified speed versus time 

relationships.

Practice runs over the prescribed driving schedules may be performed at test point, 

provided an emission sample is not taken, for the purpose of finding the appropriate throttle 

action to maintain the proper speed-time relationship, or to permit sampling system adjustment. 

Both smoothing of speed variations and excessive accelerator pedal perturbations are to be 

avoided. The driver should attempt to follow the target schedule as closely as possible. The 

speed tolerance at any given time on the dynamometer driving schedules specified in Appendix I 

of parts 40 and 600 is defined by upper and lower limits. The upper limit is 2 mph higher than 

the highest point on trace within 1 second of the given time. The lower limit is 2 mph lower than 

the lowest point on the trace within 1 second of the given time. Speed variations greater than the 

tolerances (such as may occur during gear changes) are acceptable provided they occur for less 

than 2 seconds on any occasion. Speeds lower than those prescribed are acceptable provided the 

vehicle is operated at maximum available power during such occurrences.

3.8.2 LHD UDDS and HWFE Hybrid Testing

Since LHD chassis certified vehicles share test schedules and test equipment with much 

of Light-Duty Vehicle testing, EPA believes it is appropriate to reference SAE J1711

“Recommended Practice for Measuring the Exhaust Emissions and Fuel Economy of HybridElectric Vehicles, Including Plug-in Hybrid Vehicles” instead of SAEJ2711 “Recommended 

Practice for Measuring Fuel Economy and Emissions of Hybrid-Electric and Conventional 

Heavy-Duty Vehicles”.

3.8.2.1 Charge Depleting Operation – FTP or “City” Test and HFET or “Highway” 

Test

The EPA would like comment on incorporating by reference SAE J1711 chapters 3 and 

4, as published June 2010, testing procedures for Light-Heavy-Duty chassis certified vehicles 

with the following exceptions and clarifications:

Test cycles will continue until the end of the phase in which charge sustain operation is 

confirmed. Charge sustain operation is confirmed when one or more phases or cycles satisfy the 

Net Energy Change requirements below. Optionally, a manufacturer may terminate charge 

deplete testing before charge sustain operation is confirmed provided that the Rechargeable 

Energy Storage System (RESS) has a higher State of Charge (SOC) at charge deplete testing 

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3-44

termination than in charge sustain operation. In the case of Plug In Hybrid Electric Vehicles 

(PHEV) with an all electric range, engine start time will be recorded but the test does not 

necessarily terminate with engine start. PHEVs with all electric operation follow the same test 

termination criteria as blended mode PHEVs. Testing can only be terminated at the end of a test 

cycle. The Administrator may approve alternate end of test criteria.

For the purposes of charge depleting CO2

End of test recharging procedure is intended to return the RESS to a full charge 

equivalent to pre test conditions. The recharge AC watt hours must be recorded throughout the 

charge time and soak time. Vehicle soak conditions must not be violated. The AC watt hours 

must include the charger efficiency. The measured AC watt hours are intended to reflect all 

applicable electricity consumption including charger losses, battery and vehicle conditioning 

during the recharge and soak, and the electricity consumption during the drive cycles.

and fuel efficiency testing, manufacturers may 

elect to report one measurement per phase (one bag per UDDS). Exhaust emissions need not be 

reported or measured in phases the engine does not operate.

Net Energy Change Tolerance (NEC), is to be applied to the RESS to confirm charge 

sustaining operation. The EPA intends to adopt the 1% of fuel energy NEC state of charge 

criteria as expressed in SAE J1711. The Administrator may approve alternate NEC tolerances 

and state of charge correction factors.

3.8.2.2 Hybrid Charge Sustaining Operation – FTP or “City” Test and HFET or 

“Highway” Test

The EPA proposes to incorporate by reference SAE J1711 chapters 3 and 4 for 

definitions and test procedures, respectively, where appropriate, with the following exceptions 

and clarifications. 

The EPA proposes to adopt the 1% of fuel energy NEC state of charge criteria as 

expressed in SAEJ1711. The Administrator may approve alternate NEC tolerances and state of 

charge correction factors.

Preconditioning special procedures are optional for traditional “warm” test cycles that are 

now required to test starting at full RESS charge due to charge depleting range testing. If the 

vehicle is equipped with a charge sustain switch, the preconditioning cycle may be conducted per 

600.111 provided that the RESS is not charged. Exhaust emissions are not taken in 

preconditioning drives. Alternate vehicle warm up strategies may be approved by the 

Administrator. 

State of Charge tolerance correction factors may be approved by the Administrator. RESS 

state of charge tolerances beyond the 1% of fuel energy may be approved by the Administrator.

The EPA is seeking comment on modifying the minimum and maximum allowable test 

vehicle accumulated mileage for both EVs and PHEVs. Due to the nature of PHEV and EV 

operation, testing may require many more vehicle miles than conventional vehicles. 

Furthermore, EVs and PHEVs either do not have engines or may use the engine for only a 

fraction of the miles driven.

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3-45

Electric Vehicles and PHEVs are to be recharged using the supplied manufacturer 

method provided that the methods are available to consumers. This method could include the 

electricity service requirements such as service amperage, voltage, and phase. Manufacturers 

may employ the use of voltage regulators in order to reduce test to test variability with prior 

Administrator approval.
Draft Regulatory Impact Analysis 

3-46

2 Coordinating Research Council, Inc. Phase 1 of the Advanced Collaborative Emissions Study. June 2009.

References

3 Fiest, M., C. Sharp, R. Mason, J. Buckingham. Determination of PEMS Measurement Allowances for Gaseous 

Emissions Regulated Under the Heavy-Duty Diesel Engine In-Use Testing Program.2007. Table 122 and 123.

4 § 86.004-28

5 U.S. EPA. Truck and Trailer Roof Height Match Analysis Memorandum from Amy Kopin to the Docket, August 

9, 2010. Docket Identification Number EPA-HQ-OAR-2010-0162-0045. 

6 SAE Recommended Practice 1263, Road Load Measurement and Dynamometer Simulation Using Coastdown 

Techniques, January 2009

7 SAE Recommended Practice J2263. Road Load Measurement Using Onboard Anemometry and Coastdown 

Techniques. December 2008.

8 “Heavy-Duty Coastdown Test Procedure Development,” Docket Number EPA-HQ-OAR-2010-0162-0144.

9 "Lecture Notes in Applied and Computational Mechanics, The Aerodynamics of Heavy Vehicles II: Trucks, 

Buses, and Trains; DOI: 10.1007/978-3-540-85070-0_33; “Applicability of Commercial CFD tools for assessment

of heavy vehicle aerodynamic characteristics” as created by the University of Chicago as Operator of Argonne 

National Laboratory (“Argonne”) under contract No. W-31-109-ENG-38 with the U.S. Department of Energy."

10 For more information, see CFR Title 40, Part 86.129-00 (e)(1).

11 2010 NAS Report. Finding 2-4 on page 39.

12 SAE International, 2006, Rolling Resistance measurement Procedure for Passenger Car, Light Truck, and 

Highway Truck and Bus Tires, SAE J1269, 2006-09

13 ISO, 2009, Passenger Car, Truck, and Bus Tyres – Methods of Measuring Rolling Resistance – Single Point Test 

and Correlation of Measurement Results: ISO 28580:2009(E), First Edition, 2009-07-01

14 NHTSA, 2009. “NHTSA Tire Fuel Efficiency Consumer Information Program Development: Phase 1 –

Evaluation of Laboratory Test Protocols.” DOT HS 811 119. June. (www.regulations.gov, Docket ID: NHTSA2008-0121-0019).

15 SAE International, 1999, Stepwise Coastdown Methodology for Measuring Tire Rolling Resistance,. SAE J2452, 

1999-06

16 ISO, 2005, Passenger Car, Truck, Bus, and Motorcycle Tyres – Methods of Measuring Rolling Resistance, ISO 

18164:2005(E)

17 Based on MOVES analysis.

18 University of California Riverside. Analysis of Heavy Duty Diesel Truck Activity and Emissions Data. 2006.

19 Gaines, L. “Estimation of Fuel Use by Idling Commercial Trucks”, Paper 06-2567. 2006.

20 Franzese, O., H. Knee, L. Slezak. Effect of Tires on Class-8 Heavy Truck Fuel Efficiency. July 2009. Last 

viewed on May 1, 2010 at http://info.ornl.gov/sites/publications/files/Pub20686.pdf

21 U.S. Department of Energy. “Transportation Energy Data Book. Edition 28 – 2009. Table 5.11. Last viewed on 

Mary 1, 2010 at http://cta.ornl.gov/data/tedb28/Edition28_Chapter05.pdf

22 Environmental Defense Fund. “Greenhouse Gas Management for Medium-Duty Truck Fleets.” Viewed at 

http://edf.org/documents/10860_fleets-med-ghg-management.pdf. Page 6.

23 ICF International. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for Heavy-Duty 

On-Road Vehicles. July 2010. Pages 4-16. Docket Identification Number EPA-HQ-OAR-2010-0162-0044.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Test Procedures

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24 M.J. Bradley & Associates. Setting the Stage for Regulation of Heavy-Duty Vehicle Fuel Economy and GHG 

Emissions: Issues and Opportunities. February 2009. Page 35. Analysis based on 1992 Truck Inventory and Use 

Survey data, where the survey data allowed developing the distribution of loads instead of merely the average loads.

25 The U.S. Federal Highway Administration. Development of Truck Payload Equivalent Factor. Table 11. Last 

viewed on March 9, 2010 at 

http://ops.fhwa.dot.gov/freight/freight_analysis/faf/faf2_reports/reports9/s510_11_12_tables.htm

26 Excerpted from The U.S. Federal Highway Administration. Development of Truck Payload Equivalent Factor. 

Table 11. Last viewed on March 9, 2010 at 

http://ops.fhwa.dot.gov/freight/freight_analysis/faf/faf2_reports/reports9/s510_11_12_tables.htm

27 The U.S. Federal Highway Administration. Development of Truck Payload Equivalent Factor. Table 11. Last 

viewed on March 9, 2010 at 

http://ops.fhwa.dot.gov/freight/freight_analysis/faf/faf2_reports/reports9/s510_11_12_tables.htm

28 U.S. Environmental Protection Agency, SmartWay Fuel Efficiency Test Protocol for Medium and Heavy Duty 

Vehicles – Working Draft, EPA420-P-07-003, November 2007, 

http://www.epa.gov/smartway/transport/documents/tech/420p07003.pdf, site accessed September 16, 2009.

30 SAE Recommended Practice for Measuring Fuel Economy and Emissions of Hybrid Electric and Heavy-Duty 

Vehicles, September 1, 2002

31 Cummins Incorporated, Regulation of Emissions from Commercial Hybrid Vehicles, August 2010
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-1

CHAPTER 4: VEHICLE SIMULATION MODEL.......................................... 4-2

4.1 Purpose and Scope ........................................................................................................... 4-2

4.1.1 Methods to Assess a Truck’s Greenhouse Gas Emissions.................................. 4-2

4.1.2 Proposal to Use Simulation Model to Certify Vocational Trucks and 

Combination Tractors .......................................................................................................... 4-2

4.1.3 Chapter Overview.................................................................................................. 4-2

4.2 Model Code Description .................................................................................................. 4-3

4.2.1 Engineering Foundations of Model...................................................................... 4-3

4.2.2 Vehicle Model Architecture .................................................................................. 4-3

4.2.3 Capability, Features, and Computer Resources ................................................. 4-5

4.3 Feasibility of Using a Model to Simulate Testing.......................................................... 4-5

4.3.1 Procedure for Model Validation........................................................................... 4-5

4.3.2 Validation of EPA and NHTSA Vehicle Compliance Model............................. 4-6

4.4 EPA and NHTSA Vehicle Compliance Model............................................................... 4-8

4.4.1 Vehicle Model for 2014 MY Time Frame ............................................................ 4-8

4.4.2 Standardized Model with Same Default Input Parameters for Each Truck 

Subcategory ......................................................................................................................... 4-10

4.4.3 List of Required Truck-Specific Input Parameters for Class 7/8 Combination 

Tractor Models.................................................................................................................... 4-10

4.4.4 List of Required Truck-Specific Input Parameters for Class 2b-8 Vocational 

Vehicle Models..................................................................................................................... 4-11

4.4.5 List of Default Input Parameters for Class 7/8 Combination Truck Models. 4-11

4.4.6 List of Default Input Parameters for Class 2b-8 Vocational Vehicle Models 4-16

4.5 Application of Model for Certification......................................................................... 4-19

4.5.1 Class 7/8 Combination Tractors – Use One of Seven Applicable Combination

Truck Models....................................................................................................................... 4-19

4.5.2 Class 2b-8 Vocational Vehicles – Use One of Three Applicable Vocational

Truck Models....................................................................................................................... 4-21

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Draft Regulatory Impact Analysis 

4-2

Chapter 4: Vehicle Simulation Model

4.1 Purpose and Scope 

4.1.1 Methods to Assess a Truck’s Greenhouse Gas Emissions

An important aspect of a regulatory program is to determine the environmental benefits 

of heavy-duty truck technologies through testing and analysis. There are several methods 

available today to assess greenhouse gas emissions from trucks. Truck fleets today often use 

SAE J1321 test procedures to evaluate criteria pollutant emissions changes based on paired truck 

testing.1 Light-duty trucks are assessed using chassis dynamometer test procedures.2 Heavyduty engines are evaluated with engine dynamometer test procedures.3

4.1.2 Proposal to Use Simulation Model to Certify Vocational Trucks and 

Combination Tractors

 Most large truck 

manufacturers employ various computer simulation methods to estimate truck efficiency. Each 

method has advantages and disadvantages. This section will focus on the use of truck simulation 

modeling for assessing tailpipe GHG emissions and fuel consumption. 

The agencies are proposing to use a simulation model as the primary tool to certify 

vocational and combination tractor heavy-duty vehicles (Class 2b through Class 8 heavy-duty, 

vehicles that are not heavy-duty pickups or vans). The advantages of modeling for these vehicles 

include:

• The simulation tool can model a wide range of vehicle types. 

• The vehicle components can be easily changed to match the features of a given 

vehicle. 

• The entire configuration of the vehicle can also be changed, so the same program 

can model a Class 4 pickup and delivery truck and a Class 7 or 8 combination 

truck with appropriate input parameter changes. This allows the agencies to use 

the same program to develop and certify all of the heavy-duty vehicles. 

• The modeling tool also accommodates different drive cycles. 

• It can significantly reduce truck manufacturer’s burden to conduct heavy-duty 

chassis dynamometer tests.

4.1.3 Chapter Overview

The scope of this chapter will discuss truck simulation models and their feasibility, the 

truck simulation tool, and application of models to develop certification options.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-3

4.2 Model Code Description 

4.2.1 Engineering Foundations of Model

A number of commercially available heavy-duty vehicle simulation tools are based on 

MATLAB/Simulink-based programs that can model a wide variety of vehicles, from mediumduty to Class 8 trucks.

4,5

 Generally, each vehicle component is depicted by a generic Simulink 

model that can be modified using an initialization file.

6

EPA has developed a forward-looking MATLAB/Simulink-based model termed 

Greenhouse gas Emissions Model (GEM) for Class 2b-8 vehicle compliance. GEM uses the 

same physical principles as many other existing vehicle simulation models to derive governing 

equations which describe driveline components, engine, and vehicle. These equations are then

integrated in time to calculate transient speed and torque.

 The user can utilize pre-determined 

initialization files for a given component, or modify them to reflect their particular situation. 

The following section describes the system required to model a heavy-duty non-hybrid truck. 

Once the vehicle has been specified, the user selects a drive cycle (which they can also modify) 

and runs the program. 

4.2.2 Vehicle Model Architecture 

Table 4-1 outlines the Class 2b-8 vehicle compliance model architecture, which is 

comprised of six systems: Ambient, Driver, Electric, Engine, Transmission, and Vehicle. With 

the exception of “Ambient” and “Driver,” each system consists of two to four component 

models. The function of each system and their respective component models, wherever 

applicable, is discussed in this section.

Table 4-1: Vehicle Model Architecture

System Component Models

Ambient none

Driver none

Electric Starter; Electrical Energy System; Alternator; Accessory (electrical)

Engine Cylinder; Accessory (mechanical)

Transmission Clutch; Gearbox

Vehicle Chassis; Final Drive 

Ambient – This system defines ambient conditions such as pressure, temperature, and 

road gradient, where vehicle operations are simulated.

Driver – GEM is a forward-looking driving model. Rather than constantly matching the 

exact drive cycle, the driver model considers the current speed and the desired future speed to try 

to predict the necessary power required to close the gap and follow the driving trace. If the 

driver misses the target, a different power request is sent to the engine and/or brakes are applied. 

This search for the proper vehicle speed occurs at every simulation time step. The feedback loop 

uses a PID controller. 

The “Electric” system consists of four components: Starter, Electrical Energy System, 

Alternator, and Electrical Accessory

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Draft Regulatory Impact Analysis 

4-4

Starter – This models the starter for the engine, which is identical for most vehicles. 

Electrical Energy System – GEM simulates a standard 12 or 24 volt lead-acid battery,

which provides currents to the starter and electrical systems for engine starting, lighting, and 

vehicle controls. This module estimates State-of-Charge (SOC), internal ohmic resistance and

open circuit voltage, voltage and current of electrical energy storage system. 

Alternator – This models the alternator that generates electricity for the battery and 

electrical system. The model calculates voltage and current of the AC alternator based on 

alternator performance maps and charge control strategy.

Electrical Accessory – All vehicles have a number of electrical loads, some of which are 

necessary to operate the vehicle. The engine control unit (ECU), fuel injectors and fuel pump for 

instance are electrical loads that are constantly on the battery, and these are already taken into 

account in the fuel map. 

The “Engine” system consists of two components: Cylinder and Mechanical Accessory

Cylinder – The cylinder model is based on a fuel map and torque curves at wide open 

throttle (full load) and closed throttle (no load). The engine fuel map features three sets of data: 

engine speed, torque, and fueling rate at pre-specified engine speed and torque intervals. It is not 

a physics-based model and does not attempt to model in-cylinder combustion process. The 

engine torque and speed are used to select a fuel rate based on the fuel map. This map is 

adjusted automatically by taking into account three different driving types: acceleration, braking, 

and coasting. The fuel map, torque curves, and the different driving types are pre-programmed 

into GEM for several different default engines. 

Mechanical Accessory – Most vehicles run a number of accessories that are driven via

mechanical power from the engine. Some of these accessories are necessary for the vehicle to 

run, like the coolant pump, while others are only used occasionally and at the operator’s 

discretion such as the air conditioning compressor. Some heavy-duty vehicles also use Power 

Take Off (PTO) to operate auxiliary equipment, like booms, and these would also be modeled as 

a mechanical accessory. 

The manual “Transmission” system consists of two components: a Clutch and a Gearbox

Clutch – This component model simulates the clutch for a manual transmission. 

Gearbox – A simple gearbox model is used for a manual transmission, and the number of 

gears and gear ratios is predefined in GEM. This component model consists of a map using

gearbox speed and torque as inputs to model the efficiency of each gear. 

The “Vehicle” system consists of two components: Chassis and Final Drive

Chassis – This portion models the shell of the vehicle including the tires. The drag 

coefficient, mass of the vehicle, frontal area and other parameters are housed in this component. 

For tire simulation, the user specifies the configuration of each axle on the vehicle, including the 

tire diameter and the rolling resistance.

Deleted: [TEST]

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curve, the model uses a generic curve calculated 

from parameters such as engine displacement. 

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a Torque Converter and a Gearbox

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transmission. Maps using engine output speed and 

torque as inputs are employed to model the 

efficiency of the torque converter

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-5

Final Drive – The gear ratio for the differential can be specified directly by the user. The 

efficiency is defined by a map based on the transmission output speed and torque. 

4.2.3 Capability, Features, and Computer Resources

The EPA/NHTSA vehicle compliance tool is a flexible simulation platform that can 

model a wide variety of vehicles from Class 2b to Class 8 trucks. The key to this flexibility is 

the MATLAB component files that can be modified or adjusted to accommodate vehicle-specific 

information. Parameters such as vehicle weight, fuel map settings, and tire radius, for instance,

can all be changed in this fashion. However, since the proposed rule specifies applicable drive 

cycles (the Transient mode, as defined by ARB in the HHDDT cycle, a constant speed cycle at 

65 mph and a 55 mph constant speed mode), manufacturers cannot select alternative drive cycles

(although the model is capable of incorporating other drive cycles should the agencies decide 

after considering public comment that additional or different drive cycles are necessary). 

Similarly, manufacturers cannot alter any default settings which are established by the agencies. 

After running the simulation, GEM tracks information about each component and about 

the system as a whole. Information like CO2

The system requirements for the MATLAB version of GEM include a minimum RAM of 

1 GB, MATLAB, Simulink and Stateflow (version 2009b or later), and approximately 250 MB 

of disk storage.

emissions, fuel consumption, and fidelity to the 

drive cycle are immediately available on the results screen. The output from each run can be

saved as a comma-separated values (CSV) file or an Excel file.

7,8,9

4.3 Feasibility of Using a Model to Simulate Testing 

 The simulation takes between 10 and 20 seconds per drive cycle, depending 

on the cycle duration. No separate license is required to run the program other than for 

MATLAB, Simulink, and Stateflow. Although the source code is available to users, all of the 

component initialization files, control strategies and the underlying 

MATLAB/Simulink/Stateflow-based models should remain fixed and should not be manipulated 

by the users when assessing their compliance. For these reasons, a stand-alone executable model 

independent of MATLAB/Simulink/Stateflow licenses has been created. Only the executable 

can be used when producing official truck certification results. The agencies are proposing that

the manufacturers submit both the input parameters and the modeling results.

4.3.1 Procedure for Model Validation

The agencies have assessed the predictive utility of the GEM model by comparing its 

prediction with actual test data. The agencies plan to continue this effort between proposal and 

final rule, and also plan to continue the supplemental validation effort where GEM predictions 

are compared with those of a widely-used commercial model. Validation is considered 

successful when the differences between the simulation and the test data are within the error 

limits of the test data. Before the model is validated, a quality assurance check for the input data 

needs to be made, which includes the following steps.

• Alignment of data from different sources such as dynamometer, emissions 

benches, portable emissions measurement systems, or engine control units;

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compliance purposes, manufacturers cannot alter any 

default settings or 

Deleted: . Currently, [TEST] carries out vehicle 

simulation over three drive cycles: transient, 55 mph 

and 65 mph steady-state cycles, but

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good faith

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validated to actual test data to assure accuracy.
Draft Regulatory Impact Analysis 

4-6

• Ensuring that the vehicle and engine powertrain parameters, such as vehicle 

weight, transmission, driveline, tire, and inertia for various rotational parts etc.,

represent the actual vehicle being modeled;

• Selection of the proper sensor when the same parameter is recorded by different 

sources and calibration of the sensors to the same reference value;

• Quantification of the uncertainty of each sensor.

After the operating conditions of the vehicle components have been successfully 

reproduced by the model, the final results of the vehicle simulation are compared with results of 

a representative vehicle test. If the difference is within the test error, the model can be 

considered validated and can be used for vehicle simulations.

In the past two years, the agencies have been striving to gather as much test data as 

possible from vocational trucks and combination tractors. Although it would be optimal if the 

primary source of data for validating the GEM simulation tool comes from chassis dynamometer 

testing or real world driving of these vehicles, the process involved in data acquisition for the

wide ranging heavy-duty vocational truck and combination tractor categories, which includes 

vehicle identification, procurement, coastdowns for generating dynamometer coefficients, 

emissions sampling, etc., has necessarily been tedious and time-consuming.10,11 Although the 

agencies are endeavoring to obtain test data for all categories of vocational trucks and 

combination tractors, the agencies are also using additional approaches to make as robust a 

validation effort as possible. One of these additional approaches is to compare GEM results with 

those of another well known industrial-standard simulation model. The agencies have selected

the GT-Drive model developed by Gamma Technologies for this purpose.12

4.3.2 Validation of EPA and NHTSA Vehicle Compliance Model

At this point, the agencies have GHG and fuel consumption test data from a high-roof 

Class 8 sleeper combination tractor, designated as “555” that was run on the drive cycles 

proposed for certification, i.e., transient cycle and steady-state cycles with 65 and 55 mph cruise 

speeds. The testing was conducted for EPA by Southwest Research Institute (SwRI) in which 

emissions, fuel consumption, and engine operating parameters were measured in a heavy-duty 

chassis dynamometer test cell.

13

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 The Class 8 combination tractor is a 2008 International Prostar 

equipped with a 2007 Cummins ISX engine, and this tractor was chassis tested using 

dynamometer set coefficients derived from onroad coastdown testing results obtained by SwRI 

on this same tractor combined with a 53 feet long box trailer, thus the resulting data reflect a 

high-roof sleeper tractor combined with a box trailer configuration. Table 4-2 provides further 

details on the combination tractor and the engine which were tested at SwRI and the parameters 

which were modeled in both GEM and GT-Drive.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-7

Table 4-2: Truck 555 Tractor and Engine Specifications

Tractor / Model International Prostar 

Year Model 2008

Type High Roof Sleeper 

Engine OEM Cummins ISX 

Engine Family 7CEXHO912XAK 

Displacement 15 liters 

Horsepower Rating 408 @ 1,800 RPM 

Final Drive 2.64

Transmission Model Fuller FR15210B 

Transmission Type 10 speed manual 

Steer Axle Tires Michelin XZA3 

Tire Size 275 / 80 / 22.5 

Front Rims / make Accuride DOT T 

Drive Axle Tires Michelin XDA Energy 

Tire Size 275 / 80 / 22.5 

Drive Rims / Make Accuride DOT T

Table 4-3 compares the chassis test data with results from GEM obtained using the 

methodology proposed.

13

Table 4-3: Fuel Economy (mpg) Comparison between Test Data and GEM Simulation Results

 As shown in Table 4-3, reasonably good comparisons are obtained. 

The predicted results are within the same range of variability as run-to-run variability exhibited 

in chassis dynamometer testing (± 5 percent for Truck Number 555; see DRIA section 3.6).

Cycles ProStar @ SwRI 

(Chassis Test ) GEM Difference

Transient 3.51 3.51 0.0%

65 mph 6.98 6.82 2.3%

55 mph 8.35 8.05 3.6%

The agencies also compared the results from GEM with the results obtained from 

modeling the same tractor configuration using GT-Drive. As shown in Table 4-4, a very good 

agreement between these two models is obtained. This comparison essentially demonstrates that 

both models produce very similar or even identical results. The agencies thus regard comparison 

of GEM results and GT-Drive results as a useful supplement to direct validation efforts. It 

should be noted, however, that the GT-Drive model is not suitable for regulatory purposes since 

(among other things) its code is proprietary so that the necessary degree of public transparency is 

not possible. 

Table 4-4: Fuel Economy (mpg) Comparison between GT-Drive and GEM Simulation Results

Cycles GT-Drive GEM Difference

Transient 3.51 3.51 0.0%

65 mph 6.82 6.82 0.0%

55 mph 8.13 8.05 1.0%

The agencies thus view the results from the two comparisons as a (admittedly still partial) 

validation of the GEM simulation tool.
Draft Regulatory Impact Analysis 

4-8

4.4 EPA and NHTSA Vehicle Compliance Model

Although several existing heavy-duty vehicle simulation models are widely accepted by 

the research community and industry, one drawback is that their codes are not designed for the 

proposed regulatory program. For heavy-duty vehicles to be manufactured beginning in the 

2014 MY timeframe, the proposed compliance approach is done through simulation based on a 

few user input parameters, including rolling resistance, aerodynamic drag coefficient, and 

vehicle weight. The comprehensive input structures of many commercially available models are 

more complicated than necessary for purposes of the proposed rule and may present an 

unnecessarily steep learning curve to the users. Therefore, EPA and NHTSA have sought to 

develop a forward-looking, compliance-focused vehicle model internally which includes only 

those technical features required for compliance purposes. The model structure and input are 

straightforward. The proposed model has not yet been peer reviewed but is expected to be 

before any final rule is issued. The following section describes this proposed compliance model

which is to undergo a peer review process in the coming months. 

4.4.1 Vehicle Model for 2014 MY Time Frame

After the agencies established the list of required input parameters from vehicle 

manufacturers for tractor and vocational truck certification, EPA proceeded with the 

development of a heavy-duty truck simulation package which produces GHG output comparable 

to many sophisticated forward-looking models, but eliminates the multitude of features that are 

needed for research and development, but that are overly complicated and not required for 

certification purposes.

Certification-geared truck models have been created in MATLAB/Simulink environment 

for vehicles with both manual and automatic transmissions. MATLAB scripts are also created, 

which control pre- and post-processing of truck simulations. The function of the MATLAB preprocessing scripts is to gather all the necessary component model parameters, including agencydefined fuel maps as well as manufacturer inputs (e.g., Cd, Crr, etc.). Once all the parameters 

are downloaded into the MATLAB workspace, the MATLAB/Simulink/Stateflow model is run 

to generate GHG emissions and fuel consumption for each of the three drive cycles after which 

the post-processing MATLAB scripts perform the calculation of individual cycle and cycle 

weighted fuel economy, fuel consumption and CO2 emissions as per the EPA/NHTSA

regulatory scheme in mile/gallon, gallon/ton-mile, gram CO2

Deleted: -2017

/ton-mile and generate graphs 

displaying how the certifying vehicle follows the three drive cycle simulations. Based on the 

general truck usage pattern, EPA and NHTSA have defined three sets of cycle weighting factors 

for use in the twelve regulatory classes or ten model categories. Table 4-5 shows that these 

weightings are specific to sleeper cab (long distance, typically >500 miles cruising), day cab

(<~100 miles cruising), and vocational trucks (stop and go operation).

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-9

Table 4-5: Drive Cycle Weightings

DRIVE CYCLES & 

WEIGHTINGS: SLEEPER CAB DAY CAB VOCATIONAL TRUCK

Transient 5% 19% 42%

55 mph Cruise 9% 17% 21%

65 mph Cruise 86% 64% 37%

Linking the pre- and post-processing functions to the MATLAB/Simulink/Stateflowbased vehicle compliance model, a MATLAB-based Graphical User Interface (GUI) has also 

been constructed. This GUI allows the user to select truck type, input required parameters and 

look up the MATLAB/Simulink/Stateflow source models and script files. However, to ensure 

the compliance model is not inadvertently modified during truck certification, EPA also 

compiled a C-code based model and subsequently generated a stand-alone GUI-based executable 

code which can be run with no MATLAB/Simulink/Stateflow licensing requirement. Upon 

providing all the information requested by this C-code based model and stand-alone GUI, the 

manufacturer then clicks “RUN” after which all their selections and entries are fed into the 

EPA/NHTSA compliance model without the user ever directly interacting with the underlying 

model source codes, built-in parameters, engine maps, etc. Figure 4-1 shows the GUI with ten 

model categories. It is flexible and easy to use for certification of heavy-duty vehicles in any of 

the twelve regulatory classes.

Figure 4-1: Graphical User Interface (GUI)

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Draft Regulatory Impact Analysis 

4-10

4.4.2 Standardized Model with Same Default Input Parameters for Each Truck 

Subcategory

With respect to combination tractors, as discussed in Chapter 2 of this DRIA, EPA and 

NHTSA have identified many possible technologies which can achieve GHG emissions and fuel 

consumption benefits for Class 7/8 combination tractors. However, as noted in the preamble to 

the proposed rule, some technologies may not be suited for some combination trucks’ usage 

patterns. Others may be too complex to model. For example, it may be difficult to accurately 

model those improvements which are based on each manufacturer’s proprietary control 

strategies. In developing a certification regime for the MY 2014-2017 period using GEM, EPA

and NHTSA are proposing three input parameters plus up to three adjustments to be used in the 

combination truck simulation models (see section 4.5.1). Potential improvements which are not 

proposed as part of the GEM model may be evaluated as a potential off-cycle credit opportunity.

For Class 2b to Class 8 vocational vehicles, the myriad vehicle types on the road today 

make it challenging to group them into manageable categories for compliance purposes. For 

reasons explained in Sections II and III of the preamble to the proposed rule, the agencies are 

proposing standards which reflect use of improved tire rolling resistance, along with improved 

engine performance. The only input to GEM would be tire rolling resistance (see section 4.4.4

below). Most of these trucks operate predominantly in an urban setting with transient (stop-andgo) rather than steady state operation. Improvements in vocational vehicle aerodynamic features 

are likely to generate little GHG emissions and fuel consumption benefits compared to those for 

combination tractors whose operation are often at high and continuous cruising speeds. On the 

other hand, advanced technologies such as hybrid systems are likely to result in greater fuel 

economy benefits for these vocational truck classes as these technologies have been shown to 

improve fuel efficiency for stop and go operations.

15

4.4.3 List of Required Truck-Specific Input Parameters for Class 7/8

Combination Tractor Models

 Therefore, the agencies’ proposed rule 

seeks to encourage the production of hybrid systems for these vocational vehicles by means of 

credit opportunities, where vehicle performance for GHG emissions and fuel consumption would 

be assessed using test procedures outlined in Chapter 3 of this DRIA. For non-hybrid 

conventional vocational trucks, EPA and NHTSA have grouped vocational trucks into three 

separate classes based on their shared attributes: light-heavy (LH), medium-heavy (MH), and 

heavy-heavy (HH), reflecting Classes 2b, 3, 4, or 5, Classes 6 or 7, and Class 8, respectively.

The Class 7/8 combination tractor models developed by the agencies assume each Class 

7/8 tractor is combined with a specific type of trailer that best matches the certifying tractor roof 

height. Combination tractors belonging to any of the nine regulatory classes are to be certified 

under seven model categories, i.e., two Class 7 day cab, three Class 8 sleeper cab, and two Class 

8 day cab truck models. Manufacturers are required to provide EPA and NHTSA with the 

following input parameters for certification: 

1. Aerodynamic drag coefficient (Cd) per the assigned aerodynamic bin

2. Steer tire rolling resistance coefficient (Crr, steer tires)

Deleted: Class

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nine distinct regulatory classes.

Deleted: create detrimental effects due to their

Deleted: pattern and some

Deleted: Therefore

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technologies based on their GHG emissions and fuel 

consumption reduction potential or modeling 

complexity for the 2014-17 timeframe and is

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Deleted: .

Deleted: diesel

Deleted: Thus, for the 2014-17 timeframe, the 

vocational truck models follow a similar path as 

combination truck models, but with a limited set of 

technologies, i.e., two input parameters.

Deleted: Truck

Deleted: truck
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-11

3. Drive tire rolling resistance coefficient (Crr, drive tires)

4. Weight reductions through lower weight wheels and tires

5. Governed vehicle speed, if less than 65 mph

6. Idle reduction technology, if any, for Class 8 sleeper tractors only

The manufacturers would be required to conduct appropriate testing to develop these 

inputs using the procedures described in Chapter 3 and Preamble Section 2 for Cd and Crr for 

both steer and drive tires. 

4.4.4 List of Required Truck-Specific Input Parameters for Class 2b-8 

Vocational Vehicle Models

For Class 2b to 8 vocational vehicles, the manufacturers would be required to provide

EPA and NHTSA with the same set of parameters as those required for combination tractors

except items #1, # 4, #5 and #6 for certification. Items #2 and #3 are required for certification. 

(As noted in section 4.4.6, the agencies also plan to use predefined, standardized Cd for the three 

vocational truck types (Vocational Light-Heavy (VLH), Vocational Medium-Heavy (VMH), and 

Vocational Heavy-Heavy (VHH).)

4.4.5 List of Default Input Parameters for Class 7/8 Combination Truck Models

Though many technologies can potentially achieve GHG emission and fuel consumption 

reductions, EPA and NHTSA realize that for the proposed timeframe, some may be too complex 

to model (e.g., hybrid control) while others require standardization. For example, the calculation 

of GHG and fuel consumption benefits due to aerodynamic improvements is coupled with truck 

frontal area. To better capture the GHG emission and fuel consumption benefits in the 

simulation model as well as to avoid unintended consequences in the real world, the agencies

have identified a set of parameters that are consistent across various manufacturers for this 

rulemaking period and are proposing that these parameters be used as default inputs to the 

model. EPA and NHTSA propose to standardize the truck frontal area, truck total and payload 

weight, gear box and its efficiency, final drive ratio, engine/transmission/wheel inertia, accessory 

load, axle base, tire radius, trailer tire coefficient of rolling resistance (Crr, trailer tires), and 

engine fuel map. The agencies are proposing to use these standardized input parameters in the 

simulation model for all seven model categories of combination trucks. Table 4-6 lists the

specific values of these parameters, which were developed using EPA test data, manufacturer 

supplied information, and/or literature search.

 

10,13

Deleted: manufactures shall

Deleted: per

Deleted: Truck

Deleted: trucks

Deleted: trucks

Deleted: The 

Deleted: models.

Deleted: -

Deleted: .

Deleted: adopting

Deleted: that were developed by EPA, for use 

Deleted: The

Deleted: are listed in Table 4-3.
Draft Regulatory Impact Analysis 

4-12

Table 4-6: Combination Truck Modeling Input Parameters

MODEL TYPE CLASS 8 CLASS 8 CLASS 8 CLASS 8 CLASS 8 CLASS 7 CLASS 7

Regulatory 

Subcategory

Sleeper Cab 

High Roof

Sleeper Cab 

Mid Roof

Sleeper Cab 

Low Roof

Day Cab 

High Roof

Day Cab 

Low/Mid Roof

Day Cab 

High Roof

Day Cab 

Low/Mid Roof

Fuel Map 15L - 455 HP 11L - 350 HP

Gearbox 10 speed 

Manual

10 speed 

Manual

10 speed 

Manual

10 speed 

Manual

10 speed 

Manual

10 speed 

Manual

10 speed 

Manual

Gearbox Ratio 14.8, 10.95, 8.09, 5.97, 4.46, 3.32, 2.45, 1.81, 1.35, 1

11.06, 8.19, 6.05, 4.46, 

3.34, 2.48, 1.83, 1.36, 1, 

0.75

Gearbox 

Efficiency 0.96 0.96 0.96 0.96 0.98 0.98 0.98 0.98 0.98 0.98 0.96 0.96 0.96 0.96 0.98 0.98 0.98 0.98 0.98 0.98

Engine Inertia 

(kg-m2 4.17 ) 4.17 4.17 4.17 4.17 3.36 3.36

Transmission 

Inertia (kg-m2 0.2 ) 0.2 0.2 0.2 0.2 0.2 0.2

All Axle Inertia 

(kg-m2 300 ) 300 300 300 300 240 240

Loaded Tire 

Radius (m) 0.4892 0.4892 0.4892 0.4892 0.4892 0.4892 0.4892

Body Mass (kg) 14742 13041 13154 14061 12474 11340 9752

Cargo Mass (kg) 17236 17236 17236 17236 17236 11340 11340

Total weight (kg) 31978 30277 30391 31298 29710 22680 21092

Total weight (lbs) 70500 66750 67000 69000 65500 50000 46500

Frontal Area (m2) 9.8 7.7 6 9.8 6 9.8 6

Drag Coefficient OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input

Axle Base 5 5 5 5 5 4 4

Electrical 

Accessory Power 

(W)

360 360 360 360 360 360 360

Mechanical 

Accessory Power 

(W)

1000 1000 1000 1000 1000 1000 1000

Final Drive Ratio 2.64 2.64 2.64 2.64 2.64 3.73 3.73

Tire CRR

(kg/ton) = 0.425 × Trailer CRR + 0.425 × Drive CRR + 0.15 × Steer CRR

Trailer Tire CRR

(kg/ton) 6 6 6 6 6 6 6

Steer Tire CRR OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input

Drive Tire CRR OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input

Vehicle Speed 

Limiter OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input OEM Input

Moved (insertion) [1]
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-13

Frontal Area – For Class 8 sleeper cabs, the frontal areas for high-, mid-, and low-roof 

tractors were estimated to be 9.8, 7.7 and 6 square meters, respectively. For either a Class 7 or 

Class 8 day cab, the frontal areas are assumed to be 9.8 and 6 square meters for high- and 

low/mid-roof tractors, respectively. These values were developed from actual frontal area 

measurements conducted for EPA by Automotive Testing and Development Services, Inc. based 

in California.

Truck Weight – It is assumed that the empty weight will vary by cab configuration and a 

standard weight for each category has been developed. For Class 8 trucks, the total weight 

ranges from 65,500 to 70,500 lbs, and for Class 7 trucks, 46,500 to 50,000 lbs. The payload 

capacity is assumed to be 19 and 12.5 tons for Class 8 and Class 7 trucks, respectively. The 

development of the truck weights are discussed in DRIA Chapter 3.5.

10

Gear Box and Efficiency – The typical Class 8 and Class 7 combination tractors have 10 

speed manual transmissions. The respective gear ratios for Class 8 and Class 7 combination 

tractors are: 14.8, 10.95, 8.09, 5.97, 4.46, 3.32, 2.45, 1.81, 1.35, 1 and 11.06, 8.19, 6.05, 4.46, 

3.34, 2.48, 1.83, 1.36, 1, 0.75. The agencies based the gear ratios on the actual tractors tested at 

Southwest Research Institute.13

Final Drive Ratio – As above, a typical configuration is a 10 speed manual transmission 

with a final drive ratio of approximately 2.64 and 3.73 for Class 8 and Class 7 tractors, 

respectively. The agencies based the final drive ratios on the actual tractors tested at Southwest 

Research Institute.

 The same set of efficiencies is utilized for each of these models, 

ranging from 0.96 to 0.98. The efficiencies were based on an engineering judgment of the 

agencies.

Inertia – The agencies are proposing that the engine inertia for Class 7 and Class 8 

tractors are taken to be 3.36 and 4.17 kg-m

13

2

, respectively based on the agencies’ engineering 

judgment. The transmission inertia for all combination tractors is 0.2 kg-m2 and the axle inertia 

for Class 8 and Class 7 tractors are 300 and 240 kg-m2, respectively. The axle inertia values are 

based on agencies’ engineering judgment of the actual rotational inertia measured for a Class 8 

sleeper cab at SwRI.16

Accessory Load – It is assumed that all combination tractors carry an electrical load of 

360 watts and a mechanical load of 1,000 watts.

Axle Base – Typical Class 8 tractors have 1 steer and 2 drive axles, while typical Class 7 

tractors have 1 steer and 1 drive axle. The trailer used for both Class 7 and Class 8 cabs in 

simulation modeling has 2 axles.

Tire Radius – The static loaded tire radius for all combination trucks would be 489 mm 

(or 515 mm, unloaded). The value is based on the actual tires used during the Southwest 

Research Institute testing.

10,13

Trailer Tire Coefficient of Rolling Resistance (Crr, trailer tires) – The agencies assume 

6.0 kg/ton for all trailer tires. This value was developed through the SmartWay tire testing.

13

17

Deleted: 6.6

Deleted: trucks

Deleted: is
Draft Regulatory Impact Analysis 

4-14

Engine Fuel Map – The agencies developed two sets of representative engine maps which 

are to be used by manufacturers for modeling combination and vocational truck GHG emissions

and fuel consumption. The first set would be used for 2014-16 model years and represents 

engines which meet the proposed main 2014 MY engine standard (not the proposed alternative 

standard). The second set would be used by truck manufacturers for 2017 model year and later 

compliance where the fuel maps represent engines which meet the proposed 2017 model year 

engine standard. Each set consists of two separate maps, a 455 hp @ 1800 rpm (15 liter engine) 

and 350 hp @ 1800 rpm (11 liter engine), which would be used for certification of Class 8 and 

Class 7 combination tractors. The process for engine fuel map development is described as 

follows. 

Each of these projected maps is created by merging 2007-2009 model year heavy-duty 

engine data supplied by the heavy-duty manufacturers with those collected at the EPA test site

via engine dynamometer testing, as per 40 CFR Part 1065.

18 The process of map generation is 

iterative and many factors are considered during data aggregation to ensure that the resulting, 

pre-2010 model year engine maps are consistent with those of the respective heavy-duty engine 

ratings sold in today’s market. These pre-2010 maps are subsequently adjusted to represent 2010 

model year engine maps by using predefined technologies including SCR and other advanced 

systems that are being used in current 2010 production. These 2010 engine maps are further 

transformed into 2014 engine maps by considering many potential technologies that could be 

used in the 2014 timeframe. These include, but not limited to, further reductions in parasitic and 

friction losses, more advanced combustion, and progressively higher efficient air/EGR handling 

and aftertreatment systems – the technology package on which the proposed 2014 MY engine 

standards is premised.. Lastly, the 2017 model year fuel maps are developed with a similar 

method used for generating 2014 model year maps, but with more aggressive improvements 

using the technology package on which the proposed MY 2017 standards are premised (i.e. 

addition of turbocompounding to the MY 2014 technology package). Details of the evaluation 

process by which the technologies can reduce engine CO2 emissions or fuel consumption are 

discussed in Chapter 2 of this DRIA. 

A typical engine fuel map consists of three columns – engine speed, torque, and fueling

rate in gram per second. Table 4-7 shows a small subset of a representative engine map in such a

format. Essentially, the fueling rate is a function of engine speeds and loads. Displayed in 

Figure 4-2 is an example of the fueling rate contour as function of engine torque and speed for a

Class 8 combination tractor with 455 hp rating. This map can be further processed to obtain 

other key engine performance information, such as brake specific fuel consumption (BSFC), as 

shown in Figure 4-3.

Deleted: Two

Deleted: have been created

Deleted: .

Deleted: are to

Deleted: judging the feasibility of incorporating 

various improved and/or promising

Deleted: these 2010 engines.

Deleted: using a

Deleted: .

Deleted: ¶

Table 4-3: Combination Truck Modeling Input 

Parameters¶

Moved up [1]: MODEL TYPE

Deleted: Regulatory Class ...

Deleted: 4
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-15

Table 4-7: A Small Subset of Fuel Map Input

SET

MODE

SPEED 

(RPM)

TORQUE 

(NM)

FUEL RATE 

(g/s)

Idle 600 0 0.04

A100 1233 2100 14.77

B50 1514 1040 9.36

B75 1514 1559 13.72

A50 1233 1050 7.43

A75 1233 1575 10.78

A25 1233 525 4.26

B100 1514 2079 18.38

B25 1514 520 5.68

C100 1796 1805 19.71

C25 1796 451 6.94

C75 1796 1354 14.86

C50 1796 903 10.48

2

2

2

2

2

2

4

4

4

4

4

4

6

6

6

6

6

6

8

8

8

8

8

8

10

10

10

10

10

12

12

12

12

14

12

14

14

14

16

16

16

18

18

455 HP / 15 L : 2010 Baseline Fuel Rate (g/s)

Engine Speed (RPM)

Torque (Nm)

600 800 1000 1200 1400 1600 1800 2000

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Figure 4-2: Fueling Rate (g/s) as a Function of Engine Torque and Speed for a Combination Tractor

Deleted: -4:

Formatted Table

Formatted: Font color: Black

Formatted: Indent: First line: 0.5"
Draft Regulatory Impact Analysis 

4-16

191

191

191

191

19

194

194 194

194

194

194

194

1

200

200

200

200

200

200

205

205

205

205

205

205

210

210

210

210

210

210

220

220

220

220

220

250

250

250

25

400

400

400 4

800

800

800

191

191

200

455 HP / 15 L : 2010 Baseline BSFC (g/kW-hr)

Engine Speed (RPM)

Torque (Nm)

600 800 1000 1200 1400 1600 1800 2000

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Figure 4-3: Class 8 Engine BSFC Map

4.4.6 List of Default Input Parameters for Class 2b-8 Vocational Vehicle Models

Likewise, EPA and NHTSA propose to standardize a set of parameters for the three Class

2b-8 vocational vehicle types, which the agencies refer to as Vocational Light-Heavy (VLH), 

Vocational Medium-Heavy (VMH), and Vocational Heavy-Heavy (VHH). These default

parameters include the coefficient of aerodynamic drag, truck frontal area, truck total and 

payload weight, the gear box and its efficiency, final drive ratio, engine/transmission/wheel 

inertia, accessory load, axle base, tire radius, and the engine fuel map. Standardized input 

parameters to be used in the simulation model for all three vocational trucks have been 

developed using a combination of EPA test data, manufacturer supplied information, and/or 

literature search. The specific values of these parameters are listed in Table 4-8.

Coefficient of Aerodynamic Drag (Cd) – A Cd of 0.6 for both VLH and VMH models 

and 0.7 for VHH, is adopted.

Frontal Area – For both VLH and VMH truck models, the frontal area is assumed to be 9 

square meters, and for the VHH model 9.8 square meters based on the agencies’ estimates from 

the combination tractor frontal area measurements.

Truck Weight – The total weight is established at 16,000, 25,150, and 67,000 lbs for 

VLH, VMH, and VHH models and the payload is 2.85, 5.6 and 19 tons, respectively, for VLH, 

VMH and VHH truck models

10

.

20

Deleted: 

191

191

194

200

205 210

220

250

2

400

800

455 HP / 15 L : 

En 

Torque (Nm)

600 800 1000

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Deleted: Truck

Deleted: truck models

Deleted: .

Deleted: 5

Deleted: .

Deleted: 19.
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-17

Gear Box and Efficiency – A 10 speed manual transmission is adopted in the VHH truck 

model with gear ratios at: 14.8, 10.95, 8.09, 5.97, 4.46, 3.32, 2.45, 1.81, 1.35, 1. A six speed 

manual transmission is utilized for both VLH and VMH truck models with respective gear ratios

of: 9.01, 5.27, 3.22, 2.04, 1.36, 1. Gear efficiencies of the 6 speed manual transmission range from 

0.92 to 0.95.

Final Drive Ratio – The final drive ratios are 3.25, 3.36, and 2.64 (the actual final drive 

ratio for Truck 555) for the VLH, VMH, and VHH truck models, respectively. The VLH and 

VMH final drive ratios are selected based on using powertrain selection tool21

Inertia – For VHH, it is assumed the same engine and transmission inertia values as those 

used for a Class 8 combination tractor, while the axle inertia is 168 kg-m

and agencies’ 

engineering judgment. 

2

. For both the VLH 

and VMH truck models, the engine, transmission and axle inertia values are 2.79, 0.1 and 90 kgm2

, respectively.

Accessory Load – It is estimated that all vocational trucks carry an electrical load of 360 

watts and a mechanical load of 1,000 watts.

15

Axle Base – It is assumed that both the VLH and VMH models have 1 steer and 1 drive 

axle, while the VHH trucks have 1 steer and 2 drive axles based on typical configurations found 

in use.

Tire Radius – The static loaded tire radii for VLH, VMH, and VHH trucks are 381, 395, 

and 489 mm, respectively.

Engine Fuel Map – In addition to the two sets of Class 7 and Class 8 combination tractor 

engine maps, two sets of engine maps have been created which would be used by manufacturers 

for modeling LH and MH vocational truck GHG emissions. The map created for use in Class 8 

combination truck models (455 hp @ 1800 rpm) would also be used for the Vocational HeavyHeavy truck model. Two sets of LH and MH engine maps, a 200 hp @ 2000 rpm (7 liter engine) 

and 270 hp @ 2200 rpm (also 7 liter engine), would be used by manufacturers for certification of 

LH and MH vocational trucks in 2014-16 and in 2017, respectively.

The same methodology used for generating representative 2014 and 2017 Class 7 and 

Class 8 engine maps was also used for vocational truck engine map development. Figure 4-4

shows an example of the fueling rate contour as a function of engine torque and speed for a 

vocational truck with 270 hp rating.

Table 4-8:

Deleted: five

Deleted: automatic

Deleted: 3.

Formatted: Font: Arial, 10 pt

Formatted: Font: Arial, 10 pt

Deleted: 81, 1.41, 1.0, 0.71 and 3.51, 1.9, 1.44, 

1.0, 0.74.

Deleted: 5

Deleted: automatic

Deleted: ratio is 4.10,

Deleted: 54

Formatted: Superscript

Deleted: 

Deleted: . 

Deleted: are to

Deleted: are to

Moved down [2]: 

2

2

4

2 

Torque (Nm)

800 100

0

100

200

300

400

500

600

700

800

900

Figure 4-4: Fueling Rate (g/s) as a Function of 

Engine Torque and Speed for a Vocational Truck¶
Draft Regulatory Impact Analysis 

4-18

Vocational Truck Modeling Input Parameters

Model Type Heavy Heavy-Duty Medium Heavy-Duty Light Heavy-Duty

Regulatory 

Subcategory

Vocation Truck

(Class 8)

Vocation Truck

(Class 6-7)

Vocation Truck

(Class 2b-5)

Fuel Map 15L - 455 HP 7L - 270 HP 7L - 200 HP

Gearbox 10 speed Manual 6 speed Manual 6 speed Manual

Gearbox Ratio 14.8, 10.95, 8.09, 5.97, 4.46, 

3.32, 2.45, 1.81, 1.35, 1

9.01, 5.27, 3.22, 

2.04, 1.36, 1

9.01, 5.27, 3.22, 

2.04, 1.36, 1

Gearbox Efficiency 0.96 0.96 0.96 0.96 0.98 

0.98 0.98 0.98 0.98 0.98

0.92 0.92 0.93 0.95 

0.95 0.95

0.92 0.92 0.93 0.95 

0.95 0.95

Engine Inertia (kg-m2) 4.17 2.79 2.79

Transmission Inertia

(kg-m2

0.2

)

0.1 0.1

All Axle Inertia (kg-m2) 168 90 90

Loaded Tire Radius (m) 0.4892 0.395 0.381

Body Mass (kg) 13154 6328 4672

Cargo Mass (kg) 17236 5080 2585

Total weight (kg) 30391 11408 7257

Total weight (lbs) 67000 25150 16000

Frontal Area (m2) 9.8 9 9

Drag Coefficient 0.7 0.6 0.6

Axle Base 3 2 2

Electrical Accessory 

Power (W)

360 360 360

Mechanical Accessory 

Power (W)

1000 1000 1000

Final Drive Ratio 2.64 3.36 3.25

Tire CRR

(kg/ton) = 0.5 × Drive CRR + 0.5 × Steer CRR

Trailer Tire CRR

(kg/ton)

Not applicable Not applicable Not applicable

Steer Tire CRR OEM Input OEM Input OEM Input

Drive Tire CRR OEM Input OEM Input OEM Input

Deleted: Table 4-5:

Deleted: Class

Deleted: 5

Deleted: Automatic

Deleted: 5

Deleted: Automatic

Deleted: 54

Deleted: 4.1
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-19

2

2

2

2 2 2

2

2

2

4 4

4

4

4

4

4

4

6

6

6

6

6

6

6 8 8

8

8

8

810

10

10

10

12

12

270 HP / 7 L : 2010 Baseline Fuel Rate (g/s)

Engine Speed (RPM)

Torque (Nm)

800 1000 1200 1400 1600 1800 2000 2200 2400 2600

0

100

200

300

400

500

600

700

800

900

Figure 4-4: Fueling Rate (g/s) as a Function of Engine Torque and Speed for a Vocational Truck

4.5 Application of Model for Certification 

The agencies are proposing that vehicle manufacturers demonstrate truck compliance 

using GEM for the following vehicle types.

• Class 7/8 Combination Tractors: Manufacturers use one of seven predefined 

combination truck models to generate GHG emissions and fuel consumption.

• Class 2b-8 Vocational Vehicles: Manufacturers use one of three predefined 

vocational vehicle models to generate GHG emissions and fuel consumption.

4.5.1 Class 7/8 Combination Tractors – Use One of Seven Applicable 

Combination Truck Models

As mentioned previously, EPA and NHTSA have defined three required input parameters 

and up to three allowable adjustments, the adjustments reflecting additional use of weight 

reduction, use of vehicle speed limiters, and/or use of idle reduction technologies. These 

parameters would be input to the simulation model to generate cycle-weighted GHG emissions

Moved (insertion) [2]

Deleted: Vehicle

Deleted: are to 

Deleted: the [TEST] compliance models

Deleted: Trucks

Deleted: truck

Deleted: to
Draft Regulatory Impact Analysis 

4-20

and fuel consumption for certification. For Class 7/8 combination tractor certification, the

manufacturer would provide this information to the agencies in the graphical user interface. 

For example, if the manufacturer plans to produce a Class 7 or 8 combination tractor in 

2014 to 2017, appropriate testing would be conducted by the manufacturer to assess the vehicle 

aerodynamics and rolling features as per test procedures described in Chapter 3 of this DRIA and 

Preamble Section 2. For steer and drive tire rolling friction assessment, the manufacturer would

either conduct its own testing or obtain applicable test results from the tire manufacturer. The 

vehicle manufacturer needs to document the source of these test data for Cd and Crr (steer and 

drive tires) as part of the certification process.

If applicable, the vehicle manufacturer would further input specific values reflecting use

of: (1) restricting the top speed of the vehicle to below 65 mph (2) reducing the tire weight to be 

less than the EPA-default body mass, and (3) installing special features on the vehicle to reduce 

extended idle (applicable to sleeper cabs only).

The quantification procedure to certify truck GHG emissions and fuel consumption using 

these adjustments are the following: 

Vehicle Speed Limiter (VSL) – If the manufacturer limits the vehicle in-use top speed to

below 65 mph with a Vehicle Speed Limiter device, a cycle reflecting the vehicle top speed shall 

be substituted for the 65 mph drive cycle for quantifying GHG emissions and fuel consumption

over the high speed cruising cycle. 

Weight Reduction – If the manufacturer uses alternate material for wheels and/or installs 

single wide tires in lieu of duals, it is very likely that the empty weight of the certifying Class 7/8 

tractor body mass is less than that listed in Table 4-5. Therefore, the manufacturer would be

allowed to apply adjustments to the vehicle GHG emissions and fuel consumption calculation by 

reporting the difference between the EPA/NHTSA-defined tractor mass and the actual body 

mass. This adjustment is applied during the post-processing GHG emissions and fuel 

consumption calculation, in which one third of the mass reduction is added to the defined 

payload. This would essentially increase the denominator, i.e., payload, for all three cycle

outputs, resulting in less overall gram CO2

Extended Idle Reduction Technology (applicable only to Class 8 sleeper cabs) – If the 

combination tractor is equipped with an extended idle reduction technology and an Automatic 

Engine Shutoff system, then the manufacturer would be allowed to select idle reduction in GEM 

which provides a 5 grams/ton-mile GHG emissions reduction (and equivalent fuel consumption 

reduction) from the cycle-weighted GHG emissions and fuel consumption. Table 4-9 lists some 

examples of these extended idle reduction technologies.

/ton-mile emissions or gallon/ton-mile fuel 

consumption.

Deleted: shall

Deleted: shall

Deleted: shall

Deleted: could exploit allowable credits or 

adjustments to reduce the GHG emissions and fuel 

consumption

Deleted: the certifying vehicle by any or all of the 

following means

Deleted: tractor

Deleted: feature

Deleted: is

Deleted: technologies with

Deleted: is

Deleted: subtract

Deleted: for certification.

Deleted: 6
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Simulation Model

4-21

Table 4-9: Examples of Extended Idle Reduction Technologies

Automatic Engine Shutoff Only

Auxiliary Power Unit + Shutoff

Fuel Operated Heater + Shutoff

Thermal Storage Unit + Shutoff

Battery Air Conditioner + Shutoff

Truck Stop Electrification + Shutoff

4.5.2 Class 2b-8 Vocational Vehicles – Use One of Three Applicable Vocational 

Truck Models

For Class 2b-8 vocational vehicle certification in the 2014-2017 MY timeframe, the 

manufacturer would conduct appropriate testing to assess the tire rolling features as per test 

procedures described in Chapter 3 and Preamble Section 2. The process for tire rolling friction 

assessment is identical to that required for combination tractors, i.e. the manufacturer shall either 

conduct its own testing or obtain appropriate test results from the tire manufacturer. The vehicle 

manufacturer needs to document the source of these test data, i.e., Crr as part of the certification 

process. 

The adjustments available to Class 7/8 combination tractors for reducing GHG emissions

and fuel consumption are not applicable to any of the vocational truck classes so that any further 

improvements in performance would be considered (potentially) as an off-cycle credit or 

advanced technology credit and would not be evaluated using the GEM model. 

Deleted: -6:

Formatted Table

Deleted: Trucks

Deleted: truck

Deleted: truck
Draft Regulatory Impact Analysis 

4-22

References

1 SAE International, Joint TMC/SAE Fuel consumption test procedure – Type II, SAE Surface Vehicle 

Recommended practice J1321, 1986

2 Title 40 United States Code of Federal Regulations, Part 86 Subpart B, § 86.127 Test Procedures; Overview, 2010.

3 Title 40 United States Code of Federal Regulations, Part 86 Subpart N, § 86.1327 Engine Dynamometer Test 

Procedures; Overview, 2010.

4 http://www.transportation.anl.gov/modeling_simulation/PSAT/tech_info.html.

5 http://www.carsim.com/products/trucksim/index.php.

6 “Simulink® 7 Simulation and Model-Based Design,” 9320v06_Simulink7_v7.pdf, The MathWorks, September 

2007. 

7 http://www.mathworks.com/products/matlab © 1994-2010 The MathWorks, Inc.

8 http://www.mathworks.com/products/simulink © 1994-2010 The MathWorks, Inc.

9 http://www.mathworks.com/products/stateflow © 1994-2010 The MathWorks, Inc.

10 US EPA. Heavy-Duty Coastdown Test Procedure Development. Docket # EPA-HQ-OAR-2010-0162-0144.

11 US EPA. Heavy-Duty Greenhouse Gas and Fuel Consumption Test Program Summary. Docket # EPA-HQOAR-2010-0162.

12 http://gtisoft.com/applications/a_Vehicle_driveline.php.

13 Southwest Research Institute Final Report (in preparation) for EPA Contract BPA 08-01 Task Order 1103. 

15 Christenson, M. and Greuel, J., Evaluation of the Proposed SmartWay Fuel Efficiency Test Protocol for Mediumand Heavy-duty Vehicles, Report A: Conventional and Hybrid Utility Trucks, ERMS Report No. 08-38, 2009.

16 “Rotational Inertia Measurement and Estimation of Heavy-Duty Vehicle Wheel Sets,” Southwest Research 

Institute Report (in preparation) for EPA Contract BPA 08-01 Task Order 1103. 

17 United States Environmental Protection Agency. SmartWay Transport Partnership July 2010 e-update accessed 

July 16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf

18 Title 40 United States Code of Federal Regulations, Part 1065 Subpart F, §1065.510 Engine Mapping, 2010.

20 “Greenhouse Gas Management for Medium-Duty Truck Fleets, A Framework for Improving Efficiency and 

Reducing Emissions,” 10860-fleets-med-ghg-management.pdf, http://phharval.com.

21 http://www.powerspec.cummins.com/site/home/index.html
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Emissions Inventory

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CHAPTER: 5 EMISSIONS IMPACTS.............................................................. 5-2

5.1 Executive Summary ......................................................................................................... 5-2

5.2 Introduction ...................................................................................................................... 5-3

5.2.1 Scope of Analysis.................................................................................................... 5-3

5.2.2 Downstream Contributions................................................................................... 5-3

5.2.3 Upstream Contributions........................................................................................ 5-4

5.2.4 Global Warming Potentials................................................................................... 5-4

5.3 Program Analysis and Modeling Methods..................................................................... 5-5

5.3.1 Models Used............................................................................................................ 5-5

5.3.2 Calculation of Downstream Emissions ................................................................ 5-6

5.3.3 Calculation of Upstream Emissions ................................................................... 5-10

5.3.4 Calculation of HFC Emissions............................................................................ 5-10

5.4 Greenhouse Gas Emission Impacts .............................................................................. 5-12

5.5 Non-Greenhouse Gas Emission Impacts...................................................................... 5-13

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CHAPTER: 5 Emissions Impacts

5.1 Executive Summary

Climate change is widely viewed as the most significant long-term threat to the global 

environment. According to the Intergovernmental Panel on Climate Change, anthropogenic 

emissions of greenhouse gases (GHG) are very likely (90 to 99 percent probability) the cause of 

most of the observed global warming over the last 50 years. The primary GHGs of concern are 

carbon dioxide (CO2), methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur 

hexafluoride.1 Mobile sources emitted 31 percent of all U.S. GHG in 2007 (transportation 

sources, which do not include certain off-highway sources, account for 28 percent) and have 

been the fastest-growing source of U.S. GHG since 1990.2 Mobile sources addressed in the 

recent endangerment finding under CAA section 202(a)--light-duty vehicles, heavy-duty trucks, 

buses, and motorcycles--accounted for 23 percent of all U.S. GHG in 2007.3 Heavy-duty

vehicles emit CO2, methane, nitrous oxide, and hydrofluorocarbons and are responsible for 

nearly 19 percent of all mobile source GHGs (nearly 6% of all U.S. GHGs) and about 25 percent 

of Section 202(a) mobile source GHGs. For heavy-duty vehicles in 2007, CO2 emissions 

represented more than 99 percent of all GHG emissions (including HFCs).

This proposal estimates anticipated impacts from the EPA vehicle CO2 emission 

standards. The emissions from the GHGs carbon dioxide (CO2), methane (CH4), nitrous oxide 

(N2O) and hydrofluorocarbons (HFCs) were quantified. In addition to reducing the emissions of 

greenhouse gases, this proposal would also influence the emissions of “criteria” air pollutants, 

including carbon monoxide (CO), fine particulate matter (PM2.5) and sulfur dioxide (SOX) and 

the ozone precursors hydrocarbons (VOC) and oxides of nitrogen (NOX

Downstream (tailpipe) emission impacts were developed using EPA’s Motor Vehicle 

Emission Simulator (MOVES2010). Upstream (fuel production and distribution) emission 

changes resulting from the decreased fuel consumption predicted by the downstream models 

were calculated using a spreadsheet model based on emission factors from GREET.

); and several air toxics 

(including benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein).

4

 Based on 

these analyses, this proposal would lead to 72 million metric tons (MMT) of CO2 equivalent 

(CO2EQ) of annual GHG reduction and 5.8 billion gallons of fuel savings in the year 2030.

The non-GHG impacts the proposal are driven by the increased use of auxiliary power units 

(APUs) and reduced emissions from upstream fuel production and distribution. Emissions of 

certain pollutants are further reduced through improved aerodynamics and tire rolling resistance. 

To a much smaller extent, rebound of vehicle miles traveled (VMT) increases emissions of all 

pollutants proportional to the VMT rebound amount. Table 5-1 summarizes these non-GHG 

emissions impacts.
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Table 5-1 Impacts of Program on Non-GHG Emissions (Short Tons per year)

POLLUTANT

CALENDAR 

YEAR

2030

CHANGE VS. 

2030 

BASELINE

Δ 1,3-Butadiene -1 -0.1%

Δ Acetaldehyde -1,903 -37.8%

Δ Acrolein -262 -37.7%

Δ Benzene -358 -13.0%

Δ Carbon Monoxide -56,923 -2.1%

Δ Formaldehyde -6,252 -44.0%

Δ Oxides of Nitrogen -241,254 -19.6%

Δ Particulate Matter 

(below 2.5 micrometers) 363 0.98%

Δ Oxides of Sulfur -6.650 -9.3%

Δ Volatile Organic Compounds -29,540 -14.8%

5.2 Introduction

5.2.1 Scope of Analysis

The proposed standards affect both diesel- and gasoline-fueled heavy-duty vehicles. This 

analysis accounts for the direct downstream/tailpipe reduction of GHG as well upstream (fuel 

production and distribution) reductions of GHGs and non-GHGs. Total GHG impacts will also 

be determined by any VMT rebound effects, changes in fleet turnover, and changes in fuel 

consumption globally due to reduced petroleum prices. See Chapter 9 for a further discussion of 

these aspects of the analysis. The agencies also expect this proposal to impact downstream and 

upstream emissions of non-GHG air pollutants. 

Emissions estimates for the four greenhouse gases carbon dioxide (CO2), methane (CH4), 

nitrous oxide (N2O), and hydrofluorocarbons (HFC) are presented herein. Inventories for the 

non-GHG pollutants 1,3-butadiene, acetaldehyde, acrolein, benzene, carbon monoxide (CO), 

formaldehyde, oxides of nitrogen (NOX), particulate matter below 2.5 micrometers (PM2.5), 

oxides of sulfur (SOX

5.2.2 Downstream Contributions

), and volatile organic compounds (VOC) are also presented.

The largest source of GHG and other air pollutant reductions from this proposal is from 

tailpipe emissions produced during vehicle operation. Absolute reductions from tailpipe 

emissions are projected to grow over time as the fleet turns over to vehicles affected by the 

standards, meaning the benefit of the program will continue to grow as long as the older vehicles 

in the fleet are replaced by newer, lower CO2

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As described herein, the downstream reductions in emissions due to the program are 

anticipated to be achieved through improvements in engine efficiency, road load reduction, and 

APU use during extended idling.

Changes in downstream GHG and other emissions at the fleet level will be affected by 

whether the regulations affect the timing of fleet turnover and total VMT, as discussed in Section

8 of the preamble. If the regulations spur firms to increase their purchase of new vehicles before 

efficiency standards are in place (“pre-buy”) or to delay their purchases once the standards are in 

place to avoid higher costs, then there will be a delay in achieving the full GHG and other 

emission reductions from improved fuel economy across the fleet. If the lower per-mile costs 

associated with higher fuel economy lead to an increase in VMT (the “rebound effect”), then 

total emission reductions will also be reduced. Chapter 9 of this draft RIA provides more detail 

on how the rebound effect is calculated in EPA’s analysis. The analysis discussed in this chapter 

incorporates the rebound effect into the estimates, though fleet turnover impacts are not 

estimated. 

In addition, EPA also recognizes that this proposed regulation would lower the world 

price of oil (the “monopsony” effect, further discussed in Chapter 9 of the draft RIA). Lowering 

oil prices could lead to an uptick in oil consumption globally, resulting in a corresponding 

increase in GHG emissions in other countries. This global increase in emissions could slightly 

offset some of the emission reductions achieved domestically as a result of the regulation. EPA 

does not provide quantitative estimates of the impact of the proposed regulation on global 

petroleum consumption and GHG emissions in this draft RIA. 

5.2.3 Upstream Contributions

In addition to downstream emission reductions, reductions are expected in the emissions 

associated with the processes involved in getting fuel to the pump, including the extraction and 

transportation of crude oil, the production, and the distribution of finished gasoline and diesel. 

Changes are anticipated in upstream emissions due to the expected reduction in the volume of 

fuel consumed. Less fuel consumed means less fuel transported, less fuel refined, and less crude 

oil extracted and transported to refineries. Thus, there should be reductions in the emissions 

associated with each of these steps in the fuel production and distribution process. Any changes 

in downstream reductions associated with changes in fleet turnover, VMT, and global petroleum 

consumption should be reflected in a corresponding change in upstream emissions associated 

with petroleum processing and distribution.

5.2.4 Global Warming Potentials

Throughout this document, in order to refer to the four inventoried greenhouse gases on an 

equivalent basis, Global Warming Potentials (GWPs) are used. In simple terms, GWPs provide a 

common basis with which to combine several gases with different heat trapping abilities into a 

single inventory (Table 5-2). When expressed in CO2 EQ terms, each gas is weighted by its heat 

trapping ability relative to that of carbon dioxide. The GWPs used in this chapter are drawn 

from publications by the Intergovernmental Panel on Climate Change (IPCC).5

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The global warming potentials (GWP) used in this analysis are consistent with the 2007 

Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). At this 

time, the 1996 IPCC Second Assessment Report (SAR) global warming potential values have 

been agreed upon as the official U.S. framework for addressing climate change and are used in

the official U.S. greenhouse gas inventory submission to the United Nations climate change 

framework. This is consistent with the use of the SAR global warming potential values in 

current international agreements. 

Table 5-2 Global Warming Potentials for the Inventory GHGs

GAS GLOBAL WARMING 

POTENTIAL

(CO2

CO

Equivalent)

2 1

CH4 25

N2O 298

HFC 1,430

5.3 Program Analysis and Modeling Methods

5.3.1 Models Used

The Motor Vehicle Emissions Simulator, more commonly called MOVES, EPA’s official 

mobile source emission inventory model, was the primary tool used to calculate downstream 

emissions inventories.

7

This proposal affects heavy-duty vehicles. In MOVES, which categorizes vehicle types 

by their use, these vehicle types are represented by combination tractors, single unit tractors, 

refuse trucks, motor homes, transit buses, intercity buses, school buses, and light commercial 

trucks. Changes made to the default MOVES data for the baseline and the control case are 

described below in Section 

 The 2009-December-21 version of MOVES was used along with the 

2010-May-15 default database. Some post-processing was done to MOVES output to ensure 

proper calculation of emissions inventories for each alternative.

5.3.2. All the input data and MOVES run spec files can be found in 

the docket.8

Upstream emissions were calculated using the same tools as were used for the Renewable 

Fuel Standard 2 (RFS2) rule analysis, but for the current analysis it was assumed that all impacts 

are related to changes in volume of gasoline and diesel produced and consumed, with no changes 

in volumes of ethanol or other renewable fuels such as biodiesel.

10 This assumption is 

reasonable because EISA mandates that a certain volume of renewable fuels be blended into the 

fuel supply, regardless of the quantity of conventional liquid fuels consumed. The estimate of 

emissions associated with production of gasoline and diesel from crude oil is based on emission 

factors in the “Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation”

model (GREET) developed by DOE's Argonne National Lab, and are consistent with those used 

for the Light-Duty Greenhouse Gas rulemaking.

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upstream emission impacts. This model uses the decreased volumes of the crude based fuels and 

the various crude production and transport emission factors from GREET to estimate the net 

emissions impact of fuel use changes. As just noted, the analysis for this rulemaking assumes 

that all changes in volumes of fuel used affect only gasoline and diesel, with no effects on use of 

ethanol, or other renewable fuels.

5.3.2 Calculation of Downstream Emissions

5.3.2.1 Baseline (reference case)

The baseline, or reference case, assumes no action. Since MOVES2010 vehicle sales and 

VMT inputs were developed from AEO2006, EPA first updated these data using sales and 

activity estimates from AEO2010.13 EPA also updated the fuel supply information in MOVES 

to reflect a 100% E10 “gasoline” fuel supply to reflect the Renewable Fuels Standard.

14 The 

tables that were modified and included as user input tables for the baseline run were fuelsupply, 

fuelformulation, sourcetypeyear, and hpmsvtypeyear. For HD pickups and vans, the agency 

updated sales projections for model years 2011 through 2018 using forecasts purchased from 

CSM Worldwide for the light-duty greenhouse gas rule.15

For extended idling emission inventories, MOVES defaults were post-processed to 

account for increased use of auxiliary power units (APUs) for model year 2010 and later, which 

is not assumed in default MOVES. For all alternatives, the agencies assumed that about 30 

percent of all combination long-haul tractors between model years 2010 through 2013 use an 

APU during extended idling. For alternatives where combination long-haul tractors are 

regulated, the agencies assumed that 100 percent of those trucks model year 2014 and later use 

APUs during extended idling. This assumption is based on the expectation that manufacturers 

will use APUs to meet the vehicle GHG standard for combination long-haul tractors. For 

alternatives where combination long-haul tractors are not regulated, the agencies assumed that 30 

percent of those trucks model year 2014 and later use APUs during extended idling. A diesel 

fuel consumption rate of 0.2 gallons per hour for APUs and a factor 10.180 kg CO

 This update was done through 

modifying the base population, along with the sales growth factors for model years 2011 through 

2018, in the sourcetypeyear table. The sales growth factors for the other model years were 

updated from AEO2010, as mentioned above. MOVES2010 defaults, including all emission 

rates, were used for all other parameters to estimate the baseline emissions inventories. For 

aerodynamic drag and tire rolling resistance coefficients, the default MOVES values represent a 

fleet-wide average rolling resistance and aerodynamic drag (for each MOVES source/vehicle

type), which assumes only a low level of adoption, if any, of low rolling resistance tires and 

advanced aerodynamic features. It also assumes that these fleet-wide coefficients do not change 

with future model years or by age.

2 per gallon 

diesel were assumed. EPA also considered that diesel APUs are regulated as non-road small 

engines for criteria (non-GHG) pollutants. Assuming that these APUs emit criteria pollutants at 

the EPA standard, Table 5-3 shows the emission rate of APUs, given an extended idle load 

demand of 4.5 kW (6 hp).17 For SO2

Table 5-3

, which is not regulated through engines, but rather through 

fuel, the agency assumed a diesel fuel sulfur level of 15 ppm and a diesel fuel density of 6.9 

lb/gal. Total extended idle emissions were calculated by multiplying by the number of extended 

idle hours by the emission rates in .

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Table 5-3 Estimated Emission Rates of non-GHG Pollutants from APUs

POLLUTANT EMISSION RATE 

[g/hr]

CO 36

NOX + NMHC 33.6

PM

a

1.8

SO2 0.0188

Note: aNOX rate was estimated to be 80% (26.88 g/hr), and NMHC (6.72 g/hr) was estimated to be 20% 

of the total NOX+NMHC rate, based on the 2004 model year heavy-duty engine standard.18

5.3.2.2 Control Case/Proposal

 VOC was 

estimated to be equal to NMHC for this analysis.

This case represents the proposed rules. The fuel supply and sales updates implemented

in the baseline were also used in all the alternatives, including the control case, since this fuel 

supply and sales projections are those for all future scenarios and are not affected by this 

proposal. To account for improvements of engine and vehicle efficiency, EPA developed several 

user inputs to run the alternatives in MOVES. Since MOVES does not calculate emissions based 

on engine Federal Test Procedure (FTP) cycle results, EPA used the percent reduction in engine 

CO2

5.3.2.2.1 Emission Rate and Road Load Inputs

emissions expected from the proposal to develop energy inputs for the control case runs. 

Also, EPA used the percent reduction in aerodynamic drag coefficient and tire rolling resistance 

coefficient expected from each alternative to develop road load inputs. Runs were postprocessed to calculate air toxics inventories for diesel vehicles and emissions and fuel 

consumption from APUs. 

Table 5-4 and Table 5-5 describe the estimated expected changes in engine emissions and 

vehicle technologies from this proposal, which were input into MOVES for estimating control 

case emissions inventories.

Table 5-4 Estimated Reductions in Engine CO2

GVWR CLASS

Emission Rates from this Proposal

FUEL MODEL 

YEARS

CO2

HHD (8a-8b)

REDUCTION 

FROM BASELINE

Diesel 2014-2016 3%

2017+ 6%

MHD (6-7) and LHD 4-5 Diesel 2014-2016 5%

2017+ 9%

Gasoline 2016+ 5%

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Table 5-5 Estimated Reductions in Rolling Resistance and Aerodynamic Drag Coefficients from Reference 

Case for Alternative 6 (Model Years 2014 and Later)

TRUCK TYPE REDUCTION IN TIRE 

ROLLING RESISTANCE 

COEFFICIENT FROM 

BASELINE

REDUCTION IN 

AERODYNAMIC DRAG 

COEFFICIENT FROM 

BASELINE

Combination long-haul 8.4% 7.2%

Combination short-haul 7.0% 5.3%

Straight trucks, refuse trucks, 

motor homes, transit buses, 

and other vocational vehicles

10.0% 0%

Since nearly all HD pickup trucks and vans will be certified on a chassis dynamometer, 

the CO2 reductions for these vehicles will not be represented as engine and road load reduction 

components, but total vehicle CO2

Table 5-6

reductions. These estimated reductions are described in 

.

Table 5-6 Estimated Total Vehicle CO2

GVW

R CLASS

Reductions for HD Pickup Trucks and Vans

F

UEL

MOD

EL YEARS

CO2

LHD 2b-3 REDUCTION FROM Gasoline 2014 1.5%

2015 2%

2016 4%

2017 6%

2018+ 10%

Diesel 2014 2.3%

2015 3%

2016 6%

2017 9%

2018+ 15%

Engine CO2 reductions (Table 5-4) and HD pickup/van total vehicle CO2 Table 

5-6

reductions (

) were modified in the emissionrate table in MOVES. The percentage reductions were 

applied to the default energy rates. The improvements in tire rolling resistance and drag 

coefficient were modified in the sourceusetype table. The percentage reductions were applied to 

the road load coefficients. It was assumed that 100 percent of Class 7/8 combination long-haul 

tractors model year 2014 and later use APUs during extended idling. Emissions from APUs in 

the control case were calculated in the same way as the baseline (see Table 5-3).

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5.3.2.2.2 VMT Inputs

The HPMSVtype table was modified to reflect VMT rebound. This table contains VMT 

growth factors from one calendar year to the next, starting from an absolute VMT estimate for

calendar year 1999. For the control case, we increased the HD pickup/van absolute VMT by 

1.01%, the vocational vehicle absolute VMT by 0.68%, and the combination tractor absolute

VMT by 0.71% from baseline levels, based on the analysis in RIA Section 9.2. Since VMT 

growth is by calendar year and not model year, to ensure that only model years affected by the 

proposal experienced VMT rebound, the results from the baseline run were used in the control 

case inventories for model years prior to the proposed rules’ implementation.

5.3.2.2.3 Diesel Air Toxics Calculations

The composition of VOCs for heavy-duty diesel engines without model year 2007 and 

later emission controls versus those engines with such controls vary significantly. Thus, EPA 

developed one set of toxic to VOC ratios for pre-2007 diesel engines and another set for 2007 

and later engines. Since light-duty diesels comprise a very small portion of the fleet, the same 

ratios were applied to all diesel vehicle classes to streamline modeling. 

EPA relied on a database compiled for the Coordinating Research Council (CRC E-75) 

and National Renewable Energy Laboratory (NREL) to develop toxic to VOC ratios for pre2007 model year engines.19

Toxic-to-VOC ratios for benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and 

acrolein were developed by EPA from the CRC E-75 database. EPA relied on United States data 

from heavy-duty diesel engines running on conventional diesel fuels, collected on test cycles 

representative of real world operation. Some studies measured emissions over distance, while 

other studies measure emissions relative to engine work. For studies which measured emissions 

relative to distance, we calculated mean emissions per mile for toxics and VOC, then calculated 

a ratio of toxics to VOC. For studies which measured emissions relative to engine work, we 

calculated mean emissions per brake horsepower hour for toxics and VOC, then calculated a 

second ratio of toxics to VOC. We then calculated a composite ratio using sample size to weight 

the two ratios. The resulting ratios are provided in 

 This database was developed from a literature survey and included 

data from 13 different studies. The studies included in this database were conducted in a number 

of different countries, included heavy-duty and light-duty engines, a variety of diesel and 

biodiesel fuels, and a number of different operating modes and cycles. The methodology they 

used to develop ratios is described in detail in their technical report. Data from tests using nonconventional diesel fuel (Fischer-Tropsch, bioDiesel, ethanol-Diesel blends, emulsified fuel, 

European blends, and other obvious research fuels) were excluded, as were data from non-heavyduty engines. 

Table 5-7.

For model year 2007 and later heavy-duty diesels, advanced emission controls change the 

composition of VOCs. For these engines, we relied on speciated emissions data from the 

Advanced Collaborative Emissions Study (ACES), directed by the Health Effects Institute and 

Coordinating Research Council, with participation from a range of government and private 

sector sponsors.20 Detailed emissions data from the study were provided to EPA at the request 

of the Coordinating Research Council. The data were collected on four engines on several test 
Draft Regulatory Impact Analysis 

5-10

cycles with low sulfur diesel fuel. EPA used data from a 16-hour transient cycle. Toxic to VOC 

ratios obtained from the ACES data are provided in Table 5-7. Because diesel VOC estimates 

had not been updated in MOVES for model year 2007 and later heavy-duty diesel trucks, these 

data were also used to determine a VOC-to-total hydrocarbon (THC) ratio for those trucks. This 

ratio of 0.5327 was used in conjunction with the MOVES results for THC to estimate VOC 

emissions from model year 2007 and later heavy-duty diesel trucks.

All model year APUs were treated like pre-2007 engines with respect to toxics 

calculations because APUs are not equipped with the emission controls technology of model 

year 2007 and later engines.

Table 5-7 Air Toxics Ratios Post-Processed Against Hydrocarbon Results from MOVES

MODEL YEARS POLLUTANT RATIO to VOC

Pre-2007 engines 

and all model year 

APUs

Benzene 0.0078

1,3-butadiene 0.0029

Formaldehyde 0.0782

Acetaldehyde 0.0356

Acrolein 0.0066

2007 and later 

engines

Benzene 0.0129

1,3-butadiene 0.0008

Formaldehyde 0.2174

Acetaldehyde 0.0693

Acrolein 0.0100

5.3.3 Calculation of Upstream Emissions

The term "upstream emissions" refers to air pollutant emissions generated from all crude 

oil extraction, transport, refining, and finished fuel transport, storage, and distribution; this 

includes all stages prior to the final filling of vehicle fuel tanks at retail service stations. The 

details of the assumptions, data sources, and calculations that were used to estimate the emission 

impacts presented here can be found in the Technical Support Document and the docket memo, 

“Calculation of Upstream Emissions for the GHG Vehicle Rule”, initially created for use in the 

Light-Duty Greenhouse Gas rulemaking.21 The results of this analysis are shown in Table 5-10

and Table 5-12.

5.3.4 Calculation of HFC EmissionsA

 

A The U.S. has submitted a proposal to the Montreal Protocol which, if adopted, would phase-out production and 

consumption of HFCs.

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EPA is proposing to set air conditioning (AC) leakage standards for HD pickup trucks 

and vans and combination tractors to reduce HFC emissions. The Vintaging Model, developed 

by the EPA Office of Atmospheric programs, produces HFC inventories for several categories of 

stationary and mobiles sources. However, it does not include air conditioning systems in 

medium and heavy duty trucks within its inventory calculations. For this proposal, we conducted 

a new analysis based on the inputs to the Vintaging Model and the inputs to the MOVES analysis 

discussed in Chapter 5.3.2.1 above. 

The general equation for calculating HFC emissions follows:

HFC emissionsYear x = AC SystemsYear x

We determined the number of functioning AC systems in each year based on the 

projected sales of vehicles, the fraction of vehicles with AC systems, and the average lifetime of 

an air conditioning system. Sales were drawn from the MOVES analysis and we assumed that 

every vehicle had a functioning AC system when sold based on feedback received from truck 

manufacturers. The Vintaging Model assumes that all light duty passenger vehicle AC systems 

(in the U.S.) last exactly 12 years.

x Average Charge Size x HFC loss rate 

22

The charge size was determined using the Minnesota refrigerant leakage database.

 For lack of better information, we assumed that heavy duty 

vehicles AC systems last for the same period of time as light duty vehicles. Light, medium and 

heavy duty vehicles use largely the same components in their air conditioning systems, which 

would indicate similar periods of durability. 

23

Due to the similarity in system design, we assumed that the light-duty vehicle emission 

rate in the Vintaging Model was applicable to the current analysis, as shown in 

 

EPA sorted the data based on AC charge size and evaluated only the largest 25 percent of AC 

systems. The average charge size is 1,025 grams of refrigerant.

Table 5-8. The 

Vintaging Model assumes that losses occur from three events: leak, service, and disposal. 

Although vehicle AC systems are serviced during discrete events and not usually every year, 

emissions from those events are averaged over the lifetime of the AC system in the Vintaging 

model. Leak and service emissions are considered “annual losses” and are applied every year; 

disposal is considered an “end of life loss” and is applied only once for each vintage of vehicles.B

Table 5-8 Annual In-use Vehicle HFC134a Emission Rate from Vintaging Model

Kind of Loss Loss Fraction

Leakage 8%

Maintenance /Servicing 10%

End of Life 43%

Of note, the Vintaging Model assumes that charge loss is replaced every year; i.e.,

assuming an 18 percent rate of charge loss, a vehicle with a charge of 1,000 grams would lose a 

 

B The U.S. EPA has reclamation requirements for refrigerants in place under Title VI of the Clean Air Act.
Draft Regulatory Impact Analysis 

5-12

constant rate of 180 grams per year. While this loss rate is not accurate for any single vehicle, it 

is assumed accurate for the fleet as a whole. While other emissions, such as fugitive emissions at 

a production facility, leaks from cylinders in storage, etc., are not explicitly modeled, such 

emissions are accounted for within the average annual loss rate. 

EPA’s analysis of the MN database of MY 2010 vehicles suggests that many of the 

modeled vehicles likely contain some of the technology required to meet the leakage standard, 

and as a consequence are leaking less. We assume that these improvements are independent of 

EPA regulation, rather than a preemptive response to regulation. Consequently, this rulemaking 

does not take credit for these emission reductions. EPA welcomes better information on HFC 

leakage rates in modern vehicles, with a particular emphasis on in-use vehicles. 

 Based on the MN 2010 database, we determined that it is possible to reduce the HFC 

emissions from these vehicles on average by 13 percent. EPA calculated this based on the 

assumption that vehicles currently in the fleet which meet the proposed 2014MY standard would 

not make any additional improvements to reduce leakage. We also assumed that the systems 

which currently have leakage rates above the proposed standard will reduce their leakage to the 

proposed standard level. We then applied the 13 percent reduction to the baseline 18 percent

leakage rate to develop a 15.6 percent leakage rate for 2014 MY and later vehicles to determine 

the reduction in emission rate which should be credited to this proposal.

24

We calculated our emission reductions based on the difference between the baseline case 

of 2010 vehicle technology (discussed above) and the control scenario where the loss prevention 

technology has been applied to 100 percent of the new HD pickup trucks and vans and Class 7/8

tractor starting in 2014 model year, as required by the proposed standards. 

Total HFC reductions are 249 metric tons over the MY 2010 baseline AC system in 2030 

and 292 metric tons in 2050. This is equivalent to a reduction of 118,885 metric tons of CO2e in 

2018, 355,576 metric tons of CO2eq emissions in 2030, and 417,584 metric tons CO2e in 2050.25

5.4 Greenhouse Gas Emission Impacts

After all the MOVES runs and post-processing was completed, baseline and control case 

inventories were totaled for all vehicle types and emission processes to estimate total 

downstream GHG impacts of the proposal. Table 5-9 summarizes these downstream GHG 

impacts and fuel savings from baseline to control case for calendar year 2030. All emissions 

impacts reflect the heavy-duty sector only, and do not include emissions from light-duty vehicles 

or any other vehicle sector.

Table 5-9 Downstream GHG Impacts in 2030

POLLUTANT

CALENDAR 

YEAR

2030

% CHANGE 

vs. 2030 

BASELINE

Δ CO2 (metric tons) -58,232,974 -9.32%

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Δ CH4 (metric tons CO2EQ) 279 0.34%

Δ N2O (metric tons CO2EQ) 2,478 0.36%

Δ HFC (metric tons CO2EQ) -355,576 -13%

Δ Total CO2EQ (metric tons) -58,585,784 -9.37%

Δ Gasoline Fuel (billion gallons) -0.373 -6.5%

Δ Diesel Fuel (billion gallons) -5.79 -9.6%

Table 5-10 summarizes the upstream GHG impacts in 2030. The reductions in GHGs are 

proportional to the amount of fuel saved.

Table 5-10 Upstream GHG Impacts in 2030

POLLUTANT

CALENDAR 

YEAR

2030

% CHANGE vs.

2030 

BASELINE

CO2 (metric tons) -11,794,584 -9.3%

CH4 (metric tons CO2EQ) -1,818,733 -9.3%

N2O (metric tons CO2EQ) -56,940 -9.3%

Total CO2EQ (metric tons) -13,670,257 -9.3%

5.5 Non-Greenhouse Gas Emission Impacts

After all the MOVES runs and post-processing was completed, baseline and control case 

inventories were aggregated for all vehicle types and emission processes to estimate total 

downstream non-GHG impacts of the proposal. Table 5-11 summarizes these downstream nonGHG impacts for calendar year 2030. The non-GHG impacts of the proposal are driven by the 

increased use of APUs and, for certain pollutants, improved aerodynamics and tire rolling 

resistance. Use of APUs increases PM2.5 downstream inventories compared to the baseline case 

because APUs are not required to be equipped with diesel particulate filters, like the on-road 

engines are for model year 2007 and later. To a much smaller extent, VMT rebound increases 

emissions of all pollutants proportional to the VMT rebound amount.

Table 5-11 Downstream impacts for key non-GHG pollutants (Short tons)

POLLUTANT

CALENDAR 

YEAR

2030

% CHANGE 

vs. 2030 

BASELINE

Δ 1,3-Butadiene 0.5 0.1%

Δ Acetaldehyde -1,899 -38.0%

Δ Acrolein -261 -37.9%

Δ Benzene -339 -13.5%

Δ Carbon Monoxide -53709 -2.0%

Δ Formaldehyde -6,227 -44.5%

Δ Oxides of Nitrogen -231631 -20.6%

Δ Particulate Matter 

(below 2.5 micrometers) 1,694 7.4%

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5-14

Δ Oxides of Sulfur -480 -9.5%

Δ Volatile Organic Compounds -25,121 -17.7%

Non-GHG fuel production and distribution emission impacts of the program were 

estimated in conjunction with the development of life cycle GHG emission impacts, and the 

GHG emission inventories discussed above. The basic calculation is a function of fuel volumes 

in the analysis year and the emission factors associated with each process or subprocess. In 

general this life cycle analysis uses the same methodology as the Renewable Fuel Standard 

(RFS2) rule. It relies partially on the GREET model, developed by the Department of Energy’s 

Argonne National Laboratory (ANL), but takes advantage of additional information and models 

to significantly strengthen and expand on the GREET analysis. 

Updates and enhancements to the GREET model assumptions include updated crude oil 

and gasoline transport emission factors that account for recent EPA emission standards and 

modeling, such as the Tier 4 diesel truck standards published in 2001 and the locomotive and 

commercial marine standards finalized in 200826

Results of these emission inventory impact calculations relative to the baseline for 2030 

are shown in 

. In addition, GREET does not include air 

toxics. Thus emission factors for the following air toxics were added: benzene, 1,3-butadiene, 

formaldehyde, acetaldehyde, and acrolein. These upstream toxics emission factors were 

calculated from the 2002 National Emissions Inventory (NEI), a risk and technology review for 

petroleum refineries, speciated emission profiles in EPA's SPECIATE database, or the Mobile 

Source Air Toxics rule (MSAT) inventory for benzene; these pollutant tons were divided by 

refinery energy use or gasoline distribution quantities published by the DOE Energy Information 

Administration (EIA) to get emission factors in terms of grams per million BTU of finished 

gasoline and diesel. 

Table 5-12 for the criteria pollutants and individual air toxic pollutants. 

The program is projected to provide reductions in all pollutants associated with gasoline 

production and distribution as the projected fuel savings reduce the quantity of gasoline needed.

Table 5-12 Upstream Impacts for Key non-GHG Pollutants (Short Tons)

POLLUTANT

CALENDAR YEAR

2030

% CHANGE 

vs. 2030 

BASELINE

Δ 1,3-Butadiene -1 -12.5%

Δ Acetaldehyde -4 -11.1%

Δ Acrolein -1 -20%

Δ Benzene -19 -8.6%

Δ Carbon Monoxide -3214 -9.3%

Δ Formaldehyde -25 -9.3%

Δ Oxides of Nitrogen -9623 -9.3%

Δ Particulate Matter 

(below 2.5 micrometers) -1331 -9.3%

Δ Oxides of Sulfur -6170 -9.3%

Δ Volatile Organic Compounds -4419 -7.7%

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5-15

1 Intergovernmental Panel on Climate Change Working Group I. 2007. Climate Change 2007 - The Physical 

Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on 

Climate Change.

References

2 U.S. Environmental Protection Agency. 2009. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007. 

EPA 430-R-09-004. Available at

http://epa.gov/climatechange/emissions/downloads09/GHG2007entire_report-508.pdf 

3 U.S. EPA. 2009 Technical Support Document for Endangerment and Cause or Contribute

Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act. Washington, DC. pp. 180-194. 

Available at

http://epa.gov/climatechange/endangerment/downloads/Endangerment%20TSD.pdf 

4 Argonne National Laboratory. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation 

(GREET) Model versions 1.7 and 1.8. http://www.transportation.anl.gov/modeling_simulation/GREET/. Docket 

ID: EPA-HQ-OAR-2009-0472-0215

5 Intergovernmental Panel on Climate Change. Chapter 2. Changes in Atmospheric Constituents and in Radiative 

Forcing. September 2007. http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf . Docket ID: 

EPA-HQ-OAR-2009-0472-0117

7 http://www.epa.gov/otaq/models/moves/index.htm

8 Memorandum to the Docket “Moves Inputs” Docket Number EPA-HQ-OAR-2010-0162 Docket Identification 

Number EPA-HQ-OAR-2010-0162-0153

10 U.S. EPA. Draft Regulatory Impact Analysis: Changes to Renewable Fuel Standard Program. Chapters 2 and 

3.May 26, 2009. Docket ID: EPA-HQ-OAR-2009-0472-0119

12 U.S. EPA. 2008. RFS2 Modified version of GREET1.7 Upstream Emissions Spreadsheet, October 31, 2008. 

Docket ID: EPA-HQ-OAR-2009-0472-0191

13 Annual Energy Outlook 2010. http://www.eia.doe.gov/oiaf/aeo/

14 http://www.epa.gov/otaq/fuels/renewablefuels/index.htm

15 Final Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average 

Fuel Economy Standards, Joint Technical Support Document. EPA-420-R-10-901, April 2010. 

http://www.epa.gov/otaq/climate/regulations/420r10901.pdf

17 Tier 4, less than 8 kW nonroad compression-ignition engine exhaust emissions standards assumed for APUs: 

http://www.epa.gov/otaq/standards/nonroad/nonroadci.htm

18 Heavy-duty highway compression ignition engine exhaust emission standards. For MY 2004, HD standard is 2.5 

g/bhp-hr NOx+NMHC, with a limit of 0.5 g/bhp-hr NMHC. http://www.epa.gov/otaq/standards/heavy-duty/hdciexhaust.htm For MY 2004, HD standard is 2.5 g/bhp-hr NOx+NMHC, with a limit of 0.5 g/bhp-hr NMHC. 

19 Hsu ,Y., and Mullen, M. 2007. Compilation of Diesel Emissions Speciation Data. Prepared by E. H. Pechan and 

Associates for the Coordinating Research Council. CRC Contract No. E-75, October, 2007. Available at 

www.crcao.org.
Draft Regulatory Impact Analysis 

5-16

20Khalek, I., Bougher, T., and Merritt, P. M. 2009. Phase 1 of the Advanced Collaborative Emissions Study. 

Prepared by Southwest Research Institute for the Coordinating Research Council and the Health Effects Institute, 

June 2009. Available at www.crcao.org.

21 Craig Harvey, EPA, “Calculation of Upstream Emissions for the GHG Vehicle Rule.” 2009. Docket ID: EPAHQ-OAR-2009-0472-0216

22 This is in agreement with the IPCC report IPCC/TEAP 2005 Safeguarding the Ozone Layer and the Global 

Climate System – Issues Related to Hydrofluorocarbons and Perfluorocarbons, which indicates lifetimes 

(worldwide) of 9 to 12 years.

23 The Minnesota refrigerant leakage data can be found at 

http://www.pca.state.mn.us/climatechange/mobileair.html#leakdata

24 Using 18% as the base emission rate may overstate the net emission reductions. However, (a) the net impact is 

very small, (b) these numbers have significant uncertainty, (c) it is unclear what the appropriate modification would 

be.

25 Using a Global Warming Potential of 1,430 for HFC-134a.

26 http://www.epa.gov/otaq/marine.htm, http://www.epa.gov/otaq/locomotives.htm
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-1

CHAPTER 6: RESULTS OF PROPOSED AND ALTERNATIVE STANDARDS 6-2

6.1 What Are the Alternatives that the Agencies Considered?.......................................... 6-2

6.1.1 Alternative 1: No Action........................................................................................ 6-2

6.1.2 Alternative 2: Engine Only ................................................................................... 6-3

6.1.3 Alternative 3: Class 8 Combination Tractors ..................................................... 6-4

6.1.4 Alternative 4: Engines and Class 7 and 8 Tractors ............................................ 6-6

6.1.5 Alternative 5: Engines, Class 7 and 8 Tractors, and HD Pickup Trucks and 

Vans 6-7

6.1.6 Alternative 6: Engines, Tractors, and Class 2b through 8 Trucks.................... 6-8

6.1.7 Alternative 7: Engines, Tractors, Trucks, and Trailers................................... 6-13

6.1.8 Alternative 8: Engines, Tractors, Trucks, and Trailers with Hybrid 

Powertrains.......................................................................................................................... 6-14

6.2 How Do These Alternatives Compare in Overall GHG Emissions Reductions and 

Fuel Efficiency and Cost?........................................................................................................ 6-15

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6-2

Chapter 6: Results of Proposed and Alternative Standards

The heavy-duty truck segment is very complex. The sector consists of a diverse group of 

impacted parties, including engine manufacturers, chassis manufacturers, truck manufacturers, 

trailer manufacturers, truck fleet owners and the air breathing public. The proposal the agencies

have laid out today is largely shaped to maximize the environmental and fuel savings benefits of 

the program respecting the unique and varied nature of the regulated industries. In developing 

this proposal, we considered a number of alternatives that could have resulted in fewer or 

potentially greater GHG and fuel consumption reductions than the program we are proposing. 

This section summarizes the alternatives we considered. 

6.1 What Are the Alternatives that the Agencies Considered?

In developing alternatives, NHTSA must consider EISA's requirement for the MD/HD 

fuel efficiency program noted above. 49 U.S.C. 32902(k)(2) and (3) contain the following three 

requirements specific to the MD/HD vehicle fuel efficiency improvement program: (1) The 

program must be “designed to achieve the maximum feasible improvement”; (2) the various 

required aspects of the program must be appropriate, cost-effective, and technologically feasible 

for MD/HD vehicles; and (3) the standards adopted under the program must provide not less than 

four model years of lead time and three model years of regulatory stability. In considering these 

various requirements, NHTSA will also account for relevant environmental and safety 

considerations.

Each of the alternatives proposed by NHTSA and EPA represents, in part, a different way 

the agencies could establish a HD program pursuant to EISA and the CAA. The agencies are 

proposing Alternative 6. The alternatives below represent a broad range of approaches under 

consideration for setting proposed HD vehicle fuel efficiency and GHG emissions standards. 

The alternatives that the agencies are proposing, in order of increasing fuel efficiency and GHG 

emissions reductions, are:

6.1.1 Alternative 1: No Action

A “no action” alternative assumes that the agencies would not issue a rule regarding a 

MD/HD fuel efficiency improvement program, and is considered to comply with National 

Environmental Policy Act (NEPA) and to provide an analytical baseline against which to 

compare environmental impacts of the other regulatory alternatives.1 The agencies refer to this 

as the “No Action Alternative” or as a “no increase” or “baseline” alternative.

Deleted: Agencies

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-3

Table 6-1 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 1 (Baseline) [gallons/100 

miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups and 

Vans - gasoline 6.7 6.6 6.6 6.6 6.6 6.6

HD Pickups and 

Vans- diesel 6.9 6.9 6.9 6.9 6.9 6.9

Vocational –

gasoline 11.4 11.3 11.3 11.3 11.3 11.3

Vocational –

diesel 10.2 10.2 10.2 10.2 10.2 10.2

Comb. tractors 20.2 20.2 20.2 20.2 20.2 20.2

As described in Chapter 5, this no-action alternative is considered the reference case.

6.1.2 Alternative 2: Engine Only

The EPA currently regulates heavy-duty engines, i.e., engine manufacturers, rather than 

the vehicle as a whole, in order to control criteria emissions.2

For this scenario, we assumed the following CO

Under Alternative 2, the agencies

would similarly set engine performance standards for each vehicle class, Class 2b through Class 

8, and would specify an engine cell test procedure, as EPA currently does for criteria pollutants. 

HD engine manufacturers would be responsible for ensuring that each engine could meet the 

applicable vehicle class engine performance standard when tested in accordance with the 

specified engine cell test procedure. Engine manufacturers could improve HD engines by 

applying the combinations of fuel efficiency improvements and GHG emissions reduction

technologies to the engine that they deem best achieve that result.

2 reductions stated in Table 6-2.

Table 6-2 Estimated Possible Reductions in Engine CO2

GVWR CLASS

Emission Rates in Alternative 2

FUEL MODEL YEARS CO2

HHD (8a-8b)

REDUCTION FROM 

REFERENCE CASE

Diesel 2014-2016 3%

2017+ 6%

MHD (6-7) and LHD 4-5 Diesel 2014-2016 5%

2017+ 9%

Gasoline 2016+ 5%

LHD 2b-3 Gasoline 2016+ 5%

Diesel 2016+ 9%

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Table 6-3 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 2 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.6 6.6 6.3 6.3 6.3

HD Pickups 

and Vansdiesel6.9 6.9 6.9 6.3 6.3 6.3

Vocational –

gasoline 11.4 11.3 11.3 10.8 10.8 10.8

Vocational –

diesel 10.2 9.9 9.9 9.9 9.7 9.7

Comb. tractors 20.2 19.6 19.6 19.6 19.0 19.0

6.1.3 Alternative 3: Class 8 Combination Tractors

Combination tractors consume the largest fraction of fuel within the medium- and heavyduty truck segment. Tractors also offer significant potential for fuel savings due to the high 

annual mileage and high vehicle speed of typical trucks within this segment, as compared to 

annual mileage and average speeds/duty cycles of other vehicle classes. This alternative would 

set performance standards for both the engine of Class 8 vehicles and the overall vehicle 

efficiency performance for the Class 8 combination tractor segment. Under Alternative 3, the 

agencies would set an engine performance standard, as discussed under Alternative 2, for Class 8 

tractors. In addition, Class 8 combination tractor manufacturers would be required to meet an 

overall vehicle performance standard by making various non-engine fuel saving technology 

improvements. These non-engine fuel efficiency and GHG emissions improvements could be 

accomplished, for example, by a combination of improvements to aerodynamics, lowering tire 

rolling resistance, decreasing vehicle mass (weight), reducing fuel use at idle, or by adding 

intelligent vehicle technologies.3 Compliance with the overall vehicle standard could be 

determined using a computer model that would simulate overall vehicle fuel efficiency given a 

set of vehicle component inputs. Using this compliance approach, the Class 8 vehicle 

manufacturer would supply certain vehicle characteristics (relating to the categories of 

technologies noted immediately above) that would serve as model inputs. The agencies would 

supply a standard Class 8 vehicle engine's contribution to overall vehicle efficiency, making the 

engine component a constant for purposes of compliance with the overall vehicle performance 

standard, such that compliance with the overall vehicle standard could only be achieved via 

efficiency improvements to non-engine vehicle components. Thus, vehicle manufacturers could 

use any combination of improvements of the non-engine technologies that they believe would 

best achieve the Class 8 overall vehicle performance standard. This alternative in NHTSA’s 

scoping notice involves regulating Class 8 combination tractors only. For this scenario, we 

assumed the following CO2 reductions stated in Table 6-4 and road load improvements stated in 

Table 6-5.

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6-5

Table 6-4 Estimated Possible Reductions in Class 8 Engine CO2

GVWR CLASS

Emission Rates in Alternative 3

FUEL MODEL YEARS CO2

HHD (8a-8b)

REDUCTION 

FROM REFERENCE 

CASE

Diesel 2014-2016 3%

2017+ 6%

Table 6-5 Estimated Reductions in Rolling Resistance and Aerodynamic Drag Coefficients for Model Years

2014 and Later in Alternative 3

TRUCK TYPE REDUCTION IN TIRE 

ROLLING RESISTANCE 

COEFFICIENT FROM 2010 

MY

REDUCTION IN 

AERODYNAMIC DRAG 

COEFFICIENT FROM 

2010 MY

Combination long-haul 8.4% 7.2%

Combination short-haul 7.0% 5.3%

To run MOVES for this alternative, the “samplevehiclepopulation” table was altered such 

that only the Class 8 tractors would be output in the combination long-haul and combination 

short-haul source types. These source types normally include Class 7 trucks also. Since 

MOVES outputs results by source/vehicle type and not engine class, two runs were performed 

for combination tractors. The first run included the database with the above changes and with 

the Class 7 population set to zero. The second run did not include the above changes but with 

the Class 8 population set to zero. The results from these two runs gave Class 8 combination 

tractors affected by this alternative and Class 7 combination tractors not affected by this 

alternative. The two runs were combined, preserving the total Class 7/8 combination tractor 

population, while applying the changes only to the Class 8 combination tractors. 

For the purpose of this analysis, it was assumed that 100 percent of Class 8 combination 

long-haul tractors model year 2014 and later use APUs during extended idling. This assumption 

is based on the expectation that manufacturers will use APUs to meet the vehicle GHG standard 

for Class 8 combination long-haul tractors.

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Draft Regulatory Impact Analysis 

6-6

Table 6-6 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 3 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.6 6.6 6.6 6.6 6.6

HD Pickups 

and Vansdiesel6.9 6.9 6.9 6.9 6.9 6.9

Vocational –

gasoline 11.4 11.3 11.3 11.3 11.3 11.3

Vocational –

diesel 10.2 10.2 10.2 10.2 10.2 10.2

Comb. tractors 20.2 18.7 18.7 18.7 18.2 18.2

6.1.4 Alternative 4: Engines and Class 7 and 8 Tractors

This alternative combines Alternative 2 with Alternative 3, and additionally would set an 

overall vehicle efficiency performance standard for Class 7 tractors. This alternative would, 

thus, set standards for all HD engines and would set overall vehicle performance standards for 

Class 7 and 8 tractors, as described for Class 8 combination tractors under Alternative 3. Class 7 

tractors make up a small percent of the tractor market, approximately 9 percent. 4 Though the 

segment is currently small, the agencies believe the inclusion of this class of vehicles would help 

prevent a potential class shifting, as noted in the NAS panel report.5

The engine CO2 reductions are described in Table 6-2, and the road load reductions are 

described in Table 6-7. A separate MOVES run was not performed for this scenario since it can 

be taken from Alternative 2 and Alternative 6 (described below). The pre-2014 model year 

inventories were taken from the baseline run results. The MY2014+ Class 7/8 combination 

tractor inventories were taken from the Alternative 6 run results, and the MY2014+ numbers for 

the remainder of the heavy-duty vehicles were taken from the Alternative 2 results. It was 

assumed that 100 percent of Class 7/8 combination long-haul tractors model year 2014 and later 

use APUs during extended idling. This assumption is based on the expectation that 

manufacturers will use APUs to meet the vehicle GHG standard for combination long-haul 

tractors.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-7

Table 6-7 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 4 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.6 6.6 6.3 6.3 6.3

HD Pickups 

and Vansdiesel6.9 6.9 6.9 6.3 6.3 6.3

Vocational –

gasoline 11.4 11.3 11.3 10.8 10.8 10.8

Vocational –

diesel 10.2 9.9 9.9 9.9 9.7 9.7

Comb. tractors 20.2 18.5 18.5 18.5 17.9 17.9

6.1.5 Alternative 5: Engines, Class 7 and 8 Tractors, and HD Pickup Trucks 

and Vans

This alternative builds on Alternative 4 through the addition of an overall vehicle 

efficiency performance standard for HD Pickup Trucks and Vans (or work trucks). Therefore, 

under this alternative, the agencies would set engine performance standards for each HD vehicle 

class, and would also set overall vehicle performance standards for Class 7 and 8 tractors, as well 

as for HD Pickup Trucks and Vans. Compliance for the HD pickup trucks and vans would be 

determined through a fleet averaging process similar to determining passenger car and light truck 

compliance with CAFE standards.

This is a combination of Alternative 4 with the addition of HD pickup trucks and vans. 

As with Alterative 4, a separate MOVES run was not performed. The pre-2014 model year 

inventories were taken from the baseline run results. The MY2014+ Class 7/8 combination 

tractor and HD pickup truck and van inventories were taken from the Alternative 6 run results, 

and the MY2014+ numbers for the remainder of the heavy-duty vehicles were taken from the 

Alternative 2 results. It was assumed that 100 percent of Class 7/8 combination long-haul 

tractors model year 2014 and later use APUs during extended idling.

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Draft Regulatory Impact Analysis 

6-8

Table 6-8 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 5 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.5 6.5 6.4 6.2 6.0

HD Pickups 

and Vansdiesel6.9 6.8 6.7 6.5 6.3 5.9

Vocational –

gasoline 11.4 11.3 11.3 10.8 10.8 10.8

Vocational –

diesel 10.2 9.9 9.9 9.9 9.7 9.7

Comb. tractors 20.2 18.5 18.5 18.5 17.9 17.9

6.1.6 Alternative 6: Engines, Tractors, and Class 2b through 8 Trucks. 

Alternative 6 represents the agencies’ preferred approach. This alternative would set 

engine efficiency standards, engine GHG emissions standards, overall vehicle fuel efficiency 

standards, and overall vehicle GHG emissions standards for HD pickup trucks and vans and the 

remaining Class 2b through Class 8 trucks and the engines installed in them. This alternative 

essentially sets fuel efficiency and GHG emissions performance standards for both the engines 

and the overall vehicles in the entire heavy-duty truck sector. Compliance with each vehicle 

class's engine performance standard would be determined as discussed in the description of 

Alternative 2. Compliance with the tractor and vocational vehicle classes' overall vehicle 

performance standard (Class 3 through 8 trucks) would be determined as discussed in the 

description of Alternative 3. Compliance for the Class 2b and 3 pickup trucks and vans would be 

determined as described in Alternative 5.

This is the proposed rule. Details regarding this alternative are included in Chapter 5.

Table 6-9 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 6 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.5 6.5 6.4 6.2 6.0

HD Pickups 

and Vansdiesel6.9 6.8 6.7 6.5 6.3 5.9

Vocational –

gasoline 11.4 11.3 11.3 10.7 10.7 10.7

Vocational –

diesel 10.2 9.7 9.7 9.7 9.3 9.3

Comb. tractors 20.2 18.5 18.5 18.5 17.9 17.9

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-9

The agencies also evaluated two scenarios related to Alternative 6 but with stringency 

levels which are 15 percent less stringent and 20 percent more stringent. These alternatives are 

referred to as Alternatives 6a and 6b.

6.1.6.1 Alternative 6a: Engines, Tractors, and Class 2b through 8 Trucks

Alternative 6a represents an alternative stringency level to the agencies’ preferred 

approach. Like Alternative 6, this alternative would set GHG emissions and fuel efficiency 

standards for HD pickup trucks and vans and for Class 2b through 8 vocational vehicles and 

combination tractors and the engines installed in them. The difference between Alternative 6 and 

6a is the level of stringency for each of the proposed standards. Alternative 6a represents a 

stringency level which is approximately 15 percent less stringent than the preferred approach. 

The agencies calculated the stringency level in order to meet two goals. First, we desired to 

create an alternative that was closely related to the proposal (within 10-20 percent of the 

preferred alternative). Second we wanted an alternative that reflected removal of the last 

technology we believed manufacturers would add in order to meet the preferred alternative. In 

other words, we wanted an alternative that as closely as possible reflected the last increment in 

stringency prior to reaching our preferred alternative. In general, this could be thought of as 

removing the least cost effective (final) step. Please see Table 2.35 in RIA Chapter 2 for a list of 

all of the technologies, their cost and relative effectiveness. The resulting Alternative 6a is based 

on the same technologies used in Alternative 6 except as follows:

• The combination tractor standard would be based removal of the Advanced 

SmartWay aerodynamic package and weight reduction technologies which 

reduces the average combination tractor savings by approximately 1 percent. The 

road load impacts of this alternative are listed in Table 6-10.

• The HD pickup truck and van standard would be based on removal of 

aerodynamics which reduces the average truck savings by approximately 2

percent. The estimated total vehicle CO2

Table 6-11

reductions for this alternative are listed 

in .

• The vocational vehicle standard would be based on removal of low rolling 

resistant tires which reduces the average vehicle savings by approximately 2

percent. 

Table 6-10 Estimated Reductions in Rolling Resistance and Aerodynamic Drag Coefficients from Reference 

Case for Alternative 6a (Model Years 2014 and Later)
Draft Regulatory Impact Analysis 

6-10

TRUCK TYPE REDUCTION IN TIRE 

ROLLING RESISTANCE 

COEFFICIENT FROM 2010 

MY

REDUCTION IN 

AERODYNAMIC DRAG 

COEFFICIENT FROM 

2010 MY

Combination long-haul 8.4% 6.1%

Combination short-haul 7.0% 4.6%

Table 6-11 Estimated Total Vehicle CO2

GVWR 

CLASS

Reductions for HD Pickup Trucks and Vans

FUEL MODEL 

YEARS

CO2

LHD 2b-3

REDUCTION 

FROM BASELINE

Gasoline 2014 1.2%

2015 1.6%

2016 3.2%

2017 4.8%

2018+ 8.0%

Diesel 2014 1.99%

2015 2.6%

2016 5.2%

2017 7.8%

2018+ 13.0%

The estimated fleet-wide fuel efficiency for Alternative 6a is listed in Table 6-12.

Table 6-12 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 6a [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.6 6.5 6.4 6.3 6.1

HD Pickups 

and Vansdiesel

6.9 6.8 6.7 6.6 6.4 6.0

Vocational –

gasoline

11.4 11.3 11.3 10.8 10.8 10.8

Vocational –

diesel

10.2 9.9 9.9 9.9 9.7 9.7

Comb. tractors 20.2 18.5 18.5 18.5 17.9 17.9
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-11

6.1.6.2 Alternative 6b: Engines, Tractors, and Class 2b through 8 Trucks

Alternative 6b represents an alternative stringency level to the agencies’ preferred 

approach. Like Alternative 6, this alternative would set GHG emissions and fuel efficiency 

standards for HD pickup trucks and vans and for Class 2b through 8 vocational vehicles and 

combination tractors and the engines installed in them. The difference between Alternative 6 and 

6b is the level of stringency for each of the proposed standards. Alternative 6b represents a 

stringency level which is 20 percent more stringent than the preferred approach. The agencies 

calculated the stringency level based on similar goals as for Alternative 6a. Specifically, we 

wanted an alternative that would reflect an incremental improvement over the preferred 

alternative based on the technologies we thought most likely to be applied by manufacturers if a 

more stringent standard were set. In general, this could be thought of as adding the next most 

cost effective technology in each of the categories. However, as discussed in the feasibility 

discussion in Section III, we are not proposing this level of stringency because we do not believe 

that these technologies can be developed and introduced in the timeframe of this rulemaking. 

Reflecting that given unlimited resources it might be possible to introduce these technologies in 

this timeframe, but our inability to estimate what those real costs might be (e.g. to build new 

factories in only one to two years), we have denoted the cost for this alternative with a +c. The 

+c is intended to make clear that the cost estimates we are showing do not include additional 

costs related to pulling ahead the development and expanding manufacturing base for these 

technologies.. The resulting Alternative 6b is based on the same technologies used in 

Alternative 6 except as follows:

• The combination tractor standard would be based on the addition of rankine waste 

heat recovery to the HD engines installed in combination tractors with sleeper 

cabs. The agencies assumed a 12 kWh waste heat recovery system would reduce 

CO2 emissions by 6 percent at a cost of $8,400 per truck.6

Table 6-13

 The agencies applied 

waste heat recovery systems to 80 percent of sleeper cabs. The estimated 

reduction for this alternative is included in .

• HD pickup truck and van standard would be based on the addition of a 10 percent 

mass reduction which would increase the average truck savings by approximately 

2 percent over Alternative 6. The estimated total vehicle CO2

Table 6-14

reductions for this 

alternative are listed in .

• Vocational vehicle standard would be based on the addition hybrid powertrains to 

8 percent of the vehicles. The agencies assumed a 25 percent per vehicle GHG 

emissions and fuel consumption savings due to the hybrid with a cost of $30,000 

per vehicle.7

Table 6-15

 The agencies project the hybrid penetration for this alternative, as 

described in .

Table 6-13 Estimated Reductions in Engine CO2 Emission Rates from this Alternative 6b
Draft Regulatory Impact Analysis 

6-12

GVWR CLASS FUEL MODEL YEARS CO2

HHD (8a-8b) –

Combination tractors only

REDUCTION 

FROM REFERENCE 

CASE

Diesel 2014-2016 5%

2017+ 8%

Table 6-14 Estimated Total Vehicle CO2

GVWR 

CLASS

Reductions for HD Pickup Trucks and Vans for Alternative 6b

FUEL MODEL 

YEARS

CO2

LHD 2b-3

REDUCTION 

FROM BASELINE

Gasoline 2014 1.8%

2015 2.4%

2016 4.8%

2017 7.2%

2018+ 12.0%

Diesel 2014 2.61%

2015 3.4%

2016 6.8%

2017 10.2%

2018+ 17.0%

Table 6-15 Hybrid Penetration for Vocational Vehicles for Alternative 6b

MY 2014 MY 2017

Vocational Vehicles 0% 8%

The estimated fleet-wide fuel efficiency for Alternative 6b is listed in Table 6-16.

Table 6-16 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 6b [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.5 6.5 6.3 6.2 5.8
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-13

HD Pickups 

and Vansdiesel

6.9 6.7 6.7 6.4 6.2 5.7

Vocational –

gasoline

11.4 11.3 11.3 10.7 10.7 10.7

Vocational –

diesel

10.2 9.7 9.7 9.7 9.1 9.1

Comb. tractors 20.2 18.1 18.1 18.1 17.6 17.6

6.1.7 Alternative 7: Engines, Tractors, Trucks, and Trailers. 

This alternative builds on Alternative 6 by adding a performance standard for fuel 

efficiency and GHG emissions of commercial trailers. Therefore, this alternative would include

fuel efficiency performance standards and GHG emissions standards for Class 2b and 3 work 

truck and Class 3 through Class 8 vocational vehicle engines, and the performance standards for 

the overall fuel efficiency and GHG emissions of those vehicles, as described above. 

This is Alternative 6 with the addition of a regulation of trailers on combination tractors. 

All assumptions are the same as Alternative 6 except for road load. This alternative would result 

in further reductions in drag coefficient and rolling resistance coefficient from the MY 2010 

baseline. Table 6-17 describes the road load reductions.

Table 6-17 Estimated Reductions in Rolling Resistance and Aerodynamic Drag Coefficients from Reference 

Case for Alternative 7 (Model Years 2014 and Later)

TRUCK TYPE REDUCTION IN TIRE 

ROLLING RESISTANCE 

COEFFICIENT FROM 2010 

MY

REDUCTION IN 

AERODYNAMIC DRAG 

COEFFICIENT FROM 

2010 MY

Combination long-haul 10.7% 9.2%

Combination short-haul 10.0% 10.6%

Straight trucks, refuse trucks, 

motor homes, transit buses, 

and other vocational vehicles

10.0% 0%

Since the only difference between Alternatives 6 and 7 was the inclusion of trailers, a 

MOVES run involving only combination tractors with the above changes was performed. For all 

other heavy-duty vehicles, the results from Alternative 6 were used for Alternative 7. The fuel 

economy results for Alternative 7 are summarized in Table 6-18. 

The costs for the trailer program of Alternative 7 were derived based on the assumption 

that trailer aerodynamic improvements would cost $2,150 per trailer. This cost assumes side 

fairings and gap reducers and is based on the ICF cost estimate. The agencies applied the 

aerodynamic improvement to only box trailers, which represent approximately 60 percent of the 

trailer sales. The agencies used $624 per trailer for low rolling resistance based on the agencies’ 

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Draft Regulatory Impact Analysis 

6-14

estimate of $78 per tire in the tractor program. Lastly, the agencies assumed the trailer volume is 

equal to three times the tractor volume based on the 3:1 ratio of trailers to tractors in the market 

today. 

Table 6-18 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 7 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.5 6.5 6.4 6.2 6.0

HD Pickups 

and Vansdiesel6.9 6.8 6.7 6.5 6.3 5.9

Vocational –

gasoline 11.4 11.3 11.3 10.7 10.7 10.7

Vocational –

diesel 10.2 9.7 9.7 9.7 9.3 9.3

Comb. tractors 20.2 18.2 18.2 18.2 17.7 17.7

6.1.8 Alternative 8: Engines, Tractors, Trucks, and Trailers with Hybrid 

Powertrains

Alternative 8 includes all elements of Alternative 7, plus the application of hybrid

powertrains to the pickup trucks, vans, vocational vehicles, and tractors by the 2014 and the 

2017 MY. The agencies set the hybrid penetration for each class, as described in Table 6-19. 

The agencies do not believe that it is possible to achieve hybrid technology penetration rates at or 

even near these levels in the timeframe of this rulemaking. However, we believe it is useful to 

consider what a future standard based on the use of such advanced technologies could achieve. 

As with Alternative 6b, we include a +c in our cost estimates for this alternative to reflect 

additional costs not estimated by the agencies. The agencies assumed a 25 percent reduction to 

CO2 emissions and fuel consumption, based on the findings of the NAS report.8 The agencies 

also project a cost of $30,000 per vehicle for the vocational vehicles and combination tractors, 

which is the median value described in the NAS report for the vocational vehicles and tractors. 

The agencies are projecting a cost of $9,000 per vehicle for the HD pickup trucks and vans, 

again based on the NAS report.9

Table 6-19: Hybrid Penetration by Vehicle Class

MY 2014 MY 2017

HD Pickup Trucks & Vans 10,000 units 50%

Vocational Vehicles 10,000 units 50%

Combination tractors 0% 0%

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-15

Since the only difference between Alternatives 7 and 8 was the penetration of hybrid 

technology in the vocational vehicle and HD pickup and van categories, a MOVES run involving 

only vocational vehicles and HD pickups and vans was performed. In vocational vehicles, EPA 

assumed that hybrid technology would be applied only in diesel-fueled trucks. In HD pickups 

and vans, EPA assumed that hybrid technology would be evenly divided between diesel and 

gasoline vehicles. The fuel economy results for Alternative 8 are summarized in Table 6-20.

Table 6-20 Estimated Fleet-Wide Fuel Efficiency by Model Year for Alternative 8 [gallons/100 miles]

MY 2010-2013 MY 2014 MY 2015 MY 2016 MY 2017 MY 2018

HD Pickups 

and Vans -

gasoline

6.7 6.5 6.5 6.4 5.5 5.2

HD Pickups 

and Vansdiesel6.9 6.8 6.7 6.5 5.5 5.1

Vocational –

gasoline 11.4 11.3 11.3 10.7 10.7 10.7

Vocational –

diesel 10.2 9.6 9.6 9.6 8.0 8.0

Comb. tractors 20.2 18.2 18.2 18.2 17.7 17.7

6.2 How Do These Alternatives Compare in Overall GHG Emissions 

Reductions and Fuel Efficiency and Cost?

The agencies analyzed all ten alternatives through MOVES to evaluate the impact of each 

proposed alternative, as shown in Table 6-21. The table contains both the total savings for each 

alternative, along with the contribution from each truck class.

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6-16

Table 6-21: Annual CO2 and Oil Savings in 2030 and 2050

DOWNSTREAM CO2 OIL SAVINGS (BILLION

SAVINGS (MMT) GALLONS)

2030 2050 2030 2050

Alt. 1 0 0 0 0

Alt. 2 - Total 29 46 2.9 4.6

Tractors 19 27 1.8 2.6

HD Pickup Trucks 4 7 0.4 0.7

Vocational Vehicles 6 13 0.6 1.2

Alt. 3 – Total 35 50 3.4 4.9

Tractors 35 50 3.4 4.9

HD Pickup Trucks 0 0 0 0

Vocational Vehicles 0 0 0 0

Alt. 4 – Total 50 76 5.0 7.5

Tractors 40 57 3.9 5.6

HD Pickup Trucks 4 7 0.4 0.7

Vocational Vehicles 6 13 0.6 1.2

Alt. 5 – Total 54 82 5.4 8.2

Tractors 40 57 3.9 5.6

HD Pickup Trucks 8 13 0.8 1.3

Vocational Vehicles 6 13 0.6 1.2

Alt. 6a – Total 52 79 5.1 7.8

Tractors 39 56 3.8 5.5

HD Pickup Trucks 7 11 0.7 1.1

Vocational Vehicles 6 13 0.6 1.2

Preferred – Total 58 91 5.8 9.0

Tractors 40 57 3.9 5.6

HD Pickup Trucks 8 13 0.8 1.3

Vocational Vehicles 10 21 1.0 2.1

Alt. 6b – Total 68 107 6.7 10.6

Tractors 46 65 4.5 6.4

HD Pickup Trucks 9 15 1.0 1.6

Vocational Vehicles 13 27 1.3 2.6

Alt. 7 - Total 62 96 6.1 9.5

Tractors 40 57 3.9 5.6

HD Pickup Trucks 8 13 0.8 1.3

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-17

Vocational Vehicles 10 21 1.0 2.1

Trailers 4 5 0.4 0.5

Alt. 8 - Total 86 142 8.4 14.2

Tractors 40 57 3.9 5.6

HD Pickup Trucks 16 25 1.6 2.7

Vocational Vehicles 26 55 2.5 5.4

Trailers 4 5 0.4 0.5

The aggregate technology costs for each alternative are included in Table 6-22.

Table 6-22: Technology Cost Projections for the Alternativesa

TECHNOLOGY COSTS (2008$ 

MILLIONS)

2030 2050

Alt. 1 $0 $0

Alt. 2 - Total $532 $749 

Tractors $119 $157 

HD Pickup Trucks $235 $273 

Vocational Vehicles $178 $319 

Alt. 3 – Total $708 $938 

Tractors $708 $938

HD Pickup Trucks $0 $0

Vocational Vehicles $0 $0

Alt. 4 – Total $1,155 $1,574

Tractors $742 $982

HD Pickup Trucks $235 $273 

Vocational Vehicles $178 $319 

Alt. 5 – Total $1,882 $2,420

Tractors $742 $982

HD Pickup Trucks $962 $1,119

Vocational Vehicles $178 $319 

Alt. 6a – Total $1,592 $2,041

Tractors $487 $645

HD Pickup Trucks $927 $1,078

Vocational Vehicles $178 $319

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Draft Regulatory Impact Analysis 

6-18

Preferred – Total $1,945 $2,537

Tractors $742 $982

HD Pickup Trucks $962 $1,119

Vocational Vehicles $241 $436 

Alt. 6b – Total $4,984+c $7,575+c

Tractors $1,375+c $1,819+c

HD Pickup Trucks $1,301+c $1,514+c

Vocational Vehicles $2,307+c $4,241+c

Alt. 7 - Total $2,885 $3,740 

Tractors $742 $982

HD Pickup Trucks $962 $1,119 

Vocational Vehicles $241 $436 

Trailers $910 $1,203 

Alt. 8 - Total $35,477 +c $59,000+c

Tractors $742 $982 

HD Pickup Trucks $7,760 +c $8,809+c

Vocational Vehicles $26,065+c $48,006+c

Trailers $910 $1,203 

a

The downstream impacts of NO

The +c is intended to make clear that the cost estimates we are showing do not include additional costs 

related to pulling ahead the development and expanding manufacturing base for these technologies.

x

Table 6-23

, CO, PM, and VOC emissions for each of the primary 

alternatives are included in .

Table 6-23 Downstream Impacts Relative to Alternative 1 of Key Non-GHGs for Each Alterative in 2030

NOX CO PM2.5 VOC

Alt. 1 0% 0% 0% 0%

Alt. 2 0.60% 0.32% 0.47% -0.26%

Alt. 3 -20.2% -2.3% 6.8% -17.1%

Alt. 4 -20.5% -2.0% 7.4% -17.5%

Alt. 5 -20.5% -2.0% 7.4% -17.6%

Alt. 6a -20.5% -2.0% 7.4% -17.5%

Preferred -20.6% -2.0% 7.4% -17.7%

Alt. 6b -20.8% -2.0% 7.4% -17.9%

Alt. 7 -20.9% -2.0% 7.3% -17.8%

Alt. 8 -20.9% -2.0% 7.3% -17.8%

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Results of Proposed and 

Alternative Standards

6-19

1 NEPA requires agencies to consider a “no action” alternative in their NEPA analyses and to compare the effects of 

not taking action with the effects of the reasonable action alternatives to demonstrate the different environmental 

effects of the action alternatives. See 40 CFR 1502.2(e), 1502.14(d).CEQ has explained that “[T]he regulations 

require the analysis of the no action alternative even if the agency is under a court order or legislative command to 

act. This analysis provides a benchmark, enabling decision makers to compare the magnitude of environmental 

effects of the action alternatives. It is also an example of a reasonable alternative outside the jurisdiction of the 

agency which must be analyzed. [See 40 CFR 1502.14(c).] * * * Inclusion of such an analysis in the EIS is 

necessary to inform Congress, the public, and the President as intended by NEPA. [See 40 CFR 1500.1(a).]'' Forty 

Most Asked Questions Concerning CEQ's National Environmental Policy Act Regulations, 46 FR 18026 (1981) 

(emphasis added).

References

2 There are several reasons for this approach. In many cases the engine and chassis are produced by different 

manufacturers and it is more efficient to hold a single entity responsible. Also, testing an engine cell is more 

accurate and repeatable than testing a whole vehicle.

3 See the MD/HD NAS Report for discussions of the potential fuel efficiency improvement technologies that can be 

applied to each of these vehicle components. MD/HD NAS Report, supra note 9, Chapter 5.

4 MJ Bradley. Heavy Duty Market Analysis. 2009. 5 NAS. Page 152.

6 TIAX. 2009. Page 4-20.

7 NAS Report. Page 146.

8 NAS Report. Page 146.

9 NAS Report. Page 146.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Cost per Ton

7-1

CHAPTER 7: TRUCK COSTS AND COSTS PER TON OF GHG EMISSIONS 

REDUCED 7-2

7.1 Costs Associated with the Proposed Program ............................................................... 7-2

7.1.1 Technology Costs per Truck................................................................................. 7-2

7.1.2 Annual Costs of the Proposal................................................................................ 7-4

7.2 Cost per Ton of GHG Emissions Reduced..................................................................... 7-5

7.3 Impacts of Reduction in Fuel Consumption .................................................................. 7-7

7.3.1 Gallons Reduced under the Proposal................................................................... 7-7

7.3.2 Monetized Fuel Savings......................................................................................... 7-8

7.4 Key Parameters Used in the Estimation of Costs and Fuel Savings............................ 7-8

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¶
Draft Regulatory Impact Analysis 

7-2

Chapter 7: Truck Costs and Costs per Ton of GHG 

7.1 Costs Associated with the Proposed Program

In this section, the agencies present our estimate of the costs associated with the proposed 

program. The presentation here summarizes the costs associated with new technology expected 

to be added to meet the proposed GHG and fuel consumption standards, including hardware 

costs to comply with the air conditioning (A/C) leakage program. The analysis summarized here 

provides our estimate of incremental costs on a per truck basis and on an annual total basis. 

The presentation here summarizes the best estimate by EPA and NHTSA staff as to the 

technology mix expected to be employed for compliance. For details behind the cost estimates 

associated with individual technologies, the reader is directed to Section III of the preamble and 

to Chapter 2 of the draft RIA. 

With respect to the cost estimates presented here, the agencies note that, because these 

estimates relate to technologies which are in most cases already available, these cost estimates 

are technically robust.

7.1.1 Technology Costs per Truck

For the HD pickup trucks and vans, the agencies have used a methodology consistent 

with that used for our recent light-duty joint rulemaking since most of the technologies expected 

for HD pickup trucks and vans is consistent with that expected for the larger light-duty trucks. 

The cost estimates presented in the recent light-duty joint rulemaking were then scaled upward to 

account for the larger weight, towing capacity, and work demands of the trucks in these heavier 

classes. For details on that scaling process and the resultant costs for individual technologies, the 

reader is directed to Section III of the preamble and to Chapter 2 of the draft RIA. Note also that 

all cost estimates have been updated to 2008 dollars for this analysis while the recent light-duty 

joint rulemaking was presented in 2007 dollars.1

For the loose heavy-duty gasoline engines, we have used engine-related costs from the 

HD pickup truck and van estimates since the loose heavy-duty gasoline engines are essentially 

the same engines as those sold into the HD pickup truck and van market. 

 

For heavy-duty diesel engines, the agencies have estimated costs using a different 

methodology than that employed in the recent light-duty joint rulemaking. In the recent lightduty joint rulemaking, the fixed costs were included in the hardware costs via an indirect cost 

multiplier. As such, the hardware costs presented in that analysis, and in the cost estimates for 

HD pickup trucks and vans and HD gasoline engines, included both the actual hardware and the 

associated fixed costs. For this analysis, some of the fixed costs are estimated separately for HD

diesel engines and are presented separately from the technology costs. These fixed costs are 

referred to as “Other Engineering Costs” as shown in Table 7-2 and described in the text 

surrounding that table. Importantly, once totaled both methodologies account for all the costs 

associated with the proposal. As noted above, all costs are presented in 2008 dollars.

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Chapter 2 of the draft RIA. 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Cost per Ton

7-3

The estimates of vehicle compliance costs cover the years leading up to – 2012 and 2013 

– and including implementation of the program – 2014 through 2018. Also presented are costs 

for the years following implementation to shed light on the long term (2022 and later) cost 

impacts of the program. The year 2022 was chosen here consistent with the recent light-duty 

joint rulemaking. That year was considered long term in that analysis because the short-term and 

long-term markup factors described shortly below are applied in five year increments with the 

2012 through 2016 implementation span and the 2017 through 2021 span both representing the 

short-term. Since many of the costs used in this analysis are based on costs in the recent lightduty joint rulemaking analysis, consistency with that analysis seems appropriate. 

Individual technology cost estimates are presented in Chapter 2 of this draft RIA, and 

account for both the direct and indirect costs incurred. As described fully in Chapter 2 of this 

draft RIA, the agencies have also considered the impacts of manufacturer learning on the 

technology cost estimates. 

The technology cost estimates discussed in Section III of the preamble and detailed in 

Chapter 2 of the draft RIA are used to build up technology package cost estimates. For each 

engine and truck category, a single package for each was developed capable of complying with 

the proposed standards and the costs for each package was generated. The technology packages 

and package costs are discussed in more detail in Chapter 2 of the draft RIA. The compliance 

cost estimates take into account all credits and trading programs and include costs associated 

with air conditioning controls. Table 7-1 presents the average incremental costs per truck for this 

proposal. For HD pickups and vans, costs increase as the standards become more stringent in 

2014 through 2018. Following 2018, costs then decrease going forward as learning effects result 

in decreased costs for individual technologies. By 2022, the long term ICMs take effect and 

costs decrease yet again. For vocational vehicles, cost trends are more difficult to discern as 

diesel engines begin adding technology in 2014, gasoline engines begin adding technology in 

2016, and the trucks themselves begin adding technology in 2014. With learning effects the 

costs, in general, decrease each year except for the heavy-duty gasoline engine changes in 2016. 

Long term ICMs take effect in 2022 to provide more cost reductions. For combination tractors, 

costs generally decrease each year due to learning effects with the exception of 2017 when the 

engines placed in sleeper cab tractors add turbo compounding. Following that, learning impacts 

result in cost reductions and the long term ICMs take effect in 2022 for further cost reductions. 

By 2030 and later, cost per truck estimates remain constant for all categories. Regarding the 

long term ICMs taking effect in 2022, the agencies consider this the point at which some indirect 

costs decrease or are no longer considered attributable to the program (e.g., warranty costs go

down). Costs per truck remain essentially constant thereafter.

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Draft Regulatory Impact Analysis 

7-4

Table 7-1 Estimated Hardware Cost per Truck (2008 dollars)

YEAR HD PICKUPS 

& VANS

VOCATIONAL COMBINATION 

TRACTORS

2014 $225 $374 $5,896

2015 $292 $367 $5,733

2016 $567 $400 $5,480

2017 $848 $392 $6,150

2018 $1,411 $359 $5,901

2020 $1,406 $343 $5,661

2030 $1,350 $280 $4,686

2040 $1,350 $275 $4,686

2050 $1,350 $275 $4,686

As noted above, the fixed costs were estimated separately from the hardware costs for 

the HD diesel engines. Those fixed costs are not included in Table 7-1. The agencies have 

estimated the R&D costs at $6.75 million per manufacturer per year for five years and the new 

test cell costs (to accommodate measurement of N2

Table 7-1

O emissions) at $100,000 per manufacturer. 

These costs apply individually for LHD, MHD and HHD diesel engines. Given the 14

manufacturers impacted by the proposed standards, 11 of which are estimated to sell both MHD

and HHD diesel engines and 3 of which are estimated to sell LHD diesel engines, we have 

estimated a five year annual R&D cost of $168.8 million dollars (2 x 11 x $6.75 million plus 3 x 

$6.75 million for each year 2012-2016) and a one-time test cell cost of $2.5 million dollars (2 x 

11 x $100,000 plus 3 x $100,000 in 2013). Estimating annual sales of HD diesel engines at 

roughly 600,000 units results in roughly $280 per engine per year for five years beginning in 

2012 and ending in 2016. Again, these costs are not reflected in , but are included in 

Table 7-2 as “Other Engineering Costs”.

The certification and compliance program costs, for all engine and truck types, are 

estimated at $4.4 million per year and are expected to continue indefinitely. These costs are 

detailed in the “Draft Supporting Statement for Information Collection Request” which is 

contained in the docket for this rule.2

7.1.2 Annual Costs of the Proposal

 Estimating annual sales of heavy-duty trucks at roughly 

1.5 million units would result in $3 per engine/truck per year. These costs are not reflected in 

Table VIII-1, but are included in Table VIII-2 as “Compliance Program” costs.

The costs presented here represent the incremental costs for newly added technology to 

comply with the proposal. Together with the projected increases in truck sales, the increases in 

per-truck average costs shown in Table 7-1 above result in the total annual costs presented in 

Table 7-2 below. Note that the costs presented in Table 7-2 do not include the savings that 

would occur as a result of the improvements to fuel consumption. Those impacts are presented 

in Chapter 7.2 below.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Cost per Ton

7-5

Table 7-2 Annual Costs Associated with the Proposal ($Millions of 2008 dollars)

YEAR HD PICKUPS 

& VANS

VOCATIONAL COMBINATION 

TRACTORS

OTHER

ENGINEERING 

COSTS

COMPLIANCE 

PROGRAM 

COSTS A

ANNUAL 

COSTS

2012 $0 $0 $0 $169 $0 $169

2013 $0 $0 $0 $171 $4.4 $176

2014 $177 $208 $720 $169 $4.4 $1,278

2015 $213 $211 $713 $169 $4.4 $1,310

2016 $404 $237 $693 $169 $4.4 $1,507

2017 $601 $240 $792 $0 $4.4 $1,638

2018 $1,011 $226 $776 $0 $4.4 $2,019

2020 $971 $229 $777 $0 $4.4 $1,981

2030 $962 $241 $742 $0 $4.4 $1,950

2040 $1,038 $332 $850 $0 $4.4 $2,224

2050 $1,119 $436 $982 $0 $4.4 $2,541

NPV, 

3%

$18,770 $5,728 $16,707 $787 $98 $42,089

NPV, 

7%

$9,657 $2,977 $9,114 $718 $56 $22,522

A “Other Engineering Costs” are described in Section 7.1.1. These costs represent fixed costs for heavy-duty 

diesel engines.

7.2 Cost per Ton of GHG Emissions Reduced

The agencies have calculated the cost per ton of GHG (CO2-equivalent, or CO2

Table 7-3

e) 

reductions associated with this rule using the above costs and the GHG emissions reductions 

described in Chapter 5. These values are presented in through Table 7-6 for HD 

pickup trucks & vans, Vocational vehicles, Combination tractors and the Proposal (i.e., all 

engines and trucks), respectively. The cost per metric ton of GHG emissions reductions has been 

calculated in the years 2020, 2030, 2040, and 2050 using the annual vehicle compliance costs 

and emission reductions for each of those years. The value in 2050 represents the long-term cost 

per ton of the emissions reduced. The agencies have also calculated the cost per metric ton of 

GHG emission reductions including the savings associated with reduced fuel consumption 

(presented below in Tables 7-3 through 7-6). This latter calculation does not include the other 

benefits associated with this proposal such as those associated with criteria pollutant reductions 

or energy security benefits (discussed in Chapter 9). By including the fuel savings in the cost 

estimates, the cost per ton is less than $0 since the estimated value of fuel savings outweighs the 

program costs. Also of interest is the cumulative cost per ton of cumulative CO2

Table 7-7

e reductions. 

These values are shown in both with and without cumulative fuel savings.

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Draft Regulatory Impact Analysis 

7-6

Table 7-3 Annual Cost per Metric Ton of CO2

YEAR

e Reduced – HD Pickup Trucks & Vans (2008 dollars)

PROGRAM 

COST

FUEL 

SAVINGS 

(POST-TAX)

CO2 COST PER 

TON 

(WITHOUT 

FUEL 

SAVINGS)

E 

REDUCED

COST PER 

TON (WITH 

FUEL 

SAVINGS)

2020 $1,000 $1,000 4 $270 $0

2030 $1,000 $3,000 10 $100 -$200

2040 $1,000 $4,600 13 $70 -$270

2050 $1,100 $5,800 16 $70 -$290

Table 7-4 Annual Cost per Metric Ton of CO2

YEAR

e Reduced – Vocational Vehicles (2008 dollars)

PROGRAM 

COST

FUEL 

SAVINGS 

(POST-TAX)

CO2 COST PER 

TON 

(WITHOUT 

FUEL 

SAVINGS)

E 

REDUCED

COST PER 

TON (WITH 

FUEL 

SAVINGS)

2020 $200 $1,500 6 $30 -$220

2030 $200 $3,700 13 $20 -$280

2040 $300 $6,400 19 $20 -$320

2050 $400 $8,900 26 $20 -$330

Table 7-5 Annual Cost per Metric Ton of CO2

YEAR

e Reduced – Combination Tractors (2008 dollars)

PROGRAM 

COST

FUEL 

SAVINGS 

(POST-TAX)

CO2 COST PER 

TON 

(WITHOUT 

FUEL 

SAVINGS)

E 

REDUCED

COST PER 

TON (WITH 

FUEL 

SAVINGS)

2020 $800 $6,700 26 $30 -$230

2030 $700 $14,500 48 $10 -$280

2040 $800 $19,800 59 $10 -$320

2050 $1,000 $23,700 67 $10 -$340

Table 7-6 Annual Cost per Metric Ton of CO2

YEAR

e Reduced – Proposal (2008 dollars)

PROGRAM 

COST

FUEL 

SAVINGS 

(POST-TAX)

CO2 COST PER 

TON 

(WITHOUT 

FUEL 

SAVINGS)

E 

REDUCED

COST PER 

TON (WITH 

FUEL 

SAVINGS)

2020 $2,000 $9,300 35 $50 -$210

2030 $1,900 $21,200 71 $30 -$270

2040 $2,200 $30,800 91 $20 -$310

2050 $2,500 $38,400 109 $20 -$330

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Cost per Ton

7-7

Table 7-7 Cumulative Cost per Cumulative Metric Ton of CO2

YEAR

e Reduced (2008 dollars)

PROGRAM 

COST

FUEL SAVINGS 

(POST-TAX)

CO2 COST PER 

TON 

(WITHOUT 

FUEL 

SAVINGS)

E 

REDUCED

COST PER 

TON (WITH 

FUEL 

SAVINGS)

2020 $12,100 $32,200 133 $90 -$150

2030 $31,300 $197,100 700 $40 -$240

2040 $52,300 $462,100 1,525 $30 -$270

2050 $76,200 $811,100 2,536 $30 -$290

7.3 Impacts of Reduction in Fuel Consumption

7.3.1 Gallons Reduced under the Proposal

The new CO2 standards will result in significant improvements in the fuel efficiency of 

affected trucks. Drivers of those trucks will see corresponding savings associated with reduced 

fuel expenditures. The agencies have estimated the impacts on fuel consumption for the tailpipe 

CO2 standards. To do this, fuel consumption is calculated using both current CO2 emission 

levels and the new CO2 standards. The difference between these estimates represents the net 

savings from the CO2

The expected impacts on fuel consumption are shown in 

standards. Note that the total number of miles that vehicles are driven 

each year is different under each of the control case scenarios than in the reference case due to 

the “rebound effect,” which is discussed in Chapter 9. EPA also notes that drivers who drive 

more than our average estimates for vehicle miles traveled (VMT) will experience more fuel 

savings; drivers who drive less than our average VMT estimates will experience less fuel 

savings. 

Table 7-8. The gallons shown in 

this table reflect impacts from the new CO2

Table 7-8 Fuel Consumption Reductions of the Proposal (Million gallons)

standards and include increased consumption 

resulting from the rebound effect.

GASOLINE DIESEL

YEAR HD 

PICKUPS 

& VANS

VOC COMB TOTAL

HD 

PICKUPS 

& VANS

VOC COMB TOTAL

2012 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

2013 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

2014 1.8 0.0 0.0 1.8 5.0 48 264 316

2015 5.2 0.0 0.0 5.2 12 93 519 624

2016 15 5.5 0.0 20 30 136 765 931

2017 31 11 0.0 42 57 221 1,115 1,393

2018 60 16 0.0 76 106 301 1,454 1,861

2020 114 26 0.0 140 199 445 2,079 2,723

2030 310 63 0.0 373 529 953 3,930 5,412

2040 421 75 0.0 496 715 1,483 4,805 7,004

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Draft Regulatory Impact Analysis 

7-8

2050 507 96 0.0 603 862 2,008 5,583 8,453

7.3.2 Monetized Fuel Savings

Using the fuel consumption estimates presented above, the agencies can calculate the 

monetized fuel savings associated with the proposed standards. To do this, reduced fuel 

consumption is multiplied in each year by the corresponding estimated average fuel price in that 

year, using the reference case taken from the AEO 2010. These estimates do not account for the 

significant uncertainty in future fuel prices; the monetized fuel savings will be understated if 

actual fuel prices are higher (or overstated if fuel prices are lower) than estimated. The Annual 

Energy Outlook (AEO) is a standard reference used by NHTSA and EPA and many other 

government agencies to estimate the projected price of fuel. This has been done using both the 

pre-tax and post-tax fuel prices. Since the post-tax fuel prices are the prices paid at fuel pumps, 

the fuel savings calculated using these prices represent the savings consumers would see. The 

pre-tax fuel savings are those savings that society would see. These results are shown in Table 

7-9. Note that in Chapter 9, the overall benefits and costs of the rule are presented and, for that 

reason, only the pre-tax fuel savings are presented there. 

Table 7-9 Estimated Monetized Fuel Savings ($Millions of 2008 dollars)

YEAR FUEL SAVINGS (PRE-TAX) FUEL SAVINGS (POST-TAX)

2014 $700 $800

2015 $1,400 $1,700

2016 $2,200 $2,700

2017 $3,600 $4,200

2018 $5,100 $5,900

2020 $8,100 $9,300

2030 $19,000 $21,200

2040 $28,100 $30,800

2050 $35,400 $38,400

NPV, 3% $352,300 $391,200

NPV, 7% $152,600 $170,600

7.4 Key Parameters Used in the Estimation of Costs and Fuel Savings

This section briefly presents some of the parameters used in generating costs and fuel 

savings associated with the proposal. Table 7-10 presents estimated sales of complying 

vehicles by calendar year. Table 7-11 presents VMT by age for both the reference and control 

cases where the control case includes rebound VMT. Table 7-12 presents AEO 2010 reference 

case fuel prices.

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Deleted: 389,900

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Cost per Ton

7-9

Table 7-10 Estimated Calendar Year Sales by Truck Type

Calendar Year HD Pickup Trucks 

& Vans

Vocational 

Vehicles

Combination 

Tractors Total

2014 785,224 554,944 122,156 1,462,324

2015 730,253 572,641 124,351 1,427,245

2016 712,729 591,876 126,440 1,431,046

2017 708,456 611,137 128,766 1,448,359

2018 716,957 630,101 131,577 1,478,635

2019 704,550 648,241 134,620 1,487,411

2020 690,599 665,920 137,301 1,493,820

2021 681,055 680,838 139,145 1,501,038

2022 673,953 695,073 140,712 1,509,737

2023 677,291 712,386 142,742 1,532,419

2024 686,412 732,078 145,195 1,563,686

2025 699,525 752,320 147,728 1,599,573

2026 705,204 772,814 150,169 1,628,186

2027 708,467 793,455 152,401 1,654,323

2028 707,309 814,131 154,387 1,675,827

2029 701,934 835,498 156,312 1,693,743

2030 712,494 858,568 158,403 1,729,465

2031 717,910 943,009 160,297 1,821,216

2032 723,365 967,709 162,090 1,853,165

2033 728,866 994,722 164,132 1,887,720

2034 734,401 1,021,818 166,274 1,922,493

2035 739,983 1,050,049 168,696 1,958,728

2036 745,610 1,079,070 171,153 1,995,832

2037 751,277 1,108,902 173,645 2,033,824

2038 756,984 1,139,565 176,174 2,072,723

2039 762,738 1,171,088 178,740 2,112,566

2040 768,538 1,203,492 181,343 2,153,373

2041 774,377 1,236,803 183,984 2,195,163

2042 780,262 1,271,045 186,664 2,237,970

2043 786,193 1,306,246 189,382 2,281,821

2044 792,165 1,342,427 192,140 2,326,732

2045 798,187 1,379,623 194,938 2,372,748

2046 804,251 1,417,862 197,778 2,419,890

2047 810,366 1,457,166 200,658 2,468,190

2048 816,526 1,497,578 203,580 2,517,684

2049 822,727 1,539,108 206,544 2,568,379

2050 828,980 1,581,806 209,553 2,620,338
Draft Regulatory Impact Analysis 

7-10

Table 7-11 Annual Vehicle Miles Traveled by Age for the Reference and Control Cases

Vehicle 

Age

Reference Control

HD Pickup 

Trucks & Vans

Vocational 

Vehicles

Combination 

Tractors

HD Pickup 

Trucks & Vans

Vocational 

Vehicles

Combination 

Tractors

0 13,518 20,762 137,756 13,655 20,892 138,734

1 13,412 19,092 127,350 13,547 19,212 128,254

2 13,263 17,552 117,323 13,397 17,661 118,157

3 13,072 16,118 107,887 13,204 16,218 108,653

4 12,838 14,804 99,347 12,967 14,896 100,052

5 12,569 13,586 91,299 12,696 13,670 91,947

6 12,270 12,472 83,394 12,394 12,549 83,986

7 11,945 11,428 75,595 12,066 11,499 76,132

8 11,593 10,489 68,476 11,711 10,554 68,962

9 11,216 9,650 62,087 11,330 9,710 62,528

10 10,817 8,936 56,300 10,926 8,991 56,700

11 10,405 8,263 51,145 10,510 8,313 51,508

12 9,986 7,659 46,367 10,086 7,705 46,697

13 9,566 7,126 41,939 9,663 7,170 42,237

14 9,152 6,626 37,762 9,244 6,667 38,030

15 8,747 6,168 34,079 8,835 6,205 34,321

16 8,355 5,747 30,738 8,439 5,782 30,956

17 8,037 5,368 27,800 8,118 5,401 27,998

18 7,741 5,050 25,019 7,820 5,080 25,197

19 7,470 4,741 22,587 7,546 4,769 22,748

20 7,227 4,436 20,369 7,300 4,463 20,514

21 7,020 4,202 18,486 7,090 4,227 18,618

22 6,853 3,972 16,700 6,922 3,995 16,818

23 6,733 3,773 15,078 6,801 3,795 15,185

24 6,669 3,581 13,619 6,736 3,603 13,716

25 6,661 3,397 12,294 6,728 3,417 12,381

26 6,707 3,239 11,101 6,775 3,258 11,179

27 6,765 3,118 10,044 6,833 3,136 10,116

28 6,824 2,967 9,089 6,893 2,984 9,153

29 6,884 2,853 8,202 6,954 2,869 8,260

30 6,946 2,766 7,417 7,016 2,782 7,470
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Vehicle Cost per Ton

7-11

Table 7-12 AEO 2010 Reference Case Fuel Prices (2008 dollars/gallon)

Pre-Tax Post-Tax

Vehicle Age Gasoline Diesel Gasoline Diesel

2014 $2.61 $2.61 $3.02 $3.05

2015 $2.67 $2.71 $3.07 $3.14

2016 $2.74 $2.82 $3.14 $3.24

2017 $2.81 $2.90 $3.20 $3.32

2018 $2.86 $2.99 $3.25 $3.41

2019 $2.90 $3.05 $3.29 $3.47

2020 $2.95 $3.09 $3.34 $3.51

2021 $2.98 $3.12 $3.37 $3.53

2022 $3.03 $3.17 $3.41 $3.58

2023 $3.06 $3.20 $3.44 $3.60

2024 $3.08 $3.21 $3.45 $3.61

2025 $3.12 $3.25 $3.49 $3.65

2026 $3.16 $3.29 $3.53 $3.68

2027 $3.20 $3.33 $3.57 $3.71

2028 $3.25 $3.37 $3.62 $3.76

2029 $3.30 $3.43 $3.66 $3.81

2030 $3.32 $3.46 $3.68 $3.83

2031 $3.36 $3.52 $3.72 $3.89

2032 $3.41 $3.58 $3.77 $3.94

2033 $3.45 $3.62 $3.80 $3.99

2034 $3.49 $3.68 $3.85 $4.04

2035 $3.56 $3.75 $3.91 $4.11

2036 $3.59 $3.76 $3.94 $4.12

2037 $3.62 $3.78 $3.97 $4.13

2038 $3.65 $3.79 $3.99 $4.14

2039 $3.68 $3.81 $4.02 $4.15

2040 $3.71 $3.82 $4.05 $4.17

2041 $3.74 $3.83 $4.08 $4.18

2042 $3.77 $3.85 $4.11 $4.19

2043 $3.80 $3.86 $4.13 $4.20

2044 $3.83 $3.88 $4.16 $4.21

2045 $3.86 $3.89 $4.19 $4.23

2046 $3.89 $3.91 $4.22 $4.24

2047 $3.92 $3.92 $4.25 $4.25

2048 $3.95 $3.94 $4.28 $4.26

2049 $3.98 $3.95 $4.31 $4.28

2050 $4.01 $3.97 $4.34 $4.29

Formatted: Centered, Indent: First line: 0"
Draft Regulatory Impact Analysis 

7-12

References

1 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards; Final 

Rule 75 Fed. Reg. 25323 (May 7, 2010).

2 “Draft Supporting Statement for Information Collection Request,” Control of Greenhouse Gas Emissions from 

New Motor Vehicles: Proposed Heavy-Duty Engine and Vehicle Standards, EPA ICR Tracking Number 2394.01.
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Environmental and Health 

Impacts

8-1

CHAPTER 8: HEALTH AND ENVIRONMENTAL IMPACTS.................... 8-2

8.1 Health and Environmental Effects of Non-GHG Pollutants........................................ 8-2

8.1.1 Health Effects Associated with Exposure to Non-GHG Pollutants................... 8-2

8.1.2 Environmental Effects Associated with Exposure to Non-GHG Pollutants... 8-21

8.2 Air Quality Impacts of Non-GHG Pollutants.............................................................. 8-34

8.2.1 Introduction.......................................................................................................... 8-34

8.2.2 Current Levels of Pollutants............................................................................... 8-34

8.2.3 Impacts of Future Air Quality............................................................................ 8-36

8.3 Quantified and Monetized Non-GHG Health and Environmental Impacts............. 8-39

8.3.1 Human Health and Environmental Impacts..................................................... 8-39

8.3.2 Monetized Impacts............................................................................................... 8-43

8.3.3 Other Unquantified Health and Environmental Impacts................................ 8-44

8.4 Changes in Atmospheric CO2 Concentrations, Global Mean Temperature, Sea Level 

Rise, and Ocean pH Associated with the Proposal’s GHG Emissions Reductions............ 8-46

8.4.1 Introduction.......................................................................................................... 8-46

8.4.2 Estimated Projected Change in Atmospheric CO2 Concentrations, Global 

Mean Surface Temperatures and Sea Level Rise............................................................. 8-47

8.4.3 Estimated Projected Change in Ocean pH........................................................ 8-52

8.4.4 Summary of Climate Analyses............................................................................ 8-53

8.5 Monetized CO2 Impacts ................................................................................................ 8-54

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Draft Regulatory Impact Analysis 

8-2

Chapter 8: Health and Environmental Impacts

8.1 Health and Environmental Effects of Non-GHG Pollutants

8.1.1 Health Effects Associated with Exposure to Non-GHG Pollutants

In this section we will discuss the health effects associated with non-GHG pollutants, 

specifically: particulate matter, ozone, nitrogen oxides (NOX), sulfur oxides (SOX

8.1.1.1 Background on Particulate Matter

), carbon 

monoxide and air toxics. These pollutants would not be directly regulated by the standards, but 

the standards would affect emissions of these pollutants and precursors. Reductions in these 

pollutants would be co-benefits of the final rulemaking (that is, benefits in addition to the 

benefits of reduced GHGs).

Particulate matter (PM) is a generic term for a broad class of chemically and physically 

diverse substances. It can be principally characterized as discrete particles that exist in the 

condensed (liquid or solid) phase spanning several orders of magnitude in size. Since 1987, EPA 

has delineated that subset of inhalable particles small enough to penetrate to the thoracic region 

(including the tracheobronchial and alveolar regions) of the respiratory tract (referred to as 

thoracic particles). Current National Ambient Air Quality Standards (NAAQS) use PM2.5 as the 

indicator for fine particles (with PM2.5 referring to particles with a nominal mean aerodynamic 

diameter less than or equal to 2.5 μm), and use PM10 as the indicator for purposes of regulating 

the coarse fraction of PM10 (referred to as thoracic coarse particles or coarse-fraction particles; 

generally including particles with a nominal mean aerodynamic diameter greater than 2.5 μm 

and less than or equal to 10 μm, or PM10-2.5

Particles span many sizes and shapes and consist of numerous different chemicals. 

Particles originate from sources and are also formed through atmospheric chemical reactions; the 

former are often referred to as “primary” particles, and the latter as “secondary” particles. In 

addition, there are also physical, non-chemical reaction mechanisms that contribute to secondary 

particles. Particle pollution also varies by time of year and location and is affected by several 

weather-related factors, such as temperature, clouds, humidity, and wind. A further layer of 

complexity comes from a particle’s ability to shift between solid/liquid and gaseous phases, 

which is influenced by concentration, meteorology, and temperature.

). Ultrafine particles (UFPs) are a subset of fine 

particles, generally less than 100 nanometers (0.1 μm) in aerodynamic diameter. 

Fine particles are produced primarily by combustion processes and by transformations of 

gaseous emissions (e.g., SOX, NOX and volatile organic compounds (VOCs)) in the atmosphere. 

The chemical and physical properties of PM2.5 may vary greatly with time, region, meteorology 

and source category. Thus, PM2.5 may include a complex mixture of different chemicals

including sulfates, nitrates, organic compounds, elemental carbon and metal compounds. These 

particles can remain in the atmosphere for days to weeks and travel through the atmosphere 

hundreds to thousands of kilometers.1

Deleted: rule

 

Deleted: VOCs)
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Environmental and Health 

Impacts

8-3

8.1.1.2 Particulate Matter Health Effects

This section provides a summary of the health effects associated with exposure to 

ambient concentrations of PM. A The information in this section is based on the information and 

conclusions in the Integrated Science Assessment (ISA) for Particulate Matter (December 2009) 

prepared by EPA’s Office of Research and Development (ORD).

B

The ISA concludes that ambient concentrations of PM are associated with a number of 

adverse health effects.C The ISA characterizes the weight of evidence for different health effects 

associated with three PM size ranges: PM2.5, PM10-2.5

8.1.1.2.1 Effects Associated with Short-term Exposure to PM

, and UFPs. The discussion below 

highlights the ISA’s conclusions pertaining to these three size fractions of PM, considering 

variations in both short-term and long-term exposure periods.

The ISA concludes that cardiovascular effects and all-cause cardiovascular- and 

respiratory-related mortality are causally associated with short-term exposure to PM

2.5

2.5.

2

 It also 

concludes that respiratory effects are likely to be causally associated with short-term exposure to 

PM2.5

8.1.1.2.2 Effects Associated with Long-term Exposure to PM

, including respiratory emergency department (ED) visits and hospital admissions for 

chronic obstructive pulmonary disease (COPD), respiratory infections, and asthma; and 

exacerbation of respiratory symptoms in asthmatic children.

The ISA concludes that there are causal associations between long-term exposure to 

PM

2.5

2.5 and cardiovascular effects, such as the development/progression of cardiovascular disease 

(CVD), and premature mortality, particularly from cardiopulmonary causes.3 It also concludes 

that long-term exposure to PM2.5 is likely to be causally associated with respiratory effects, such 

as reduced lung function growth, increased respiratory symptoms, and asthma development. The 

ISA characterizes the evidence as suggestive of a causal relationship for associations between 

long-term PM2.5 exposure and reproductive and developmental outcomes, such as low birth 

weight and infant mortality. It also characterizes the evidence as suggestive of a causal 

relationship between PM2.5

 

A Personal exposure includes contributions from many different types of particles, from many sources, and in many 

different environments. Total personal exposure to PM includes both ambient and nonambient components; and 

both components may contribute to adverse health effects.

and cancer incidence, mutagenicity, and genotoxicity.

B

 The ISA is available at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546 C The ISA evaluates the health evidence associated with different health effects, assigning one of five “weight of 

evidence” determinations: causal relationship, likely to be a causal relationship, suggestive of a causal relationship, 

inadequate to infer a causal relationship, and not likely to be a causal relationship. For definitions of these levels of 

evidence, please refer to Section 1.5 of the ISA. 
Draft Regulatory Impact Analysis 

8-4

8.1.1.2.3 Effects Associated with PM

The ISA summarizes evidence related to short-term exposure to PM

10-2.5

10-2.5. PM10-2.5 is the 

fraction of PM10 particles that is larger than PM2.5.

4

 The ISA concludes that available evidence 

is suggestive of a causal relationship between short-term exposures to PM10-2.5 and 

cardiovascular effects, such as hospitalizations for ischemic heart disease. It also concludes that 

the available evidence is suggestive of a causal relationship between short-term exposures to 

PM10-2.5 and respiratory effects, including respiratory-related ED visits and hospitalizations and 

pulmonary inflammation. The ISA also concludes that the available literature suggests a causal 

relationship between short-term exposures to PM10-2.5 and mortality. Data are inadequate to 

draw conclusions regarding health effects associated with long-term exposure to PM10-2.5.

5

8.1.1.2.4 Effects Associated with Ultrafine Particles

The ISA concludes that the evidence is suggestive of a causal relationship between shortterm exposures to UFPs and cardiovascular effects, including changes in heart rhythm and 

vasomotor function (the ability of blood vessels to expand and contract).6

The ISA also concludes that there is suggestive evidence of a causal relationship between 

short-term UFP exposure and respiratory effects. The types of respiratory effects examined in 

epidemiologic studies include respiratory symptoms and asthma hospital admissions, the results 

of which are not entirely consistent. There is evidence from toxicological and controlled human 

exposure studies that exposure to UFPs may increase lung inflammation and produce small 

asymptomatic changes in lung function. Data are inadequate to draw conclusions regarding 

health effects associated with long-term exposure to UFPs.

 

7

8.1.1.3 Background on Ozone

Ground-level ozone pollution is typically formed by the reaction of VOCs and NOX in 

the lower atmosphere in the presence of sunlight. These pollutants, often referred to as ozone 

precursors, are emitted by many types of pollution sources such as highway and nonroad motor 

vehicles and engines, power plants, chemical plants, refineries, makers of consumer and 

commercial products, industrial facilities, and smaller area sources.

The science of ozone formation, transport, and accumulation is complex. Ground-level 

ozone is produced and destroyed in a cyclical set of chemical reactions, many of which are 

sensitive to temperature and sunlight. When ambient temperatures and sunlight levels remain 

high for several days and the air is relatively stagnant, ozone and its precursors can build up and 

result in more ozone than typically occurs on a single high-temperature day. Ozone can be 

transported hundreds of miles downwind of precursor emissions, resulting in elevated ozone 

levels even in areas with low VOC or NOX

The highest levels of ozone are produced when both VOC and NO

emissions. 

X emissions are 

present in significant quantities on clear summer days. Relatively small amounts of NOX enable 

ozone to form rapidly when VOC levels are relatively high, but ozone production is quickly 

limited by removal of the NOX. Under these conditions NOX reductions are highly effective in 

reducing ozone while VOC reductions have little effect. Such conditions are called “NOX

Deleted: D

-
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Environmental and Health 

Impacts

8-5

limited.” Because the contribution of VOC emissions from biogenic (natural) sources to local 

ambient ozone concentrations can be significant, even some areas where man-made VOC 

emissions are relatively low can be NOX

Ozone concentrations in an area also can be lowered by the reaction of nitric oxide (NO) 

with ozone, forming nitrogen dioxide (NO

-limited.

2); as the air moves downwind and the cycle 

continues, the NO2 forms additional ozone. The importance of this reaction depends, in part, on 

the relative concentrations of NOX, VOC, and ozone, all of which change with time and location. 

When NOX levels are relatively high and VOC levels relatively low, NOX forms inorganic 

nitrates (i.e., particles) but relatively little ozone. Such conditions are called “VOC-limited.” 

Under these conditions, VOC reductions are effective in reducing ozone, but NOX reductions can 

actually increase local ozone under certain circumstances. Even in VOC-limited urban areas, 

NOX reductions are not expected to increase ozone levels if the NOX reductions are sufficiently 

large. Rural areas are usually NOX-limited, due to the relatively large amounts of biogenic VOC 

emissions in such areas. Urban areas can be either VOC- or NOX

8.1.1.4 Ozone Health Effects

-limited, or a mixture of both, 

in which ozone levels exhibit moderate sensitivity to changes in either pollutant.

Exposure to ambient ozone contributes to a wide range of adverse health effects. E 

These health effects are well documented and are critically assessed in the EPA ozone air quality 

criteria document (ozone AQCD) and EPA staff paper.8,9

Ozone-related health effects include lung function decrements, respiratory symptoms, 

aggravation of asthma, increased hospital and emergency room visits, increased asthma 

medication usage, and a variety of other respiratory effects. Cellular-level effects, such as 

inflammation of lungs, have been documented as well. In addition, there is suggestive evidence 

of a contribution of ozone to cardiovascular-related morbidity and highly suggestive evidence 

that short-term ozone exposure directly or indirectly contributes to non-accidental and 

cardiopulmonary-related mortality, but additional research is needed to clarify the underlying 

mechanisms causing these effects. In a recent report on the estimation of ozone-related 

premature mortality published by the National Research Council (NRC), a panel of experts and 

reviewers concluded that short-term exposure to ambient ozone is likely to contribute to 

premature deaths and that ozone-related mortality should be included in estimates of the health 

benefits of reducing ozone exposure.

 We are relying on the data and 

conclusions in the ozone AQCD and staff paper, regarding the health effects associated with 

ozone exposure.

10

 

E

 Human exposure to ozone varies over time due to changes in ambient ozone concentration and because people 

move between locations which have notable different ozone concentrations. Also, the amount of ozone delivered to 

the lung is not only influenced by the ambient concentrations but also by the individuals breathing route and rate.

 People who appear to be more susceptible to effects 

associated with exposure to ozone include children, asthmatics and the elderly. Those with 
Draft Regulatory Impact Analysis 

8-6

greater exposures to ozone, for instance due to time spent outdoors (e.g., children and outdoor 

workers), are also of concern.

Based on a large number of scientific studies, EPA has identified several key health 

effects associated with exposure to levels of ozone found today in many areas of the country. 

Short-term (1 to 3 hours) and prolonged exposures (6 to 8 hours) to ambient ozone 

concentrations have been linked to lung function decrements, respiratory symptoms, increased 

hospital admissions and emergency room visits for respiratory problems.11, 12, 13, 14, 15, 16 

Repeated exposure to ozone can increase susceptibility to respiratory infection and lung 

inflammation and can aggravate preexisting respiratory diseases, such as asthma.17, 18, 19, 20, 21

Repeated exposure to sufficient concentrations of ozone can also cause inflammation of the lung, 

impairment of lung defense mechanisms, and possibly irreversible changes in lung structure, 

which over time could affect premature aging of the lungs and/or the development of chronic 

respiratory illnesses, such as emphysema and chronic bronchitis.22, 23, 24, 25

Children and adults who are outdoors and active during the summer months, such as 

construction workers, are among those most at risk of elevated ozone exposures.26 Children and 

outdoor workers tend to have higher ozone exposure because they typically are active outside, 

working, playing and exercising, during times of day and seasons (e.g., the summer) when ozone 

levels are highest.27 For example, summer camp studies in the Eastern United States and 

Southeastern Canada have reported statistically significant reductions in lung function in 

children who are active outdoors.28, 29, 30, 31, 32, 33, 34, 35 Further, children are more at risk of 

experiencing health effects from ozone exposure than adults because their respiratory systems 

are still developing. These individuals (as well as people with respiratory illnesses, such as 

asthma, especially asthmatic children) can experience reduced lung function and increased 

respiratory symptoms, such as chest pain and cough, when exposed to relatively low ozone levels 

during prolonged periods of moderate exertion.36, 37, 38, 39

8.1.1.5 Background on Nitrogen Oxides and Sulfur Oxides

Sulfur dioxide (SO2), a member of the sulfur oxide (SOX) family of gases, is formed 

from burning fuels containing sulfur (e.g., coal or oil), extracting gasoline from oil, or extracting 

metals from ore. Nitrogen dioxide (NO2) is a member of the nitrogen oxide (NOX) family of 

gases. Most NO2 is formed in the air through the oxidation of nitric oxide (NO) emitted when 

fuel is burned at a high temperature. SO2 andNO2

8.1.1.2

can dissolve in water droplets and further 

oxidize to form sulfuric and nitric acid which react with ammonia to form sulfates and nitrates, 

both of which are important components of ambient PM. The health effects of ambient PM are 

discussed in Section . NOX

8.1.1.4

along with non-methane hydrocarbons (NMHC) are the two 

major precursors of ozone. The health effects of ozone are covered in Section .

8.1.1.6 Health Effects of SO

This section provides an overview of the health effects associated with SO

2

2. Additional 

information on the health effects of SO2 can be found in the EPA Integrated Science Assessment 

for Sulfur Oxides.40 Following an extensive evaluation of health evidence from epidemiologic 

and laboratory studies, the U.S. EPA has concluded that there is a causal relationship between 

respiratory health effects and short-term exposure to SO2. The immediate effect of SO2 on the 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Environmental and Health 

Impacts

8-7

respiratory system in humans is bronchoconstriction. Asthmatics are more sensitive to the effects 

of SO2 likely resulting from preexisting inflammation associated with this disease. In laboratory 

studies involving controlled human exposures to SO2, respiratory effects have consistently been 

observed following 5-10 min exposures at SO2 concentrations ≥ 0.4 ppm in asthmatics engaged 

in moderate to heavy levels of exercise, with more limited evidence of respiratory effects among 

exercising asthmatics exposed to concentrations as low as 0.2-0.3 ppm. A clear concentrationresponse relationship has been demonstrated in these studies following exposures to SO2

In epidemiologic studies, respiratory effects have been observed in areas where the mean 

24-hour SO

at 

concentrations between 0.2 and 1.0 ppm, both in terms of increasing severity of respiratory 

symptoms and decrements in lung function, as well as the percentage of asthmatics adversely 

affected. 

2 levels range from 1 to 30 ppb, with maximum 1 to 24-hour average SO2 values 

ranging from 12 to 75 ppb. Important new multicity studies and several other studies have found 

an association between 24-hour average ambient SO2 concentrations and respiratory symptoms 

in children, particularly those with asthma. Generally consistent associations also have been 

observed between ambient SO2 concentrations and emergency department visits and 

hospitalizations for all respiratory causes, particularly among children and older adults (≥ 65 

years), and for asthma. A limited subset of epidemiologic studies have examined potential 

confounding by copollutants using multipollutant regression models. These analyses indicate 

that although copollutant adjustment has varying degrees of influence on the SO2 effect 

estimates, the effect of SO2 on respiratory health outcomes appears to be generally robust and 

independent of the effects of gaseous and particulate copollutants, suggesting that the observed 

effects of SO2

Consistent associations between short-term exposure to SO

on respiratory endpoints occur independent of the effects of other ambient air 

pollutants. 

2 and mortality have been 

observed in epidemiologic studies, with larger effect estimates reported for respiratory mortality 

than for cardiovascular mortality. While this finding is consistent with the demonstrated effects 

of SO2 on respiratory morbidity, uncertainty remains with respect to the interpretation of these 

associations due to potential confounding by various copollutants. The U.S. EPA has therefore 

concluded that the overall evidence is suggestive of a causal relationship between short-term 

exposure to SO2 and mortality. Significant associations between short-term exposure to SO2

and emergency department visits and hospital admissions for cardiovascular diseases have also 

been reported. However, these findings have been inconsistent across studies and do not provide 

adequate evidence to infer a causal relationship between SO2

8.1.1.7 Health Effects of NO

exposure and cardiovascular 

morbidity. 

Information on the health effects of NO

2

2 can be found in the EPA Integrated Science 

Assessment (ISA) for Nitrogen Oxides.41 The EPA has concluded that the findings of 

epidemiologic, controlled human exposure, and animal toxicological studies provide evidence 

that is sufficient to infer a likely causal relationship between respiratory effects and short-term 

NO2 exposure. The ISA concludes that the strongest evidence for such a relationship comes from 

epidemiologic studies of respiratory effects including symptoms, emergency department visits, 

and hospital admissions. The ISA also draws two broad conclusions regarding airway 
Draft Regulatory Impact Analysis 

8-8

responsiveness following NO2 exposure. First, the ISA concludes that NO2 exposure may 

enhance the sensitivity to allergen-induced decrements in lung function and increase the 

allergen-induced airway inflammatory response following 30-minute exposures of asthmatics to 

NO2 concentrations as low as 0.26 ppm. In addition, small but significant increases in nonspecific airway hyperresponsiveness were reported following 1-hour exposures of asthmatics to

0.1 ppm NO2. Second, exposure to NO2 has been found to enhance the inherent responsiveness 

of the airway to subsequent nonspecific challenges in controlled human exposure studies of 

asthmatic subjects. Enhanced airway responsiveness could have important clinical implications 

for asthmatics since transient increases in airway responsiveness following NO2 exposure have 

the potential to increase symptoms and worsen asthma control. Together, the epidemiologic and 

experimental data sets form a plausible, consistent, and coherent description of a relationship 

between NO2

Although the weight of evidence supporting a causal relationship is somewhat less certain 

than that associated with respiratory morbidity, NO

exposures and an array of adverse health effects that range from the onset of 

respiratory symptoms to hospital admission. 

2

8.1.1.8 Health Effects of Carbon Monoxide

has also been linked to other health 

endpoints. These include all-cause (nonaccidental) mortality, hospital admissions or emergency 

department visits for cardiovascular disease, and decrements in lung function growth associated 

with chronic exposure.

Information on the health effects of carbon monoxide (CO) can be found in the EPA

Integrated Science Assessment (ISA) for Carbon Monoxide.

42 The ISA concludes that ambient 

concentrations of CO are associated with a number of adverse health effects.F This section 

provides a summary of the health effects associated with exposure to ambient concentrations of 

CO.

G

Human clinical studies of subjects with coronary artery disease show a decrease in the 

time to onset of exercise-induced angina (chest pain) and electrocardiogram changes following 

CO exposure. In addition, epidemiologic studies show associations between short-term CO 

exposure and cardiovascular morbidity, particularly increased emergency room visits and 

hospital admissions for coronary heart disease (including ischemic heart disease, myocardial 

infarction, and angina). Some epidemiologic evidence is also available for increased hospital 

admissions and emergency room visits for congestive heart failure and cardiovascular disease as 

a whole. The ISA concludes that a causal relationship is likely to exist between short-term 

exposures to CO and cardiovascular morbidity. It also concludes that available data are 

 

 

F

 The ISA evaluates the health evidence associated with different health effects, assigning one of five “weight of 

evidence” determinations: causal relationship, likely to be a causal relationship, suggestive of a causal relationship, 

inadequate to infer a causal relationship, and not likely to be a causal relationship. For definitions of these levels of 

evidence, please refer to Section 1.6 of the ISA. 

G Personal exposure includes contributions from many sources, and in many different environments. Total personal 

exposure to CO includes both ambient and nonambient components; and both components may contribute to adverse 

health effects.
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inadequate to conclude that a causal relationship exists between long-term exposures to CO and 

cardiovascular morbidity. 

Animal studies show various neurological effects with in-utero CO exposure. Controlled 

human exposure studies report inconsistent neural and behavioral effects following low-level CO 

exposures. The ISA concludes the evidence is suggestive of a causal relationship with both 

short- and long-term exposure to CO and central nervous system effects.

A number of epidemiologic and animal toxicological studies cited in the ISA have 

evaluated associations between CO exposure and birth outcomes such as preterm birth or cardiac 

birth defects. The epidemiologic studies provide limited evidence of a CO-induced effect on 

preterm births and birth defects, with weak evidence for a decrease in birth weight. Animal 

toxicological studies have found associations between perinatal CO exposure and decrements in 

birth weight, as well as other developmental outcomes. The ISA concludes these studies are 

suggestive of a causal relationship between long-term exposures to CO and developmental 

effects and birth outcomes.

Epidemiologic studies provide evidence of effects on respiratory morbidity such as 

changes in pulmonary function, respiratory symptoms, and hospital admissions associated with 

ambient CO concentrations. A limited number of epidemiologic studies considered copollutants 

such as ozone, SO2

Finally, the ISA concludes that the epidemiologic evidence is suggestive of a causal 

relationship between short-term exposures to CO and mortality. Epidemiologic studies provide 

evidence of an association between short-term exposure to CO and mortality, but limited 

evidence is available to evaluate cause-specific mortality outcomes associated with CO exposure. 

In addition, the attenuation of CO risk estimates which was often observed in copollutant models 

contributes to the uncertainty as to whether CO is acting alone or as an indicator for other 

combustion-related pollutants. The ISA also concludes that there is not likely to be a causal 

relationship between relevant long-term exposures to CO and mortality.

, and PM in two-pollutant models and found that CO risk estimates were 

generally robust, although this limited evidence makes it difficult to disentangle effects attributed 

to CO itself from those of the larger complex air pollution mixture. Controlled human exposure 

studies have not extensively evaluated the effect of CO on respiratory morbidity. Animal studies 

at levels of 50-100 ppm CO show preliminary evidence of altered pulmonary vascular 

remodeling and oxidative injury. The ISA concludes that the evidence is suggestive of a causal 

relationship between short-term CO exposure and respiratory morbidity, and inadequate to 

conclude that a causal relationship exists between long-term exposure and respiratory morbidity. 

8.1.1.9 Health Effects of Air Toxics

Motor vehicle emissions contribute to ambient levels of air toxics known or suspected as 

human or animal carcinogens, or that have noncancer health effects. The population experiences 

an elevated risk of cancer and other noncancer health effects from exposure to air toxics.43 

These compounds include, but are not limited to, benzene, 1,3-butadiene, formaldehyde, 

acetaldehyde, acrolein, diesel particulate matter and exhaust organic gases, polycyclic organic 

matter (POM), and naphthalene. These compounds were identified as national or regional risk 

drivers in past National-scale Air Toxics Assessments (NATA) and have significant inventory 
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contributions from mobile sources. Although the 2002 NATA did not quantify cancer risks 

associated with exposure to diesel exhaust, EPA has concluded that diesel exhaust ranks with the 

other emissions that the 2002 NATA suggests pose the greatest relative risk. According to 

NATA for 2002, mobile sources were responsible for 47 percent of outdoor toxic emissions, over 

50 percent of the cancer risk, and over 80 percent of the noncancer hazard. Data from the 2002 

National Emissions Inventory (NEI), which is the basis for NATA, show that thirty percent of 

national diesel PM emissions are attributable to heavy-duty vehicles.44

Noncancer health effects can result from chronic,H subchronic,I or acuteJ inhalation 

exposures to air toxics, and include neurological, cardiovascular, liver, kidney, and respiratory 

effects as well as effects on the immune and reproductive systems. According to the 2002 

NATA, nearly the entire U.S. population was exposed to an average concentration of air toxics 

that has the potential for adverse noncancer respiratory health effects. This will continue to be 

the case in 2030, even though toxics concentrations will be lower.45

The NATA modeling framework has a number of limitations which prevent its use as the 

sole basis for setting regulatory standards. These limitations and uncertainties are discussed on 

the 2002 NATA website.

 

46

8.1.1.9.1 Diesel Exhaust PM

 Even so, this modeling framework is very useful in identifying air 

toxic pollutants and sources of greatest concern, setting regulatory priorities, and informing the 

decision making process.

Heavy-duty diesel engines emit diesel exhaust (DE), a complex mixture comprised of 

carbon dioxide, oxygen, nitrogen, water vapor, carbon monoxide, nitrogen compounds, sulfur 

compounds and numerous low-molecular-weight hydrocarbons. A number of these gaseous 

hydrocarbon components are individually known to be toxic including aldehydes, benzene and 

1,3-butadiene. The diesel particulate matter (DPM) present in diesel exhaust consists of fine 

particles (< 2.5μm), including a subgroup with a large number of ultrafine particles (< 0.1 μm). 

These particles have large surface areas which make them an excellent medium for adsorbing 

organics, and their small size makes them highly respirable and able to deposit deep in the lung. 

Diesel PM contains small quantities of numerous mutagenic and carcinogenic compounds 

associated with the particles (and also organic gases). In addition, while toxic trace metals 

emitted by heavy-duty diesel engines represent a very small portion of the national emissions of 

metals (less than one percent) and are a small portion of diesel PM (generally much less than one 

percent of diesel PM), we note that several trace metals of potential toxicological significance 

and persistence in the environment are emitted by diesel engines. These trace metals include 

chromium, manganese, mercury and nickel. In addition, small amounts of dioxins have been 

 

H Chronic exposure is defined in the glossary of the Integrated Risk Information (IRIS) database 

(http://www.epa.gov/iris) as repeated exposure by the oral, dermal, or inhalation route for more than approximately 

10% of the life span in humans (more than approximately 90 days to 2 years in typically used laboratory animal 

species).

I

 Defined in the IRIS database as exposure to a substance spanning approximately 10% of the lifetime of an 

organism.

J Defined in the IRIS database as exposure by the oral, dermal, or inhalation route for 24 hours or less. 
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measured in highway engine diesel exhaust, some of which may partition into the particulate 

phase. Dioxins are a major health concern but diesel engines are a minor contributor to overall 

dioxin emissions. 

Diesel exhaust varies significantly in chemical composition and particle sizes between 

different engine types (heavy-duty, light-duty), engine operating conditions (idle, accelerate, 

decelerate), and fuel formulations (high/low sulfur fuel). 47

A number of health studies have been conducted regarding diesel exhaust. These include

epidemiologic studies of lung cancer in groups of workers and animal studies focusing on noncancer effects specific to diesel exhaust exposure. Diesel exhaust PM (including the associated 

organic compounds which are generally high molecular weight hydrocarbon types but not the 

more volatile gaseous hydrocarbon compounds) is generally used as a surrogate measure for 

diesel exhaust.

 Also, there are emission differences 

between on-road and nonroad engines because the nonroad engines are generally of older 

technology. After being emitted, diesel exhaust undergoes dilution as well as chemical and 

physical changes in the atmosphere. The lifetime for some of the compounds present in diesel 

exhaust ranges from hours to days.

8.1.1.9.1.1 Potential Cancer Effects of Exposure to Diesel Exhaust

Exposure to diesel exhaust is of specific concern because it has been judged by EPA to 

pose a lung cancer hazard for humans at environmental levels of exposure.

EPA’s 2002 final “Health Assessment Document for Diesel Engine Exhaust” (the EPA 

Diesel HAD) classified exposure to diesel exhaust as likely to be carcinogenic to humans by 

inhalation at environmental exposures, in accordance with the revised draft 1996/1999 EPA 

cancer guidelines.48,49 In accordance with earlier EPA guidelines, exposure to diesel exhaust 

would similarly be classified as probably carcinogenic to humans (Group B1).50,51 A number of 

other agencies (National Institute for Occupational Safety and Health, the International Agency 

for Research on Cancer, the World Health Organization, California EPA, and the U.S.

Department of Health and Human Services) have made similar classifications.52, 53,54,55,56 The 

Health Effects Institute has prepared numerous studies and reports on the potential 

carcinogenicity of exposure to diesel exhaust.57,58,59

More specifically, the EPA Diesel HAD states that the conclusions of the document apply 

to diesel exhaust in use today including both on-road and nonroad engines. The EPA Diesel 

HAD acknowledges that the studies were done on engines with generally older technologies and 

that “there have been changes in the physical and chemical composition of some DE [diesel 

exhaust] emissions (onroad vehicle emissions) over time, though there is no definitive 

information to show that the emission changes portend significant toxicological changes.” 

 

For the Diesel HAD, EPA reviewed 22 epidemiologic studies on the subject of the 

carcinogenicity of exposure to diesel exhaust in various occupations, finding increased lung 

cancer risk, although not always statistically significant, in 8 out of 10 cohort studies and 10 out 

of 12 case-control studies which covered several industries. Relative risk for lung cancer, 

associated with exposure, ranged from 1.2 to 1.5, although a few studies show relative risks as 
Draft Regulatory Impact Analysis 

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high as 2.6. Additionally, the Diesel HAD also relied on two independent meta-analyses, which 

examined 23 and 30 occupational studies respectively, and found statistically significant 

increases of 1.33 to 1.47 in smoking-adjusted relative lung cancer risk associated with diesel 

exhaust. These meta-analyses demonstrate the effect of pooling many studies and in this case 

show the positive relationship between diesel exhaust exposure and lung cancer across a variety 

of diesel exhaust-exposed occupations.60,61,62

EPA generally derives cancer unit risk estimates to calculate population risk more 

precisely from exposure to carcinogens. In the simplest terms, the cancer unit risk is the 

increased risk associated with average lifetime exposure of 1 μg/m3

In the absence of a cancer unit risk, the Diesel HAD sought to provide additional insight 

into the significance of the diesel exhaust-cancer hazard by estimating possible ranges of risk 

that might be present in the population. An exploratory analysis was used to characterize a 

possible risk range by comparing a typical environmental exposure level for highway diesel 

sources to a selected range of occupational exposure levels. The occupationally observed risks 

were then proportionally scaled according to the exposure ratios to obtain an estimate of the 

possible environmental risk. If the occupational and environmental exposures are similar, the 

environmental risk would approach the risk seen in the occupational studies whereas a much 

higher occupational exposure indicates that the environmental risk is lower than the occupational 

risk. A comparison of environmental and occupational exposures showed that for certain 

occupations the exposures are similar to environmental exposures while, for others, they differ 

by a factor of about 200 or more.

. EPA concluded in the 

Diesel HAD that it is not currently possible to calculate a cancer unit risk for diesel exhaust due 

to a variety of factors that limit the current studies, such as a lack of standard exposure metric for 

diesel exhaust and the absence of quantitative exposure characterization in retrospective studies.

A number of calculations are involved in the exploratory analysis of a possible risk range, 

and these can be seen in the EPA Diesel HAD. The outcome was that environmental risks from 

diesel exhaust exposure could range from a low of 10-4 to 10-5 to as high as 10-3

, reflecting the 

range of occupational exposures that could be associated with the relative and absolute risk 

levels observed in the occupational studies. Because of uncertainties, the analysis acknowledged 

that the risks could be lower than 10-4 or 10-5

As mentioned in Section 

, and a zero risk from diesel exhaust exposure was 

not ruled out.

8.1.1.9, EPA recently assessed air toxic emissions and their 

associated risk (the National-Scale Air Toxics Assessment or NATA for 2002), and we 

concluded that diesel exhaust ranks with other emissions that the national-scale assessment 

suggests pose the greatest relative risk.63

In summary, even though EPA does not have a specific carcinogenic potency with which 

to accurately estimate the carcinogenic impact of exposure to diesel exhaust, the likely hazard to 

humans together with the potential for significant environmental risks leads us to conclude that 

This national assessment estimates average population 

inhalation exposures to DPM for nonroad as well as on-highway sources. These are the sum of 

ambient levels in various locations weighted by the amount of time people spend in each of the 

locations. 
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diesel exhaust emissions from heavy-duty diesel engines present public health issues of concern 

to this proposal.

8.1.1.9.1.2 Other Health Effects of Exposure to Diesel Exhaust

Noncancer health effects of acute and chronic exposure to diesel exhaust emissions are 

also of concern to the EPA. The Diesel HAD established an inhalation Reference Concentration 

(RfC) specifically based on animal studies of diesel exhaust exposure. An RfC is defined by 

EPA as “an estimate of a continuous inhalation exposure to the human population, including 

sensitive subgroups, with uncertainty spanning perhaps an order of magnitude, which is likely to 

be without appreciable risks of deleterious noncancer effects during a lifetime.” EPA derived the 

RfC from consideration of four well-conducted chronic rat inhalation studies showing adverse 

pulmonary effects.64,65,66,67 The diesel RfC is based on a “no observable adverse effect” level of 

144 μg/m3 that is further reduced by applying uncertainty factors of 3 for interspecies 

extrapolation and 10 for human variations in sensitivity. The resulting RfC derived in the Diesel 

HAD is 5 μg/m3

While there have been relatively few human studies associated specifically with the 

noncancer impact of exposure to DPM alone, DPM is a component of the ambient particles 

studied in numerous epidemiologic studies. The conclusion that health effects associated with 

ambient PM in general are relevant to DPM is supported by studies that specifically associate 

observable human noncancer health effects with exposure to DPM. As described in the Diesel 

HAD, these studies identified some of the same health effects reported for ambient PM, such as 

respiratory symptoms (cough, labored breathing, chest tightness, wheezing), and chronic 

respiratory disease (cough, phlegm, chronic bronchitis and suggestive evidence for decreases in 

pulmonary function). Symptoms of immunological effects such as wheezing and increased 

allergenicity are also seen. Studies in rodents, especially rats, show the potential for human 

inflammatory effects in the lung and consequential lung tissue damage from chronic diesel 

exhaust inhalation exposure. The Diesel HAD concludes “that acute exposure to DE [diesel 

exhaust] has been associated with irritation of the eye, nose, and throat, respiratory symptoms 

(cough and phlegm), and neurophysiological symptoms such as headache, lightheadedness, 

nausea, vomiting, and numbness or tingling of the extremities.”

for diesel exhaust as measured by DPM. This RfC does not consider allergenic 

effects such as those associated with asthma or immunologic effects. There is growing evidence 

that exposure to diesel exhaust can exacerbate these effects, but the exposure-response data is 

presently lacking to derive an RfC. The EPA Diesel HAD states, “With DPM [diesel particulate 

matter] being a ubiquitous component of ambient PM, there is an uncertainty about the adequacy 

of the existing DE [diesel exhaust] noncancer database to identify all of the pertinent DE-caused 

noncancer health hazards.”

68 There is also evidence for an 

immunologic effect such as the exacerbation of allergenic responses to known allergens and 

asthma-like symptoms.69,70,71

The Diesel HAD briefly summarizes health effects associated with ambient PM and 

discusses the PM

 

2.5 NAAQS. There is a much more extensive body of human data, which is also 

mentioned earlier in the health effects discussion for PM2.5 (Section 8.1.1.2 of this RIA), 

showing a wide spectrum of adverse health effects associated with exposure to ambient PM, of 

which diesel exhaust is an important component. The PM2.5 NAAQS is designed to provide 

protection from the non-cancer and premature mortality effects of PM2.5

Deleted: rule

as a whole.
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8.1.1.9.1.3 Ambient Levels of Diesel Exhaust PM

Because DPM is part of overall ambient PM and cannot be easily distinguished from 

overall PM, we do not have direct measurements of DPM in the ambient air. DPM 

concentrations are estimated using ambient air quality modeling based on DPM emission 

inventories. DPM concentrations were recently estimated as part of the 2002 NATA.

72

Concentrations of DPM were calculated at the census tract level in the 2002 NATA. 

 Ambient 

impacts of mobile source emissions were predicted using the Assessment System for Population 

Exposure Nationwide (ASPEN) dispersion model.

Table 8-1 below summarizes the distribution of ambient DPM concentrations at the national 

scale. The median DPM concentration calculated nationwide is 0.89 μg/m3

Figure 8-1

. Over 30% of the 

DPM and diesel exhaust organic gases can be attributed to onroad diesels. A map of ambient 

diesel PM concentrations is provided in . Areas with high median concentrations are 

clustered in the Northeast, Great Lake States, California, and the Gulf Coast States, and are also 

distributed throughout the rest of the U.S.

Figure 8-1 Estimated County Ambient Concentration of Diesel Particulate Matter

Formatted: Indent: First line: 0"

Formatted: Centered
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Table 8-1Distribution of Census Tract Ambient Concentrations of DPM at the National Scale in 2002 NATAa 

Nationwide 

(μg/m3

5

) th Percentile 0.21

25th Percentile 0.54

Median 0.89

75th Percentile 1.34

95th Percentile 2.63

Onroad 

Contribution to Mean

31%

Note:

a

8.1.1.9.1.4 Exposure to Diesel Exhaust PM

This table is generated from data contained in the diesel particulate matter Microsoft Access database file 

found in the Tract-Level Ambient Concentration Summaries section of the 2002 NATA webpage 

(http://www.epa.gov/ttn/atw/nata2002/tables.html). 

Exposure of people to diesel exhaust depends on their various activities, the time spent in 

those activities, the locations where these activities occur, and the levels of diesel exhaust 

pollutants in those locations. The major difference between ambient levels of diesel particulate 

and exposure levels for diesel particulate is that exposure levels account for a person moving 

from location to location, the proximity to the emission source, and whether the exposure occurs 

in an enclosed environment.

8.1.1.9.1.4.1 Occupational Exposures

Occupational exposures to diesel exhaust from mobile sources can be several orders of 

magnitude greater than typical exposures in the non-occupationally exposed population.

Over the years, diesel particulate exposures have been measured for a number of 

occupational groups resulting in a wide range of exposures from 2 to 1280 μg/m3

8.1.1.9.1.4.2 Elevated Concentrations and Ambient Exposures in Mobile Source 

Impacted Areas

for a variety of 

occupations. As discussed in the Diesel HAD, the National Institute of Occupational Safety and 

Health (NIOSH) has estimated a total of 1,400,000 workers are occupationally exposed to diesel 

exhaust from on-road and nonroad vehicles.

Regions immediately downwind of highways or truck stops may experience elevated 

ambient concentrations of directly-emitted PM2.5 from diesel engines. Due to the unique nature 

of highways and truck stops, emissions from a large number of diesel engines are concentrated in 

a small area. Studies near roadways with high truck traffic indicate higher concentrations of 

components of diesel PM than other locations.73,74,75 High ambient particle concentrations have 

also been reported near trucking terminals, truck stops, and bus garages.76,77,78

8.1.1.10

 Additional 

discussion of exposure and health effects associated with traffic is included below in Section 

. 

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8.1.1.9.2 Benzene

The EPA’s IRIS database lists benzene as a known human carcinogen (causing leukemia) 

by all routes of exposure, and concludes that exposure is associated with additional health 

effects, including genetic changes in both humans and animals and increased proliferation of 

bone marrow cells in mice.79,80,81 EPA states in its IRIS database that data indicate a causal 

relationship between benzene exposure and acute lymphocytic leukemia and suggest a 

relationship between benzene exposure and chronic non-lymphocytic leukemia and chronic 

lymphocytic leukemia. The International Agency for Research on Carcinogens (IARC) has 

determined that benzene is a human carcinogen and the U.S. Department of Health and Human 

Services (DHHS) has characterized benzene as a known human carcinogen.82,83

A number of adverse noncancer health effects including blood disorders, such as 

preleukemia and aplastic anemia, have also been associated with long-term exposure to 

benzene.84,85 The most sensitive noncancer effect observed in humans, based on current data, is 

the depression of the absolute lymphocyte count in blood.86,87 In addition, recent work, 

including studies sponsored by the Health Effects Institute (HEI), provides evidence that 

biochemical responses are occurring at lower levels of benzene exposure than previously 

known.88,89,90,91

8.1.1.9.3 1,3-Butadiene

 EPA’s IRIS program has not yet evaluated these new data.

EPA has characterized 1,3-butadiene as carcinogenic to humans by inhalation.92,93 The 

IARC has determined that 1,3-butadiene is a human carcinogen and the U.S. DHHS has 

characterized 1,3-butadiene as a known human carcinogen.94,9596 There are numerous studies 

consistently demonstrating that 1,3-butadiene is metabolized into genotoxic metabolites by 

experimental animals and humans. The specific mechanisms of 1,3-butadiene-induced 

carcinogenesis are unknown; however, the scientific evidence strongly suggests that the 

carcinogenic effects are mediated by genotoxic metabolites. Animal data suggest that females 

may be more sensitive than males for cancer effects associated with 1,3-butadiene exposure; 

there are insufficient data in humans from which to draw conclusions about sensitive 

subpopulations. 1,3-butadiene also causes a variety of reproductive and developmental effects in 

mice; no human data on these effects are available. The most sensitive effect was ovarian 

atrophy observed in a lifetime bioassay of female mice.97

8.1.1.9.4 Formaldehyde

Since 1987, EPA has classified formaldehyde as a probable human carcinogen based on 

evidence in humans and in rats, mice, hamsters, and monkeys.98 EPA is currently reviewing 

recently published epidemiological data. For instance, research conducted by the National 

Cancer Institute (NCI) found an increased risk of nasopharyngeal cancer and 

lymphohematopoietic malignancies such as leukemia among workers exposed to 

formaldehyde.99,100 In an analysis of the lymphohematopoietic cancer mortality from an 

extended follow-up of these workers, NCI confirmed an association between 

lymphohematopoietic cancer risk and peak exposures.101 A recent NIOSH study of garment 

workers also found increased risk of death due to leukemia among workers exposed to 

formaldehyde.102

Deleted: National Institute of Occupational Safety 

and Health (

 Extended follow-up of a cohort of British chemical workers did not find Deleted: )
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evidence of an increase in nasopharyngeal or lymphohematopoietic cancers, but a continuing 

statistically significant excess in lung cancers was reported.103

In the past 15 years there has been substantial research on the inhalation dosimetry for 

formaldehyde in rodents and primates by the CIIT Centers for Health Research (formerly the 

Chemical Industry Institute of Toxicology), with a focus on use of rodent data for refinement of 

the quantitative cancer dose-response assessment.104,105,106 CIIT’s risk assessment of 

formaldehyde incorporated mechanistic and dosimetric information on formaldehyde. However, 

it should be noted that recent research published by EPA indicates that when two-stage modeling 

assumptions are varied, resulting dose-response estimates can vary by several orders of 

magnitude.107,108,109,110 These findings are not supportive of interpreting the CIIT model results 

as providing a conservative (health protective) estimate of human risk.111 EPA research also 

examined the contribution of the two-stage modeling for formaldehyde towards characterizing 

the relative weights of key events in the mode-of-action of a carcinogen. For example, the 

model-based inference in the published CIIT study that formaldehyde’s direct mutagenic action 

is not relevant to the compound’s tumorigenicity was found not to hold under variations of 

modeling assumptions.112

Based on the developments of the last decade, in 2004, the working group of the IARC 

concluded that formaldehyde is carcinogenic to humans (Group 1), on the basis of sufficient 

evidence in humans and sufficient evidence in experimental animals - a higher classification than 

previous IARC evaluations. After reviewing the currently available epidemiological evidence, 

the IARC (2006) characterized the human evidence for formaldehyde carcinogenicity as 

“sufficient,” based upon the data on nasopharyngeal cancers; the epidemiologic evidence on 

leukemia was characterized as “strong.”113

Formaldehyde exposure also causes a range of noncancer health effects, including 

irritation of the eyes (burning and watering of the eyes), nose and throat. Effects from repeated 

exposure in humans include respiratory tract irritation, chronic bronchitis and nasal epithelial 

lesions such as metaplasia and loss of cilia. Animal studies suggest that formaldehyde may also 

cause airway inflammation – including eosinophil infiltration into the airways. There are several 

studies that suggest that formaldehyde may increase the risk of asthma – particularly in the 

young.

EPA is reviewing the recent work cited above from 

the NCI and NIOSH, as well as the analysis by the CIIT Centers for Health Research and other 

studies, as part of a reassessment of the human hazard and dose-response associated with 

formaldehyde.

114,115

8.1.1.9.5 Acetaldehyde

Acetaldehyde is classified in EPA’s IRIS database as a probable human carcinogen, 

based on nasal tumors in rats, and is considered toxic by the inhalation, oral, and intravenous 

routes.116 Acetaldehyde is reasonably anticipated to be a human carcinogen by the U.S. DHHS 

in the 11th Report on Carcinogens and is classified as possibly carcinogenic to humans (Group 

2B) by the IARC.117,118 EPA is currently conducting a reassessment of cancer risk from 

inhalation exposure to acetaldehyde.
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The primary noncancer effects of exposure to acetaldehyde vapors include irritation of 

the eyes, skin, and respiratory tract.119 In short-term (4 week) rat studies, degeneration of 

olfactory epithelium was observed at various concentration levels of acetaldehyde 

exposure.120,121 Data from these studies were used by EPA to develop an inhalation reference 

concentration. Some asthmatics have been shown to be a sensitive subpopulation to decrements 

in functional expiratory volume (FEV1 test) and bronchoconstriction upon acetaldehyde 

inhalation.122

8.1.1.9.6 Acrolein

 The agency is currently conducting a reassessment of the health hazards from 

inhalation exposure to acetaldehyde. 

Acrolein is extremely acrid and irritating to humans when inhaled, with acute exposure 

resulting in upper respiratory tract irritation, mucus hypersecretion and congestion. The intense 

irritancy of this carbonyl has been demonstrated during controlled tests in human subjects, who 

suffer intolerable eye and nasal mucosal sensory reactions within minutes of exposure.123 These 

data and additional studies regarding acute effects of human exposure to acrolein are 

summarized in EPA’s 2003 IRIS Human Health Assessment for acrolein.124 Evidence available 

from studies in humans indicate that levels as low as 0.09 ppm (0.21 mg/m3) for five minutes 

may elicit subjective complaints of eye irritation with increasing concentrations leading to more 

extensive eye, nose and respiratory symptoms.125 Lesions to the lungs and upper respiratory 

tract of rats, rabbits, and hamsters have been observed after subchronic exposure to acrolein.126 

Acute exposure effects in animal studies report bronchial hyper-responsiveness.127 In a recent 

study, the acute respiratory irritant effects of exposure to 1.1 ppm acrolein were more 

pronounced in mice with allergic airway disease by comparison to non-diseased mice which also 

showed decreases in respiratory rate.128

EPA determined in 2003 that the human carcinogenic potential of acrolein could not be 

determined because the available data were inadequate. No information was available on the 

carcinogenic effects of acrolein in humans and the animal data provided inadequate evidence of 

carcinogenicity.

 Based on these animal data and demonstration of similar 

effects in humans (e.g., reduction in respiratory rate), individuals with compromised respiratory 

function (e.g., emphysema, asthma) are expected to be at increased risk of developing adverse 

responses to strong respiratory irritants such as acrolein. 

129 The IARC determined in 1995 that acrolein was not classifiable as to its 

carcinogenicity in humans.

130

8.1.1.9.7 Polycyclic Organic Matter (POM)

 

POM is generally defined as a large class of organic compounds which have multiple 

benzene rings and a boiling point greater than 100 degrees Celsius. Many of the compounds 

included in the class of compounds known as POM are classified by EPA as probable human 

carcinogens based on animal data. One of these compounds, naphthalene, is discussed separately 

below. Polycyclic aromatic hydrocarbons (PAHs) are a subset of POM that contain only 

hydrogen and carbon atoms. A number of PAHs are known or suspected carcinogens. Recent 

studies have found that maternal exposures to PAHs (a subclass of POM) in a population of 

pregnant women were associated with several adverse birth outcomes, including low birth 

weight and reduced length at birth, as well as impaired cognitive development at age three.131,132 

EPA has not yet evaluated these recent studies.
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8.1.1.9.8 Naphthalene

Naphthalene is found in small quantities in gasoline and diesel fuels. Naphthalene 

emissions have been measured in larger quantities in both gasoline and diesel exhaust compared 

with evaporative emissions from mobile sources, indicating it is primarily a product of 

combustion. EPA released an external review draft of a reassessment of the inhalation 

carcinogenicity of naphthalene based on a number of recent animal carcinogenicity studies.133 

The draft reassessment completed external peer review.134 Based on external peer review 

comments received, additional analyses are being undertaken. This external review draft does 

not represent official agency opinion and was released solely for the purposes of external peer 

review and public comment. The National Toxicology Program listed naphthalene as 

"reasonably anticipated to be a human carcinogen" in 2004 on the basis of bioassays reporting 

clear evidence of carcinogenicity in rats and some evidence of carcinogenicity in mice.135 

California EPA has released a new risk assessment for naphthalene, and the IARC has 

reevaluated naphthalene and re-classified it as Group 2B: possibly carcinogenic to humans.136 

Naphthalene also causes a number of chronic non-cancer effects in animals, including abnormal 

cell changes and growth in respiratory and nasal tissues.137

8.1.1.9.9 Other Air Toxics

In addition to the compounds described above, other compounds in gaseous hydrocarbon 

and PM emissions from vehicles would be affected by today’s proposed action. Mobile source 

air toxic compounds that would potentially be impacted include ethylbenzene, propionaldehyde, 

toluene, and xylene. Information regarding the health effects of these compounds can be found 

in EPA’s IRIS database.

8.1.1.10 Exposure and Health Effects Associated with Traffic

K

Populations who live, work, or attend school near major roads experience elevated 

exposure concentrations to a wide range of air pollutants, as well as higher risks for a number of 

adverse health effects. While the previous sections of this RIA have focused on the health 

effects associated with individual criteria pollutants or air toxics, this section discusses the 

mixture of different exposures near major roadways, rather than the effects of any single 

pollutant. As such, this section emphasizes traffic-related air pollution, in general, as the 

relevant indicator of exposure rather than any particular pollutant.

Concentrations of many traffic-generated air pollutants are elevated for up to 300-500 

meters downwind of roads with high traffic volumes.138

 

K U.S. EPA Integrated Risk Information System (IRIS) database is available at: www.epa.gov/iris

 Numerous sources on roads contribute 

to elevated roadside concentrations, including exhaust and evaporative emissions, and 

resuspension of road dust and tire and brake wear. Concentrations of several criteria and 

hazardous air pollutants are elevated near major roads. Furthermore, different semi-volatile 
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organic compounds and chemical components of particulate matter, including elemental carbon, 

organic material, and trace metals, have been reported at higher concentrations near major roads. 

Populations near major roads experience greater risk of certain adverse health effects. 

The Health Effects Institute published a report on the health effects of traffic-related air 

pollution.139 It concluded that evidence is “sufficient to infer the presence of a causal 

association” between traffic exposure and exacerbation of childhood asthma symptoms. The 

HEI report also concludes that the evidence is either “sufficient” or “suggestive but not 

sufficient” for a causal association between traffic exposure and new childhood asthma cases. A 

review of asthma studies by Salam et al. (2008) reaches similar conclusions.140 The HEI report 

also concludes that there is “suggestive” evidence for pulmonary function deficits associated 

with traffic exposure, but concluded that there is “inadequate and insufficient” evidence for 

causal associations with respiratory health care utilization, adult-onset asthma, COPD symptoms, 

and allergy. A review by Holguin (2008) notes that the effects of traffic on asthma may be 

modified by nutrition status, medication use, and genetic factors.141

The HEI report also concludes that evidence is “suggestive” of a causal association 

between traffic exposure and all-cause and cardiovascular mortality. There is also evidence of 

an association between traffic-related air pollutants and cardiovascular effects such as changes in 

heart rhythm, heart attack, and cardiovascular disease. The HEI report characterizes this 

evidence as “suggestive” of a causal association, and an independent epidemiological literature 

review by Adar and Kaufman (2007) concludes that there is “consistent evidence” linking 

traffic-related pollution and adverse cardiovascular health outcomes.142

Some studies have reported associations between traffic exposure and other health 

effects, such as birth outcomes (e.g., low birth weight) and childhood cancer. The HEI report 

concludes that there is currently “inadequate and insufficient” evidence for a causal association 

between these effects and traffic exposure. A review by Raaschou-Nielsen and Reynolds (2006) 

concluded that evidence of an association between childhood cancer and traffic-related air 

pollutants is weak, but noted the inability to draw firm conclusions based on limited evidence.143

There is a large population in the U.S. living in close proximity of major roads. 

According to the Census Bureau’s American Housing Survey for 2007, approximately 20 million 

residences in the U.S., 15.6% of all homes, are located within 300 feet (91 m) of a highway with 

4+ lanes, a railroad, or an airport.144

People living near roads are often socioeconomically disadvantaged. According to the 

2007 American Housing Survey, a renter-occupied property is over twice as likely as an owneroccupied property to be located near a highway with 4+ lanes, railroad or airport. In the same 

survey, the median household income of rental housing occupants was less than half that of 

 Therefore, at current population of approximately 309 

million, assuming that population and housing are similarly distributed, there are over 48 million 

people in the U.S. living near such sources. The HEI report also notes that in two North 

American cities, Los Angeles and Toronto, over 40% of each city’s population live within 500 

meters of a highway or 100 meters of a major road. It also notes that about 33% of each city’s 

population resides within 50 meters of major roads. Together, the evidence suggests that a large 

U.S. population lives in areas with elevated traffic-related air pollution.
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owner-occupants ($28,921/$59,886). Numerous studies in individual urban areas report higher 

levels of traffic-related air pollutants in areas with high minority or poor populations.145,146,147

Students may also be exposed in situations where schools are located near major roads. 

In a study of nine metropolitan areas across the U.S., Appatova et al. (2008) found that on 

average greater than 33% of schools were located within 400 m of an Interstate, US, or state 

highway, while 12% were located within 100 m.148

Demographic studies of students in schools near major roadways suggest that this 

population is more likely than the general student population to be of non-white race or Hispanic 

ethnicity, and more often live in low socioeconomic status locations.

 The study also found that among the 

metropolitan areas studied, schools in the Eastern U.S. were more often sited near major 

roadways than schools in the Western U.S.

149,150,151

8.1.2 Environmental Effects Associated with Exposure to Non-GHG Pollutants

 There is some 

inconsistency in the evidence, which may be due to different local development patterns and 

measures of traffic and geographic scale used in the studies.148 

In this section we will discuss the environmental effects associated with non-GHG 

pollutants, specifically: particulate matter, ozone, NOX, SOX

8.1.2.1 Visibility Degradation

and air toxics. 

Emissions from heavy-duty vehicles contribute to poor visibility in the U.S. through their 

emissions of primary PM2.5 and secondary PM2.5 precursors such as NOX

EPA is pursuing a two-part strategy to address visibility. First, EPA has concluded that 

PM

. Airborne particles 

degrade visibility by scattering and absorbing light. Good visibility increases the quality of life 

where individuals live and work, and where they engage in recreational activities.

2.5 causes adverse effects on visibility in various locations, depending on PM concentrations

and factors such as chemical composition and average relative humidity, and has set secondary 

PM2.5 standards.L The secondary PM2.5 standards act in conjunction with the regional haze 

program. EPA’s regional haze rule (64 FR 35714) was put in place in July 1999 to protect the 

visibility in Mandatory Class I Dederal areas. There are 156 national parks, forests and 

wilderness areas categorized as Mandatory Class I Federal areas (62 FR 38680-81, July 18, 

1997).M Visibility can be said to be impaired in both PM2.5

Figure 8-2

nonattainment areas and mandatory 

class I federal areas. shows the location of the 156 Mandatory Class I Federal areas.

 

L

 The existing annual primary and secondary PM2.5 standards have been remanded and are being addressed in the 

currently ongoing PM NAAQS review.

M These areas are defined in CAA section 162 as those national parks exceeding 6,000 acres, wilderness areas and 

memorial parks exceeding 5,000 acres, and all international parks which were in existence on August 7, 1977.

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Figure 8-2

8.1.2.1.1 Visibility Monitoring

Mandatory Class I Federal Areas in the U.S.

In conjunction with the U.S. National Park Service, the U.S. Forest Service, other Federal 

land managers, and State organizations in the U.S., the U.S. EPA has supported visibility 

monitoring in national parks and wilderness areas since 1988. The monitoring network was 

originally established at 20 sites, but it has now been expanded to 110 sites that represent all but 

one of the 156 Mandatory Federal Class I areas across the country (see Figure 8-2). This longterm visibility monitoring network is known as IMPROVE (Interagency Monitoring of Protected 

Visual Environments).

IMPROVE provides direct measurement of fine particles that contribute to visibility 

impairment. The IMPROVE network employs aerosol measurements at all sites, and optical and 

scene measurements at some of the sites. Aerosol measurements are taken for PM10 and PM2.5

mass, and for key constituents of PM2.5, such as sulfate, nitrate, organic and elemental carbon, 

soil dust, and several other elements. Measurements for specific aerosol constituents are used to 

calculate "reconstructed" aerosol light extinction by multiplying the mass for each constituent by 

its empirically-derived scattering and/or absorption efficiency, with adjustment for the relative 

humidity. Knowledge of the main constituents of a site's light extinction "budget" is critical for 

source apportionment and control strategy development. In addition to this indirect method of 

assessing light extinction, there are optical measurements which directly measure light extinction 

or its components. Such measurements are taken principally with either a transmissometer, 

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which measures total light extinction, or by combining the PM light scattering measured by 

integrating nephelometers with the PM light absorption measured by an aethalometer. Scene 

characteristics are typically recorded three times daily with 35 millimeter photography and are 

used to determine the quality of visibility conditions (such as effects on color and contrast) 

associated with specific levels of light extinction as measured under both direct and aerosolrelated methods. Directly measured light extinction is used under the IMPROVE protocol to 

cross check that the aerosol-derived light extinction levels are reasonable in establishing current 

visibility conditions. Aerosol-derived light extinction is used to document spatial and temporal 

trends and to determine how proposed changes in atmospheric constituents would affect future 

visibility conditions.

Annual average visibility conditions (reflecting light extinction due to both anthropogenic 

and non-anthropogenic sources) vary regionally across the U.S. Visibility is typically worse in 

the summer months and the rural East generally has higher levels of impairment than remote 

sites in the West. Figures 9-9 through 9-11 in the PM ISA detail the percent contributions to 

particulate light extinction for ammonium nitrate and sulfate, EC and OC, and coarse mass and 

fine soil, by season.152

8.1.2.2 Plant and Ecosystem Effects of Ozone

There are a number of environmental or public welfare effects associated with the 

presence of ozone in the ambient air.153

The Air Quality Criteria Document for Ozone and related Photochemical Oxidants notes 

that, “ozone affects vegetation throughout the United States, impairing crops, native vegetation, 

and ecosystems more than any other air pollutant.”

 In this section we discuss the impact of ozone on plants, 

including trees, agronomic crops and urban ornamentals.

154 Like carbon dioxide (CO2) and other 

gaseous substances, ozone enters plant tissues primarily through apertures (stomata) in leaves in 

a process called “uptake.”155 Once sufficient levels of ozone (a highly reactive substance), or its 

reaction products, reaches the interior of plant cells, it can inhibit or damage essential cellular 

components and functions, including enzyme activities, lipids, and cellular membranes, 

disrupting the plant's osmotic (i.e., water) balance and energy utilization patterns.156,157 If 

enough tissue becomes damaged from these effects, a plant’s capacity to fix carbon to form 

carbohydrates, which are the primary form of energy used by plants is reduced,158 while plant 

respiration increases. With fewer resources available, the plant reallocates existing resources 

away from root growth and storage, above ground growth or yield, and reproductive processes, 

toward leaf repair and maintenance, leading to reduced growth and/or reproduction. Studies 

have shown that plants stressed in these ways may exhibit a general loss of vigor, which can lead 

to secondary impacts that modify plants' responses to other environmental factors. Specifically,

plants may become more sensitive to other air pollutants, more susceptible to disease, insect 

attack, harsh weather (e.g., drought, frost) and other environmental stresses. Furthermore, there 

is evidence that ozone can interfere with the formation of mycorrhiza, essential symbiotic fungi 

associated with the roots of most terrestrial plants, by reducing the amount of carbon available 

for transfer from the host to the symbiont.159,160

This ozone damage may or may not be accompanied by visible injury on leaves, and 

likewise, visible foliar injury may or may not be a symptom of the other types of plant damage 
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described above. When visible injury is present, it is commonly manifested as chlorotic or 

necrotic spots, and/or increased leaf senescence (accelerated leaf aging). Because ozone damage 

can consist of visible injury to leaves, it can also reduce the aesthetic value of ornamental 

vegetation and trees in urban landscapes, and negatively affects scenic vistas in protected natural 

areas. 

Ozone can produce both acute and chronic injury in sensitive species depending on the 

concentration level and the duration of the exposure. Ozone effects also tend to accumulate over 

the growing season of the plant, so that even lower concentrations experienced for a longer 

duration have the potential to create chronic stress on sensitive vegetation. Not all plants, 

however, are equally sensitive to ozone. Much of the variation in sensitivity between individual 

plants or whole species is related to the plant’s ability to regulate the extent of gas exchange via 

leaf stomata (e.g., avoidance of ozone uptake through closure of stomata)161,162,163 Other 

resistance mechanisms may involve the intercellular production of detoxifying substances. 

Several biochemical substances capable of detoxifying ozone have been reported to occur in 

plants, including the antioxidants ascorbate and glutathione. After injuries have occurred, plants 

may be capable of repairing the damage to a limited extent.164

Because of the differing sensitivities among plants to ozone, ozone pollution can also 

exert a selective pressure that leads to changes in plant community composition. Given the range 

of plant sensitivities and the fact that numerous other environmental factors modify plant uptake 

and response to ozone, it is not possible to identify threshold values above which ozone is 

consistently toxic for all plants. The next few paragraphs present additional information on 

ozone damage to trees, ecosystems, agronomic crops and urban ornamentals.

Ozone also has been conclusively shown to cause discernible injury to forest trees.165,166 

In terms of forest productivity and ecosystem diversity, ozone may be the pollutant with the 

greatest potential for regional-scale forest impacts. Studies have demonstrated repeatedly that 

ozone concentrations commonly observed in polluted areas can have substantial impacts on plant 

function.167,168

Because plants are at the base of the food web in many ecosystems, changes to the plant 

community can affect associated organisms and ecosystems (including the suitability of habitats 

that support threatened or endangered species and below ground organisms living in the root 

zone). Ozone impacts at the community and ecosystem level vary widely depending upon 

numerous factors, including concentration and temporal variation of tropospheric ozone, species 

composition, soil properties and climatic factors.169 In most instances, responses to chronic or 

recurrent exposure in forested ecosystems are subtle and not observable for many years. These 

injuries can cause stand-level forest decline in sensitive ecosystems.170,171,172

Laboratory and field experiments have also shown reductions in yields for agronomic 

crops exposed to ozone, including vegetables (e.g., lettuce) and field crops (e.g., cotton and 

wheat). The most extensive field experiments, conducted under the National Crop Loss 

Assessment Network (NCLAN) examined 15 species and numerous cultivars. The NCLAN 

 It is not yet 

possible to predict ecosystem responses to ozone with much certainty; however, considerable 

knowledge of potential ecosystem responses has been acquired through long-term observations 

in highly damaged forests in the United States.
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results show that “several economically important crop species are sensitive to ozone levels 

typical of those found in the United States.”173 In addition, economic studies have shown 

reduced economic benefits as a result of predicted reductions in crop yields associated with 

observed ozone levels.174,175,176

Urban ornamentals represent an additional vegetation category likely to experience some 

degree of negative effects associated with exposure to ambient ozone levels. It is estimated that 

more than $20 billion (1990 dollars) are spent annually on landscaping using ornamentals, both 

by private property owners/tenants and by governmental units responsible for public areas.177

Air pollution can have noteworthy cumulative impacts on forested ecosystems by 

affecting regeneration, productivity, and species composition.

 

This is therefore a potentially costly environmental effect. However, in the absence of adequate 

exposure-response functions and economic damage functions for the potential range of effects

relevant to these types of vegetation, no direct quantitative analysis has been conducted.

178 In the U.S., ozone in the lower 

atmosphere is one of the pollutants of primary concern. Ozone injury to forest plants can be 

diagnosed by examination of plant leaves. Foliar injury is usually the first visible sign of injury 

to plants from ozone exposure and indicates impaired physiological processes in the leaves.179

In the U.S. this indicator is based on data from the U.S. Department of Agriculture 

(USDA) Forest Service Forest Inventory and Analysis (FIA) program. As part of its Phase 3 

program, formerly known as Forest Health Monitoring, FIA examines ozone injury to ozonesensitive plant species at ground monitoring sites in forest land across the country. For this 

indicator, forest land does not include woodlots and urban trees. Sites are selected using a 

systematic sampling grid, based on a global sampling design.180,181

8.1.2.2.1 Recent Ozone Data for the U.S.

 At each site that has at least 

30 individual plants of at least three ozone-sensitive species and enough open space to ensure 

that sensitive plants are not protected from ozone exposure by the forest canopy, FIA looks for 

damage on the foliage of ozone-sensitive forest plant species. Monitoring of ozone injury to 

plants by the USDA Forest Service has expanded over the last 10 years from monitoring sites in 

10 states in 1994 to nearly 1,000 monitoring sites in 41 states in 2002. 

There is considerable regional variation in ozone-related visible foliar injury to sensitive 

plants in the U.S. The U.S. EPA has developed an environmental indicator based on data from 

the USDA FIA program which examines ozone injury to ozone-sensitive plant species at ground 

monitoring sites in forest land across the country (This indicator does not include woodlots and 

urban trees). Sites are selected using a systematic sampling grid, based on a global sampling 

design.182, 183 Because ozone injury is cumulative over the course of the growing season, 

examinations are conducted in July and August, when ozone injury is typically highest. The data 

underlying the indicator in 

Figure 8-3 are based on averages of all observations collected in 2002, the latest year for 

which data are publicly available at the time the study was conducted, and are broken down by 

U.S. EPA Region. Ozone damage to forest plants is classified using a subjective five-category 

biosite index based on expert opinion, but designed to be equivalent from site to site. Ranges of 

biosite values translate to no injury, low or moderate foliar injury (visible foliar injury to highly 

Deleted: U.S. Department of Agriculture (USDA) 

Forest Service Forest Inventory and Analysis (FIA)
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sensitive or moderately sensitive plants, respectively), and high or severe foliar injury, which 

would be expected to result in tree-level or ecosystem-level responses, respectively.184,185

The highest percentages of observed high and severe foliar injury, those which are most 

likely to be associated with tree or ecosystem-level responses, are primarily found in the MidAtlantic and Southeast regions. In EPA Region 3 (which comprises the States of Pennsylvania, 

West Virginia, Virginia, Delaware, Maryland and Washington D.C.), 12% of ozone-sensitive 

plants showed signs of high or severe foliar damage, and in Regions 2 (States of New York, New 

Jersey), and 4 (States of North Carolina, South Carolina, Kentucky, Tennessee, Georgia, Florida, 

Alabama, and Mississippi) the values were 10% and 7%, respectively. The sum of high and 

severe ozone injury ranged from 2% to 4% in EPA Region 1 (the six New England States), 

Region 7 (States of Missouri, Iowa, Nebraska and Kansas), and Region 9 (States of California, 

Nevada, Hawaii and Arizona). The percentage of sites showing some ozone damage was about 

45% in each of these EPA Regions. 

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Figure 8-3 Ozone Injury to Forest Plants in U.S. by EPA Regions, 2002ab

8.1.2.2.1.1 Indicator Limitations

Field and laboratory studies were reviewed to identify the forest plant species in each 

region that are highly sensitive to ozone air pollution. Other forest plant species, or even genetic 

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variants of the same species, may not be harmed at ozone levels that cause effects on the selected 

ozone-sensitive species. 

Because species distributions vary regionally, different ozone-sensitive plant species 

were examined in different parts of the country. These target species could vary with respect to 

ozone sensitivity, which might account for some of the apparent differences in ozone injury 

among regions of the U.S.

Ozone damage to foliage is considerably reduced under conditions of low soil moisture, 

but most of the variability in the index (70%) was explained by ozone concentration.186 Ozone 

may have other adverse impacts on plants (e.g., reduced productivity) that do not show signs of 

visible foliar injury.187

Though FIA has extensive spatial coverage based on a robust sample design, not all 

forested areas in the U.S. are monitored for ozone injury. Even though the biosite data have been 

collected over multiple years, most biosites were not monitored over the entire period, so these 

data cannot provide more than a baseline for future trends.

8.1.2.3 Ozone Impacts on Forest Health

Air pollution can impact the environment and affect ecological systems, leading to 

changes in the biological community (both in the diversity of species and the health and vigor of 

individual species). As an example, many studies have shown that ground-level ozone reduces 

the health of plants including many commercial and ecologically important forest tree species 

throughout the United States.188

When ozone is present in the air, it can enter the leaves of plants, where it can cause 

significant cellular damage. Since photosynthesis occurs in cells within leaves, the ability of the 

plant to produce energy by photosynthesis can be compromised if enough damage occurs to 

these cells. If enough tissue becomes damaged it can reduce carbon fixation and increase plant 

respiration, leading to reduced growth and/or reproduction in young and mature trees. Ozone 

stress also increases the susceptibility of plants to disease, insects, fungus, and other 

environmental stressors (e.g., harsh weather). Because ozone damage can consist of visible 

injury to leaves, it also reduces the aesthetic value of ornamental vegetation and trees in urban 

landscapes, and negatively affects scenic vistas in protected natural areas.

Assessing the impact of ground-level ozone on forests in the eastern United States 

involves understanding the risks to sensitive tree species from ambient ozone concentrations and 

accounting for the prevalence of those species within the forest. As a way to quantify the risks to 

particular plants from ground-level ozone, scientists have developed ozone-exposure/treeresponse functions by exposing tree seedlings to different ozone levels and measuring reductions 

in growth as “biomass loss.” Typically, seedlings are used because they are easy to manipulate 

and measure their growth loss from ozone pollution. The mechanisms of susceptibility to ozone 

within the leaves of seedlings and mature trees are identical, though the magnitude of the effect 

may be higher or lower depending on the tree species. 189
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Some of the common tree species in the United States that are sensitive to ozone are 

black cherry (Prunus serotina), tulip-poplar (Liriodendron tulipifera), eastern white pine (Pinus 

strobus). Ozone-exposure/tree-response functions have been developed for each of these tree 

species, as well as for aspen (Populus tremuliodes), and ponderosa pine (Pinus ponderosa). 

Other common tree species, such as oak (Quercus spp.) and hickory (Carya spp.), are not nearly 

as sensitive to ozone. Consequently, with knowledge of the distribution of sensitive species and 

the level of ozone at particular locations, it is possible to estimate a “biomass loss” for each 

species across their range. 

8.1.2.4 Particulate Matter Deposition

Particulate matter contributes to adverse effects on vegetation and ecosystems, and to 

soiling and materials damage. These welfare effects result predominately from exposure to 

excess amounts of specific chemical species, regardless of their source or predominant form 

(particle, gas or liquid). The following characterizations of the nature of these environmental

effects are based on information contained in the 2009 PM ISA and the 2005 PM Staff Paper as 

well as the Integrated Science Assessment for Oxides of Nitrogen and Sulfur- Ecological 

Criteria.

190,191,192

8.1.2.4.1 Deposition of Nitrogen and Sulfur

Nitrogen and sulfur interactions in the environment are highly complex. Both are 

essential, and sometimes limiting, nutrients needed for growth and productivity. Excesses of 

nitrogen or sulfur can lead to acidification, nutrient enrichment, and eutrophication of aquatic 

ecosystems.193

The process of acidification affects both freshwater aquatic and terrestrial ecosystems. 

Acid deposition causes acidification of sensitive surface waters. The effects of acid deposition 

on aquatic systems depend largely upon the ability of the ecosystem to neutralize the additional 

acid. As acidity increases, aluminum leached from soils and sediments, flows into lakes and 

streams and can be toxic to both terrestrial and aquatic biota. The lower pH concentrations and 

higher aluminum levels resulting from acidification make it difficult for some fish and other 

aquatic organisms to survive, grow, and reproduce. Research on effects of acid deposition on 

forest ecosystems has come to focus increasingly on the biogeochemical processes that affect 

uptake, retention, and cycling of nutrients within these ecosystems. Decreases in available base 

cations from soils are at least partly attributable to acid deposition. Base cation depletion is a 

cause for concern because of the role these ions play in acid neutralization, and because calcium, 

magnesium and potassium are essential nutrients for plant growth and physiology. Changes in 

the relative proportions of these nutrients, especially in comparison with aluminum 

concentrations, have been associated with declining forest health.

 

At current ambient levels, risks to vegetation from short-term exposures to dry deposited 

particulate nitrate or sulfate are low. However, when found in acid or acidifying deposition, such 

particles do have the potential to cause direct leaf injury. Specifically, the responses of forest 

trees to acid precipitation (rain, snow) include accelerated weathering of leaf cuticular surfaces, 

increased permeability of leaf surfaces to toxic materials, water, and disease agents; increased 

leaching of nutrients from foliage; and altered reproductive processes—all which serve to 
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weaken trees so that they are more susceptible to other stresses (e.g., extreme weather, pests, 

pathogens). Acid deposition with levels of acidity associated with the leaf effects described 

above are currently found in some locations in the eastern U.S.194 Even higher concentrations of 

acidity can be present in occult depositions (e.g., fog, mist or clouds) which more frequently 

impacts higher elevations. Thus, the risk of leaf injury occurring from acid deposition in some 

areas of the eastern U.S. is high. Nitrogen deposition has also been shown to impact ecosystems 

in the western U.S. A study conducted in the Columbia River Gorge National Scenic Area 

(CRGNSA), located along a portion of the Oregon/Washington border, indicates that lichen 

communities in the CRGNSA have shifted to a higher proportion of nitrophilous species and the 

nitrogen content of lichen tissue is elevated.195

Some of the most significant detrimental effects associated with excess nitrogen 

deposition are those associated with a condition known as nitrogen saturation. Nitrogen 

saturation is the condition in which nitrogen inputs from atmospheric deposition and other 

sources exceed the biological requirements of the ecosystem. The effects associated with 

nitrogen saturation include: (1) decreased productivity, increased mortality, and/or shifts in plant 

community composition, often leading to decreased biodiversity in many natural habitats 

wherever atmospheric reactive nitrogen deposition increases significantly above background and 

critical thresholds are exceeded; (2) leaching of excess nitrate and associated base cations from 

soils into streams, lakes, and rivers, and mobilization of soil aluminum; and (3) fluctuation of 

ecosystem processes such as nutrient and energy cycles through changes in the functioning and 

species composition of beneficial soil organisms.

 Lichens are sensitive indicators of nitrogen 

deposition effects to terrestrial ecosystems and the lichen studies in the Columbia River Gorge 

clearly show that ecological effects from air pollution are occurring.

196

In the U.S. numerous forests now show severe symptoms of nitrogen saturation. These 

forests include: the northern hardwoods and mixed conifer forests in the Adirondack and 

Catskill Mountains of New York; the red spruce forests at Whitetop Mountain, Virginia, and 

Great Smoky Mountains National Park, North Carolina; mixed hardwood watersheds at Fernow 

Experimental Forest in West Virginia; American beech forests in Great Smoky Mountains 

National Park, Tennessee; mixed conifer forests and chaparral watersheds in southern California 

and the southwestern Sierra Nevada in Central California; the alpine tundra/subalpine conifer 

forests of the Colorado Front Range; and red alder forests in the Cascade Mountains in 

Washington.

Excess nutrient inputs into aquatic ecosystems (i.e. streams, rivers, lakes, estuaries or 

oceans) either from direct atmospheric deposition, surface runoff, or leaching from nitrogen 

saturated soils into ground or surface waters can contribute to conditions of severe water oxygen 

depletion; eutrophication and algae blooms; altered fish distributions, catches, and physiological 

states; loss of biodiversity; habitat degradation; and increases in the incidence of disease.

Atmospheric deposition of nitrogen is a significant source of total nitrogen to many 

estuaries in the United States. The amount of nitrogen entering estuaries that is ultimately 

attributable to atmospheric deposition is not well-defined. On an annual basis, atmospheric 

nitrogen deposition may contribute significantly to the total nitrogen load, depending on the size 

and location of the watershed. In addition, episodic nitrogen inputs, which may be ecologically 

important, may play a more important role than indicated by the annual average concentrations. 
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Estuaries in the U.S. that suffer from nitrogen enrichment often experience a condition known as 

eutrophication. Symptoms of eutrophication include changes in the dominant species of 

phytoplankton, low levels of oxygen in the water column, fish and shellfish kills, outbreaks of 

toxic alga, and other population changes which can cascade throughout the food web. In 

addition, increased phytoplankton growth in the water column and on surfaces can attenuate light 

causing declines in submerged aquatic vegetation, which serves as an important habitat for many 

estuarine fish and shellfish species.

Severe and persistent eutrophication often directly impacts human activities. For 

example, losses in the nation’s fishery resources may be directly caused by fish kills associated 

with low dissolved oxygen and toxic blooms. Declines in tourism occur when low dissolved 

oxygen causes noxious smells and floating mats of algal blooms create unfavorable aesthetic 

conditions. Risks to human health increase when the toxins from algal blooms accumulate in 

edible fish and shellfish, and when toxins become airborne, causing respiratory problems due to 

inhalation. According to a NOAA report, more than half of the nation’s estuaries have moderate 

to high expressions of at least one of these symptoms – an indication that eutrophication is well 

developed in more than half of U.S. estuaries.197

8.1.2.4.2 Deposition of Heavy Metals

Heavy metals, including cadmium, copper, lead, chromium, mercury, nickel and zinc, 

have the greatest potential for impacting forest growth.

198 Investigation of trace metals near 

roadways and industrial facilities indicate that a substantial load of heavy metals can accumulate 

on vegetative surfaces. Copper, zinc, and nickel have been documented to cause direct toxicity 

to vegetation under field conditions. Little research has been conducted on the effects associated 

with mixtures of contaminants found in ambient PM. While metals typically exhibit low 

solubility, limiting their bioavailability and direct toxicity, chemical transformations of metal 

compounds occur in the environment, particularly in the presence of acidic or other oxidizing 

species. These chemical changes influence the mobility and toxicity of metals in the 

environment. Once taken up into plant tissue, a metal compound can undergo chemical changes, 

exert toxic effects on the plant itself, accumulate and be passed along to herbivores or can reenter the soil and further cycle in the environment. Although there has been no direct evidence 

of a physiological association between tree injury and heavy metal exposures, heavy metals have 

been implicated because of similarities between metal deposition patterns and forest decline. 

This hypothesized relationship/correlation was further explored in high elevation forests in the 

northeastern U.S. These studies measured levels of a group of intracellular compounds found in 

plants that bind with metals and are produced by plants as a response to sublethal concentrations 

of heavy metals. These studies indicated a systematic and significant increase in concentrations 

of these compounds associated with the extent of tree injury. These data strongly imply that 

metal stress causes tree injury and contributes to forest decline in the northeastern United 

States.199 Contamination of plant leaves by heavy metals can lead to elevated soil levels. Trace 

metals absorbed into the plant frequently bind to the leaf tissue, and then are lost when the leaf 

drops. As the fallen leaves decompose, the heavy metals are transferred into the soil.200,201 

Upon entering the soil environment, PM pollutants can alter ecological processes of energy flow 

and nutrient cycling, inhibit nutrient uptake, change ecosystem structure, and affect ecosystem 

biodiversity. Many of the most important effects occur in the soil. The soil environment is one 
Draft Regulatory Impact Analysis 

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of the most dynamic sites of biological interaction in nature. It is inhabited by microbial 

communities of bacteria, fungi, and actinomycetes. These organisms are essential participants in 

the nutrient cycles that make elements available for plant uptake. Changes in the soil 

environment that influence the role of the bacteria and fungi in nutrient cycling determine plant 

and ultimately ecosystem response.202

The environmental sources and cycling of mercury are currently of particular concern due 

to the bioaccumulation and biomagnification of this metal in aquatic ecosystems and the potent 

toxic nature of mercury in the forms in which is it ingested by people and other animals. 

Mercury is unusual compared with other metals in that it largely partitions into the gas phase (in 

elemental form), and therefore has a longer residence time in the atmosphere than a metal found 

predominantly in the particle phase. This property enables mercury to travel far from the 

primary source before being deposited and accumulating in the aquatic ecosystem. The major 

source of mercury in the Great Lakes is from atmospheric deposition, accounting for 

approximately eighty percent of the mercury in Lake Michigan.203,204 Over fifty percent of the 

mercury in the Chesapeake Bay has been attributed to atmospheric deposition.205 Overall, the 

National Science and Technology Council identifies atmospheric deposition as the primary 

source of mercury to aquatic systems.206

Elevated levels of zinc and lead have been identified in streambed sediments, and these 

elevated levels have been correlated with population density and motor vehicle use.

 Forty-four states have issued health advisories for the 

consumption of fish contaminated by mercury; however, most of these advisories are issued in 

areas without a mercury point source.

207,208 Zinc 

and nickel have also been identified in urban water and soils. In addition, platinum, palladium, 

and rhodium, metals found in the catalysts of modern motor vehicles, have been measured at 

elevated levels along roadsides.209

8.1.2.4.3 Deposition of Polycyclic Organic Matter

 Plant uptake of platinum has been observed at these 

locations.

Polycyclic organic matter (POM) is a byproduct of incomplete combustion and consists 

of organic compounds with more than one benzene ring and a boiling point greater than or equal 

to 100 degrees centigrade.210

Major sources of PAHs include mobile sources. PAHs in the environment may be 

present as a gas or adsorbed onto airborne particulate matter. Since the majority of PAHs are 

adsorbed onto particles less than 1.0 μm in diameter, long range transport is possible. However, 

studies have shown that PAH compounds adsorbed onto diesel exhaust particulate and exposed 

to ozone have half lives of 0.5 to 1.0 hours.

 Polycyclic aromatic hydrocarbons (PAHs) are a class of POM that 

contains compounds which are known or suspected carcinogens.

211

Since PAHs are insoluble, the compounds generally are particle reactive and accumulate 

in sediments. Atmospheric deposition of particles is believed to be the major source of PAHs to 

the sediments of Lake Michigan.

 

212,213 Analyses of PAH deposition in Chesapeake and 

Galveston Bay indicate that dry deposition and gas exchange from the atmosphere to the surface 

water predominate.214,215 Sediment concentrations of PAHs are high enough in some segments 

of Tampa Bay to pose an environmental health threat. EPA funded a study to better characterize 
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the sources and loading rates for PAHs into Tampa Bay.216 PAHs that enter a water body 

through gas exchange likely partition into organic rich particles and can be biologically recycled, 

while dry deposition of aerosols containing PAHs tend to be more resistant to biological 

recycling.217

Trends in PAH deposition levels are difficult to discern because of highly variable 

ambient air concentrations, lack of consistency in monitoring methods, and the significant 

influence of local sources on deposition levels.

Thus, dry deposition is likely the main pathway for PAH concentrations in 

sediments while gas/water exchange at the surface may lead to PAH distribution into the food 

web, leading to increased health risk concerns.

218 Van Metre et al. noted PAH concentrations in 

urban reservoir sediments have increased by 200-300% over the last forty years and correlate 

with increases in automobile use.219

Cousins et al. estimate that more than ninety percent of semi-volatile organic compound 

(SVOC) emissions in the United Kingdom deposit on soil.

 

220 An analysis of PAH 

concentrations near a Czechoslovakian roadway indicated that concentrations were thirty times 

greater than background.221

8.1.2.4.4 Materials Damage and Soiling

The effects of the deposition of atmospheric pollution, including ambient PM, on 

materials are related to both physical damage and impaired aesthetic qualities. The deposition of 

PM (especially sulfates and nitrates) can physically affect materials, adding to the effects of 

natural weathering processes, by potentially promoting or accelerating the corrosion of metals, 

by degrading paints, and by deteriorating building materials such as concrete and limestone. 

Only chemically active fine particles or hygroscopic coarse particles contribute to these physical 

effects. In addition, the deposition of ambient PM can reduce the aesthetic appeal of buildings 

and culturally important articles through soiling. Particles consisting primarily of carbonaceous 

compounds cause soiling of commonly used building materials and culturally important items 

such as statues and works of art.

8.1.2.5 Environmental Effects of Air Toxics

Emissions from producing, transporting and combusting fuel contribute to ambient levels 

of pollutants that contribute to adverse effects on vegetation. Volatile organic compounds 

(VOCs), some of which are considered air toxics, have long been suspected to play a role in 

vegetation damage.222 In laboratory experiments, a wide range of tolerance to VOCs has been 

observed.223 Decreases in harvested seed pod weight have been reported for the more sensitive 

plants, and some studies have reported effects on seed germination, flowering and fruit ripening. 

Effects of individual VOCs or their role in conjunction with other stressors (e.g., acidification, 

drought, temperature extremes) have not been well studied. In a recent study of a mixture of 

VOCs including ethanol and toluene on herbaceous plants, significant effects on seed production, 

leaf water content and photosynthetic efficiency were reported for some plant species.224

Research suggests an adverse impact of vehicle exhaust on plants, which has in some 

cases been attributed to aromatic compounds and in other cases to nitrogen oxides.225,226,227 The 

impacts of VOCs on plant reproduction may have long-term implications for biodiversity and 
Draft Regulatory Impact Analysis 

8-34

survival of native species near major roadways. Most of the studies of the impacts of VOCs on 

vegetation have focused on short-term exposure and few studies have focused on long-term 

effects of VOCs on vegetation and the potential for metabolites of these compounds to affect 

herbivores or insects. 

8.2 Air Quality Impacts of Non-GHG Pollutants

8.2.1 Introduction 

Chapter 6 of this draft RIA presents the projected emissions changes due to the proposal. 

Once the emissions changes are projected the next step is to look at how the ambient air quality 

would be impacted by those emissions changes. Although the purpose of this proposal is to 

address greenhouse gas emissions, this proposal would also impact emissions of criteria and 

hazardous air pollutants. Section 8.2.2 describes current ambient levels of PM, ozone, and some 

air toxics without the standards being proposed. No air quality modeling was done for this draft 

RIA to project the impacts of the proposal. Air quality modeling will be done for the final 

rulemaking, however, and those plans are discussed in Section 8.2.3.

8.2.2 Current Levels of Pollutants

8.2.2.1 Particulate Matter

As described in Section 8.1.1.1, PM causes adverse health effects, and the EPA has set 

national standards to provide requisite protection against those health effects. There are two 

National Ambient Air Quality Standards (NAAQS) for PM2.5: an annual standard (15 μg/m3) and 

a 24-hour standard (35 μg/m3

). The most recent revisions to these standards were in 1997 and 

2006. In 2005 the U.S. EPA designated nonattainment areas for the 1997 PM2.5 NAAQS (70 FR 

19844, April 14, 2005).N As of January 6, 2010, approximately 88 million people live in the 39 

areas that are designated as nonattainment for the 1997 PM2.5 NAAQS. These PM2.5

nonattainment areas are comprised of 208 full or partial counties. On October 8, 2009, the EPA 

issued final nonattainment area designations for the 2006 24-hour PM2.5 NAAQS (74 FR 58688, 

November 13, 2009). These designations include 31 areas composed of 120 full or partial 

counties with a population of over 70 million. In total, there are 54 PM2.5

States with PM

nonattainment areas 

composed of 245 counties with a population of 101 million people. 

2.5 nonattainment areas will be required to take action to bring those areas 

into compliance in the future. Most 1997 PM2.5 nonattainment areas are required to attain the 

1997 PM2.5 NAAQS in the 2010 to 2015 time frame and then be required to maintain the 1997 

PM2.5 NAAQS thereafter.228 The 2006 24-hour PM2.5 nonattainment areas will be required to 

attain the 2006 24-hour PM2.5 NAAQS in the 2014 to 2019 time frame and then be required to 

maintain the 2006 24-hour PM2.5 NAAQS thereafter.229

 

N A nonattainment area is defined in the Clean Air Act (CAA) as an area that is violating an ambient standard or is 

contributing to a nearby area that is violating the standard.

 The heavy-duty vehicle standards 

proposed here first apply to model year 2014 vehicles.

Deleted: DRIA

Deleted: proposed rule

Deleted: proposed rule

Deleted: in this rule.

Deleted: DRIA

Deleted: proposed rule.

Deleted: rule
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8.2.2.2 Ozone

As described in Section 8.1.1.3, ozone causes adverse health effects, and the EPA has set 

national standards to protect against those health effects. The primary and secondary NAAQS 

for ozone are 8-hour standards set at 0.075 ppm. The most recent revision to the ozone standards 

was in 2008; the previous 8-hour ozone standards, set in 1997, had been set at 0.08 ppm. In 

2004, the U.S. EPA designated nonattainment areas for the 1997 8-hour ozone NAAQS (69 FR 

23858, April 30, 2004). As of January 6, 2010, there are 51 8-hour ozone nonattainment

If EPA promulgates new ozone standards in 2010, EPA intends to accelerate the 

designations process for the primary standard so that the designations would be effective in 

August 2011. EPA is considering two alternative schedules for designating areas for a new 

seasonal secondary standard, an accelerated schedule or a 2-year schedule. 

areas 

for the 1997 ozone NAAQS composed of 266 full or partial counties with a total population of 

over 122 million. On January 6, 2010, EPA proposed to reconsider the 2008 ozone NAAQS to 

ensure that they are requisite to protect public health with an ample margin of safety, and 

requisite to protect public welfare. EPA intends to complete the reconsideration by August 31, 

2010. If, as a result of the reconsideration, EPA promulgates different ozone standards, the new 

2010 ozone standards would replace the 2008 ozone standards and the requirement to designate 

areas for the replaced 2008 standards would no longer apply. Because of the significant 

uncertainty the reconsideration proposal creates regarding the continued applicability of the 2008 

ozone NAAQS, EPA has extended the deadline for designating areas for the 2008 NAAQS by 

one year. This will allow EPA to complete its reconsideration of the 2008 ozone NAAQS before 

determining whether designations for those standards are necessary.

States with ozone nonattainment areas are required to take action to bring those areas into 

compliance in the future. The attainment date assigned to an ozone nonattainment area is based 

on the area’s classification. Most ozone nonattainment areas are required to attain the 1997 8-

hour ozone NAAQS in the 2007 to 2013 time frame and then be required to maintain it 

thereafter.O

 

O The Los Angeles South Coast Air Basin 8-hour ozone nonattainment area is designated as severe and will have to 

attain before June 15, 2021. The South Coast Air Basin has requested to be reclassified as an extreme nonattainment 

area which will make their attainment date June 15, 2024. The San Joaquin Valley Air Basin 8-hour ozone 

nonattainment area is designated as serious and will have to attain before June 15, 2013. The San Joaquin Valley 

Air Basin has requested to be reclassified as an extreme nonattainment area which will make their attainment date 

June 15, 2024.

 In addition, there will be attainment dates associated with the designation of 

nonattainment areas as a result of the reconsideration of the 2008 ozone NAAQS. If the ozone 

NAAQS reconsideration action is completed on the proposed schedule, the primary NAAQS 

attainment dates would be in the 2014-2031 time frame. The heavy-duty vehicle standards 

proposed here first apply to model year 2014 vehicles.
Draft Regulatory Impact Analysis 

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8.2.2.3 Air Toxics

The majority of Americans continue to be exposed to ambient concentrations of air toxics 

at levels which have the potential to cause adverse health effects.230 The levels of air toxics to 

which people are exposed vary depending on where people live and work and the kinds of 

activities in which they engage, as discussed in detail in U.S. EPA’s most recent Mobile Source 

Air Toxics (MSAT) Rule.231 According to the National Air Toxics Assessment (NATA) for 

2002, mobile sources were responsible for 47 percent of outdoor toxic emissions and over 50 

percent of the cancer risk.232 Nearly the entire U.S. population was exposed to an average 

concentration of air toxics that has the potential for adverse noncancer respiratory health effects. 

EPA recently finalized vehicle and fuel controls to reduce mobile source air toxics.233 In 

addition, over the years, EPA has implemented a number of mobile source and fuel controls 

resulting in VOC reductions, which also reduce air toxic emissions. Modeling from the recent 

MSAT rule suggests that the mobile source contribution to ambient benzene concentrations is 

projected to decrease over 40% by 2015, with a decrease in ambient benzene concentration from 

all sources of about 25%. Although benzene is used as an example, the downward trend is 

projected for other air toxics as well. See the RIA for the final MSAT rule for more information 

on ambient air toxics projections.234

8.2.3 Impacts of Future Air Quality

 Air quality models use mathematical and numerical techniques to simulate the physical 

and chemical processes that affect air pollutants as they disperse and react in the atmosphere. 

Based on inputs of meteorological data and source information, these models are designed to 

characterize primary pollutants that are emitted directly into the atmosphere and secondary 

pollutants that are formed as a result of complex chemical reactions within the atmosphere. 

Photochemical air quality models have become widely recognized and routinely utilized tools for 

regulatory analysis by assessing the effectiveness of control strategies. These models are applied 

at multiple spatial scales from local, regional, national, and global. 

Full-scale photochemical air quality modeling is necessary to accurately project levels of 

criteria and air toxic pollutants. For the final rulemaking, a national-scale air quality modeling 

analysis will be performed to analyze the impacts of the standards on PM2.5

Section VII of the preamble presents projections of the changes in criteria pollutant and 

air toxics emissions due to the proposed standards; the basis for those estimates is set out in 

Chapter 6 of the draft RIA. The atmospheric chemistry related to ambient concentrations of 

PM

, ozone, and selected 

air toxics (i.e., benzene, formaldehyde, acetaldehyde, acrolein and 1,3-butadiene). The length of 

time needed to prepare the necessary emissions inventories, in addition to the processing time 

associated with the modeling itself, has precluded us from performing air quality modeling for 

this proposal. 

2.5

Deleted: rule

, ozone and air toxics is very complex, and making predictions based solely on emissions 

changes is extremely difficult. However, based on the magnitude of the emissions changes 

predicted to result from the proposed standards, we expect that there will be a relatively small 

change in ambient air quality, pending a more comprehensive analysis for the final rulemaking.

Deleted: DRIA

Deleted: rule
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For the final rulemaking, EPA intends to use a 2005-based Community Multi-scale Air 

Quality (CMAQ) modeling platform as the tool for the air quality modeling. The CMAQ 

modeling system is a comprehensive three-dimensional grid-based Eulerian air quality model 

designed to estimate the formation and fate of oxidant precursors, primary and secondary PM 

concentrations and deposition, and air toxics, over regional and urban spatial scales (e.g., over 

the contiguous U.S.).235,236,237 ,238 The CMAQ model is a well-known and well-established tool 

and is commonly used by EPA for regulatory analyses, for instance the recent ozone NAAQS 

proposal, and by States in developing attainment demonstrations for their State Implementation 

Plans.239 The CMAQ model version 4.7 was most recently peer-reviewed in February of 2009

for the U.S. EPA.240

CMAQ includes many science modules that simulate the emission, production, decay, 

deposition and transport of organic and inorganic gas-phase and particle-phase pollutants in the 

atmosphere. EPA intends to use the most recent version of CMAQ which reflects updates to 

version 4.7 to improve the underlying science. These include aqueous chemistry mass 

conservation improvements, improved vertical convective mixing and lowered CB05 mechanism 

unit yields for acrolein from 1,3-butadiene tracer reactions which were updated to be consistent 

with laboratory measurements. 

 

The CMAQ modeling domain will encompass all of the lower 48 States and portions of 

Canada and Mexico. The modeling domain will include a large continental U.S. 36 km grid and 

two 12 km grids (an Eastern U.S. and a Western U.S. domain), as shown in Figure 8-4. The 

modeling domain will contain 14 vertical layers with the top of the modeling domain at about 

16,200 meters, or 100 millibars (mb).

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Formatted: Font: 12 pt, Not Bold, Superscript
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Figure 8-4 CMAQ 12-km Eastern and Western US Modeling Domains

The key inputs to the CMAQ model include emissions from anthropogenic and biogenic 

sources, meteorological data, and initial and boundary conditions. The CMAQ meteorological 

input files will be derived from simulations of the Pennsylvania State University / National 

Center for Atmospheric Research Mesoscale Model241 for the entire year of 2005. This model, 

commonly referred to as MM5, is a limited-area, nonhydrostatic, terrain-following system that 

solves for the full set of physical and thermodynamic equations which govern atmospheric 

motions.242

The lateral boundary and initial species concentrations will be provided by a threedimensional global atmospheric chemistry model, the GEOS-CHEM model.

 The meteorology for the national 36 km grid and the 12 km Eastern and Western 

U.S. grids will be developed by EPA and described in more detail within the final RIA and the 

technical support document for the final rulemaking air quality modeling. 

243

Deleted: rule

 The global 

GEOS-CHEM model simulates atmospheric chemical and physical processes driven by 

assimilated meteorological observations from the NASA’s Goddard Earth Observing System 

(GEOS). This model will be run for 2005 with a grid resolution of 2 degree x 2.5 degree 

(latitude-longitude) and 20 vertical layers. The predictions will be used to provide one-way 

dynamic boundary conditions at three-hour intervals and an initial concentration field for the 36 

km CMAQ simulations. The future base conditions from the 36 km coarse grid modeling will be 

used as the initial/boundary state for all subsequent 12 km finer grid modeling.
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8.3 Quantified and Monetized Non-GHG Health and Environmental 

Impacts

This section discusses the non-GHG health and environmental impacts that can be 

expected to occur as a result of the proposed heavy-duty vehicle GHG rule. GHG emissions are 

predominantly the byproduct of fossil fuel combustion processes that also produce criteria and 

hazardous air pollutants. The vehicles that are subject to the proposed standards are also 

significant sources of mobile source air pollution such as direct PM, NOx, VOCs and air toxics. 

The proposed standards would affect exhaust emissions of these pollutants from vehicles. They 

would also affect emissions from upstream sources related to changes in fuel consumption. 

Changes in ambient ozone, PM2.5

It is important to quantify the health and environmental impacts associated with the 

proposed standard because a failure to adequately consider these ancillary co-pollutant impacts 

could lead to an incorrect assessment of their net costs and benefits. Moreover, co-pollutant 

impacts tend to accrue in the near term, while any effects from reduced climate change mostly 

accrue over a time frame of several decades or longer. 

, and air toxics that would result from the proposed standards 

are expected to affect human health in the form of premature deaths and other serious human 

health effects, as well as other important public health and welfare effects. 

EPA typically quantifies and monetizes the health and environmental impacts related to 

both PM and ozone in its regulatory impact analyses (RIAs), when possible. However, EPA was 

unable to do so in time for this proposal. EPA attempts to make emissions and air quality 

modeling decisions early in the analytical process so that we can complete the photochemical air 

quality modeling and use that data to inform the health and environmental impacts analysis. 

Resource and time constraints precluded the Agency from completing this work in time for the 

proposal. Instead, we provide a characterization of the health and environmental impacts that 

will be quantified and monetized for the final rulemaking. 

EPA bases its analyses on peer-reviewed studies of air quality and health and welfare 

effects and peer-reviewed studies of the monetary values of public health and welfare 

improvements, and is generally consistent with benefits analyses performed for the analysis of 

the final Ozone National Ambient Air Quality Standard (NAAQS) and the final PM NAAQS 

analysis, as well as the proposed Portland Cement National Emissions Standards for Hazardous 

Air Pollutants (NESHAP) RIA, and final NO2 NAAQS.244,245, 246,247

8.3.1 Human Health and Environmental Impacts

To model the ozone and PM air quality benefits of the final rule, EPA will use the 

Community Multiscale Air Quality (CMAQ) model (see Section 8.2.3 for a description of the 

CMAQ model). The modeled ambient air quality data will serve as an input to the 

Environmental Benefits Mapping and Analysis Program (BenMAP).248 BenMAP is a computer 

program developed by EPA that integrates a number of the modeling elements used in previous 

RIAs (e.g., interpolation functions, population projections, health impact functions, valuation 

functions, analysis and pooling methods) to translate modeled air concentration estimates into 

health effects incidence estimates and monetized benefits estimates. 
Draft Regulatory Impact Analysis 

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Table 8-2 lists the co-pollutant health effect exposure-response functions we will use to 

quantify the co-pollutant incidence impacts associated with the final heavy-duty vehicles 

standard.

(Table 8-2starts on the following page)

Deleted: Table 8-1

Deleted: (Table 8-1 is

Deleted: Table 8-1:
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Table 8-2: Health Impact Functions Used in BenMAP to Estimate Impacts of PM2.5 and Ozone Reductions Formatted: Caption,RIA: Caption,RIA: Caption

+ 12 pt,RIA: Caption1,RIA: Caption2,RIA:

Caption3,RIA: Caption4,RIA: Caption5,RIA:

Caption6,RIA: Caption7,RIA: Caption8,RIA:

Caption9,RIA: Caption10,RIA: Caption11, Left,

Widow/Orphan control, Don't adjust space

between Latin and Asian text

Formatted: Font: Not Bold

Formatted: Font: Not Bold

Formatted: Font: Not Bold
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ENDPOINT POLLUTANT STUDY STUDY POPULATION

Premature Mortality

Premature mortality –

daily time series

O3 

Bell et al (2004) (NMMAPS study)

Multi-city 249

Huang et al (2005)

– Nonaccidental 250

Schwartz (2005)

- Cardiopulmonary 251 – Non-accidental

Bell et al (2005)

Meta-analyses: 252

Ito et al (2005)

– All cause 253

Levy et al (2005)

– Non-accidental 254

All ages

– All cause

Premature mortality 

—cohort study, allcause

PM2.5 Pope et al. (2002)255

Laden et al. (2006)256 >29 years

>25 years

Premature mortality, 

total exposures

PM2.5 Expert Elicitation (IEc, 2006)257 >24 years

Premature mortality 

— all-cause

PM2.5 Woodruff et al. (1997)258 Infant (<1 year)

Chronic Illness

Chronic bronchitis PM2.5 Abbey et al. (1995)259 >26 years

Nonfatal heart attacks PM2.5 Peters et al. (2001)260 Adults (>18 years)

Hospital Admissions 

Respiratory

O3

Pooled estimate:

Schwartz (1995) - ICD 460-519 (all resp)261

Schwartz (1994a; 1994b) - ICD 480-486 

(pneumonia)262,263

Moolgavkar et al. (1997) - ICD 480-487 

(pneumonia)264

Schwartz (1994b) - ICD 491-492, 494-496 

(COPD)

Moolgavkar et al. (1997) – ICD 490-496 

(COPD)

>64 years

Burnett et al. (2001)265 <2 years

PM2.5 Pooled estimate:

Moolgavkar (2003)—ICD 490-496 (COPD)266

Ito (2003)—ICD 490-496 (COPD)267

>64 years

PM2.5 Moolgavkar (2000)—ICD 490-496 (COPD)268 20–64 years

PM2.5 Ito (2003)—ICD 480-486 (pneumonia) >64 years

PM2.5 Sheppard (2003)—ICD 493 (asthma)269 <65 years

Cardiovascular PM Pooled estimate:

Moolgavkar (2003)—ICD 390-429 (all 

cardiovascular)

Ito (2003)—ICD 410-414, 427-428 (ischemic 

heart disease, dysrhythmia, heart failure)

2.5 >64 years

PM Moolgavkar (2000)—ICD 390-429 (all 

cardiovascular)

2.5 20–64 years

Asthma-related ER O3 Pooled estimate:
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visits Peel et al (2005)270

Wilson et al (2005)271

All ages

All ages

Asthma-related ER 

visits (con’t)

PM2.5 Norris et al. (1999)272 0–18 years

Other Health Endpoints

Acute bronchitis PM2.5 Dockery et al. (1996)273 8–12 years

Upper respiratory 

symptoms

PM2.5 Pope et al. (1991)274 Asthmatics, 9–11 

years

Lower respiratory 

symptoms

PM2.5 Schwartz and Neas (2000)275 7–14 years

Asthma exacerbations PM Pooled estimate: 2.5 

Ostro et al. (2001)276 (cough, wheeze and 

shortness of breath)

Vedal et al. (1998)277

6–18 years

(cough)

Work loss days

a

PM2.5 Ostro (1987)278 18–65 years

School absence days

O3 Gilliland et al. (2001)

Pooled estimate: 279

Chen et al. (2000)280

5–17 years

Minor Restricted 

Activity Days 

(MRADs)

b

O3 Ostro and Rothschild (1989)281 18–65 years

PM2.5 Ostro and Rothschild (1989) 18–65 years

Notes:

a

 The original study populations were 8 to 13 for the Ostro et al. (2001) study and 6 to 13 for the Vedal et al. (1998) 

study. Based on advice from the Science Advisory Board Health Effects Subcommittee (SAB-HES), we extended 

the applied population to 6 to 18, reflecting the common biological basis for the effect in children in the broader age 

group. See: U.S. Science Advisory Board. 2004. Advisory Plans for Health Effects Analysis in the Analytical Plan 

for EPA’s Second Prospective Analysis –Benefits and Costs of the Clean Air Act, 1990—2020. EPA-SABCOUNCIL-ADV-04-004. See also National Research Council (NRC). 2002. Estimating the Public Health Benefits 

of Proposed Air Pollution Regulations. Washington, DC: The National Academies Press. b

8.3.2 Monetized Impacts

 Gilliland et al. (2001) studied children aged 9 and 10. Chen et al. (2000) studied children 6 to 11. Based on recent 

advice from the National Research Council and the EPA SAB-HES, we have calculated reductions in school 

absences for all school-aged children based on the biological similarity between children aged 5 to 17.

Table 8-3presents the monetary values we will apply to changes in the incidence of health 

and welfare effects associated with reductions in non-GHG pollutants that will occur when these 

GHG control strategies are finalized. 

Deleted: Table 8-2 

Deleted: Table 8-2:

Formatted: Caption,RIA: Caption,RIA: Caption

+ 12 pt,RIA: Caption1,RIA: Caption2,RIA:

Caption3,RIA: Caption4,RIA: Caption5,RIA:

Caption6,RIA: Caption7,RIA: Caption8,RIA:

Caption9,RIA: Caption10,RIA: Caption11, Left
Draft Regulatory Impact Analysis 

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Table 8-3: Valuation Metrics Used in BenMAP to Estimate Monetary Co-Benefits 

Endpoint Valuation Method

Valuation

(2000$)

Premature mortality Assumed Mean VSL $6,300,000

Chronic Illness

 Chronic Bronchitis WTP: Average Severity $340,482

 Myocardial Infarctions, Nonfatal Medical Costs Over 5 Years. Varies by 

age and discount rate. Russell 

(1998)282

---

Medical Costs Over 5 Years. Varies by 

age and discount rate. Wittels 

(1990)283

---

Hospital Admissions

 Respiratory, Age 65+ COI: Medical Costs + Wage Lost $18,353

 Respiratory, Ages 0-2 COI: Medical Costs $7,741

 Chronic Lung Disease (less 

 Asthma)

COI: Medical Costs + Wage Lost $12,378

 Pneumonia COI: Medical Costs + Wage Lost $14,693

 Asthma COI: Medical Costs + Wage Lost $6,634

 Cardiovascular COI: Medical Costs + Wage Lost (20-

64)

$22,778

COI: Medical Costs + Wage Lost (65-

99)

$21,191

ER Visits, Asthma COI: Smith et al. (1997)284 $312

COI: Standford et al. (1999)285 $261

Other Health Endpoints

 Acute Bronchitis WTP: 6 Day Illness, CV Studies $356

 Upper Respiratory Symptoms WTP: 1 Day, CV Studies $25

 Lower Respiratory Symptoms WTP: 1 Day, CV Studies $16

 Asthma Exacerbation WTP: Bad Asthma Day, Rowe and 

Chestnut (1986) 286 $43

 Work Loss Days Median Daily Wage, County-Specific ---

 Minor Restricted Activity Days WTP: 1 Day, CV Studies $51

 School Absence Days Median Daily Wage, Women 25+ $75

 Worker Productivity Median Daily Wage, Outdoor 

Workers, County-Specific

---

Environmental Endpoints

 Recreational Visibility WTP: 86 Class I Areas ---

Source: Dollar amounts for each valuation method were extracted from BenMAP version 3.0. 

8.3.3 Other Unquantified Health and Environmental Impacts

In addition to the co-pollutant health and environmental impacts we will quantify for the 

analysis of the heavy-duty vehicle GHG standard, there are a number of other health and human 

welfare endpoints that we will not be able to quantify because of current limitations in the 

methods or available data. These impacts are associated with emissions of air toxics (including 

benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein), ambient ozone, and ambient 

PM2.5 exposures. For example, we have not quantified a number of known or suspected health 

effects linked with ozone and PM for which appropriate health impact functions are not available 

or which do not provide easily interpretable outcomes (e.g., changes in heart rate variability). In 

addition, we are currently unable to quantify a number of known welfare effects, including 

reduced acid and particulate deposition damage to cultural monuments and other materials, and 

Formatted: Font: Not Bold
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environmental benefits due to reductions of impacts of eutrophication in coastal areas. Table 8-3 

lists these unquantified health and environmental impacts.

Table 8-3: Unquantified and Non-Monetized Potential Effects

POLLUTANT/EFFECTS EFFECTS NOT INCLUDED IN ANALYSIS - CHANGES IN:

Ozone Healtha Chronic respiratory damage

Premature aging of the lungs

Non-asthma respiratory emergency room visits

Exposure to UVb (+/-)

d

Ozone Welfare Yields for 

-commercial forests

-some fruits and vegetables

-non-commercial crops

Damage to urban ornamental plants

Impacts on recreational demand from damaged forest aesthetics

Ecosystem functions

Exposure to UVb (+/-)

PM Healthb Premature mortality - short term exposuresc

Low birth weight

Pulmonary function

Chronic respiratory diseases other than chronic bronchitis

Non-asthma respiratory emergency room visits

Exposure to UVb (+/-)

PM Welfare Residential and recreational visibility in non-Class I areas

Soiling and materials damage

Damage to ecosystem functions

Exposure to UVb (+/-)

Nitrogen and Sulfate 

Deposition Welfare

Commercial forests due to acidic sulfate and nitrate deposition 

Commercial freshwater fishing due to acidic deposition 

Recreation in terrestrial ecosystems due to acidic deposition 

Existence values for currently healthy ecosystems 

Commercial fishing, agriculture, and forests due to nitrogen deposition 

Recreation in estuarine ecosystems due to nitrogen deposition

Ecosystem functions

Passive fertilization

CO Health Behavioral effects

Hydrocarbon (HC)/Toxics 

Healthe Cancer (benzene, 1,3-butadiene, formaldehyde, acetaldehyde)

Anemia (benzene)

Disruption of production of blood components (benzene)

Reduction in the number of blood platelets (benzene)

Excessive bone marrow formation (benzene)

Depression of lymphocyte counts (benzene)

Reproductive and developmental effects (1,3-butadiene)

Irritation of eyes and mucus membranes (formaldehyde)

Respiratory irritation (formaldehyde)

Asthma attacks in asthmatics (formaldehyde)

Asthma-like symptoms in non-asthmatics (formaldehyde)

Irritation of the eyes, skin, and respiratory tract (acetaldehyde)

Upper respiratory tract irritation and congestion (acrolein)
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HC/Toxics Welfaref Direct toxic effects to animals

Bioaccumulation in the food chain

Damage to ecosystem function

Odor

Notes:

a

 In addition to primary economic endpoints, there are a number of biological responses that have been associated 

with ozone health effects including increased airway responsiveness to stimuli, inflammation in the lung, acute 

inflammation and respiratory cell damage, and increased susceptibility to respiratory infection. The public health 

impact of these biological responses may be partly represented by our quantified endpoints.

b In addition to primary economic endpoints, there are a number of biological responses that have been associated 

with PM health effects including morphological changes and altered host defense mechanisms. The public health 

impact of these biological responses may be partly represented by our quantified endpoints.

c While some of the effects of short-term exposures are likely to be captured in the estimates, there may be 

premature mortality due to short-term exposure to PM not captured in the cohort studies used in this analysis. 

However, the PM mortality results derived from the expert elicitation do take into account premature mortality 

effects of short term exposures.

d May result in benefits or disbenefits.

e Many of the key hydrocarbons related to this rule are also hazardous air pollutants listed in the Clean Air Act. 

Please refer to Chapter 8.1.1 for additional information on the health effects of air toxics. f

Please refer to Chapter 8.1.2 for additional information on the welfare effects of air toxics.

While there will be impacts associated with air toxic pollutant emission changes that 

result from the final standard, we will not attempt to monetize those impacts. This is primarily 

because currently available tools and methods to assess air toxics risk from mobile sources at the 

national scale are not adequate for extrapolation to incidence estimations or benefits assessment. 

The best suite of tools and methods currently available for assessment at the national scale are 

those used in the National-Scale Air Toxics Assessment (NATA). The EPA Science Advisory 

Board specifically commented in their review of the 1996 NATA that these tools were not yet 

ready for use in a national-scale benefits analysis, because they did not consider the full 

distribution of exposure and risk, or address sub-chronic health effects.287 While EPA has since 

improved the tools, there remain critical limitations for estimating incidence and assessing 

benefits of reducing mobile source air toxics. EPA continues to work to address these 

limitations; however, we do not anticipate having methods and tools available for national-scale 

application in time for the analysis of the final rules.288

8.4 Changes in Atmospheric CO2

8.4.1 Introduction

Concentrations, Global Mean 

Temperature, Sea Level Rise, and Ocean pH Associated with the 

Proposal’s GHG Emissions Reductions

Based on modeling analysis performed by the EPA, reductions in CO2 and other GHG

emissions associated with this proposal will affect climate change projections. Since GHGs are 

well-mixed in the atmosphere and have long atmospheric lifetimes, changes in GHG emissions 

will affect atmospheric concentrations of greenhouse gases and future climate for decades to 

centuries and even millennia. This section provides estimates of the projected change in 

atmospheric CO2

Deleted: GHGs

concentrations based on the emission reductions estimated for this proposal 

Deleted: the proposed rule

Deleted: proposed rule.
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(preferred approach). In addition, this section analyzes the following climate-related variables:

global mean temperature, sea level rise, and ocean pH. Provided here are projected estimates for 

the response in atmospheric CO2

8.4.2 Estimated Projected Change in Atmospheric CO

concentrations, global mean temperature, sea level rise, and 

ocean pH to the estimated net global GHG emissions reductions associated with the preferred 

approach of this proposal (see Chapter 5 for the estimated net reductions in global emissions 

over time by GHG). 

2

 To assess the impact of the emissions reductions from the proposed standards, EPA 

estimated changes in projected atmospheric CO

Concentrations, Global 

Mean Surface Temperatures and Sea Level Rise

2 concentrations, global mean surface 

temperature and sea-level rise to 2100 using the GCAM (Global Change Assessment Model, 

formerly MiniCAM), integrated assessment modelP,289 coupled with the MAGICC (Model for 

the Assessment of Greenhouse-gas Induced Climate Change) simple climate model.Q,290,291

8.4.2.2 Methodology 

GCAM was used to create the globally and temporally consistent set of climate relevant 

variables required for running MAGICC. MAGICC was then used to estimate the projected

change in these variables over time. Given the magnitude of the estimated emissions reductions 

associated with the rule, a simple climate model such as MAGICC is reasonable for estimating 

the atmospheric and climate response.

An emissions scenario for the proposal was developed by applying the estimated 

emissions reductions from the proposal’s primary alternative to the GCAM reference (no climate 

policy or baseline) scenario (used as the basis for the Representative Concentration Pathway 

RCP4.5).292 Specifically, the annual CO2, N2O, and CH4

 

P GCAM is a long-term, global integrated assessment model of energy, economy, agriculture and land use, that 

considers the sources of emissions of a suite of greenhouse gases (GHG's), emitted in 14 globally disaggregated 

regions, the fate of emissions to the atmosphere, and the consequences of changing concentrations of greenhouse 

related gases for climate change. GCAM begins with a representation of demographic and economic developments 

in each region and combines these with assumptions about technology development to describe an internally 

consistent representation of energy, agriculture, land-use, and economic developments that in turn shape global 

emissions. 

emissions reductions from Chapter 5 

were applied as net reductions to the GCAM global baseline net emissions for each GHG. All 

emissions reductions were assumed to begin in 2014, with zero emissions change in 2013 and 

linearly increasing to equal the value supplied (in Chapter 5) for 2018, 2030, and 2050 (CO, 

Q MAGICC consists of a suite of coupled gas-cycle, climate and ice-melt models integrated into a single framework. 

The framework allows the user to determine changes in greenhouse-gas concentrations, global-mean surface air 

temperature and sea-level resulting from anthropogenic emissions of carbon dioxide (CO2), methane (CH4), nitrous 

oxide (N2O), reactive gases (CO, NOx, VOCs), the halocarbons (e.g. HCFCs, HFCs, PFCs) and sulfur dioxide 

(SO2). MAGICC emulates the global-mean temperature responses of more sophisticated coupled 

Atmosphere/Ocean General Circulation Models (AOGCMs) with high accuracy. 

Deleted: surface 

Deleted: surface 

Deleted: projections 

Deleted: proposed rule

Deleted: Reductions

Deleted: rule

Deleted: rule

Deleted: rule’s

Deleted: R).

Deleted: CH4, 

Deleted: HFC-134a

Deleted: .

Deleted: MiniCAM

Deleted: MiniCAM

Deleted: ¶

Brenkert A, S. Smith, S. Kim, and H. Pitcher, 2003: 

Model Documentation for the MiniCAM. PNNL14337, Pacific Northwest National Laboratory, 

Richland, Washington.

Deleted: Wigley, T.M.L. and Raper, S.C.B. 1992. 

Implications for Climate And Sea-Level of Revised 

IPCC Emissions Scenarios Nature 357, 293-300. 

Raper, S.C.B., Wigley T.M.L. and Warrick R.A. 

1996. in Sea-Level Rise and Coastal Subsidence: 

Causes, Consequences and Strategies J.D. Milliman, 

B.U. Haq, Eds., Kluwer Academic Publishers, 

Dordrecht, The Netherlands, pp. 11-45. ¶

Wigley, T.M.L. and Raper, S.C.B. 2002. Reasons for 

larger warming projections in the IPCC Third 

Assessment Report J. Climate 15, 2945-2952.
Draft Regulatory Impact Analysis 

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SO2, VOCs, and NOx emissions reductions were only provided for these years). EPA linearly 

scaled emissions reductions between the 0 input value in 2013 and the value supplied for 2018 to 

produce the reductions between 2014 and 2018. A similar scaling was used for 2019-2029 and 

2031-2050. The emissions reductions past 2050 were scaled with total U.S. road transportation 

fuel consumption from the GCAM reference scenario. This was chosen as a simple scale factor 

given that both direct and upstream emissions changes are included in the emissions reduction 

scenario provided. Road transport fuel consumption past 2050 does not change significantly and 

thus emissions reductions remain relatively constant from 2050 through 2100.

The GCAM reference scenario293 depicts a world in which global population reaches a 

maximum of more than 9 billion in 2065 and then declines to 8.7 billion in 2100 while global 

GDP grows by an order of magnitude and global energy consumption triples. The reference 

scenario includes no explicit policies to limit carbon emissions, and therefore fossil fuels 

continue to dominate global energy consumption, despite substantial growth in nuclear and 

renewable energy. Atmospheric CO2 concentrations rise throughout the century and reach 792 

ppmv by 2100, with total radiative forcing approaching 7 Watts per square meter (W/m2

The GCAM reference scenario uses non-CO2 and pollutant emissions implemented as 

described in Smith and Wigley (2006); land-use change emissions as described in Wise et al. 

(2009); and updated base-year estimates of global GHG emissions. This scenario was created as 

part of the Climate Change Science Program (CCSP) effort to develop a set of long-term global 

emissions scenarios that incorporate an update of economic and technology data and utilize 

improved scenario development tools compared to the IPCC Special Report on Emissions 

Scenarios (SRES) (IPCC 2000). 

) Forest 

land declines in the reference scenario to accommodate increases in land use for food and 

bioenergy crops. Even with the assumed agricultural productivity increases, the amount of land 

devoted to crops increases in the first half of the century due to increases in population and 

income (higher income drives increases in land-intensive meat consumption). After 2050 the 

rate of growth in food demand slows, in part due to declining population. As a result the amount 

of cropland and also land use change (LUC) emissions decline as agricultural crop productivity 

continues to increase. 

Using MAGICC 5.3 v2,

294 the change in atmospheric CO2 concentrations, global mean 

temperature, and sea level were projected at five-year time steps to 2100 for both the reference 

(no climate policy) scenario and the emissions reduction scenario specific to the preferred 

approach of this proposal. To capture some of the uncertainty in the climate system, the changes 

in projected atmospheric CO2 concentrations, global mean temperature and sea level were 

estimated across the most current Intergovernmental Panel on Climate Change (IPCC) range of 

climate sensitivities, 1.5°C to 6.0°C.S

 

S In IPCC reports, equilibrium climate sensitivity refers to the equilibrium change in the annual mean 

global surface temperature following a doubling of the atmospheric equivalent carbon dioxide 

concentration. The IPCC states that climate sensitivity is “likely” to be in the range of 2°C to 4.5°C, “very 

unlikely” to be less than 1.5°C, and “values substantially higher than 4.5°C cannot be excluded.” IPCC 

The range as illustrated in Chapter 10, Box 10.2, Figure 2

Deleted: Using MAGICC,
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8-49

of the IPCC’s Working Group I is approximately consistent with the 10-90% probability 

distribution of the individual cumulative distributions of climate sensitivity.295

The integrated impact of the following pollutant and greenhouse gas emissions changes 

are considered: CO

 

2, CH4, N2O, VOC, NOx, CO, and SO2. For CO, SO2, and NOx, emissions 

reductions were estimated for 2018, 2030, and 2050. For CO2, CH4, and N2

MAGICC is a global model and is primarily concerned with climate, therefore the impact 

of short-lived climate forcing agents (e.g., O

O an annual timeseries of (upstream + downstream) emissions reductions estimated from the proposal were input 

directly. The GHG emissions reductions, from Chapter 5, were applied as net reductions to a 

global reference case (or baseline) emissions scenario in GCAM to generate an emissions 

scenario specific to this proposal. EPA linearly scaled emissions reductions between a zero input 

value in 2013 and the value supplied for 2018 to produce the reductions for 2014-2018. A 

similar scaling was used for 2019-2029 and 2031-2050. The emissions reductions past 2050 

were scaled with total U.S. road transportation fuel consumption from the GCAM reference 

scenario. Road transport fuel consumption past 2050 does not change significantly and thus 

emissions reductions remain relatively constant from 2050 through 2100. Specific details about 

the reference case scenario and how the emissions reductions were applied to generate the 

scenario can be found in the proposal’s RIA, Chapter 8.4. 

3) are not explicitly simulated as in regional air 

quality models. While many precursors to short-lived climate forcers such as ozone are 

considered, MAGICC simulates the longer term effect on climate from long-lived GHGs. The 

impacts to ground-level ozone and other non-GHGs are discussed in Section VII of this proposal 

and the draft RIA, Chapter 8.2. Some aerosols, such as black carbon, cause a positive forcing or 

warming effect by absorbing incoming solar radiation. There remain some significant scientific 

uncertainties about black carbon’s total climate effect,T as well as concerns about how to treat 

the short-lived black carbon emissions alongside the long-lived, well-mixed greenhouse gases in 

a common framework (e.g., what are the appropriate metrics to compare the warming and/or 

climate effects of the different substances, given that, unlike greenhouse gases, the magnitude of 

aerosol effects can vary immensely with location and season of emissions). Further, estimates of 

the direct radiative forcing of individual species are less certain than the total direct aerosol 

radiative forcing.

There is no single accepted methodology for transforming black carbon emissions into 

temperature change or CO2-equivalent emissions. The interaction of black carbon (and other coemitted aerosol species) with clouds is especially poorly quantified, and this factor is key to any 

 

WGI, 2007, Climate Change 2007 - The Physical Science Basis, Contribution of Working Group I to the 

Fourth Assessment Report of the IPCC, http://www.ipcc.ch/.

T The range of uncertainty in the current magnitude of black carbon’s climate forcing effect is evidenced by the 

ranges presented by the IPCC Fourth Assessment Report (2007) and the more recent study by Ramanathan, V. and 

Carmichael, G. (2008) Global and regional climate changes due to black carbon. Nature Geoscience, 1(4): 221–227.
Draft Regulatory Impact Analysis 

8-50

attempt to estimate the net climate impacts of black carbon. While black carbon is likely to be 

an important contributor to climate change, it would be premature to include quantification of 

black carbon climate impacts in an analysis of the proposed standards at this time.

To compute the reductions in atmospheric CO2 concentration, global mean temperature,

and sea level rise specifically attributable to the impacts of the proposed standards, the output 

from the proposal’s primary emissions scenario was subtracted from the reference case (base 

case) emissions scenario. As a result of the proposal’s specified emissions reductions from the 

primary alternative, the concentration of atmospheric CO2 is projected to be reduced by 

approximately 0.693 to 0.784 parts per million by volume (ppmv), the global mean temperature 

is projected to be reduced by approximately 0.002-0.004°C by 2100 and global mean sea level 

rise is projected to be reduced by approximately 0.012-0.48 cm by 2100. The reference (no 

policy) and the specified emission reductions scenarios were subtracted from global emissions 

for the years 2000-2100. The difference between these two results is the impact of the preferred 

approach of this proposal on global CO2

Figure 8-5

concentrations and other key climate variables. 

provides the results over time for the estimated reductions in atmospheric CO2

concentration associated with the proposal. Figure 8-6 provides the estimated change in 

projected global mean temperatures associated with the proposal. Figure 8-7 provides the 

estimated reductions in global mean sea level rise associated with the proposal. The range of 

reductions in global mean temperature and sea level rise is larger because CO2 concentrations 

are not tightly coupled to climate sensitivity, whereas the magnitude of temperature change 

response to CO2 changes (and therefore sea level rise) is tightly coupled to climate sensitivity in 

the MAGICC model. 

Change in CO2 Concentration 

(Primary Alternative - Reference) 

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

2000 2020 2040 2060 2080 2100

ppmv

CS 1.5

CS 2.0

CS 2.5

CS 3.0

CS 4.5

CS 6.0

Figure 8-5 Estimated Projected Reductions in Atmospheric CO2 Concentrations (parts per million by 

volume) from Baseline for the Proposed Heavy-Duty Rule (climate sensitivity (CS) cases ranging from 1.5-

6°C)

Deleted: rule

Deleted: proposed rule’s

Deleted: (no policy or baseline

Deleted: case 

Deleted: (or preferred

Deleted: ),

Deleted: X.X

Deleted: X.X

Deleted: (ppm

Deleted: 00X

Deleted: 0XX

Deleted: 0X

Deleted: XX

Deleted: specified proposed heavy-duty emissions 

changes

Field Code Changed

Deleted: proposed rule

Field Code Changed

Deleted: reductions

Deleted: proposed rule.

Field Code Changed

Deleted: proposed rule

Deleted: 

CO2 Concen 

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

2000 2020 2040

Yea

Difference (ppmv)

Deleted: for 

Deleted: sensitivities
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Environmental and Health 

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8-51

Change in Global Mean Temperature

(Primary Alternative - Reference)

-0.005

-0.004

-0.003

-0.002

-0.001

0.000

2000 2020 2040 2060 2080 2100

degree C

CS 1.5

CS 2.0

CS 2.5

CS 3.0

CS 4.5

CS 6.0

Figure 8-6 Estimated Projected Reductions in Global Mean Surface Temperatures from Baseline for the 

Proposed Heavy-Duty Rule (climate sensitivity (CS) cases ranging from 1.5-6°C)

Change in Global Mean Sea Level Rise

(Primary Alternative - Reference)

-0.06

-0.05

-0.04

-0.03

-0.02

-0.01

0

2000 2020 2040 2060 2080 2100

cm

CS 1.5

CS 2.0

CS 2.5

CS 3.0

CS 4.5

CS 6.0

Figure 8-7 Estimated Projected Reductions in Global Mean Sea Level Rise from Baseline for the Final

Proposed Heavy-Duty Rule (climate sensitivity (CS) cases ranging from 1.5-6°C)

The results in Figure 8-6 and Figure 8-7 show a relatively small reduction in the 

projected global mean temperature and sea level respectively, across all climate sensitivities. The 

projected reductions are small relative to the IPCC’s 2100 “best estimates” for global mean 

Deleted: 

Global Mean T 

-0.0180

-0.0160

-0.0140

-0.0120

-0.0100

-0.0080

-0.0060

-0.0040

-0.0020

0.0000

2000 2020 2040

Y

Difference (°C)

¶

Deleted: for 

Deleted: sensitivities

Deleted: 

Global Mea 

-0.16

-0.14

-0.12

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

2000 2020 2040

Ye

Difference (cm)

Deleted: 

Deleted: for 

Deleted: sensitivities

Deleted: both 

Field Code Changed

Field Code Changed
Draft Regulatory Impact Analysis 

8-52

temperature increases (1.1 – 6.4oC) and sea level rise (0.18-0.59 cm) for all global GHG 

emissions sources for a range of emissions scenarios.U,297

8.4.3 Estimated Projected Change in Ocean pH 

 However, this is to be expected given 

the magnitude of reductions from the proposal in the context of global emissions. 

For this proposal, EPA analyzes another key climate-related variable and calculates 

projected change in ocean pH for tropical waters. For this analysis, changes in ocean pH are 

related to the change in the atmospheric concentration of carbon dioxide (CO2) resulting from 

the preferred approach of this proposal. EPA used the program developed for CO2 System 

Calculations (CO2SYS) CO2SYS,298 version 1.05, a program which performs calculations 

relating parameters of the carbon dioxide (CO2

The program uses two of the four measurable parameters of the CO

) system in seawater. The program was 

developed by Ernie Lewis at Brookhaven National Laboratory and Doug Wallace at the Insitut 

fuer Meereskunde in Germany, supported by the U.S. Department of Energy, Office of 

Biological and Environmental Research, under Contract No. DE-ACO2-76CH00016.

2 system [total 

alkalinity (TA), total inorganic CO2 (TC), pH, and either fugacity (fCO2) or partial pressure of 

CO2 (pCO2)] to calculate the other two parameters given a specific set of input conditions 

(temperature and pressure) and output conditions chosen by the user. EPA utilized the DOS 

version (Lewis and Wallace, 1998)299

1) A reference case scenario

of the program to compute pH under two emissions 

scenarios as follows:

which was based on the change in atmospheric CO2 

2) An emissions reduction scenario

concentrations (also known as partial pressure) in 2100 in parts per million by volume

(ppmv) from reference scenario developed for the MAGICC modeling [modeling was 

performed across a range of climate sensitivities 1.5-6.0°C]. 

based on the proposal’s preferred alternative which

reduces atmospheric CO2

In order to determine the change in pH resulting from the emissions reduction, EPA 

subtracted the reference scenario pH from the emission reduction scenario pH for each climate 

sensitivity case. The analysis indicates that the emissions reductions in 2100 result in a slight

increase in ocean pH of 0.0003 by the year 2100. The values for pH under the two scenarios 

varied according to the climate sensitivity being evaluated. Using the set of seawater parameters 

detailed below and the climate sensitivity case of 3.0, the reference scenario pH was 7.7888 and 

the emissions reduction scenario was 7.7891 resulting in a difference of 0.0003.

concentrations in 2100 by 0.693 to 0.784 ppmv [MAGICC 

modeling was performed across a range of climate sensitivities 1.5-6.0°C]. 

The CO2SYS program required the input of a number of variables and constants for each 

scenario for calculated the result for both the reference case and the proposal’s emissions 

 

U IPCC WGI, 2007. The IPCC “best estimates” include only emissions uncertainty, and not any climate parameter 

uncertainty. The sea level rise estimates exclude any possible future dynamical changes in ice flow from ice sheets. 

The baseline temperature increases by 2100 from our MiniCAM-MAGICC runs are 1.8°C to 4.5°C.

Deleted: 8 – 4.0oC

Deleted: 20

Deleted: 59m

Deleted: 296

Deleted: Changes

Deleted: In today’s proposed rule,

Deleted: the 

Deleted: changes

Deleted: To calculate the

Deleted: oceanic

Deleted: resulting arising from

Deleted: ,

Deleted: ..

Deleted: The program CO2SYS performs 

calculations relating parameters of the carbon ...

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8-53

reduction case. EPA used the following inputs, with justification and references for these inputs 

provided in brackets:

1) Input mode: Single-input [This simply means that the program calculates pH for one set 

of input variables at a time, instead of a batch of variables. The choice has no affect on

results].

2) Choice of constants: Mehrbach et al. (1973)302, refit by Dickson and Millero (1987)303

3) Choice of fCO2 or pCO2: pCO2 [pCO2 

4) Choice of KSO4: Dickson (1990)

is the partial pressure of CO2 and can be 

converted to fugacity (fCO2) if desired] 304 [Lewis and Wallace (1998)305 recommend using the 

equation of Dickson (1990) for this dissociation constant. The model also allows the use 

of the equation of Khoo et al. (1977).306

5) Choice of pH scale: Total scale [The model allows pH outputs to be provided on the total 

scale, the seawater scale, the free scale, and the National Bureau of Standards (NBS) 

scale. The various pH scales can be interrelated using equations provided by Lewis and 

Wallace (1998)].

Switching this parameter to Khoo et al. (1977) 

instead of Dickson (1990) had no effect on the calculated result].

The program provides several choices of constants for saltwater that are needed for the 

calculations. EPA calculated pH values using all choices and found that in all cases the choice 

had an indistinguishable effect on the results. Additional inputs are required and EPA ran the 

model using a variety of input values to test whether the model was sensitive to these inputs. 

EPA found the model was not sensitive to these inputs in terms of the incremental change in pH 

calculated for each climate sensitivity case. The input values are derived from certified reference 

materials of sterilized natural sea water (Dickson, 2003, 2005, and 2009).307 Based on the

projected atmospheric CO2 concentration reductions that would result from this proposal (0.731 

ppmv for a climate sensitivity of 3.0), the modeling program calculates an increase in ocean pH 

of approximately 0.0003 pH units in 2100. Thus, this analysis indicates the projected decrease in 

atmospheric CO2

Table 8-4

concentrations from the preferred approach of this proposal yields an increase 

in ocean pH. contains the projected change results in ocean pH based the change in 

atmospheric CO2

Table 8-4: Impact of Proposal’s GHG Emissions Reductions On Ocean pH 

concentrations.

CLIMATE 

SENSITIVITY

DIFFERENCE 

IN CO2

YEAR aPROJECTED 

CHANGE

3.0 -0.731 2100 0.0003

a represents the change in atmospheric CO2

8.4.4 Summary of Climate Analyses

concentrations in 2100 based on the difference from the 

proposal’s preferred alternative from the GCAM reference scenario used in the MAGICC modeling.

EPA’s analysis of the impact of the proposal’s preferred approach on global climate 

conditions is intended to quantify these potential reductions using the best available science. 

While EPA’s modeling results of the impact of the preferred approach alone show small 

differences in climate effects (CO2

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concentration, global mean temperature, sea level rise, and 

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and emissions scenario].

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Draft Regulatory Impact Analysis 

8-54

ocean pH), when expressed in terms of global climate endpoints and global GHG emissions, they 

yield results that are repeatable and consistent within the modeling frameworks used. The results 

are summarized in Table 8-5, Impact of GHG Emissions Reductions On Projected Changes in 

Global Climate Associated with the Proposal. 

These projected reductions are proportionally representative of changes to U.S. GHG 

emissions in the transportation sector. While not formally estimated for this proposal, a reduction 

in projected global mean temperature and sea level rise implies a reduction in the risks associated 

with climate change. The figures for these variables illustrate that the distribution across a range 

of climate sensitivities for projected global mean temperature and sea level rise shifts down. The 

benefits of GHG emissions reductions can be characterized both qualitatively and quantitatively, 

some of which can be monetized (see Chapter 8.5). There are substantial uncertainties in 

modeling the global risks of climate change, which complicates quantification and cost-benefits

assessments. Changes in climate variables are a meaningful proxy for changes in the risk of all

potential impacts--including those that can be monetized, and those that have not been monetized 

but can be quantified in physical terms (e.g., water availability), as well as those that have not yet 

been quantified or are extremely difficult to quantify (e.g., forest disturbance and catastrophic 

events such as collapse of large ice sheets and subsequent sea level rise).

Table 8-5 Impact of GHG Emissions Reductions On Projected Changes in Global Climate Associated with the 

Proposal (based on a range of climate sensitivities from 1.5-6°C) 

VARIABLE UNITS YEAR PROJECTED 

CHANGE

Atmospheric CO2 ppmv Concentration 2100 -0.693 to -0.784

Global Mean Surface 

Temperature o C 2100 -0.002 to -0.004

Sea Level Rise cm 2100 -0.012 to -0.048

Ocean pH pH units 2100 0.0003b

b

8.5 Monetized CO

The value for projected change in ocean pH is based on a climate sensitivity of 3.0.

2

We assigned a dollar value to reductions in carbon dioxide (CO

Impacts

2

Deleted: A summary of

) emissions using recent 

estimates of the “social cost of carbon” (SCC). The SCC is an estimate of the monetized 

damages associated with an incremental increase in carbon emissions in a given year. It is 

intended to include (but is not limited to) changes in net agricultural productivity, human health, 

property damages from increased flood risk, and the value of ecosystem services due to climate 

change. The SCC estimates used in this analysis were developed through an interagency process 

that included EPA, DOT/NHTSA, and other executive branch entities, and concluded in 

February 2010. We first used these SCC estimates in the benefits analysis for the final joint 

EPA/DOT Rulemaking to establish Light-Duty Vehicle Greenhouse Gas Emission Standards and 

Corporate Average Fuel Economy Standards; see the rule’s preamble for discussion about 

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8-55

application of the SCC (75 FR 25324; 5/7/10). The SCC Technical Support Document (SCC 

TSD) provides a complete discussion of the methods used to develop these SCC estimates.V

The interagency group selected four SCC values for use in regulatory analyses, which we 

have applied in this analysis: $5, $22, $36, and $66 per metric ton of CO

 

2 emissions in 2010, in 

2008 dollars.W ,X

The SCC increases over time because future emissions are expected to produce larger 

incremental damages as physical and economic systems become more stressed in response to 

greater climatic change. Note that the interagency group estimated the growth rate of the SCC 

directly using the three integrated assessment models rather than assuming a constant annual 

growth rate. This helps to ensure that the estimates are internally consistent with other modeling 

assumptions. Table VIII.G.1-1 presents the SCC estimates used in this analysis.

 The first three values are based on the average SCC from three integrated 

assessment models, at discount rates of 5, 3, and 2.5 percent, respectively. SCCs at several 

discount rates are included because the literature shows that the SCC is quite sensitive to 

assumptions about the discount rate, and because no consensus exists on the appropriate rate to 

use in an intergenerational context. The fourth value is the 95th percentile of the SCC from all 

three models at a 3 percent discount rate. It is included to represent higher-than-expected 

impacts from temperature change further out in the tails of the SCC distribution. Low 

probability, high impact events are incorporated into all of the SCC values through explicit 

consideration of their effects in two of the three models as well as the use of a probability density 

function for equilibrium climate sensitivity. Treating climate sensitivity probabilistically results

in more high temperature outcomes, which in turn lead to higher projections of damages.

When attempting to assess the incremental economic impacts of carbon dioxide 

emissions, the analyst faces a number of serious challenges. A recent report from the National 

Academies of Science (NRC 2009) points out that any assessment will suffer from uncertainty, 

speculation, and lack of information about (1) future emissions of greenhouse gases, (2) the 

effects of past and future emissions on the climate system, (3) the impact of changes in climate 

 

V Docket ID EPA-HQ-OAR-2009-0472-114577, Technical Support Document: Social Cost of Carbon for 

Regulatory Impact Analysis Under Executive Order 12866, Interagency Working Group on Social Cost of Carbon, 

with participation by Council of Economic Advisers, Council on Environmental Quality, Department of Agriculture, 

Department of Commerce, Department of Energy, Department of Transportation, Environmental Protection Agency, 

National Economic Council, Office of Energy and Climate Change, Office of Management and Budget, Office of 

Science and Technology Policy, and Department of Treasury (February 2010). Also available at 

http://epa.gov/otaq/climate/regulations.htm

W The interagency group decided that these estimates apply only to CO2 emissions. Given that warming profiles and 

impacts other than temperature change (e.g. ocean acidification) vary across GHGs, the group concluded 

“transforming gases into CO2-equivalents using GWP, and then multiplying the carbon-equivalents by the SCC, 

would not result in accurate estimates of the social costs of non-CO2 gases” (SCC TSD, pg 13).

X The SCC estimates were converted from 2007 dollars to 2008 dollars using a GDP price deflator (1.021) obtained 

from the Bureau of Economic Analysis, National Income and Product Accounts Table 1.1.4, Prices Indexes for 

Gross Domestic Product.

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Draft Regulatory Impact Analysis 

8-56

on the physical and biological environment, and (4) the translation of these environmental 

impacts into economic damages.308

The interagency group noted a number of limitations to the SCC analysis, including the 

incomplete way in which the integrated assessment models capture catastrophic and noncatastrophic impacts, their incomplete treatment of adaptation and technological change, 

uncertainty in the extrapolation of damages to high temperatures, and assumptions regarding risk 

aversion. The limited amount of research linking climate impacts to economic damages makes 

the interagency modeling exercise even more difficult. The interagency group hopes that over 

time researchers and modelers will work to fill these gaps and that the SCC estimates used for 

regulatory analysis by the Federal government will continue to evolve with improvements in 

modeling. Additional details on these limitations are discussed in the SCC TSD.

 As a result, any effort to quantify and monetize the harms 

associated with climate change will raise serious questions of science, economics, and ethics and 

should be viewed as provisional. 

In light of these limitations, the interagency group has committed to updating the current 

estimates as the science and economic understanding of climate change and its impacts on 

society improves over time. Specifically, the interagency group has set a preliminary goal of 

revisiting the SCC values in the next few years or at such time as substantially updated models 

become available, and to continue to support research in this area. 

Applying the global SCC estimates, shown in Table 8-6, to the estimated reductions in 

domestic CO2 emissions for the proposed rule, we estimate the dollar value of the climate related 

benefits for each analysis year. For internal consistency, the annual benefits are discounted back 

to net present value terms using the same discount rate as each SCC estimate (i.e. 5%, 3%, and 

2.5%) rather than 3% and 7%.Y The SCC estimates are presented in and the associated CO2

benefit estimates for each calendar year are shown in Table 8-7.

Table 8-6 Social Cost of CO2, 2010 – 2050a

 

Y It is possible that other benefits or costs of proposed regulations unrelated to CO2 emissions will be discounted at 

rates that differ from those used to develop the SCC estimates.

(in 2008 dollars)

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8-57

Year Discount Rate and Statistic

5% Average 3% Average 2.5% Average 3% 

95th

2010

percentile

$4.80 $21.85 $35.84 $66.26

2015 $5.87 $24.35 $39.21 $74.33

2020 $6.94 $26.85 $42.58 $82.39

2025 $8.45 $30.15 $46.84 $92.25

2030 $9.95 $33.44 $51.10 $102.10

2035 $11.46 $36.73 $55.36 $111.95

2040 $12.97 $40.02 $59.63 $121.81

2045 $14.50 $42.93 $63.00 $130.43

2050 $16.03 $45.84 $66.37 $139.06

a

Table 8-7 Upstream and Downstream CO

The SCC values are dollar-year and emissions-year specific.

2 Benefits for the Given SCC Value, Calendar Year Analysisa

(Millions of 2008 dollars) 

YEAR

5%

(AVERAGE SCC = 

$5 IN 2010)

3% 

(AVERAGE SCC = 

$22 IN 2010)

2.5% 

(AVERAGE SCC =

$36 IN 2010)

3%

(95TH PERCENTILE =

$66 IN 2010)

2012 $0 $0 $0 $0 

2013 $0 $0 $0 $0 

2014 $23 $97 $156 $294

2015 $47 $196 $315 $597

2016 $74 $301 $483 $919

2017 $112 $452 $722 $1,381

2018 $154 $612 $976 $1,875

2019 $195 $766 $1,217 $2,347

2020 $237 $916 $1,452 $2,810

2021 $280 $1,064 $1,680 $3,264

2022 $324 $1,208 $1,899 $3,703

2023 $368 $1,352 $2,117 $4,143

2024 $414 $1,497 $2,335 $4,584

2025 $460 $1,641 $2,550 $5,022

2026 $506 $1,782 $2,759 $5,451

2027 $552 $1,919 $2,961 $5,868

2028 $598 $2,052 $3,156 $6,272

2029 $643 $2,183 $3,346 $6,668

2030 $689 $2,313 $3,535 $7,063

2031 $733 $2,436 $3,712 $7,435

2032 $776 $2,556 $3,883 $7,798

2033 $821 $2,677 $4,056 $8,165

2034 $866 $2,798 $4,229 $8,532

2035 $912 $2,922 $4,405 $8,908

2036 $959 $3,047 $4,582 $9,286

2037 $1,006 $3,173 $4,760 $9,666

2038 $1,054 $3,301 $4,939 $10,051

2039 $1,103 $3,429 $5,120 $10,440

2040 $1,153 $3,559 $5,302 $10,832

2041 $1,203 $3,682 $5,467 $11,201

2042 $1,255 $3,806 $5,635 $11,575

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2043 $1,307 $3,933 $5,805 $11,957

2044 $1,361 $4,063 $5,979 $12,347

2045 $1,416 $4,193 $6,153 $12,740

2046 $1,472 $4,327 $6,331 $13,141

2047 $1,529 $4,463 $6,513 $13,551

2048 $1,588 $4,602 $6,697 $13,968

2049 $1,648 $4,743 $6,884 $14,392

2050 $1,709 $4,888 $7,076 $14,826

NPVb $8,605 $43,991 $74,572 $134,077 a

The SCC values are dollar-year and emissions-year specific. b Note that net present value of reduced GHG emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used to 

calculate net present value of SCC for internal consistency. Refer to SCC TSD for more detail.

We also conducted a separate analysis of the CO2 benefits over the model year lifetimes 

of the 2014 through 2018 model year vehicles. In contrast to the calendar year analysis, the 

model year lifetime analysis shows the lifetime impacts of the program on each of these MY 

fleets over the course of its lifetime. Full details of the inputs to this analysis can be found in 

RIA chapter 5. The CO2

Table 8-8

benefits of the full life of each of the five model years from 2014

through 2018 are shown in through Table 8-11 for each of the four different social cost 

of carbon values. The CO2 benefits are shown for each year in the model year life and in net 

present value. The same discount rate used to discount the value of damages from future 

emissions (SCC at 5, 3, 2.5 percent) is used to calculate net present value of SCC for internal 

consistency.

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8-59

Table 8-8 Upstream and Downstream CO2

YEAR

Benefits for the 5% (Average SCC) Value, Model Year Analysisa

(Millions of 2008 dollars)

MY 2014 MY 2015 MY 2016 MY 2017 MY 2018 SUM

2012 $0 $0 $0 $0 $0 $0

2013 $0 $0 $0 $0 $0 $0

2014 $18 $0 $0 $0 $0 $18

2015 $17 $19 $0 $0 $0 $37

2016 $16 $19 $22 $0 $0 $57

2017 $16 $18 $21 $35 $0 $90

2018 $15 $17 $20 $33 $40 $125

2019 $14 $16 $19 $32 $38 $119

2020 $13 $15 $18 $30 $36 $112

2021 $12 $14 $17 $29 $35 $106

2022 $11 $13 $16 $27 $33 $99

2023 $10 $12 $15 $25 $31 $92

2024 $9 $11 $14 $23 $29 $85

2025 $8 $10 $13 $21 $27 $78

2026 $7 $9 $11 $19 $25 $72

2027 $7 $8 $10 $18 $23 $65

2028 $6 $7 $9 $16 $20 $59

2029 $5 $6 $8 $14 $19 $53

2030 $5 $6 $7 $13 $17 $47

2031 $4 $5 $7 $11 $15 $42

2032 $4 $4 $6 $10 $13 $37

2033 $3 $4 $5 $9 $12 $33

2034 $3 $3 $4 $8 $10 $29

2035 $2 $3 $4 $7 $9 $25

2036 $2 $2 $3 $6 $8 $22

2037 $2 $2 $3 $5 $7 $19

2038 $1 $2 $2 $4 $6 $16

2039 $1 $2 $2 $4 $5 $14

2040 $1 $1 $2 $3 $5 $12

2041 $1 $1 $2 $3 $4 $10

2042 $1 $1 $1 $2 $3 $9

2043 $1 $1 $1 $2 $3 $8

2044 $1 $1 $1 $2 $3 $7

2045 $0 $1 $1 $2 $2 $5

2046 $0 $0 $1 $1 $2 $4

2047 $0 $0 $0 $2 $2 $3

2048 $0 $0 $0 $0 $2 $2

2049 $0 $0 $0 $0 $0 $0

2050 $0 $0 $0 $0 $0 $0

NPV, 

5%

$200 $200 $200 $300 $300 $1,100

a

The SCC values are dollar-year and emissions-year specific. 

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Table 8-9 Upstream and Downstream CO2

YEAR

Benefits for the 3% (Average SCC) SCC Value, Model Year 

Analysisa (Millions of 2008 dollars) 

MY 2014 MY 2015 MY 2016 MY 2017 MY 2018 SUM

2012 $0 $0 $0 $0 $0 $0

2013 $0 $0 $0 $0 $0 $0

2014 $75 $0 $0 $0 $0 $75

2015 $71 $81 $0 $0 $0 $152

2016 $67 $76 $91 $0 $0 $234

2017 $63 $72 $86 $140 $0 $361

2018 $59 $68 $81 $132 $157 $497

2019 $54 $63 $76 $125 $148 $466

2020 $50 $58 $71 $117 $140 $435

2021 $45 $53 $65 $108 $131 $403

2022 $41 $48 $60 $99 $122 $369

2023 $37 $43 $54 $91 $112 $338

2024 $33 $39 $49 $83 $104 $308

2025 $30 $35 $45 $76 $95 $280

2026 $26 $32 $40 $69 $86 $253

2027 $23 $28 $36 $61 $78 $227

2028 $20 $25 $32 $55 $70 $202

2029 $18 $22 $28 $49 $63 $180

2030 $16 $19 $25 $43 $56 $159

2031 $13 $16 $22 $38 $50 $140

2032 $12 $14 $19 $33 $44 $122

2033 $10 $12 $17 $29 $39 $107

2034 $8 $11 $14 $25 $34 $92

2035 $7 $9 $12 $22 $29 $80

2036 $6 $8 $11 $19 $26 $69

2037 $5 $7 $9 $16 $22 $59

2038 $4 $6 $8 $14 $19 $51

2039 $4 $5 $7 $12 $16 $43

2040 $3 $4 $6 $10 $14 $37

2041 $3 $3 $5 $9 $12 $32

2042 $2 $3 $4 $7 $10 $27

2043 $2 $2 $3 $6 $9 $23

2044 $2 $2 $3 $5 $7 $20

2045 $0 $2 $2 $5 $6 $16

2046 $0 $0 $3 $4 $5 $12

2047 $0 $0 $0 $5 $5 $9

2048 $0 $0 $0 $0 $6 $6

2049 $0 $0 $0 $0 $0 $0

2050 $0 $0 $0 $0 $0 $0

NPV, 

3%

$600 $600 $700 $1,000 $1,200 $4,200

a

The SCC values are dollar-year and emissions-year specific. 

Table 8-10Upstream and Downstream CO2

YEAR

Benefits for the from 2.5% (Average SCC) SCC Value, Model 

Year Analysisa (Millions of 2008 dollars)

MY 2014 MY 2015 MY 2016 MY 2017 MY 2018 SUM

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2012 $0 $0 $0 $0 $0 $0

2013 $0 $0 $0 $0 $0 $0

2014 $121 $0 $0 $0 $0 $121

2015 $115 $130 $0 $0 $0 $245

2016 $108 $122 $146 $0 $0 $376

2017 $101 $115 $137 $224 $0 $577

2018 $94 $108 $129 $211 $250 $792

2019 $86 $100 $121 $198 $236 $741

2020 $79 $92 $112 $185 $221 $689

2021 $71 $83 $103 $171 $207 $635

2022 $64 $75 $94 $156 $192 $581

2023 $58 $68 $85 $143 $176 $529

2024 $51 $61 $77 $129 $162 $481

2025 $46 $55 $70 $117 $147 $435

2026 $41 $49 $62 $106 $134 $392

2027 $36 $43 $56 $95 $121 $350

2028 $31 $38 $49 $85 $108 $311

2029 $27 $33 $43 $75 $97 $275

2030 $24 $29 $38 $66 $86 $243

2031 $21 $25 $33 $58 $76 $213

2032 $18 $22 $29 $51 $67 $186

2033 $15 $19 $25 $44 $58 $161

2034 $13 $16 $22 $38 $51 $140

2035 $11 $14 $19 $33 $44 $121

2036 $9 $12 $16 $28 $38 $104

2037 $8 $10 $14 $24 $33 $89

2038 $7 $8 $12 $21 $28 $76

2039 $6 $7 $10 $18 $24 $65

2040 $5 $6 $8 $15 $21 $55

2041 $4 $5 $7 $13 $18 $47

2042 $3 $4 $6 $11 $15 $40

2043 $3 $4 $5 $9 $13 $34

2044 $3 $3 $4 $8 $11 $29

2045 $0 $3 $4 $7 $9 $23

2046 $0 $0 $4 $6 $8 $18

2047 $0 $0 $0 $7 $7 $14

2048 $0 $0 $0 $0 $8 $8

2049 $0 $0 $0 $0 $0 $0

2050 $0 $0 $0 $0 $0 $0

NPV, 

2.5%

$1,000 $1,000 $1,100 $1,600 $1,800 $6,500

a

The SCC values are dollar-year and emissions-year specific. 

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8-62

Table 8-11 Upstream and Downstream CO2

YEAR

Benefits for the 3% (95th Percentile) SCC Value, Model Year 

Analysisa (Millions of 2008 dollars)

MY 2014 MY 2015 MY 2016 MY 2017 MY 2018 SUM

2012 $0 $0 $0 $0 $0 $0

2013 $0 $0 $0 $0 $0 $0

2014 $229 $0 $0 $0 $0 $229

2015 $217 $247 $0 $0 $0 $464

2016 $205 $233 $277 $0 $0 $715

2017 $193 $220 $262 $429 $0 $1,104

2018 $180 $207 $248 $405 $481 $1,521

2019 $166 $193 $234 $382 $455 $1,429

2020 $152 $177 $217 $358 $428 $1,333

2021 $138 $162 $200 $332 $402 $1,234

2022 $125 $146 $183 $305 $374 $1,132

2023 $113 $133 $166 $279 $345 $1,036

2024 $101 $120 $151 $254 $318 $944

2025 $91 $108 $137 $231 $290 $857

2026 $80 $96 $123 $210 $264 $774

2027 $71 $85 $110 $188 $240 $694

2028 $62 $75 $98 $168 $215 $619

2029 $55 $66 $87 $149 $193 $549

2030 $47 $58 $76 $132 $171 $485

2031 $41 $50 $67 $116 $152 $427

2032 $35 $44 $58 $102 $134 $373

2033 $30 $38 $51 $89 $118 $325

2034 $26 $32 $44 $77 $103 $282

2035 $22 $28 $38 $67 $90 $244

2036 $19 $24 $32 $57 $78 $210

2037 $16 $20 $28 $49 $67 $180

2038 $14 $17 $24 $43 $58 $155

2039 $11 $14 $20 $36 $50 $132

2040 $10 $12 $17 $31 $43 $113

2041 $8 $10 $15 $27 $36 $96

2042 $7 $9 $12 $22 $31 $81

2043 $6 $7 $11 $19 $27 $69

2044 $7 $6 $9 $16 $23 $61

2045 $0 $7 $8 $14 $20 $48

2046 $0 $0 $9 $12 $17 $37

2047 $0 $0 $0 $14 $14 $28

2048 $0 $0 $0 $0 $17 $17

2049 $0 $0 $0 $0 $0 $0

2050 $0 $0 $0 $0 $0 $0

NPV, 

3%

$1,900 $2,000 $2,200 $3,200 $3,500 $13,000

a

The SCC values are dollar-year and emissions-year specific. 

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27 U.S. EPA. (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). EPA/600/R05/004aF-cF. Washington, DC: U.S. EPA. Docket EPA-HQ-OAR-2010-0162.

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34 Spektor, D. M., Thurston, G.D., Mao, J., He, D., Hayes, C., Lippmann, M. (1991). Effects of single- and multiday 

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48 U.S. EPA (2002). Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office of 

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50 U.S. EPA. (1986).Guidelines for carcinogen risk assessment. EPA/630/R-00/004. Washington, DC: U.S. EPA. 

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59 Health Effects Institute (HEI). (2002). Research directions to improve estimates of human exposure and risk 

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65 Heinrich, U., Fuhst, R., Rittinghausen, S., et al. (1995). Chronic inhalation exposure of Wistar rats and two 

different strains of mice to diesel engine exhaust, carbon black, and titanium dioxide. Inhal Toxicol, 7, 553-556.

66 Mauderly, J.L., Jones, R.K., Griffith, W.C., et al. (1987). Diesel exhaust is a pulmonary carcinogen in rats exposed 

chronically by inhalation. Fundam. Appl. Toxicol., 9, 208-221.

67 Nikula, K.J., Snipes, M.B., Barr, E.B., et al. (1995). Comparative pulmonary toxicities and carcinogenicities of 

chronically inhaled diesel exhaust and carbon black in F344 rats. Fundam. Appl. Toxicol, 25,80-94.

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68 U.S. EPA (2002). Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office of 

Research and Development, Washington DC. Retrieved on March 17, 2009 from 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060.

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69Reger, R., Hancock, J., Hankinson, J., et al. (1982). Coal miners exposed to diesel exhaust emissions. Ann Occup 

Hyg, 26, 799-815.

70 Attfield, MD. (1978). The effect of exposure to silica and diesel exhaust in underground metal and nonmetal 

miners. In Kelley, W.D., (ed.), Industrial hygiene for mining and tunneling: proceedings of a topical symposium; 

Cincinnati, OH: The American Conference of Governmental Industrial Hygienists, Inc.

71Wade, J.F., III, Newman, L.S. (1993) Diesel asthma: reactive airways disease following overexposure to 

locomotive exhaust. J Occup Med, 35, 149-154.

72 U.S. EPA (2009) 2002 National-Scale Air Toxics Assessment. http://www.epa.gov/ttn/atw/nata2002. Docket 

EPA-HQ-OAR-2010-0162.

73 Zhu, Y.; Hinds, W.C.; Kim, S.; Shen, S.; Sioutas, C. (2002) Study of ultrafine particles near a major highway with 

heavy-duty diesel traffic. Atmospheric Environment 36: 4323-4335.

74 Lena, T.S; Ochieng, V.; Holguín-Veras, J.; Kinney, P.L. (2002) Elemental carbon and PM2.5 levels in an urban 

community heavily impacted by truck traffic. Environ Health Perspect 110: 1009-1015.

75 Soliman, A.S.M.; Jacko, J.B.; Palmer, G.M. (2006) Development of an empirical model to estimate real-world 

fine particulate matter emission factors: the Traffic Air Quality model. J Air & Waste Manage Assoc 56: 1540-

1549.

76 Davis, M.E.; Smith, T.J.; Laden, F.; Hart, J.E.; Ryan, L.M.; Garshick, E. (2006) Modeling particle exposure in 

U.S. trucking terminals. Environ Sci Techol 40: 4226-4232.

77 Miller, T.L.; Fu, J.S.; Hromis, B.; Storey, J.M. (2007) Diesel truck idling emissions – measurments at a PM2.5 hot 

spot. Proceedings of the Annual Conference of the Transportation Research Board, paper no. 07-2609.

78 Ramachandran, G.; Paulsen, D.; Watts, W.; Kittelson, D. (2005) Mass, surface area, and number metrics in diesel 

occupational exposure assessment. J Environ Monit 7: 728-735.

79 U.S. EPA. 2000. Integrated Risk Information System File for Benzene. This material is available electronically at: 

http://www.epa.gov/iris/subst/0276.htm. Docket EPA-HQ-OAR-2010-0162.

80 International Agency for Research on Cancer, IARC monographs on the evaluation of carcinogenic risk of 

chemicals to humans, Volume 29, Some industrial chemicals and dyestuffs, International Agency for Research on 

Cancer, World Health Organization, Lyon, France 1982. Docket EPA-HQ-OAR-2010-0162.

81 Irons, R.D.; Stillman, W.S.; Colagiovanni, D.B.; Henry, V.A. (1992) Synergistic action of the benzene metabolite 

hydroquinone on myelopoietic stimulating activity of granulocyte/macrophage colony-stimulating factor in vitro, 

Proc. Natl. Acad. Sci. 89:3691-3695. Docket EPA-HQ-OAR-2010-0162.

82 International Agency for Research on Cancer (IARC). 1987. Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, Volume 29, Supplement 7, Some industrial chemicals and dyestuffs, World Health 

Organization, Lyon, France. Docket EPA-HQ-OAR-2010-0162.

83 U.S. Department of Health and Human Services National Toxicology Program 11th Report on Carcinogens 

available at: http://ntp.niehs.nih.gov/go/16183. 

84 Aksoy, M. (1989). Hematotoxicity and carcinogenicity of benzene. Environ. Health Perspect. 82: 193-197. 

EPA-HQ-OAR-2010-0162

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85 Goldstein, B.D. (1988). Benzene toxicity. Occupational medicine. State of the Art Reviews. 3: 541-554. Docket 

EPA-HQ-OAR-2010-0162.

86Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E. Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu, M.T. 

Smith, N. Titenko-Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B. Hayes (1996) Hematotoxicity among Chinese 

workers heavily exposed to benzene. Am. J. Ind. Med. 29: 236-246. Docket EPA-HQ-OAR-2010-0162.

87 U.S. EPA 2002 Toxicological Review of Benzene (Noncancer Effects). Environmental Protection Agency, 

Integrated Risk Information System (IRIS), Research and Development, National Center for Environmental 

Assessment, Washington DC. This material is available electronically at http://www.epa.gov/iris/subst/0276.htm. 

Docket EPA-HQ-OAR-2010-0162.

88 Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; Cohen, B.; Melikian, A.; Eastmond, D.; Rappaport, S.; Li, H.; Rupa, 

D.; Suramaya, R.; Songnian, W.; Huifant, Y.; Meng, M.; Winnik, M.; Kwok, E.; Li, Y.; Mu, R.; Xu, B.; Zhang, 

X.; Li, K. (2003). HEI Report 115, Validation & Evaluation of Biomarkers in Workers Exposed to Benzene in 

China. Docket EPA-HQ-OAR-2010-0162.

89 Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et al. (2002). Hematological changes among Chinese 

workers with a broad range of benzene exposures. Am. J. Industr. Med. 42: 275-285. Docket EPA-HQ-OAR-2010-

0162.

90 Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004). Hematotoxically in Workers Exposed to Low Levels 

of Benzene. Science 306: 1774-1776. Docket EPA-HQ-OAR-2010-0162.

91 Turtletaub, K.W. and Mani, C. (2003). Benzene metabolism in rodents at doses relevant to human exposure from 

Urban Air. Research Reports Health Effect Inst. Report No.113. Docket EPA-HQ-OAR-2010-0162.

92 U.S. EPA. 2002. Health Assessment of 1,3-Butadiene. Office of Research and Development, National Center for 

Environmental Assessment, Washington Office, Washington, DC. Report No. EPA600-P-98-001F. This document 

is available electronically at http://www.epa.gov/iris/supdocs/buta-sup.pdf. Docket EPA-HQ-OAR-2010-0162.

93 U.S. EPA. 2002 “Full IRIS Summary for 1,3-butadiene (CASRN 106-99-0)” Environmental Protection Agency, 

Integrated Risk Information System (IRIS), Research and Development, National Center for Environmental 

Assessment, Washington, DC http://www.epa.gov/iris/subst/0139.htm. Docket EPA-HQ-OAR-2010-0162.

94 International Agency for Research on Cancer (IARC) (1999) Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, Volume 71, Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide 

and Volume 97 (in preparation), World Health Organization, Lyon, France. Docket EPA-HQ-OAR-2010-0162.

95 International Agency for Research on Cancer (IARC) (2008) Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, 1,3-Butadiene, Ethylene Oxide and Vinyl Halides (Vinyl Fluoride, Vinyl Chloride and 

Vinyl Bromide) Volume 97, World Health Organization, Lyon, France. Docket EPA-HQ-OAR-2010-0162.

96 U.S. Department of Health and Human Services National Toxicology Program 11th Report on Carcinogens 

available at: http://ntp.niehs.nih.gov/go/16183.

97Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996) Subchronic toxicity of 4-vinylcyclohexene in rats and mice by 

inhalation. Fundam. Appl. Toxicol. 32:1-10. Docket EPA-HQ-OAR-2010-0162.

98 U.S. EPA. 1987. Assessment of Health Risks to Garment Workers and Certain Home Residents from Exposure to 

Formaldehyde, Office of Pesticides and Toxic Substances, April 1987. Docket EPA-HQ-OAR-2010-0162.

99 Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2003. Mortality from lymphohematopoetic 

malignancies among workers in formaldehyde industries. Journal of the National Cancer Institute 95: 1615-1623. 

Docket EPA-HQ-OAR-2010-0162.

100 Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2004. Mortality from solid cancers among 

workers in formaldehyde industries. American Journal of Epidemiology 159: 1117-1130. Docket EPA-HQ-OAR2010-0162.

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101 Beane Freeman, L. E.; Blair, A.; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Hoover, R. N.; Hauptmann, M. 2009. 

Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries: The National Cancer 

Institute cohort. J. National Cancer Inst. 101: 751-761. Docket EPA-HQ-OAR-2010-0162.

102 Pinkerton, L. E. 2004. Mortality among a cohort of garment workers exposed to formaldehyde: an update. 

Occup. Environ. Med. 61: 193-200. Docket EPA-HQ-OAR-2010-0162.

103 Coggon, D, EC Harris, J Poole, KT Palmer. 2003. Extended follow-up of a cohort of British chemical workers 

exposed to formaldehyde. J National Cancer Inst. 95:1608-1615. Docket EPA-HQ-OAR-2010-0162.

104Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2003. Biologically 

motivated computational modeling of formaldehyde carcinogenicity in the F344 rat. Tox Sci 75: 432-447. Docket 

EPA-HQ-OAR-2010-0162.

105Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2004. Human 

respiratory tract cancer risks of inhaled formaldehyde: Dose-response predictions derived from biologicallymotivated computational modeling of a combined rodent and human dataset. Tox Sci 82: 279-296. Docket EPAHQ-OAR-2010-0162.

106Chemical Industry Institute of Toxicology (CIIT).1999. Formaldehyde: Hazard characterization and doseresponse assessment for carcinogenicity by the route of inhalation. CIIT, September 28, 1999. Research Triangle 

Park, NC. Docket EPA-HQ-OAR-2010-0162.

107 U.S. EPA. Analysis of the Sensitivity and Uncertainty in 2-Stage Clonal Growth Models for Formaldehyde with 

Relevance to Other Biologically-Based Dose Response (BBDR) Models. U.S. Environmental Protection Agency, 

Washington, D.C., EPA/600/R-08/103, 2008. Docket EPA-HQ-OAR-2010-0162.

108 Subramaniam, R; Chen, C; Crump, K; .et .al. (2008) Uncertainties in biologically-based modeling of 

formaldehyde-induced cancer risk: identification of key issues. Risk Anal 28(4):907-923. Docket EPA-HQ-OAR2010-0162.

109 Subramaniam, R; Chen, C; Crump, K; .et .al. (2007). Uncertainties in the CIIT 2-stage model for formaldehydeinduced nasal cancer in the F344 rat: a limited sensitivity analysis-I. Risk Anal 27:1237. Docket EPA-HQ-OAR2010-0162.

110 Crump, K; Chen, C; Fox, J; .et .al. (2008) Sensitivity analysis of biologically motivated model for formaldehydeinduced respiratory cancer in humans. Ann Occup Hyg 52:481-495. Docket EPA-HQ-OAR-2010-0162.

111 Crump, K; Chen, C; Fox, J; .et .al. (2008) Sensitivity analysis of biologically motivated model for formaldehydeinduced respiratory cancer in humans. Ann Occup Hyg 52:481-495. Docket EPA-HQ-OAR-2010-0162.

112 Subramaniam, R; Chen, C; Crump, K; .et .al. (2007). Uncertainties in the CIIT 2-stage model for formaldehydeinduced nasal cancer in the F344 rat: a limited sensitivity analysis-I. Risk Anal 27:1237. Docket EPA-HQ-OAR2010-0162.

113 International Agency for Research on Cancer (2006) Formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan2-ol. Monographs Volume 88. World Health Organization, Lyon, France. Docket EPA-HQ-OAR-2010-0162.

114 Agency for Toxic Substances and Disease Registry (ATSDR). 1999. Toxicological profile for Formaldehyde. 

Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. 

http://www.atsdr.cdc.gov/toxprofiles/tp111.html. Docket EPA-HQ-OAR-2010-0162.

115 WHO (2002) Concise International Chemical Assessment Document 40: Formaldehyde. Published under the 

joint sponsorship of the United Nations Environment Programme, the International Labour Organization, and the 

World Health Organization, and produced within the framework of the Inter-Organization Programme for the Sound 

Management of Chemicals. Geneva. Docket EPA-HQ-OAR-2010-0162.

116 U.S. EPA (1988). Integrated Risk Information System File of Acetaldehyde. Research and Development, 

National Center for Environmental Assessment, Washington, DC. This material is available electronically at 

http://www.epa.gov/iris/subst/0290.htm. Docket EPA-HQ-OAR-2010-0162.

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117 U.S. Department of Health and Human Services National Toxicology Program 11th Report on Carcinogens 

available at: http://ntp.niehs.nih.gov/go/16183.

118 International Agency for Research on Cancer (IARC). 1999. Re-evaluation of some organic chemicals, 

hydrazine, and hydrogen peroxide. IARC Monographs on the Evaluation of Carcinogenic Risk of Chemical to 

Humans, Vol 71. Lyon, France.

119 U.S. EPA (1988). Integrated Risk Information System File of Acetaldehyde. This material is available 

electronically at http://www.epa.gov/iris/subst/0290.htm. Docket EPA-HQ-OAR-2010-0162.

120 U.S. EPA. (2003). Integrated Risk Information System File of Acrolein. Research and Development, National 

Center for Environmental Assessment, Washington, DC. This material is available electronically at 

http://www.epa.gov/iris/subst/0364.htm. Docket EPA-HQ-OAR-2010-0162.

121 Appleman, L.M., R.A. Woutersen, and V.J. Feron. (1982). Inhalation toxicity of acetaldehyde in rats. I. Acute 

and subacute studies. Toxicology. 23: 293-297. Docket EPA-HQ-OAR-2010-0162.

122 Myou, S.; Fujimura, M.; Nishi K.; Ohka, T.; and Matsuda, T. (1993) Aerosolized acetaldehyde induces 

histamine-mediated bronchoconstriction in asthmatics. Am. Rev. Respir.Dis.148(4 Pt 1): 940-943. Docket EPAHQ-OAR-2010-0162.

123 U.S. EPA. (2003) Toxicological review of acrolein in support of summary information on Integrated Risk 

Information System (IRIS) National Center for Environmental Assessment, Washington, DC. EPA/635/R-03/003. p. 

10. Available online at: http://www.epa.gov/ncea/iris/toxreviews/0364tr.pdf. Docket EPA-HQ-OAR-2010-0162. 124 U.S. EPA. (2003) Toxicological review of acrolein in support of summary information on Integrated Risk 

Information System (IRIS) National Center for Environmental Assessment, Washington, DC. EPA/635/R-03/003. 

Available online at: http://www.epa.gov/ncea/iris/toxreviews/0364tr.pdf. Docket EPA-HQ-OAR-2010-0162. 125 U.S. EPA. (2003) Toxicological review of acrolein in support of summary information on Integrated Risk 

Information System (IRIS) National Center for Environmental Assessment, Washington, DC. EPA/635/R-03/003. p. 

11. Available online at: http://www.epa.gov/ncea/iris/toxreviews/0364tr.pdf. Docket EPA-HQ-OAR-2010-0162. 126 U.S. EPA. (2003). Integrated Risk Information System File of Acrolein. Office of Research and Development, 

National Center for Environmental Assessment, Washington, DC. This material is available at 

http://www.epa.gov/iris/subst/0364.htm. Docket EPA-HQ-OAR-2010-0162. 127 U.S. EPA. (2003) Toxicological review of acrolein in support of summary information on Integrated Risk 

Information System (IRIS) National Center for Environmental Assessment, Washington, DC. EPA/635/R-03/003. p. 

15. Available online at: http://www.epa.gov/ncea/iris/toxreviews/0364tr.pdf. Docket EPA-HQ-OAR-2010-0162. 128 Morris JB, Symanowicz PT, Olsen JE, et al. 2003. Immediate sensory nerve-mediated respiratory responses to 

irritants in healthy and allergic airway-diseased mice. J Appl Physiol 94(4):1563-1571. Docket EPA-HQ-OAR2010-0162. 129 U.S. EPA. (2003). Integrated Risk Information System File of Acrolein. Research and Development, National 

Center for Environmental Assessment, Washington, DC. This material is available at 

http://www.epa.gov/iris/subst/0364.htm. Docket EPA-HQ-OAR-2010-0162. 130 International Agency for Research on Cancer (IARC). 1995. Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, Volume 63. Dry cleaning, some chlorinated solvents and other industrial chemicals, World 

Health Organization, Lyon, France. Docket EPA-HQ-OAR-2010-0162.

131 Perera, F.P.; Rauh, V.; Tsai, W-Y.; et al. (2002) Effect of transplacental exposure to environmental pollutants on 

birth outcomes in a multiethnic population. Environ Health Perspect. 111: 201-205. Docket EPA-HQ-OAR-2010-

0162.

132 Perera, F.P.; Rauh, V.; Whyatt, R.M.; Tsai, W.Y.; Tang, D.; Diaz, D.; Hoepner, L.; Barr, D.; Tu, Y.H.; Camann, 

D.; Kinney, P. (2006) Effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons on 

neurodevelopment in the first 3 years of life among inner-city children. Environ Health Perspect 114: 1287-1292. 

Docket EPA-HQ-OAR-2010-0162.

133 U. S. EPA. 1998. Toxicological Review of Naphthalene (Reassessment of the Inhalation Cancer Risk), 

Environmental Protection Agency, Integrated Risk Information System, Research and Development, National 

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Center for Environmental Assessment, Washington, DC. This material is available electronically at 

http://www.epa.gov/iris/subst/0436.htm. Docket EPA-HQ-OAR-2010-0162.

134 Oak Ridge Institute for Science and Education. (2004). External Peer Review for the IRIS Reassessment of the 

Inhalation Carcinogenicity of Naphthalene. August 2004. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=84403. Docket EPA-HQ-OAR-2010-0162.

135 National Toxicology Program (NTP). (2004). 11th Report on Carcinogens. Public Health Service, U.S. 

Department of Health and Human Services, Research Triangle Park, NC. Available from: http://ntpserver.niehs.nih.gov.

136 International Agency for Research on Cancer (IARC). (2002). Monographs on the Evaluation of the 

Carcinogenic Risk of Chemicals for Humans. Vol. 82. Lyon, France. Docket EPA-HQ-OAR-2010-0162.

137 U. S. EPA. 1998. Toxicological Review of Naphthalene, Environmental Protection Agency, Integrated Risk 

Information System, Research and Development, National Center for Environmental Assessment, Washington, DC. 

This material is available electronically at http://www.epa.gov/iris/subst/0436.htm

138 Zhou, Y.; Levy, J.I. (2007) Factors influencing the spatial extent of mobile source air pollution impacts: a metaanalysis. BMC Public Health 7: 89. doi:10.1186/1471-2458-7-89. Docket EPA-HQ-OAR-2010-0162.

139 HEI Panel on the Health Effects of Air Pollution. (2010) Traffic-related air pollution: a critical review of the 

literature on emissions, exposure, and health effects. [Online at www.healtheffects.org]. Docket EPA-HQ-OAR2010-0162.

140 Salam, M.T.; Islam, T.; Gilliland, F.D. (2008) Recent evidence for adverse effects of residential proximity to 

traffic sources on asthma. Current Opin Pulm Med 14: 3-8. Docket EPA-HQ-OAR-2010-0162.

141 Holguin, F. (2008) Traffic, outdoor air pollution, and asthma. Immunol Allergy Clinics North Am 28: 577-588.

142 Adar, S.D.; Kaufman, J.D. (2007) Cardiovascular disease and air pollutants: evaluating and improving 

epidemiological data implicating traffic exposure. Inhal Toxicol 19: 135-149. Docket EPA-HQ-OAR-2010-0162.

143 Raaschou-Nielsen, O.; Reynolds, P. (2006) Air pollution and childhood cancer: a review of the epidemiological 

literature. Int J Cancer 118: 2920-2929. Docket EPA-HQ-OAR-2010-0162.

144 U.S. Census Bureau (2008) American Housing Survey for the United States in 2007. Series H-150 (National 

Data), Table 1A-6. [Accessed at http://www.census.gov/hhes/www/housing/ahs/ahs07/ahs07.html on January 22, 

2009]

145 Lena, T.S.; Ochieng, V.; Carter, M.; Holguín-Veras, J.; Kinney, P.L. (2002) Elemental carbon and PM2.5 levels 

in an urban community heavily impacted by truck traffic. Environ Health Perspect 110: 1009-1015. Docket EPAHQ-OAR-2010-0162.

146 Wier, M.; Sciammas, C.; Seto, E.; Bhatia, R.; Rivard, T. (2009) Health, traffic, and environmental justice: 

collaborative research and community action in San Francisco, California. Am J Public Health 99: S499-S504. 

Docket EPA-HQ-OAR-2010-0162.

147 Forkenbrock, D.J. and L.A. Schweitzer, Environmental Justice and Transportation Investment Policy. Iowa 

City: Univerity of Iowa, 1997.

148 Appatova, A.S.; Ryan, P.H.; LeMasters, G.K.; Grinshpun, S.A. (2008) Proximal exposure of public schools and 

students to major roadways: a nationwide US survey. J Environ Plan Mgmt. Docket EPA-HQ-OAR-2010-0162.

149 Green, R.S.; Smorodinsky, S.; Kim, J.J.; McLaughlin, R.; Ostro, B. (2004) Proximity of California public schools 

to busy roads. Environ Health Perspect 112: 61-66. Docket EPA-HQ-OAR-2010-0162.

150 Houston, D.; Ong, P.; Wu, J.; Winer, A. (2006) Proximity of licensed child care facilities to near-roadway vehicle 

pollution. Am J Public Health 96: 1611-1617. Docket EPA-HQ-OAR-2010-0162.

151 Wu, Y.; Batterman, S. (2006) Proximity of schools in Detroit, Michigan to automobile and truck traffic. J 

Exposure Sci Environ Epidemiol 16: 457-470. Docket EPA-HQ-OAR-2010-0162.

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152 U.S. EPA (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, 2009. pg 9-19 through 9-23. Docket EPA-HQ-OAR2010-0162- XXXX.

153 U.S. EPA. 1999. The Benefits and Costs of the Clean Air Act, 1990-2010. Prepared for U.S. Congress by U.S. 

EPA, Office of Air and Radiation, Office of Policy Analysis and Review, Washington, DC, November; EPA report 

no. EPA410-R-99-001. Docket EPA-HQ-OAR-2010-0162.

154 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

155Winner, W.E., and C.J. Atkinson. 1986. “Absorption of air pollution by plants, and consequences for growth.” 

Trends in Ecology and Evolution 1:15-18. Docket EPA-HQ-OAR-2010-0162.

156 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

157 Tingey, D.T., and Taylor, G.E. (1982) Variation in plant response to ozone: a conceptual model of physiological 

events. In M.H. Unsworth & D.P. Omrod (Eds.), Effects of Gaseous Air Pollution in Agriculture and Horticulture. 

(pp.113-138). London, UK: Butterworth Scientific. Docket EPA-HQ-OAR-2010-0162.

158 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

159 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

160 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

161 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

162 Ollinger, S.V., Aber, J.D., Reich, P.B. (1997). Simulating ozone effects on forest productivity: interactions 

between leaf canopy and stand level processes. Ecological Applications, 7, 1237-1251. Docket EPA-HQ-OAR2010-0162.

163Winner, W.E. (1994). Mechanistic analysis of plant responses to air pollution. Ecological Applications, 4(4), 651-

661. Docket EPA-HQ-OAR-2010-0162.

164 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

165 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

166 Fox, S., Mickler, R. A. (Eds.). (1996). Impact of Air Pollutants on Southern Pine Forests, Ecological Studies.

(Vol. 118, 513 pp.) New York: Springer-Verlag.

167 De Steiguer, J., Pye, J., Love, C. (1990). Air Pollution Damage to U.S. Forests. Journal of Forestry, 88(8), 17-

22. Docket EPA-HQ-OAR-2010-0162.

168 Pye, J.M. (1988). Impact of ozone on the growth and yield of trees: A review. Journal of Environmental Quality, 

17, 347-360. Docket EPA-HQ-OAR-2010-0162.

169 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

 

170 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

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171 McBride, J.R., Miller, P.R., Laven, R.D. (1985). Effects of oxidant air pollutants on forest succession in the 

mixed conifer forest type of southern California. In: Air Pollutants Effects On Forest Ecosystems, Symposium 

Proceedings, St. P, 1985, p. 157-167. Docket EPA-HQ-OAR-2010-0162.

172 Miller, P.R., O.C. Taylor, R.G. Wilhour. 1982. Oxidant air pollution effects on a western coniferous forest 

ecosystem. Corvallis, OR: U.S. Environmental Protection Agency, Environmental Research Laboratory (EPA600-D82-276). Docket EPA-HQ-OAR-2010-0162.

173 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

 

174 Kopp, R. J., Vaughn, W. J., Hazilla, M., Carson, R. (1985). Implications of environmental policy for U.S. 

agriculture: the case of ambient ozone standards. Journal of Environmental Management, 20, 321-331. Docket 

EPA-HQ-OAR-2010-0162.

175 Adams, R. M., Hamilton, S. A., McCarl, B. A. (1986). The benefits of pollution control: the case of ozone and 

U.S. agriculture. American Journal of Agricultural Economics, 34, 3-19. Docket EPA-HQ-OAR-2010-0162.

176 Adams, R. M., Glyer, J. D., Johnson, S. L., McCarl, B. A. (1989). A reassessment of the economic effects of 

ozone on U.S. agriculture. Journal of the Air Pollution Control Association, 39, 960-968. Docket EPA-HQ-OAR2010-0162.

177 Abt Associates, Inc. 1995. Urban ornamental plants: sensitivity to ozone and potential economic losses. U.S. 

EPA, Office of Air Quality Planning and Standards, Research Triangle Park. Under contract to RADIAN 

Corporation, contract no. 68-D3-0033, WA no. 6. pp. 9-10. Docket EPA-HQ-OAR-2010-0162.

178 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA, 

Washington, DC, EPA/600/R-05/004aF-cF, 2006. Docket EPA-HQ-OAR-2010-0162.

179 Grulke, N.E. (2003). The physiological basis of ozone injury assessment attributes in Sierran conifers. In A. 

Bytnerowicz, M.J. Arbaugh, & R. Alonso (Eds.), Ozone air pollution in the Sierra Nevada: Distribution and effects 

on forests. (pp. 55-81). New York, NY: Elsevier Science, Ltd. Docket EPA-HQ-OAR-2010-0162.

180White, D., Kimerling, A.J., Overton, W.S. (1992). Cartographic and geometric component of a global sampling 

design for environmental monitoring. Cartography and Geographic Information Systems, 19, 5-22. Docket EPAHQ-OAR-2010-0162.

181 Smith, G., Coulston, J., Jepsen, E., Prichard, T. (2003). A national ozone biomonitoring program—results from 

field surveys of ozone sensitive plants in Northeastern forests (1994-2000). Environmental Monitoring and 

Assessment, 87, 271-291. Docket EPA-HQ-OAR-2010-0162. 

182White, D., Kimerling, A.J., Overton, W.S. (1992). Cartographic and geometric component of a global sampling 

design for environmental monitoring. Cartography and Geographic Information Systems, 19, 5-22. Docket EPAHQ-OAR-2010-0162.

183 Smith, G., Coulston, J., Jepsen, E., Prichard, T. (2003). A national ozone biomonitoring program—results from 

field surveys of ozone sensitive plants in Northeastern forests (1994-2000). Environmental Monitoring and 

Assessment, 87, 271-291. Docket EPA-HQ-OAR-2010-0162. 

184Coulston, J.W., Riitters, K.H., Smith, G.C. (2004). A preliminary assessment of the Montréal process indicators 

of air pollution for the United States. Environmental Monitoring and Assessment, 95, 57-74. Docket EPA-HQOAR-2010-0162.

185 U.S. EPA. (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants. EPA/600/R-05/004aFcF. Docket EPA-HQ-OAR-2010-0162.

186 Smith, G., Coulston, J., Jepsen, E., Prichard, T. (2003). A national ozone biomonitoring program—results from 

field surveys of ozone sensitive plants in Northeastern forests (1994-2000). Environmental Monitoring and 

Assessment, 87, 271-291. Docket EPA-HQ-OAR-2010-0162. 

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187 U.S. EPA (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants. EPA/600/R-05/004aF-cF. 

Docket EPA-HQ-OAR-2010-0162.

188 US EPA. (2007) Review of the National Ambient Air Quality Standards for Ozone: Policy assessment of 

scientific and technical information. Office of Air Quality Planning and Standards staff paper. EPA-452/R-07-003. 

Docket EPA-HQ-OAR-2010-0162.

189Chappelka, A.H., Samuelson, L.J. (1998). Ambient ozone effects on forest trees of the eastern United States: a 

review. New Phytologist, 139, 91-108. Docket EPA-HQ-OAR-2010-0162

190 U.S. EPA (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, 2009. Docket EPA-HQ-OAR-2010-0162.

191 U.S. EPA (2005) Review of the National Ambient Air Quality Standard for Particulate Matter: Policy 

Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. Docket EPA-HQOAR-2010-0162.

192 U.S. EPA, 2008. Integrated Science Assessment for Oxides of Nitrogen and Sulfur- Ecological Criteria (Final). 

U.S. EPA, Washington D.C., EPA/600/R-08/082F. Docket EPA-HQ-OAR-2010-0162.

193 U.S. EPA, 2008. Integrated Science Assessment for Oxides of Nitrogen and Sulfur- Ecological Criteria (Final). 

U.S. EPA, Washington D.C., EPA/600/R-08/082F. Docket EPA-HQ-OAR-2010-0162.

194 Environmental Protection Agency (2003). Response Of Surface Water Chemistry to the Clean Air Act 

Amendments of 1990. National Health and Environmental Effects Research Laboratory, Office of Research and 

Development, U.S. Environmental Protection Agency. Research Triangle Park, NC. EPA 620/R–03/001. Docket 

EPA-HQ-OAR-2010-0162.

195 Fenn, M.E. and Blubaugh, T.J. (2005) Winter Deposition of Nitrogen and Sulfur in the Eastern Columbia River 

Gorge National Scenic Area, USDA Forest Service. Docket EPA-HQ-OAR-2010-0162.

196 Galloway, J. N.; Cowling, E. B. (2002). Reactive nitrogen and the world: 200 years of change. Ambio 31: 64–71. 

Docket EPA-HQ-OAR-2010-0162.

197Bricker, Suzanne B., et al., National Estuarine Eutrophication Assessment, Effects of Nutrient Enrichment in the 

Nation’s Estuaries, National Ocean Service, National Oceanic and Atmospheric Administration, September, 1999. 

Docket EPA-HQ-OAR-2010-0162.

198 Smith, W.H. 1991. “Air pollution and Forest Damage.” Chemical Engineering News, 69(45): 30-43. Docket 

EPA-HQ-OAR-2010-0162.

199 Gawel, J.E.; Ahner, B.A.; Friedland, A.J.; and Morel, F.M.M. 1996. “Role for heavy metals in forest decline 

indicated by phytochelatin measurements.” Nature, 381: 64-65. Docket EPA-HQ-OAR-2010-0162.

200Cotrufo, M.F.; DeSanto, A.V.; Alfani, A.; et al. 1995. “Effects of urban heavy metal pollution on organic matter 

decomposition in Quercus ilix L. woods.” Environmental Pollution, 89: 81-87. Docket EPA-HQ-OAR-2010-0162.

201 Niklinska, M.; Laskowski, R.; Maryanski, M. 1998. “Effect of heavy metals and storage time on two types of 

forest litter: basal respiration rate and exchangeable metals.” Ecotoxicological Environmental Safety, 41: 8-18. 

Docket EPA-HQ-OAR-2010-0162.

202 U.S. EPA (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, 2009. Section 9.4.5.2. Docket EPA-HQ-OAR-2010-

0162

203 Mason, R.P. and Sullivan, K.A. 1997. “Mercury in Lake Michigan.” Environmental Science & Technology, 31: 

942-947. (from Delta Report “Atmospheric deposition of toxics to the Great Lakes”). Docket EPA-HQ-OAR-2010-

0162.

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204 Landis, M.S. and Keeler, G.J. 2002. “Atmospheric mercury deposition to Lake Michigan during the Lake 

Michigan Mass Balance Study.” Environmental Science & Technology, 21: 4518-24. Docket EPA-HQ-OAR-2010-

0162.

205 U.S. EPA. 2000. EPA453/R-00-005, “Deposition of Air Pollutants to the Great Waters: Third Report to 

Congress,” Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. Docket EPAHQ-OAR-2010-0162.

206 National Science and Technology Council (NSTC) 1999. “The Role of Monitoring Networks in the Management 

of the Nation’s Air Quality.” Docket EPA-HQ-OAR-2010-0162.

207Callender, E. and Rice, K.C. 2000. “The Urban Environmental Gradient: Anthropogenic Influences on the Spatial 

and Temporal Distributions of Lead and Zinc in Sediments.” Environmental Science & Technology, 34: 232-238. 

Docket EPA-HQ-OAR-2010-0162.

208Rice, K.C. 1999. “Trace Element Concentrations in Streambed Sediment Across the Conterminous United 

States.” Environmental Science & Technology, 33: 2499-2504. Docket EPA-HQ-OAR-2010-0162.

209 Ely, JC; Neal, CR; Kulpa, CF; et al. 2001. “Implications of Platinum-Group Element Accumulation along U.S.

Roads from Catalytic-Converter Attrition.” Environ. Sci. Technol. 35: 3816-3822. Docket EPA-HQ-OAR-2010-

0162.

210 U.S. EPA. 1998. EPA454/R-98-014, “Locating and Estimating Air Emissions from Sources of Polycyclic 

Organic Matter,” Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. Docket 

EPA-HQ-OAR-2010-0162.

211 U.S. EPA. 1998. EPA454/R-98-014, “Locating and Estimating Air Emissions from Sources of Polycyclic 

Organic Matter,” Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. Docket 

EPA-HQ-OAR-2010-0162.

212 Simcik, M.F.; Eisenreich, S.J.; Golden, K.A.; et al. 1996. “Atmospheric Loading of Polycyclic Aromatic 

Hydrocarbons to Lake Michigan as Recorded in the Sediments.” Environmental Science and Technology, 30: 3039-

3046. Docket EPA-HQ-OAR-2010-0162.

213 Simcik, M.F.; Eisenreich, S.J.; and Lioy, P.J. 1999. “Source apportionment and source/sink relationship of PAHs 

in the coastal atmosphere of Chicago and Lake Michigan.” Atmospheric Environment, 33: 5071-5079. Docket 

EPA-HQ-OAR-2010-0162.

214 Arzayus, K.M.; Dickhut, R.M.; and Canuel, E.A. 2001. “Fate of Atmospherically Deposited Polycyclic Aromatic 

Hydrocarbons (PAHs) in Chesapeake Bay.” Environmental Science & Technology, 35, 2178-2183. Docket EPAHQ-OAR-2010-0162.

215 Park, J.S.; Wade, T.L.; and Sweet, S. 2001. “Atmospheric distribution of polycyclic aromatic hydrocarbons and 

deposition to Galveston Bay, Texas, USA.” Atmospheric Environment, 35: 3241-3249. Docket EPA-HQ-OAR2010-0162.

216 Poor, N.; Tremblay, R.; Kay, H.; et al. 2002. “Atmospheric concentrations and dry deposition rates of polycyclic 

aromatic hydrocarbons (PAHs) for Tampa Bay, Florida, USA.” Atmospheric Environment 38: 6005-6015. Docket 

EPA-HQ-OAR-2010-0162.

217 Arzayus, K.M.; Dickhut, R.M.; and Canuel, E.A. 2001. “Fate of Atmospherically Deposited Polycyclic Aromatic 

Hydrocarbons (PAHs) in Chesapeake Bay.” Environmental Science & Technology, 35, 2178-2183. Docket EPAHQ-OAR-2010-0162.

218 U.S. EPA. 2000. EPA453/R-00-005, “Deposition of Air Pollutants to the Great Waters: Third Report to 

Congress,” Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. Docket EPAHQ-OAR-2010-0162.

219 Van Metre, P.C.; Mahler, B.J.; and Furlong, E.T. 2000. “Urban Sprawl Leaves its PAH Signature.” 

Environmental Science & Technology, 34: 4064-4070. Docket EPA-HQ-OAR-2010-0162.

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220Cousins, I.T.; Beck, A.J.; and Jones, K.C. 1999. “A review of the processes involved in the exchange of semivolatile organic compounds across the air-soil interface.” The Science of the Total Environment, 228: 5-24. Docket 

EPA-HQ-OAR-2010-0162.

221 Tuhackova, J. et al. (2001) Hydrocarbon deposition and soil microflora as affected by highway traffic. 

Environmental Pollution, 113: 255-262. Docket EPA-HQ-OAR-2010-0162.

222 U.S. EPA. 1991. Effects of organic chemicals in the atmosphere on terrestrial plants. EPA/600/3-91/001. Docket 

EPA-HQ-OAR-2010-0162.

223Cape JN, ID Leith, J Binnie, J Content, M Donkin, M Skewes, DN Price AR Brown, AD Sharpe. 2003. Effects 

of VOCs on herbaceous plants in an open-top chamber experiment. Environ. Pollut. 124:341-343. Docket EPA-HQOAR-2010-0162.

224Cape JN, ID Leith, J Binnie, J Content, M Donkin, M Skewes, DN Price AR Brown, AD Sharpe. 2003. Effects 

of VOCs on herbaceous plants in an open-top chamber experiment. Environ. Pollut. 124:341-343. Docket EPA-HQOAR-2010-0162.

225 Viskari E-L. 2000. Epicuticular wax of Norway spruce needles as indicator of traffic pollutant deposition. Water, 

Air, and Soil Pollut. 121:327-337. Docket EPA-HQ-OAR-2010-0162.

226 Ugrekhelidze D, F Korte, G Kvesitadze. 1997. Uptake and transformation of benzene and toluene by plant leaves. 

Ecotox. Environ. Safety 37:24-29. Docket EPA-HQ-OAR-2010-0162.

227 Kammerbauer H, H Selinger, R Rommelt, A Ziegler-Jons, D Knoppik, B Hock. 1987. Toxic components of 

motor vehicle emissions for the spruce Picea abies. Environ. Pollut. 48:235-243. Docket EPA-HQ-OAR-2010-

0162.

228 U.S. EPA. (2007). PM2.5 National Ambient Air Quality Standard Implementation Rule (Final). Washington, 

DC: U.S. EPA. 72 FR 20586, April 25, 2007.

229 PM Standards Revision – 2006: Timeline. Docket EPA-HQ-OAR-2010-0162. 

http://www.epa.gov/PM/naaqsrev2006.html#timeline

230 U. S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile Sources; Final 

Rule. 72 FR 8434, February 26, 2007.

231 U. S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile Sources; Final 

Rule. 72 FR 8434, February 26, 2007.

232 U.S. EPA. (2009) Summary of Results for the 2002 National-Scale Assessment. 

http://www.epa.gov/ttn/atw/nata1999/risksum.html. Docket EPA-HQ-OAR-2010-0162.

233 U. S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile Sources; Final 

Rule. 72 FR 8434, February 26, 2007.

234 US EPA (2007) Control of Hazardous Air Pollutants from Mobile Sources Regulatory Impact Analysis. EPA 

document number 420-R-07-002, February 2007. Docket EPA-HQ-OAR-2010-0162.

235 U.S. Environmental Protection Agency, Byun, D.W., and Ching, J.K.S., Eds, 1999. Science algorithms of EPA 

Models-3 Community Multiscale Air Quality (CMAQ modeling system, EPA/600/R-99/030, Office of Research and 

Development). Docket EPA-HQ-OAR-2010-0162.

236Byun, D.W., and Schere, K.L., 2006. Review of the Governing Equations, Computational Algorithms, and Other 

Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System, J. Applied Mechanics 

Reviews, 59 (2), 51-77. Docket EPA-HQ-OAR-2010-0162.

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237 Dennis, R.L., Byun, D.W., Novak, J.H., Galluppi, K.J., Coats, C.J., and Vouk, M.A., 1996. The next generation 

of integrated air quality modeling: EPA’s Models-3, Atmospheric Environment, 30, 1925-1938. Docket EPA-HQOAR-2010-0162.

238 Carlton, A., Bhave, P., Napelnok, S., Edney, E., Sarwar, G., Pinder, R., Pouliot, G., and Houyoux, M. Model 

Representation of Secondary Organic Aerosol in CMAQv4.7. Ahead of Print in Environmental Science and 

Technology. Accessed at: http://pubs.acs.org/doi/abs/10.1021/es100636q?prevSearch=CMAQ&searchHistoryKey

Docket EPA-HQ-OAR-2010-0162.

239 US EPA (2007). Regulatory Impact Analysis of the Proposed Revisions to the National Ambient Air Quality 

Standards for Ground-Level Ozone. EPA document number 442/R-07-008, July 2007. Docket EPA-HQ-OAR2010-0162.

240 Allen, D. et al (2009). Report on the Peer Review of the Atmospheric Modeling and Analysis Division, National 

Exposure Research Laboratory, Office of Research and Development, U.S.EPA.

http://www.epa.gov/asmdnerl/peer/reviewdocs.html 

241 Grell, G., Dudhia, J., Stauffer, D. (1994). A Description of the Fifth-Generation Penn State/NCAR Mesoscale 

Model (MM5), NCAR/TN-398+STR., 138 pp, National Center for Atmospheric Research, Boulder CO. Docket EPAHQ-OAR-2010-0162.

242 Grell, G., Dudhia, J., Stauffer, D. (1994). A Description of the Fifth-Generation Penn State/NCAR Mesoscale 

Model (MM5), NCAR/TN-398+STR., 138 pp, National Center for Atmospheric Research, Boulder CO. Docket EPAHQ-OAR-2010-0162.

243 Le Sager, P. Yantosca, B., Carouge, C. (2008). GEOS-CHEM v8-01-02 User’s Guide, Atmospheric Chemistry 

Modeling Group, Harvard University, Cambridge, MA, December 18, 2008.Docket EPA-HQ-OAR-2010-0162

244 U.S. Environmental Protection Agency. (2008). Final Ozone NAAQS Regulatory Impact Analysis. Prepared 

by: Office of Air and Radiation, Office of Air Quality Planning and Standards. March.

245 U.S. Environmental Protection Agency. October 2006. Final Regulatory Impact Analysis (RIA) for the 

Proposed National Ambient Air Quality Standards for Particulate Matter. Prepared by: Office of Air and Radiation. 

246 U.S. Environmental Protection Agency (U.S. EPA). 2009. Regulatory Impact Analysis: National Emission 

Standards for Hazardous Air Pollutants from the Portland Cement Manufacturing Industry. Office of Air Quality 

Planning and Standards, Research Triangle Park, NC. April. Available on the Internet at 

<http://www.epa.gov/ttn/ecas/regdata/RIAs/portlandcementria_4-20-09.pdf>. EPA-HQ-OAR-2009-0472-0241

247 U.S. Environmental Protection Agency (U.S. EPA). 2010. Final NO2 NAAQS Regulatory Impact Analysis 

(RIA). Office of Air Quality Planning and Standards, Research Triangle Park, NC. April. Available on the Internet 

at http://www.epa.gov/ttn/ecas/regdata/RIAs/FinalNO2RIAfulldocument.pdf. Accessed March 15. EPA-HQ-OAR2009-0472-0237

248 Information on BenMAP, including downloads of the software, can be found at http://www.epa.gov/ttn/ecas/ 

benmodels.html.

249 Bell, M.L., et al. (2004). Ozone and short-term mortality in 95 US urban communities, 1987-2000. JAMA, 2004. 

292(19): p. 2372-8.

250 Huang, Y.; Dominici, F.; Bell, M. L. (2005) Bayesian hierarchical distributed lag models for summer ozone 

exposure and cardio-respiratory mortality. Environmetrics. 16: 547-562.

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251 Schwartz, J. (2005) How sensitive is the association between ozone and daily deaths to control for temperature? 

Am. J. Respir. Crit. Care Med. 171: 627-631.

252 Bell, M.L., F. Dominici, and J.M. Samet. (2005). A meta-analysis of time-series studies of ozone and mortality 

with comparison to the national morbidity, mortality, and air pollution study. Epidemiology. 16(4): p. 436-45.

253 Ito, K., S.F. De Leon, and M. Lippmann (2005). Associations between ozone and daily mortality: analysis and 

meta-analysis. Epidemiology. 16(4): p. 446-57.

254 Levy, J.I., S.M. Chemerynski, and J.A. Sarnat. (2005). Ozone exposure and mortality: an empiric bayes 

metaregression analysis. Epidemiology. 16(4): p. 458-68.

255 Pope, C.A., III, R.T. Burnett, M.J. Thun, E.E. Calle, D. Krewski, K. Ito, and G.D. Thurston. (2002). “Lung 

Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution.” Journal of the 

American Medical Association 287:1132-1141.

256 Laden, F., J. Schwartz, F.E. Speizer, and D.W. Dockery. (2006). Reduction in Fine Particulate Air 

Pollution and Mortality. American Journal of Respiratory and Critical Care Medicine. 173: 667-672.

257 Industrial Economics, Incorporated (IEc). (2006). Expanded Expert Judgment Assessment of the ConcentrationResponse Relationship Between PM2.5 Exposure and Mortality. Peer Review Draft. Prepared for: Office of Air 

Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC. August.

258 Woodruff, T.J., J. Grillo, and K.C. Schoendorf. (1997). The Relationship Between Selected Causes of 

Postneonatal Infant Mortality and Particulate Air Pollution in the United States. Environmental Health 

Perspectives. 105(6):608-612.

259 Abbey, D.E., B.L. Hwang, R.J. Burchette, T. Vancuren, and P.K. Mills. (1995). Estimated Long-Term Ambient 

Concentrations of PM(10) and Development of Respiratory Symptoms in a Nonsmoking Population. Archives of 

Environmental Health. 50(2): 139-152.

260 Peters, A., D.W. Dockery, J.E. Muller, and M.A. Mittleman. (2001). Increased Particulate Air Pollution and the 

Triggering of Myocardial Infarction. Circulation. 103:2810-2815.

261 Schwartz J. (1995). Short term fluctuations in air pollution and hospital admissions of the elderly for respiratory 

disease. Thorax. 50(5):531-538.

262 Schwartz J. (1994a). PM(10) Ozone, and Hospital Admissions For the Elderly in Minneapolis St Paul, 

Minnesota. Arch Environ Health. 49(5):366-374.

263 Schwartz J. (1994b). Air Pollution and Hospital Admissions For the Elderly in Detroit, Michigan. Am J Respir 

Crit Care Med. 150(3):648-655.

264 Moolgavkar SH, Luebeck EG, Anderson EL. (1997). Air pollution and hospital admissions for respiratory causes 

in Minneapolis St. Paul and Birmingham. Epidemiology. 8(4):364-370.

265 Burnett RT, Smith-Doiron M, Stieb D, Raizenne ME, Brook JR, Dales RE, et al. (2001). Association between 

ozone and hospitalization for acute respiratory diseases in children less than 2 years of age. Am J Epidemiol. 

153(5):444-452.

266 Moolgavkar, S.H. (2003). “Air Pollution and Daily Deaths and Hospital Admissions in Los Angeles and Cook 

Counties.” In Revised Analyses of Time-Series Studies of Air Pollution and Health. Special Report. Boston, MA: 

Health Effects Institute.

267 Ito, K. (2003). “Associations of Particulate Matter Components with Daily Mortality and Morbidity in Detroit, 

Michigan.” In Revised Analyses of Time-Series Studies of Air Pollution and Health. Special Report. Health Effects 

Institute, Boston, MA.

268 Moolgavkar, S.H. (2000). Air Pollution and Hospital Admissions for Diseases of the Circulatory System in 

Three U.S. Metropolitan Areas. Journal of the Air and Waste Management Association 50:1199-1206.
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Environmental and Health 

Impacts

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269 Sheppard, L. (2003). Ambient Air Pollution and Nonelderly Asthma Hospital Admissions in Seattle, 

Washington, 1987-1994. In Revised Analyses of Time-Series Studies of Air Pollution and Health. Special Report. 

Boston, MA: Health Effects Institute.

270 Peel, J. L., P. E. Tolbert, M. Klein, et al. (2005). Ambient air pollution and respiratory emergency department 

visits. Epidemiology. Vol. 16 (2): 164-74.

271 Wilson, A. M., C. P. Wake, T. Kelly, et al. (2005). Air pollution, weather, and respiratory emergency room visits 

in two northern New England cities: an ecological time-series study. Environ Res. Vol. 97 (3): 312-21.

272 Norris, G., S.N. YoungPong, J.Q. Koenig, T.V. Larson, L. Sheppard, and J.W. Stout. (1999). An Association 

between Fine Particles and Asthma Emergency Department Visits for Children in Seattle. Environmental Health 

Perspectives 107(6):489-493.

273 Dockery, D.W., J. Cunningham, A.I. Damokosh, L.M. Neas, J.D. Spengler, P. Koutrakis, J.H. Ware, M. 

Raizenne, and F.E. Speizer. (1996). Health Effects of Acid Aerosols On North American Children-Respiratory 

Symptoms. Environmental Health Perspectives 104(5):500-505.

274 Pope, C.A., III, D.W. Dockery, J.D. Spengler, and M.E. Raizenne. (1991). Respiratory Health and PM10

Pollution: A Daily Time Series Analysis. American Review of Respiratory Diseases 144:668-674.

275 Schwartz, J., and L.M. Neas. (2000). Fine Particles are More Strongly Associated than Coarse Particles with 

Acute Respiratory Health Effects in Schoolchildren. Epidemiology 11:6-10.

276 Ostro, B., M. Lipsett, J. Mann, H. Braxton-Owens, and M. White. (2001). Air Pollution and Exacerbation of 

Asthma in African-American Children in Los Angeles. Epidemiology 12(2):200-208.

277 Vedal, S., J. Petkau, R. White, and J. Blair. (1998). Acute Effects of Ambient Inhalable Particles in Asthmatic 

and Nonasthmatic Children. American Journal of Respiratory and Critical Care Medicine 157(4):1034-1043.

278 Ostro, B.D. (1987). Air Pollution and Morbidity Revisited: A Specification Test. Journal of Environmental 

Economics Management 14:87-98.

279 Gilliland FD, Berhane K, Rappaport EB, Thomas DC, Avol E, Gauderman WJ, et al. (2001). The effects of 

ambient air pollution on school absenteeism due to respiratory illnesses. Epidemiology 12(1):43-54.

280 Chen L, Jennison BL, Yang W, Omaye ST. (2000). Elementary school absenteeism and air pollution. Inhal 

Toxicol 12(11):997-1016.

281 Ostro, B.D. and S. Rothschild. (1989). Air Pollution and Acute Respiratory Morbidity: An Observational Study 

of Multiple Pollutants. Environmental Research 50:238-247.

282 Russell, M.W., D.M. Huse, S. Drowns, E.C. Hamel, and S.C. Hartz. (1998). Direct Medical Costs of Coronary 

Artery Disease in the United States. American Journal of Cardiology 81(9):1110-1115. 

283 Wittels, E.H., J.W. Hay, and A.M. Gotto, Jr. (1990). Medical Costs of Coronary Artery Disease in the United 

States. American Journal of Cardiology 65(7):432-440.

284 Smith, D.H., D.C. Malone, K.A. Lawson, L.J. Okamoto, C. Battista, and W.B. Saunders. (1997). A National 

Estimate of the Economic Costs of Asthma. American Journal of Respiratory and Critical Care Medicine 156(3 Pt 

1):787-793.

285 Stanford, R., T. McLaughlin, and L.J. Okamoto. (1999). The Cost of Asthma in the Emergency Department and 

Hospital. American Journal of Respiratory and Critical Care Medicine 160(1):211-215.

286 Rowe, R.D., and L.G. Chestnut. (1986). Oxidants and Asthmatics in Los Angeles: A Benefits Analysis—

Executive Summary. Prepared by Energy and Resource Consultants, Inc. Report to the U.S. Environmental 

Protection Agency, Office of Policy Analysis. EPA-230-09-86-018. Washington, DC.

287 Science Advisory Board. 2001. NATA – Evaluating the National-Scale Air Toxics Assessment for 1996 – an 

SAB Advisory. http://www.epa.gov/ttn/atw/sab/sabrev.html.
Draft Regulatory Impact Analysis 

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288 In April, 2009, EPA hosted a workshop on estimating the benefits or reducing hazardous air pollutants. This 

workshop built upon the work accomplished in the June 2000 Science Advisory Board/EPA Workshop on the 

Benefits of Reductions in Exposure to Hazardous Air Pollutants, which generated thoughtful discussion on 

approaches to estimating human health benefits from reductions in air toxics exposure, but no consensus was 

reached on methods that could be implemented in the near term for a broad selection of air toxics. Please visit 

http://epa.gov/air/toxicair/2009workshop.html for more information about the workshop and its associated materials.

289 Brenkert A, S. Smith, S. Kim, and H. Pitcher, 2003: Model Documentation for the MiniCAM. PNNL-14337, 

Pacific Northwest National Laboratory, Richland, Washington.

290 Wigley, T.M.L. and Raper, S.C.B. 1992. Implications for Climate And Sea-Level of Revised IPCC Emissions 

Scenarios Nature 357, 293-300. Raper, S.C.B., Wigley T.M.L. and Warrick R.A. 1996. in Sea-Level Rise and 

Coastal Subsidence: Causes, Consequences and Strategies J.D. Milliman, B.U. Haq, Eds., Kluwer Academic 

Publishers, Dordrecht, The Netherlands, pp. 11-45. 

291 Wigley, T.M.L. and Raper, S.C.B. 2002. Reasons for larger warming projections in the IPCC Third Assessment 

Report J. Climate 15, 2945-2952.

292 Thompson AM, KV Calvin, SJ Smith, GP Kyle, A Volke, P Patel, S Delgado-Arias, B Bond-Lamberty, MA 

Wise, LE Clarke and JA Edmonds. 2010. “RCP4.5: A Pathway for Stabilization of Radiative Forcing by 2100.” 

Climatic Change (in review)

293 Clarke, L., J. Edmonds, H. Jacoby, H. Pitcher, J. Reilly, R. Richels, (2007) Scenarios of Greenhouse Gas 

Emissions and Atmospheric Concentrations. Sub-report 2.1A of Synthesis and Assessment Product 2.1 by the U.S. 

Climate Change Science Program and the Subcommittee on Global Change Research (Department of Energy, Office 

of Biological & Environmental Research, Washington, DC., USA, 154 pp.).

294 Wigley, T.M.L. 2008. MAGICC 5.3.v2 User Manual. UCAR – Climate and Global Dynamics Division, Boulder, 

Colorado. http://www.cgd.ucar.edu/cas/wigley/magicc/

295 Meehl, G.A. et al. (2007) Global Climate Projections. In: Climate Change 2007: The Physical Science Basis. 

Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate 

Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. 

Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

297 Meehl, G.A. et al. (2007) Global Climate Projections. In: Climate Change 2007: The Physical Science Basis. 

Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate 

Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. 

Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

298 Lewis, E., and D. W. R. Wallace. 1998. Program Developed for CO2 System Calculations. ORNL/CDIAC-105. 

Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak 

Ridge, Tennessee.

299 Lewis, E., and D. W. R. Wallace. 1998. Program Developed for CO2 System Calculations. ORNL/CDIAC105. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, 

Oak Ridge, Tennessee.

302 Mehrbach, C., C. H. Culberson, J. E. Hawley, and R. N. Pytkowicz. 1973. Measurement of the apparent 

dissociation constants of carbonic acid in seawater at atmospheric pressure. Limnology and Oceanography 18:897-

907.
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Impacts

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303 Dickson, A. G. and F. J. Millero. 1987. A comparison of the equilibrium constants for the dissociation of 

carbonic acid in seawater media. Deep-Sea Res. 34, 1733-1743. (Corrigenda. Deep-Sea Res. 36, 983).

304 A. G. Dickson. 1990. Thermodynamics of the dissociation of boric acid in synthetic sea water from 273.15 to 

318.15 K. Deep-Sea Res. 37, 755-766.

305 Lewis, E., and D. W. R. Wallace. 1998. Program Developed for CO2 System Calculations. ORNL/CDIAC105. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, 

Oak Ridge, Tennessee.

306 Khoo, K.H., R.W. Ramette, C.H. Culberson, and R. G. Bates. 1977. Determination of hydrogen ion 

concentrations in seawater from 5 to 40°C: Standard potentials at salinities from 20 to 45‰. Analytical Chemistry

49(1): 29-34.

307 Dickson, A. G. 2003. Certificate of Analysis – Reference material for oceanic CO2 measurements (Batch #62, 

bottled on August 21, 2003). Certified by Andrew Dickson, Scripps Institution of Oceanography. November 21, 

2003.

Dickson, A. G. 2005. Certificate of Analysis – Reference material for oceanic CO2 measurements (Batch #69, 

bottled on January 4, 2005). Certified by Andrew Dickson, Scripps Institution of Oceanography. July 12, 2005.

Dickson, A. G. 2009. Certificate of Analysis – Reference material for oceanic CO2 measurements (Batch #100, 

bottled on November 13, 2009). Certified by Andrew Dickson, Scripps Institution of Oceanography. February 10, 

2010.

308 National Research Council (2009). Hidden Costs of Energy: Unpriced Consequences of Energy Production and 

Use. National Academies Press. See docket ID EPA-HQ-OAR-2009-0472-11486.
9-1

CHAPTER 9. ECONOMIC AND SOCIAL IMPACTS ................................... 9-2

9.1 Framework for Benefits and Costs................................................................................. 9-2

9.2 Rebound Effect................................................................................................................. 9-3

9.2.1 Factors Affecting the Magnitude of the Rebound Effect ................................... 9-5

9.2.2 Options for Quantifying the Rebound Effect...................................................... 9-5

9.2.3 Estimates of the Rebound Effect .......................................................................... 9-8

9.2.4 Application of the Rebound Effect to VMT Estimates..................................... 9-11

9.3 Other Economic Impacts............................................................................................... 9-13

9.3.1 Noise, Congestion, and Accidents....................................................................... 9-13

9.3.2 Savings due to Reduced Refueling Time............................................................ 9-16

9.4 The Effect of Safety Standards and Voluntary Safety Improvements on Vehicle 

Weight....................................................................................................................................... 9-19

9.4.1 Weight Impacts of Required Safety Standards................................................. 9-19

9.4.2 Electronic Stability Control Systems (ESC) for Medium- and Heavy-Duty 

(MD/HD) Vehicles............................................................................................................... 9-20

9.4.3 Summary – Overview of Anticipated Weight Increases .................................. 9-21

9.4.4 Effects of Vehicle Mass Reduction on Safety .................................................... 9-21

9.5 Petroleum and energy security impacts....................................................................... 9-22

9.5.1 Impact on U.S. Petroleum Imports .................................................................... 9-22

9.5.2 Background on U.S. Energy Security ................................................................ 9-22

9.6 Summary of Benefits and Costs.................................................................................... 9-33

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Chapter 9. Economic and Social Impacts

9.1 Framework for Benefits and Costs

The net benefits of the proposed National Program consist of the effects of the program on: 

• the engine and truck program costs,

• fuel savings associated with reduced fuel usage resulting from the program,

• greenhouse gas emissions, 

• other air pollutants, 

• noise, congestion, accidents resulting from truck use, 

• refueling savings,

• energy security impacts,

• increased driving due to the “rebound” effect.

At this time some impacts, such as the effects of the rule on public health, are not included in this 

analysis. We plan to address as many of these omitted impacts as possible for the final rule.

As discussed in preamble Section VIII.A, this proposal identifies technologies that reduce 

fuel costs enough to pay for themselves over short periods of time. Assuming full information,

perfect foresight, perfect competition, and financially rational vehicle producers and buyers, 

standard economic theory suggests that, under normal market operations, interactions between 

the buyers and producers would lead to incorporation into the vehicles of all cost-effective 

technology without government intervention. Unlike in the light-duty vehicle market, the vast 

majority of vehicles in the medium- and heavy-duty truck market are purchased and operated by 

businesses; for them, fuel costs may represent substantial operating expenses. Even in the 

presence of uncertainty and imperfect information – conditions that hold to some degree in every 

market – we generally expect firms to be cost-minimizing to survive in a competitive 

marketplace and to make decisions that are therefore in the best interest of the company and its 

owners and/or shareholders. In this case, the benefits of the rule would be due to external 

benefits. The analysis in Chapter 7 of this draft RIA nevertheless is based on the observation 

that fuel savings that appear to be cost-effective in our analysis have not been generally adopted.

As discussed in preamble Section VIII.A., several explanations have been offered for 

why there appear to be cost-effective fuel-saving technologies that are not generally adopted. In 

the original sales market, there appears to be poor information available about the effectiveness 

of fuel-saving technologies for new vehicles. The SmartWay program has helped to improve the 

reliability of information, but the technological diffusion process appears to be gradual even 

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Regulatory Impact Analysis 

9-3

when information is well demonstrated. Similar issues arise in the resale market, where lack of 

trust in information about the effectiveness of fuel-saving technology may lead to lack of 

willingness to pay for fuel-saving technology. This inability to recover some of the value of 

fuel-saving technology in the resale market may contribute to the observed very short payback 

periods that original equipment buyers expect. It also appears that market coordination is 

incomplete. Different agents in the market, such as those who buy trucks and those who pay for 

operating costs, may not coordinate their activities; those who buy trucks may not fully consider 

the effects of their activities on those who incur fuel expenses. Finally, future fuel savings are 

uncertain due, among other factors, to fluctuating fuel prices, while technology costs are 

immediate and certain; risk-averse or loss-averse truck purchasers may put more emphasis on the 

immediate costs than the uncertain future benefits when deciding what vehicles to purchase.

Several of these explanations, including imperfect information and split incentives, imply 

problems in the markets for trucks. Uncertainty and loss aversion reflect buyers’ preferences; 

requiring them to buy additional fuel-saving technology may affect the utility they receive from 

purchasing trucks. These factors could also influence the extent of any increases in VMT due to 

the “rebound effect” (discussed below), as well as any impacts on fleet turnover.

Preamble Section VIII.A. discusses these explanations in more detail. We seek comment 

on these and other explanations for why our analysis shows cost-effective fuel-saving 

technologies that truck purchasers have not adopted. 

9.2 Rebound Effect

The VMT rebound effect refers to the fraction of fuel savings expected to result from an 

increase in fuel efficiency that is offset by additional vehicle use. If truck shipping costs 

decrease as a result of lower fuel costs, an increase in truck VMT may occur. Unlike the lightduty rebound effect, the medium-duty and heavy-duty rebound effect has not been extensively 

studied. Because the factors influencing the medium- and heavy-duty rebound effect are 

generally different from those affecting the light-duty rebound effect, much of the research on 

the light-duty is not likely to apply to the medium- and heavy- duty sectors. One of the major 

differences between the medium- and heavy-duty rebound effect and the light-duty rebound 

effect is that heavy-duty trucks are used primarily for commercial and business purposes. Since 

these businesses are profit driven, decision makers are highly likely to be aware of the costs and 

benefits of different operating and shipping decisions, both in the near-term and long-term. 

Therefore, both truck operators and shippers are likely to take into account changes in the overall 

operating costs per mile when making operating and shipping decisions that affect truck usage. 

Another difference from the light-duty case is that, as discussed in the recent NAS 

Report, when calculating the change in trucking costs that causes the rebound effect, all 

components of truck operating costs should be considered. The cost of labor and fuel generally 

constitute the two largest shares of truck operating costs, depending on the price of petroleum,

distance traveled, type of truck, and commodity (see Figure 9-1).

12

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depreciation costs associated with the purchase or leasing of the truck is also a significant 

component of total operating costs. Even though vehicle purchases are lump-sum costs, they are 

likely to be considered as operating costs by trucking firms, and these costs are, in many cases, 

expected to be passed onto the final consumers of shipping services. By partially offsetting the 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-4

reduction in fuel costs resulting from higher fuel efficiency, higher vehicle purchase or lease 

prices could thus help temper the magnitude of the fuel economy rebound effect relative to that 

for light-duty vehicles, in which vehicle depreciation costs may not be considered as operating 

costs by vehicle owners.

When calculating the net change in operating costs, both the increase in new vehicle costs 

and the decrease in fuel costs per mile should be taken into consideration. The higher the net 

cost savings, the higher the expected rebound effect. Conversely, if the upfront vehicle costs 

outweighed future cost savings and total costs increased, shipping costs would rise, which would 

likely result in a decrease in truck VMT. In theory, other cost changes resulting from any 

requirement to achieve higher fuel economy, such as changes in maintenance costs or insurance 

rates, should also be taken into account, although information on potential changes in these 

elements of truck operating costs is extremely limited. 

Figure 9-1 Average Truck Operating Costs

The following sections describe the factors affecting the rebound effect, different 

methodologies for estimating the rebound effect, and examples of different estimates of the 

rebound effect to date. According to the NAS study, it is “not possible to provide a confident 

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Regulatory Impact Analysis 

9-5

measure of the rebound effect,” yet NAS concluded that a rebound effect likely exists and that 

“estimates of fuel savings from regulatory standards will be somewhat misestimated if the 

rebound effect is not considered.” While we believe the medium- and heavy- duty rebound 

effect needs to be studied in more detail, we have attempted to capture the potential impact of the 

rebound effect in our analysis. For this proposal, we have used a rebound effect for single unit 

trucks of 15%, a rebound effect for medium-duty (2b and 3) trucks of 10%, and a rebound effect 

for combination tractors of 5%. These VMT impacts are reflected in the estimates of total GHG 

and other air pollution reductions presented in Chapter 5 of the draft RIA. 

9.2.1 Factors Affecting the Magnitude of the Rebound Effect

The heavy-duty vehicle rebound effect is driven by the interaction of several different 

factors. In the short-run, decreasing the fuel cost per mile of operating trucks could lead to a 

decrease in delivered prices for products shipped by truck. Lower delivered prices could 

stimulate additional demand for those products, which would then result in an increase in truck 

usage and VMT. In the long- run, shippers could reorganize their logistics and distribution 

networks to take advantage of lower truck shipping costs. For example, shippers may shift away 

from other modes of shipping such as rail, barge, or air. In addition, shippers may also choose to 

reduce the number of warehouses, reduce load rates, and make smaller, more frequent shipments, 

all of which could also lead to an increase in heavy-duty VMT. Finally, the benefits of the fuel 

savings could ripple through the economy and increase overall economic activity, which would 

in turn increase overall demand for goods and services, and therefore increase truck VMT. 

Conversely, if a fuel economy regulation leads to net increases in the cost of trucking 

because fuel savings do not fully offset the increase in upfront vehicle costs, then the price of 

trucking services could rise, spurring a decrease in heavy-duty VMT and shift to rail shipping. 

These effects would also ripple through the economy.

As discussed in Section 8 of the preamble, the magnitude of the rebound effect is likely 

to be determined by the extent of market failures that affect demand for fuel economy in 

medium- and heavy-duty fleets, such as split incentives and imperfect information, as well as 

rational firm responses to the tradeoff between higher certain upfront vehicle costs and lower but 

uncertain future expenditures on fuel. 

9.2.2 Options for Quantifying the Rebound Effect

As described in the previous section, the fuel economy rebound effect for heavy-duty 

trucks has not been studied as extensively as the rebound effect for light-duty vehicles, and 

virtually no research has been conducted on the medium-duty truck rebound effect. In this 

proposal, we discuss four options for quantifying the rebound effect. 

9.2.2.1 Aggregate Estimates

The aggregate approximation approach quantifies the overall change in truck VMT as a 

result of a percentage change in truck shipping prices. This approach relies on estimates of 

aggregate price elasticity of demand for trucking services, given a percentage change in trucking 

prices, which is generally referred to as an “own price elasticity.” Estimates of trucking ownDeleted: ”,

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

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price elasticities vary widely, and there is no general consensus on the most appropriate values to 

use. A 2004 literature survey cited in the recent NAS report found aggregate elasticity estimates 

in the range of -0.5 to -1.5.

3

 In other words, given an own price elasticity of -1.5, a 10% 

decrease in trucking prices leads to a 15% increase in demand for truck shipping demand. 

However, this survey does not differentiate between studies that quantify change in tons shipped 

or ton-miles. In addition, most of the studies find that these elasticity estimates vary 

substantially based on the length of the trip and the type of cargo. For example, one study 

estimated an own-price elasticity of -0.1 for the lumber sector and -2.3 for the chemical sector.4

The increase in overall truck VMT resulting from the rebound effect implicitly includes 

some component of mode shifting. Since there are differences in GHG emissions per ton of 

freight moved by different modes (e.g., rail, barge, air) compared to truck, any potential shifting 

of freight from one mode to the other could have GHG impacts. Although the total demand for 

freight transport is generally determined by economic activity, there is often the choice of 

shipping by either truck or other modes when freight is transported. This is because the United 

States has both an extensive highway network and extensive rail, waterway and air transport

networks; these networks often closely parallel each other and are often viable choices for freight 

transport for many origin and destination pairs within the continent. If rates go down for one 

mode, there will be an increase in demand for that mode and some demand will be shifted from 

other modes. This “cross-price elasticity” is a measure of the percentage change in demand for 

shipping by another mode (e.g., rail) given a percentage change in the price of trucking. 

Aggregate estimates of cross-price elasticities also vary widely, and there is no general 

consensus on the most appropriate value to use for analytical purposes. The NAS report cites 

values ranging from 0.35 to 0.59.

 

5

 Other reports provide significantly different cross-price 

elasticities, ranging from 0.16 to 2.0. See Figure 9-2.

7
Regulatory Impact Analysis 

9-7

Figure 9-2 Examples of Road Elasticity and Cross Elasticity Estimates

When considering intermodal shift, one of the most relevant kinds of shipments are those 

that are competitive between rail and truck modes. These trips include long-haul shipments 

greater than 500 miles, which weigh between 50,000 and 80,000 pounds (the legal road limit in 

many states). Special kinds of cargo like coal and short-haul deliveries are of less interest 

because they are generally not economically transferable between truck and rail modes, and they 

would not be expected to shift modes except under an extreme price change. However, the total 

volume of ton-miles that could potentially be subject to mode shifting has also not been studied 

extensively. 

9.2.2.2 Sector-Specific Estimates

Given the limited data available regarding the medium- and heavy- duty rebound effect, 

the aggregate approach greatly simplifies many of the assumptions associated with calculations 

of the rebound effect. In reality, however, responses to changes in fuel efficiency and new 

vehicle costs will vary significantly based on the commodities affected. A detailed, sector

specific approach, would be expected to more accurately reflect changes in the trucking market 

given these standards. For example, input-output tables could be used to determine the trucking 

cost share of the total delivered price of a product or sector. Using the change in trucking prices 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-8

described in the aggregate approach, the product-specific demand elasticities could be used to 

calculate the change in sales and shipments for each product. The change in shipment increases 

could then be weighted by the share of the trucking industry total, and then summed to get the 

total increase in trucking output. A simplifying assumption could then be made that the increase 

in output results in an increase in VMT. This type of detailed data has not yet been collected, 

therefore we do not have any calculations available for the proposal. While we hope to have this 

data available for the final rulemaking, gathering high quality data may take a longer time frame. 

We invite the submission of comments or data that could be used as part of this methodology. 

9.2.2.3 Econometric Estimates

Similar to the methodology used to estimate the light-duty rebound effect, the heavy-duty 

rebound effect could be modeled econometrically by estimating truck demand as a function of 

economic activity (e.g., GDP) and different input prices (e.g., vehicle prices, driver wages, and 

fuel costs per mile). This type of econometric model could be estimated for either truck VMT or 

ton-miles as a measure of demand. The resulting elasticity estimates could then be used to 

determine the change in trucking demand, given the change in fuel cost and truck prices per mile 

from these standards.

9.2.2.4 Other Modeling Approaches

Regulation of the heavy-duty vehicle industry has been studied in more detail in Europe,

as the European Commission (EC) has considered allowing longer and heavier trucks for freight 

transport. Part of the analysis considered by the EC relies on country-specific modeling of 

changes in the freight sector that would result from changes in regulations.8 This approach 

attempts to explicitly calculate modal shift decisions and impacts on GHG emissions. Although 

similar types of analysis have not been conducted extensively in the U.S., research is currently 

underway that explores the potential for intermodal shifting in the U.S. For example, Winebrake 

and Corbett have developed the Geospatial Intermodal Freight Transportation (GIFT) model, 

which evaluates the potential for GHG emissions reductions based on mode shifting, given 

existing limitations of infrastructure and other route characteristics in the U.S.9

 This model 

connects multiple road, rail, and waterway transportation networks and embeds activity-based 

calculations in the model. Within this intermodal network, the model assigns various economic, 

time-of-delivery, energy, and environmental attributes to real-world goods movement routes. 

The model can then calculate different network optimization scenarios, based on changes in 

prices and policies.10

9.2.3 Estimates of the Rebound Effect

 However, more work is needed in this area to determine whether this type 

of methodology is appropriate for the purposes of capturing the rebound effect. We invite 

comment on this approach, as well as suggestions on alternative modeling frameworks that could 

be used to assess mode shifting, fuel consumption, and the GHG emission implications of these 

proposed regulations. 

The aggregate methodology was used by Cambridge Systematics, Inc. (CSI) to show 

several examples of the magnitude of the rebound effect.11 In their paper commissioned by the 

NAS in support of the recent medium- and heavy-duty report, CSI calculated an effective 

rebound effect for two different technology cost and fuel savings scenarios associated with an 
Regulatory Impact Analysis 

9-9

example Class 8 combination tractor. Scenario 1 increased average fuel economy from 5.59 mpg 

to 6.8 mpg, with an additional cost of $22,930. Scenario 2 increased the average fuel economy 

to 9.1 mpg, at an incremental cost of $71,630 per vehicle. Both of these scenarios were based on 

the technologies and targets from a recent Northeast States Center for a Clean Air Future 

(NESCCAF) and International Council on Clean Transportation (ICCT) report.

12

For CSI’s calculations, all costs except fuel costs and vehicle costs were taken from the 

2008 ATRI study. It is not clear from the report how the new vehicle costs were incorporated 

into the per mile operating costs calculations. For example, in both the ATRI report and the CSI 

report, assumptions about depreciation, useful life, and the opportunity cost of capital are not 

explicitly discussed. 

The CSI 

examples provided estimates using a range of own price elasticities (-0.5 to -1.5) and cross-price 

elasticities (0.35 to 0.59) from the literature. For these calculations, CSI assumed 142,706 

million miles of truck VMT and 1,852 billion ton-miles were affected. The truck VMT was 

based on the Bureau of Transportation Statistics (BTS) highway miles for combination tractors

in 2006, and the rail ton-miles were based on the 2006 BTS total railroad miles. This assumption 

may overstate the potential rebound effect, since not all highway miles and rail ton miles are in 

direct competition. However, this assumption appears to be reasonable in the absence of more 

detailed information on the percentage of total miles and ton-miles that are subject to potential 

mode shifting. 

Based on these two scenarios, CSI found a rebound effect of 11-31% for Scenario 1 and 

5-16% for Scenario 2 when the fuel savings from rail were not taken into account (“First rebound 

effect”). When the fuel savings from reduced rail usage were included in the calculations, the 

overall rebound effect was between 9-13% for Scenario 1 and 3-15% for Scenario 2 (“Second 

Rebound Effect”). See Table 9-1. 

CSI included a number of caveats associated with these calculations. Namely, the 

elasticity estimates derived from the literature are “heavily reliant on factors including the type 

of demand measures analyzed (vehicle-miles of travel, ton-miles, or tons), geography, trip 

lengths, markets served, and commodities transported.” Furthermore, the CSI example only 

focused on Class 8 trucks and did not attempt to quantify the potential rebound effect for any 

other truck classes. Finally, these scenarios were characterized as “sketches” and were not 

included in the final NAS report. In fact, the NAS report asserted that it is “not possible to 

provide a confident measure of the rebound effect”, yet concluded that a rebound effect likely 

exists and that “estimates of fuel savings from regulatory standards will be somewhat 

misestimated if the rebound effect is not considered.”

Deleted: trucks

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Table 9-1 Range of Rebound Effect Estimates from Cambridge Systematics Aggregate Assessment

Scenario 1 

(6.8 mpg, $22,930)

Scenario 2

(9.1 mpg, $71,630)

“First Rebound Effect” 

(increase in truck VMT 

resulting from decrease in 

operating costs)

11-31% 5-16%

“Second Rebound Effect” 

(net fuel savings when 

decreases from rail are 

taken into account)

9-13 % 3-15%

As an alternative, using the econometric approach, NHTSA has estimated the rebound 

effect in the short-run and long run for single unit (Class 4-7) and combination (Class 8) trucks. 

As shown in Table 9-2, the estimates for the long-run rebound effect are larger than the estimates 

in the short run, which is consistent with the theory that shippers have more flexibility to change 

their behavior (e.g., restructure contracts or logistics) when they are given more time. In 

addition, the estimates derived from the national data also showed larger rebound effects 

compared to the state data. A

One possible explanation for the difference in the estimates is that the national rebound 

estimates are capturing some of the impacts of changes in economic activity. Historically, large 

increases in fuel prices are highly correlated with economic downturns, and there may not be 

enough variation in the national data to differentiate the impact of fuel price changes from 

changes in economic activity. In contrast, some states may see an increase in output when 

energy prices increase (e.g., large oil producing states such as Texas and Alaska), therefore the 

state data may be more accurately isolating the impact of fuel price changes from that of changes 

in economic activity. It is important to note that these estimates of the rebound effect reflect the 

partial effects of fuel prices and fuel economy changes on truck usage, but not the effect of truck 

prices. Therefore, these estimates do not take into account the partially offsetting impacts of 

increases in new vehicle costs that are likely to result from regulations requiring higher fuel 

economy. For example, if the increase in new vehicle prices associated with increased fuel 

economy offset half of the resulting savings in fuel costs, then the effective rebound effect would 

be half of the value shown in Table 9-2. 

 

 

A

 NHTSA’s estimates of the rebound effect are derived from econometric analysis of national and state VMT data 

reported in Federal Highway Administration, Highway Statistics, various editions, Tables VM-1 and VM-4. 

Specifically, the estimates of the rebound effect reported in Table 9-2 are ranges of the estimated short-run and 

long-run elasticities of annual VMT by single-unit and combination trucks with respect to fuel cost per mile driven. 

(Fuel cost per mile driven during each year is equal to average fuel price per gallon during that year divided by 

average fuel economy of the truck fleet during that same year.) These estimates are derived from time-series 

regression of annual national aggregate VMT for the period 1970-2008 on measures of nationwide economic 

activity , including aggregate GDP, the value of durable and nondurable goods production, and the volume of U.S. 

exports and imports of goods, and variables affecting the price of trucking services (driver wage rates, truck 

purchase prices, and fuel costs), and from regression of VMT for each individual state over the period 1994-2008 on 

similar variables measured at the state level.

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9-11

Table 9-2 Range of Rebound Effect Estimates from NHTSA Econometric Analysis

Truck Type National Data State Data

Short Run Long Run Short Run Long Run

Single Unit 13-22% 28-45% 3-8% 12-21%

Combination N/A 12-14% N/A 4-5%

As discussed throughout this section, there are multiple methodologies for quantifying 

the rebound effect, and these different methodologies produce a large range of potential values of 

the rebound effect. However, for the purposes of quantifying the rebound effect for this 

rulemaking, we have used a rebound effect with respect to changes in fuel costs per mile on the 

lower range of the long-run estimates. Given the fact that the long-run state econometric 

estimates are generally more consistent with the aggregate estimates, for this proposal we have 

chosen a rebound effect for vocational vehicles of 15% that is within the range of estimates from 

both methodologies. Similarly, we have chosen a rebound effect for combination tractors of 5%. 

To date, no estimates of the HD pickup truck and van (Class 2b and 3) rebound effect 

have been cited in the literature. Since these vehicles are used for very different purposes than 

heavy-duty vehicles, it does not necessarily seem appropriate to apply one of the heavy-duty 

estimates to the HD pickup trucks and vans. These vehicles are more similar in use to large 

light-duty vehicles, so for the purposes of our analysis, we have chosen to apply the light-duty 

rebound effect of 10% to this class of vehicles. 

9.2.4 Application of the Rebound Effect to VMT Estimates

It should be noted that the NHTSA econometric analysis attempts to isolate the rebound 

effect with respect to changes in the fuel cost per mile driven. As described previously, the 

rebound effect should be a measure of the change in VMT with respect to the change in overall 

operating costs. Therefore, NHTSA’s rebound estimates with respect to fuel costs per mile must 

be “scaled” to apply to total operating costs. For example, we assumed the elasticity of Class 8 

truck use with respect to fuel cost per mile driven is -0.05 (which corresponds to a 5% fuel 

economy rebound effect), and that fuel costs average 43% of total truck operating costs;

therefore, the elasticity of truck use with respect to total operating costs is -0.05/0.43 = -0.116. 

This calculation would correspond to an “overall” rebound effect value – that is, a rebound effect 

with respect to total truck operating costs – of -11.6%. In other words, cutting fuel costs per 

mile by 10% would correspond to only a 4.3% decline in total truck operating costs, so the 

elasticity of truck use with respect to total operating costs would have to be 2.3 times 

(100%/43%) larger than the elasticity of truck use with respect to fuel cost alone, in order to 

produce the same response in truck VMT (4%* -0.116 = 10%*-0.05). We conducted similar 

calculations for 2b/3 trucks assuming fuel costs are on average 25% of total operating costs, and 

for vocational vehicles assuming fuel costs are on average 21% of total operating costs. 

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Furthermore, we assumed an “average” incremental technology cost of $9,500 for Class 8 

combination tractors, $2,000 for Class 2b and 3 trucks, and $300 for vocational vehicles.

For the purposes of this proposal, we made several additional simplifying assumptions 

when applying the overall rebound effect to each class of truck. For example, we assumed that 

per mile vehicle costs were based on the new vehicle cost (e.g., $100,000 for the reference case 

Class 8 combination tractor) divided by the total lifetime number of expected vehicle miles (e.g., 

1.26 million miles for a Class 8 combination tractor, 288,000 miles for 2b/3 trucks, and 334,000 

miles for vocational vehicles). We recognize that this calculation implicitly assumes that truck 

depreciation is strictly a function of usage, and that it does not take into account the opportunity 

cost of alternative uses of capital. As a result, the new vehicle cost per mile assumptions used in 

these calculations represent a smaller percentage of total operating costs compared to the ATRI 

and CSI examples. We expect to refine this assumption between the proposal and final 

rulemakings, and invite submission of data on how truck owners and operators incorporate new 

vehicle costs into their operating cost per mile calculations. 

B

In the costs and benefits summarized in Chapter 9.5, we have not taken into account any 

potential fuel savings or GHG emission reductions from the rail, air or water-borne shipping 

sectors due to mode shifting. However, we have provided CSI’s example calculations in Table 

9-1 and request comment on these values. The rebound effect values used in the cost and benefit 

analysis fall within the range of the “second rebound effect” identified in the CSI analysis, which 

does account for offsetting savings from reduced rail shipping. 

In addition, we have not attempted to capture how current market failures might impact 

the rebound effect. The direction and magnitude of the rebound effect in the medium- and 

heavy-duty truck market are expected to vary depending on the existence and types of market 

failures affecting the fuel economy of the trucking fleet. If firms are already accurately 

accounting for the costs and benefits of these technologies and fuel savings, then these 

regulations would increase their net costs, because trucks would already include all cost-effective

fuel saving technologies. As a result, the rebound effect would actually be negative and truck 

VMT would decrease as a result of these proposed regulations. 

However, if firms are not optimizing their behavior today due to factors such as lack of 

reliable information (see preamble Section VIII.A. for further discussion), it is more likely that 

truck VMT would increase. If firms recognize their lower net costs as a result of these 

regulations and pass those costs along to their customers, then the rebound effect would increase 

truck VMT. This response assumes that trucking rates include both truck purchase costs and fuel 

costs, and that the truck purchase costs included in the rates spread those costs over the full 

expected lifetime of the trucks. If those costs are spread over a shorter period, as the expected 

 

B These cost estimates include indirect costs. Due to timing constraints, preliminary estimates were used to calculate 

the rebound effect, which differ slightly from the costs presented in Chapter 7. In addition, the same "overall" VMT 

rebound effect values were used for Alternatives 2 through 8 as analyzed in Chapter 6, despite the fact that each 

alternative results in a different change in incremental technology costs and operating costs. For the final 

rulemaking, we plan to estimate the overall VMT rebound effect values for each alternative. 

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Regulatory Impact Analysis 

9-13

short payback period implies, then those purchase costs will inhibit reduction of freight rates, and 

to the extent that they do so the rebound effect will be proportionally smaller. 

As discussed in more detail in preamble Section VIII.A, if there are market failures such 

as split incentives, estimating the rebound effect may depend on the nature of the failures. For 

example, if the original purchaser cannot fully recoup the higher upfront costs through fuel 

savings before selling the vehicle nor pass those costs onto the resale buyer, the firm would be 

expected to raise shipping rates. A firm purchasing the truck second-hand might lower shipping 

rates if the firm recognizes the cost savings after operating the vehicle, leading to an increase in 

VMT. Similarly, if there are split incentives and the vehicle buyer isn’t the same entity that 

purchases the fuel, than there would theoretically be a positive rebound effect. In this scenario, 

fuel savings would lower the net costs to the fuel purchaser, which would result in a larger 

increase in truck VMT. 

If all of these scenarios occur in the marketplace, their consequences for the rebound

effect will depend on the extent and magnitude of their relative effects, which are also likely to 

vary across truck classes (for instance, split incentives may be a much larger problem for Class 7 

and 8 combination tractor than they are for heavy-duty pickup trucks). 

9.3 Other Economic Impacts

9.3.1 Noise, Congestion, and Accidents

Section 9.2 discusses the likely sign of the rebound effect. If net operating costs of the 

vehicle decline, then we expect a positive rebound effect. Increased vehicle use associated with 

a positive rebound effect also contributes to increased traffic congestion, motor vehicle 

accidents, and highway noise. Depending on how the additional travel is distributed throughout

the day and on where it takes place, additional vehicle use can contribute to traffic congestion 

and delays by increasing traffic volumes on facilities that are already heavily traveled during 

peak periods. These added delays impose higher costs on drivers and other vehicle occupants in 

the form of increased travel time and operating expenses. Because drivers do not take these 

added costs into account in deciding when and where to travel, they must be accounted for 

separately as a cost of the added driving associated with the rebound effect.

Increased vehicle use due to a positive rebound effect may also increase the costs 

associated with traffic accidents. Drivers may take account of the potential costs they (and their 

passengers) face from the possibility of being involved in an accident when they decide to make 

additional trips. However, they probably do not consider all of the potential costs they impose 

on occupants of other vehicles and on pedestrians when accidents occur, so any increase in these 

“external” accident costs must be considered as another cost of additional rebound-effect driving. 

Like increased delay costs, any increase in external accident costs caused by added driving is 

likely to depend on the traffic conditions under which it takes place, since accidents are more 

frequent in heavier traffic (although their severity may be reduced by the slower speeds at which 

heavier traffic typically moves).

Finally, added vehicle use associated with a positive rebound effect may also increase 

traffic noise. Noise generated by vehicles causes inconvenience, irritation, and potentially even 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-14

discomfort to occupants of other vehicles, to pedestrians and other bystanders, and to residents or 

occupants of surrounding property. Because these effects are unlikely to be taken into account 

by the drivers whose vehicles contribute to traffic noise, they represent additional externalities 

associated with motor vehicle use. Although there is considerable uncertainty in measuring their 

value, any increase in the economic costs of traffic noise resulting from added vehicle use should

be included together with other increased external costs from the rebound effect.

EPA and NHTSA rely on estimates of congestion, accident, and noise costs caused by 

pickup trucks and vans, single unit trucks, buses, and combination tractors developed by the 

Federal Highway Administration to estimate the increased external costs caused by added 

driving due to the rebound effect.13

FHWA’s congestion cost estimates for trucks, which are weighted averages based on the 

estimated fractions of peak and off-peak freeway travel for each class of trucks, already account 

for the fact that trucks make up a smaller fraction of peak period traffic on congested roads

because they try to avoid peak periods when possible. FHWA’s congestion cost estimates focus

on freeways because non-freeway effects are less serious due to lower traffic volumes and 

opportunities to re-route around the congestion. The agencies, however, applied the congestion 

cost to the overall VMT increase, though the fraction of VMT on each road type used in MOVES 

range from 27 to 29 percent of the vehicle miles on freeways for vocational vehicles and 53 

percent for combination tractors. The results of this analysis potentially overestimate the 

congestions costs associated with increased truck use, and thus lead to a conservative estimate of 

benefits. 

 The FHWA estimates are intended to measure the increases 

in costs from added congestion, property damages and injuries in traffic accidents, and noise 

levels caused by various classes of trucks that are borne by persons other than their drivers (or 

“marginal” external costs). EPA and NHTSA employed estimates from this source previously in 

the analysis accompanying the Light-Duty GHG final rule. The agencies continue to find them 

appropriate for this analysis after reviewing the procedures used by FHWA to develop them and 

considering other available estimates of these values. 

EPA and NHTSA estimated the costs of additional vocational vehicle travel using a 

weighted average of 15 percent of the FHWA estimate for bus costs and 85 percent of the 

FHWA estimate for single unit truck costs to reflect the make-up of this segment. The low, mid, 

and high cost estimates from FHWA updated to 2008 dollars are included in Table 9-3.

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estimated percent of peak and off-peak freeway 

travel for each of the classes of trucks. FHWA 

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Regulatory Impact Analysis 

9-15

Table 9-3: Low-Mid-High Cost Estimates ($/mile) 

Noise

High Middle Low

Pickup Truck, Van $0.002 $0.001 $0.000

Vocational Vehicle $0.024 $0.009 $0.003

Combination Tractor $0.052 $0.020 $0.006

Accidents

High Middle Low

Pickup Truck, Van $0.082 $0.026 $0.014

Vocational Vehicle $0.058 $0.019 $0.010

Combination Tractor $0.069 $0.022 $0.010

Congestion

High Middle Low

Pickup Truck, Van $0.144 $0.049 $0.013

Vocational Vehicle $0.324 $0.110 $0.029

Combination Tractor $0.316 $0.107 $0.028

The agencies are proposing to use FHWA’s “Middle” estimates for marginal congestion, 

accident, and noise costs caused by increased travel from trucks.

14

EPA and NHTSA use the aggregate per mile costs, as shown in Table 9-4. Table 9-5 

presents total monetized estimates of external costs associated with noise, accidents, and 

congestion.

 This approach is consistent 

with the current methodology used in the Light-Duty GHG rulemaking analysis. These costs are 

multiplied by the annual increases in vehicle miles travelled from the rebound effect to yield the 

estimated increases in congestion, accident, and noise externality costs during each future year.

Table 9-4 Combined Costs of Congestion, Accidents and Noise (2008$ per mile)

Pickup Truck, Van $0.076

Vocational Vehicle $0.138

Combination Tractor $0.149

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Table 9-5: Annual External Costs Associated with the Heavy-Duty Vehicle Proposal (Millions of 2008 dollars)

YEAR Class 2b&3 Vocational Combination Total

2012 $0 $0 $0 $0

2013 $0 $0 $0 $0

2014 $8 $10 $18 $36

2015 $16 $19 $35 $70

2016 $23 $30 $52 $104

2017 $30 $39 $68 $137

2018 $37 $48 $83 $168

2019 $44 $56 $98 $198

2020 $50 $64 $111 $225

2021 $55 $71 $123 $249

2022 $60 $78 $133 $271

2023 $65 $84 $143 $292

2024 $70 $90 $153 $312

2025 $74 $96 $161 $331

2026 $77 $101 $169 $348

2027 $81 $107 $176 $364

2028 $84 $112 $182 $378

2029 $86 $117 $188 $391

2030 $89 $122 $193 $404

2031 $91 $128 $198 $417

2032 $94 $134 $202 $430

2033 $96 $141 $206 $443

2034 $98 $147 $210 $455

2035 $101 $153 $214 $467

2036 $103 $159 $218 $480

2037 $105 $164 $222 $491

2038 $107 $170 $226 $503

2039 $109 $176 $230 $515

2040 $112 $182 $233 $527

2041 $114 $188 $237 $539

2042 $116 $194 $241 $551

2043 $118 $200 $245 $562

2044 $120 $206 $248 $575

2045 $122 $212 $252 $586

2046 $124 $219 $256 $598

2047 $126 $225 $259 $610

2048 $128 $231 $263 $623

2049 $131 $238 $267 $635

2050 $133 $245 $271 $648

NPV, 3% $1,606 $2,407 $3,439 $7,452

NPV, 7% $746 $1,070 $1,614 $3,429

9.3.2 Savings due to Reduced Refueling Time

Reducing the fuel consumption of heavy-duty trucks will either increase their driving 

range before they require refueling, or lead truck manufacturers to offer, and truck purchasers to 

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Regulatory Impact Analysis 

9-17

buy, smaller fuel tanks. Keeping the fuel tank the same size will allow truck operators to reduce

the frequency with which drivers typically refuel their vehicles, by extending the upper limit on

the distance they can travel before requiring refueling. Alternatively, if truck purchasers and 

manufacturers respond to improved fuel economy by reducing the size of fuel tanks, the smaller 

tank will require less time to fill during each refueling stop. 

Because refueling time represents a time cost of truck operation, these time savings 

should be incorporated into truck purchasers’ decisions about how much fuel-saving technology 

they purchase as part of their choices of new vehicles. The savings calculated here thus raise the 

same questions discussed in preamble VIII.A and draft RIA Section 9.1: does the apparent 

existence of these savings reflect failures in the market for fuel economy, or does it reflect costs 

that are not addressed in this analysis? The response to these questions could vary across truck 

segment. See those sections for further analysis of this question.

No direct estimates of the value of extended vehicle range or reduced fuel tank size are 

readily available. Instead, this analysis calculates the reduction in the annual amount of time a 

driver of each type of truck will spend filling its fuel tank; this reduced time could result either 

from fewer refueling events, if new trucks’ fuel tanks stay the same size, or from less time spent 

filling the tank during each refueling stop, if new trucks’ fuels tank are made proportionately 

smaller. As discussed in Section 9.2 in this draft RIA, the average number of miles each type of 

truck is driven annually will increase under the proposed regulation, as truck operators respond 

to lower fuel costs (the “rebound effect”). The estimates of refueling time with the regulation in 

effect allow for this increase in truck use. However, EPA’s estimate of the rebound effect does 

not account for any reduction in net operating costs from lower refueling time. Because the 

rebound effect should measure the change in VMT with respect to the net change in overall 

operating costs, refueling time costs would ideally factor into this calculation. The effect of this 

omission is expected to be minor because refueling time savings are small relative to the value of

reduced fuel expenditures.

The savings in refueling time are calculated as the total amount of time the driver of a 

typical truck in each class will save each year as a consequence of pumping less fuel into the 

vehicle’s tank. The calculation does not include any reduction in time spent searching for a 

fueling station or other time spent at the station; it is assumed that time savings occur only when 

truck operators are actually refueling their vehicles. 

The calculation uses the reduced number of gallons consumed by truck type and divides 

that value by the fuel dispense rate (shown in Table 9-3) to determine the number of house saved 

in a given year. The calculation then applies DOT-recommended values of travel time savings to 

convert the resulting time savings to their economic value. The DOT-recommended value of 

travel time per vehicle-hour for truck drivers is $22.15 in 2008$ (converted from $18.10 in 

2000$).15 The inputs used in the analysis are included Table 9-3. The savings associated with 

reduced refueling time for trucks of each type throughout it lifetime are shown in Table 9-4. The 

aggregate savings associated with reduced refueling time are shown in Table 9-5 for vehicles 

sold in 2014 through 2050.

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station; it is assumed that the time savings occur only 

when truck operators would otherwise be refueling, 

and it incorporates additional driving due

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comment on whether

Deleted: refueling time will result from greater 

fuel efficiency and how it may vary by truck 

segment

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-18

Table 9-3: Inputs to Calculate Refueling Time Savings

HD PICKUP TRUCK 

AND VAN

VOCATIONAL 

VEHICLE TRACTOR

Fuel Economy 

Baseline (mpg) 15.3 9.7 5.0

Fuel Economy 

Scenario (mpg) 17.4 10.5 5.6

Fuel Dispensing Rate 

(gallon/minute)16 10 10 20

Table 9-4: Lifetime Refueling Savings for a 2018MY Truck of Each Type (2008$)

PICKUP 

TRUCKS AND 

VANS

VOCATIONAL 

VEHICLES TRACTORS

3% Discount Rate $64 $220 $294

7% Discount Rate $50 $176 $235

The aggregate savings of the vehicles sold in 2014 through 2050 are listed in Table 9-5.

Table 9-5 Annual Refueling Savings (dollar values in Millions of 2008 dollars)

CLASS 2B&3 VOCATIONAL COMBINATION

Year Hours Saved Savings Hours Saved Savings Hours Saved Savings Total 

Savings

0 $0 0 $0 0 $0 $0

2013 0 $0 0 $0 0 $0 $0

2014 11,462 $0 79,190 $1.8 219,593 $4.9 $6.9

2015 28,880 $0.6 154,810 $3.4 432,794 $10 $14

2016 73,842 $1.6 236,421 $5.2 637,785 $14 $21

2017 146,255 $3.2 386,323 $8.6 929,379 $21 $32

2018 276,082 $6.1 527,777 $12 1,211,476 $27 $45

2020 521,325 $12 785,283 $17 1,732,760 $38 $67

2030 1,397,977 $31 1,693,263 $38 3,275,326 $73 $141

2040 1,892,106 $42 2,597,856 $58 4,004,536 $89 $188

2050 2,281,344 $51 3,506,131 $78 4,652,762 $103 $231

NPV, 

3% $532 $730 $1,267 $2,529

NPV, 

7% $229 $316 $584 $1,129

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Regulatory Impact Analysis 

9-19

9.4 The Effect of Safety Standards and Voluntary Safety Improvements on Vehicle 

Weight

Safety regulations developed by NHTSA in previous regulations may make compliance 

with the proposed standards more difficult or may reduce the projected benefits of the program. 

The primary way that safety regulations can impact fuel efficiency and GHG emissions is 

through increased vehicle weight, which reduces the fuel efficiency of the vehicle. Using MY 

2010 as a baseline, this section discusses the effects of other government regulations on model 

year (MY) 2014-2016 medium and heavy-duty vehicle fuel efficiency. At this time, no known 

safety standards will affect new models in MY 2017 or 2018. The agency’s estimates are based 

on cost and weight tear-down studies of a few vehicles and cannot possibly cover all the 

variations in the manufacturers’ fleets. National Highway Traffic Safety Administration 

(NHTSA) requested, and various manufacturers provided, confidential estimates of increases in 

weight resulting from safety improvements. Those increases are shown in subsequent tables. 

We have broken down our analysis of the impact of safety standards that might affect the 

MY 2014-16 fleets into three parts: 1) those NHTSA final rules with known effective dates, 2) 

proposed rules or soon to be proposed rules by NHTSA with or without final effective dates, and 

3) currently voluntary safety improvements planned by the manufacturers. 

9.4.1 Weight Impacts of Required Safety Standards 

NHTSA has undertaken several rulemakings in which several standards would become 

effective for medium- and heavy-duty (MD/HD) vehicles between MY 2014 and MY 2016. We 

will examine the potential impact on MD/HD vehicle weights for MY 2014-2016 using MY 

2010 as a baseline. 

1. FMVSS 119, Heavy Truck Tires Endurance and High Speed Tests

2. FMVSS 121, Air Brake Systems Stopping Distance 

3. FMVSS 214, Motor Coach Lap/Shoulder Belts

4. MD/HD Vehicle Electronic Stability Control Systems

9.4.1.1 FMVSS 119, Heavy Truck Tires Endurance and High Speed Tests

The data in the large truck crash causation study (LTCCS) and the agency’s test results 

indicate that J and L load range tires are more likely to fail the proposed requirements among the 

targeted F, G, H, J and L load range tires.C

 

C “Preliminary Regulatory Impact Analysis, FMVSS No. 119, New Pneumatic Tires for Motor Vehicles with a 

GVWR of More Than 4,536 kg (10,000 pounds), June 2010. 

 As such the J and L load range tires specifically need 

to be addressed to meet the proposed requirements since the other load range tires are likely to 

pass the requirements. Rubber material improvements such as improving rubber compounds 

would be a countermeasure that reduces heat retention and improve the durability of the tires. 

Using high tensile strength steel chords in tire bead, carcass and belt would enable a weight 

reduction in construction with no strength penalties. The rubber material improvements and 

using high tensile strength steel would not add any additional weight to the current production 

Deleted: 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-20

heavy truck tires. Thus there may not be an incremental weight per vehicle for the period of MY 

2014-2016 compared to the MY 2010 baseline. This proposal could become a final rule with an 

effective date of MY2016.

9.4.1.2 FMVSS No. 121, Airbrake Systems Stopping Distance

The most recent major final rule was published on July 27, 2009 and became effective on 

November 24, 2009 (MY2009) with different compliance dates. The final rule requires the vast 

majority of new heavy truck tractors (approximately 99 percent of the fleet) to achieve a 30 

percent reduction in stopping distance compared to currently required levels. Three-axel tractors 

with a gross vehicle weight rating (GVWR) of 59,600 pounds or less must meet the reduced 

stopping distance requirements by August 1, 2011 (MY2011). Two-axle tractors and tractors 

with a GVWR above 59,600 pounds must meet the reduced stopping distance requirements by 

August 1, 2013 (MY2013). There are several brake systems that can meet the requirements in 

the final rule. Those systems include installation of larger S-cam drum brakes or disc brake 

systems at all positions, or hybrid disc and larger rear S-cam drum brake systems. 

According to the data provided by a manufacturer (Bendix), the heaviest drum brakes 

weigh more than the lightest disc brakes while the heaviest disc brakes weigh more than the 

lightest drum brakes. For a three-axle tractor equipped with all disc brakes, the total weight 

could increase by 212 pounds or could decrease by 134 pounds compared to an all drum braked 

tractor depending on which disc or drum brakes are used for comparison. The improved brakes 

may add a small amount of weight to the affected vehicle for MY2014-2016 resulting in a slight 

increase in fuel consumption. 

9.4.1.3 FMVSS No. 208, Motor coach Lap/Shoulder Belts

Based on preliminary results from the agency’s cost/weight teardown studies of motor 

coach seats, D

9.4.2 Electronic Stability Control Systems (ESC) for Medium- and Heavy-Duty 

(MD/HD) Vehicles

it is estimated that the weight added by 3-point lap/shoulder belts ranges from 5.96 

to 9.95 pounds per 2-person seat. This is the weight only of the seat belt assembly itself and 

does not include changing the design of the seat, reinforcing the floor, walls or other areas of the 

motor coach. Few current production motor coaches have been installed with lap/shoulder belts 

on their seats, and the number could be negligible. Assuming a 54 passenger motor coach, the 

added weight for the 3-point lap/shoulder belt assembly is in the range of 161 to 269 pounds (27 

* (5.96 to 9.95)) per vehicle. This proposal could become a final rule with an effective date of 

MY2016. 

The ESC is not currently required in MD/HD vehicles and could be proposed to be 

required in the vehicles by NHTSA. FMVSS No. 105, Hydraulic and electric brake systems, 

requires multipurpose passenger vehicles, trucks and buses with a GVWR greater than 4,536 kg 

 

D Cost and Weight Analysis of Two Motorcoach Seating Systems: One With and One Without Three-Point 

Lap/Shoulder Belt Restraints, Ludkes and Associates, July 2010.

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9-21

(10,000 pounds) to be equipped with an antilock brake system (ABS). All MD/HD vehicles 

have a GVWR of more than 10,000 pounds, and these vehicles are required to be installed with 

an ABS by the same standard.

The ESC incorporates yaw rate control into the ABS, and yaw is a rotation around the 

vertical axis. The ESC system uses several sensors in addition to the sensors used in the ABS, 

which is required in MD/HD vehicles. Those additional sensors could include steering wheel 

angle sensor, yaw rate sensor, lateral acceleration sensor and wheel speed sensor. According to 

the data provided by Meritor WABCO, the weight of the ESC for the model 4S4M tractor is 

estimated to be around 55.494 pounds, and the weight of the ABS only is estimated to be 45.54 

pounds. Then the added weight for the ESC for the vehicle is estimated to be 9.954 (55.494 –

45.54) pounds. 

9.4.3 Summary – Overview of Anticipated Weight Increases

Table 9-6 summarizes estimates made by the agency regarding the weight added by the 

above discussed standards or likely rulemakings. The agency estimates that weight additions 

required by final rules and likely NHTSA regulations effective in MY 2016 compared to the MY 

2010 fleet will increase motor coach vehicle weight by 171-279 pounds and will increase other 

heavy-duty truck weights by a minor 10 pounds. 

Table 9-6 Weight Additions Due to Final Rules or Likely NHTSA Regulations: Comparing MY 2016 to the 

MY 2010 Baseline Fleet

Standard Number Added Weight in 

pounds

MD/HD Vehicle

Added Weight in 

kilograms

MD/HD Vehicle

119 0 0

121 0 (?) 0 (?)

208

Motor coaches only

161-269 73-122

MD/HD Vehicle Electronic 

Stability Control Systems

10 4.5

Total

Motor coaches

171- 279 77.5-126.5

Total

All other MD/HD vehicles

10 4.5

9.4.4 Effects of Vehicle Mass Reduction on Safety

NHTSA and EPA have been considering the effect of vehicle weight on vehicle safety for 

the past several years in the context of our joint rulemaking for light-duty vehicle CAFE and 

GHG standards, consistent with NHTSA’s long-standing consideration of safety effects in setting 

CAFE standards. Combining all modes of impact, the latest analysis by NHTSA for the MYs 

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2012-2016 final ruleE

In the context of the current rulemaking for HD fuel consumption and GHG standards, 

one would expect that reducing the weight of medium-duty trucks similarly would, if anything, 

have a positive impact on safety. However, given the large difference in weight between lightduty vehicles and medium-duty trucks, and even larger difference between light-duty vehicles 

and heavy-duty vehicles with loads, the agencies believe that the impact of weight reductions of 

medium- and heavy-duty trucks would not have a noticeable impact on safety for any of these 

classes of vehicles.

found that reducing the weight of the heavier light trucks (LT > 3,870) had 

a positive overall effect on safety, reducing societal fatalities. 

However, the agencies recognize that it is important to conduct further study and research 

into the interaction of mass, size and safety to assist future rulemakings, and we expect that the 

collaborative interagency work currently on-going to address this issue for the light-duty vehicle 

context may also be able to inform our evaluation of safety effects for the final HD vehicle rule. 

We seek comment regarding potential safety effects due to weight reduction in the HD vehicle 

context, with particular emphasis on commenters providing supporting data and research for HD 

vehicle weight reduction. 

9.5 Petroleum and energy security impacts

9.5.1 Impact on U.S. Petroleum Imports

In 2008, U.S. petroleum import expenditures represented 21 percent of total U.S. imports 

of all goods and services.17 In 2008, the United States imported 66 percent of the petroleum it 

consumed, and the transportation sector accounted for 70 percent of total U.S. petroleum 

consumption. This compares roughly to 37 percent of petroleum from imports and 55 percent 

consumption of petroleum in the transportation sector in 1975.18

9.5.2 Background on U.S. Energy Security

 It is clear that petroleum 

imports have a significant impact on the U.S. economy. Requiring lower GHG-emitting heavyduty vehicles and improved fuel economy in the U.S. is expected to lower U.S. petroleum 

imports.

U.S. energy security is broadly defined as protecting the U.S. economy against 

circumstances that result in significant short- and long-term increases in energy costs. Most 

discussion of U.S. energy security revolves around the topic of the economic costs of U.S. 

dependence on oil imports. The U.S.’s energy security problem is that the U.S. relies on 

imported oil from potentially unstable sources. In addition, oil exporters have the ability to raise 

the price of oil by exerting monopoly power through the formation of a cartel, the Organization 

of Petroleum Exporting Countries (OPEC). Finally, these factors contribute to the vulnerability 

of the U.S. economy to episodic oil supply shocks and price spikes. In 2008, U.S. net 

 

E “Final Regulatory Impact Analysis, Corporate Average Fuel Economy for MY 2012 - MY 2016 Passenger Cars 

and Light Trucks”, NHTSA, March 2010, (Docket No. NHTSA-2009-0059-0344.1). 

Deleted: petroleum imports

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9-23

expenditures for imports of crude oil and petroleum products were $336 billion (in 2008$, see

Figure 9-3).

U.S. Expenditures on Crude Oil

0

100

200

300

400

500

600

700

1970 1975 1980 1985 1990 1995 2000 2005

Year

(2007$ Billions)

Domestic

Imported

Figure 9-3: U.S. Expenditures on Crude Oil from 1970 through 2008

One effect of the EPA/NHTSA joint heavy-duty vehicle rule is that it promotes more 

efficient use of transportation fuels in the U.S. The result is that it reduces U.S. oil imports, 

which reduces both financial and strategic risks associated with a potential disruption in supply 

or a spike in the cost of a particular energy source. This reduction in risks is a measure of 

improved U.S. energy security. For this rule, an “oil premium” approach is utilized to identify 

those energy security related impacts which are not reflected in the market price of oil, and 

which are expected to change in response to an incremental change in the level of U.S. oil 

imports.

F

9.5.2.1 Methodology Used to Estimate U.S. Energy Security Benefits

In order to understand the energy security implications of reducing U.S. oil imports, EPA

has worked with Oak Ridge National Laboratory (ORNL), which has developed approaches for 

evaluating the social costs and energy security implications of oil use. The energy security 

estimates provided below are based upon a methodology developed in a peer-reviewed study 

entitled, “The Energy Security Benefits of Reduced Oil Use, 2006-2015,” completed in March 

2008. This recent study is included as part of the docket for this rulemaking.19

 

F For historical data through 2006: EIA Annual Energy Review, various editions.

 This ORNL 

For data 2006-2008: EIA Annual Energy Outlook (AEO) 2009 (Update Reference (Stimulus) Base Case).

See file "aeostimtab_11.xls" available at http://www.eia.doe.gov/oiaf/servicerpt/stimulus/aeostim.html

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study is an update version of the approach used for estimating the energy security benefits of 

U.S. oil import reductions developed in an ORNL 1997 Report by Leiby, Paul N., Donald W. 

Jones, T. Randall Curlee, and Russell Lee, entitled “Oil Imports: An Assessment of Benefits and 

Costs.” 20

When conducting this recent analysis, ORNL considered the full cost of importing 

petroleum into the U.S. The full economic cost is defined to include two components in addition 

to the purchase price of petroleum itself. These are: (1) the higher costs for oil imports resulting 

from the effect of U.S. import demand on the world oil price and on OPEC market power (i.e., 

the “demand” or “monopsony” costs); and (2) the risk of reductions in U.S. economic output and 

disruption to the U.S. economy caused by sudden disruptions in the supply of imported oil to the 

U.S. (i.e., macroeconomic disruption/adjustment costs). Maintaining a U.S. military presence to 

help secure stable oil supply from potentially vulnerable regions of the world was not included in

this analysis because its attribution to particular missions or activities is difficult (as discussed 

further below). 

The literature on the energy security for the last two decades has routinely combined the 

monopsony and the macroeconomic disruption components when calculating the total value of 

the energy security premium. However, in the context of using a global value for the Social Cost 

of Carbon (SCC) the question arises: How should the energy security premium be used when 

some benefits from the rule, such as the benefits of reducing greenhouse gas emissions, are 

calculated using a global value? Monopsony benefits represent avoided payments by the U.S. to 

oil producers in foreign countries that result from a decrease in the world oil price as the U.S. 

decreases its consumption of imported oil. Although there is clearly a benefit to the U.S. when 

considered from the domestic perspective, the decrease in price due to decreased demand in the 

U.S. also represents a loss of income to oil-producing countries. 

Given the redistributive nature of this effect, do the negative effects on other countries

‘‘net out’’ the positive impacts to the U.S.? If this is the case, then the monopsony portion of the 

energy security premium should be excluded from the net benefits calculation for the rule. 

OMB’s Circular A–4 gives guidance in this regard. Domestic pecuniary benefits (or transfers 

between buyers and sellers) generally should not be included because they do not represent real 

resource costs, though A– 4 notes that transfers to the U.S. from other countries may be counted 

as benefits as long as the analysis is conducted from a U.S. perspective. Energy security is 

broadly defined as protecting the U.S. economy against circumstances that threaten significant 

short- and long-term increases in energy costs. Energy security is inherently a domestic benefit. 

Accordingly, it is possible to argue that the use of the domestic monopsony benefit may not 

necessarily be in conflict with the use of the global SCC, because the global SCC represents the 

benefits against which the costs of our (i.e., the U.S.’s) domestic mitigation efforts should be 

judged. In the final analysis, the Agency has determined that using only the macroeconomic 

disruption component of the energy security benefit is the appropriate metric for this rule. 

Section VIII.I of the preamble contains more discussion of how the monopsony and 

macroeconomic disruption/adjustment components are treated for this analysis. 

As part of the process for developing the ORNL energy security estimates, EPA 

sponsored an independent, expert peer review of the 2008 ORNL study. A report compiling the

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Regulatory Impact Analysis 

9-25

peer reviewers’ comments is provided in the docket.21

For this rule, ORNL further updated the energy security premium by incorporating the 

most recent oil price forecast and energy market trends in AEO 2010 into its model. In order for 

the energy security premium to be used in EPA’s MOVES model, ORNL developed energy 

security premium estimates for a number of different years; i.e., 2020, 2030, and 2040. 

 In addition, EPA has worked with ORNL 

to address comments raised in the peer review and to develop estimates of the energy security 

benefits associated with a reduction in U.S. oil imports for this heavy-duty vehicle rule. In 

response to peer reviewer comments, ORNL modified its model by changing several key 

parameters involving OPEC supply behavior, the responsiveness of oil demand and supply to a 

change in the world oil price, and the responsiveness of U.S. economic output to a change in the 

world oil price.

For 2020, ORNL has estimated that the total energy security premium associated with a 

reduction of imported oil is $19.66/barrel. On a dollar per gallon basis, energy security benefits 

for 2020 are $0.47/gallon. Table 9-6 provides estimates for energy security premium for the 

years 2020, 2030 and 2040, H

Table 9-6 Energy Security Premium in 2020, 2030 and 2040

as well as a breakdown of the components of the energy security 

premium for each year. The components of the energy security premium and their values are 

discussed below.

(2008$/Barrel)

YEAR MONOPSONY

(RANGE)

MACROECONOMIC 

DISRUPTION/ADJUSTMENT 

COSTS

(RANGE)

TOTAL MID-POINT

(RANGE)

2020 $12.28

($4.16 - $23.74)

$7.39

($3.39 – $11.92)

$19.66

($10.27 - $30.90)

2030 $12.69

($4.43 – 23.80)

$8.54

($4.10 – $13.60)

$21.23

($11.30 - $32.88)

2040 $12.68

($4.41 – $23.41)

$8.99

($4.48 – $14.08)

$21.67

($11.54 - $31.10)

9.5.2.2 Effect of Oil Use on Long-Run Oil Price, U.S. Import Costs, and 

Economic Output

The first component of the full economic costs of importing petroleum into the U.S. 

follows from the effect of U.S. import demand on the world oil price over the long-run. Because 

the U.S. is a sufficiently large purchaser of foreign oil supplies, its purchases can affect the world 

oil price. This monopsony power means that increases in U.S. petroleum demand can cause the 

 

H AEO 2010 forecasts energy market trends and values only to 2035. The energy security premia post-2035 are

assumed to be the 2035 estimate.

Deleted: 

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Deleted: long-run oil price

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

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world price of crude oil to rise, and conversely, that reduced U.S. petroleum demand can reduce 

the world price of crude oil. Thus, one benefit of decreasing U.S. oil purchases, due to the 

increased availability and use of other transportation fuels, is the potential decrease in the crude 

oil price paid for all crude oil purchased.

The demand or monopsony effect can be readily illustrated with an example. If the U.S. 

imports 10 million barrels per day at a world oil price of $50 per barrel, its total daily bill for oil 

imports is $500 million. If a decrease in U.S. imports to 9 million barrels per day causes the 

world oil price to drop to $49 per barrel, the daily U.S. oil import bill drops to $441 million (9 

million barrels times $49 per barrel). While the world oil price only declines $1, the resulting 

decrease in oil purchase payments of $59 million per day ($500 million minus $441 million) is 

equivalent to an incremental benefit of $59 per barrel of oil imports reduced, or $10 more than 

the newly-decreased world price of $49 per barrel. This additional $10 per barrel “import cost 

premium” represents the incremental external benefits to the U.S. for avoided import costs 

beyond the price paid oil purchases. This additional benefit arises only to the extent that 

reduction in U.S. oil imports affects the world oil price. ORNL estimates this component of the 

energy security benefit in 2020 to be $12.28/barrel, with a range of $4.16/barrel to $23.74/barrel 

of imported oil reduced.

It is important to note that the decrease in global petroleum prices resulting from the 

proposed rule could spur increased consumption of petroleum in other sectors and countries, 

leading to a small uptick in GHG emissions outside of the United States. This global fuel 

consumption increase could offset some portion of the GHG reduction benefits associated with 

the rule. EPA has not quantified this increase in global GHG emissions in the draft RIA and

requests comment on whether to do so for the final RIA.

9.5.2.3 Short-Run Disruption Premium from Expected Costs of Sudden Supply 

Disruptions 

The second component of the oil import premium, “macroeconomic 

disruption/adjustment costs,” arises from the effect of oil imports on the expected cost of 

disruptions. A sudden increase in oil prices triggered by a disruption in world oil supplies has 

two main effects: (1) it increases the costs of oil imports in the short run and (2) it can lead to 

macroeconomic contraction, dislocation and Gross Domestic Product (GDP) losses. ORNL 

estimates the composite estimate of these two factors that comprise the macroeconomic 

disruption/adjustment costs premium to be $7.39/barrel in 2020, with a range of $3.39/barrel to 

$11.92/barrel of imported oil reduced.

9.5.2.3.1 Macroeconomic Disruption Adjustment Costs 

There are two main effects of macroeconomic disruption/adjustment costs. The first is 

the short-run price increases with an oil shock. The oil price shock results in a combination of 

real resource shortages, costly short-run shifts in energy supply, behavioral and demand 

adjustments by energy users, and other response costs. Unlike pure transfers, the root cause of 

the disruption price increase is a real resource supply reduction due, for example, to disaster or 

war. Regions where supplies are disrupted, such as the U.S., suffer very high costs. Businesses’ 

Deleted: run disruption premium

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Regulatory Impact Analysis 

9-27

and households’ emergency responses to supply disruptions and rapid price increases consume 

real economic resources. 

While households and businesses can reduce their petroleum consumption, invest in fuel

switching technologies, or use futures markets to insulate themselves in advance against the

potential costs of rapid increases in oil prices, when deciding how extensively to do so, they are

unlikely to account for the effect of their petroleum consumption on the magnitude of costs that

supply interruptions and accompanying price shocks impose on others. As a consequence, the

U.S. economy as a whole will not make sufficient use of these mechanisms to insulate itself from 

the real costs of rapid increases in energy prices and outlays that usually accompany oil supply

interruptions. Therefore, the ORNL estimate of macroeconomic disruption and adjustment

costs that the EPA uses to value energy security benefits includes the increased oil import costs

stemming from oil price shocks that are unanticipated and not internalized by advance actions of 

U.S. consumers.

The second main effect of macroeconomic disruption/adjustment costs is the 

macroeconomic losses during price shocks that reflect both aggregate output losses and 

“allocative” losses. The former are a reduction in the level of output that the U.S. economy can 

produce fully using its available resources; and the latter stem from temporary dislocation and 

underutilization of available resources due to the shock, such as labor unemployment and idle 

plant capacity. The aggregate output effect, a reduction in “potential” economic output, will last 

so long as the price is elevated. It depends on the extent and duration of any disruption in the 

world supply of oil, since these factors determine the magnitude of the resulting increase in 

prices for petroleum products, as well as whether and how rapidly these prices return to their predisruption levels.

In addition to the aggregate contraction, there are “allocative” or “adjustment” costs 

associated with dislocated energy markets. Because supply disruptions and resulting price 

increases occur suddenly, empirical evidence shows they also impose additional costs on 

businesses and households which must adjust their use of petroleum and other productive factors 

more rapidly than if the same price increase had occurred gradually. Dislocational effects 

include the unemployment of workers and other resources during the time needed for their 

intersectoral or interregional reallocation, and pauses in capital investment due to uncertainty. 

These adjustments temporarily reduce the level of economic output that can be achieved even 

below the “potential” output level that would ultimately be reached once the economy’s 

adaptation to higher petroleum prices is complete. The additional costs imposed on businesses 

and households for making these adjustments reflect their limited ability to adjust prices, output 

levels, and their use of energy, labor and other inputs quickly and smoothly in response to rapid 

changes in prices for petroleum products.

Since future disruptions in foreign oil supplies are an uncertain prospect, each of the 

disruption cost components must be weighted by the probability that the supply of petroleum to 

the U.S. will actually be disrupted. Thus, the “expected value” of these costs – the product of the 

probability that a supply disruption will occur and the sum of costs from reduced economic 

output and the economy’s abrupt adjustment to sharply higher petroleum prices – is the relevant 

measure of their magnitude. Further, when assessing the energy security value of a policy to 

reduce oil use, it is only the change in the expected costs of disruption that results from the 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-28

policy that is relevant. The expected costs of disruption may change from lowering the normal 

(i.e., pre-disruption) level of domestic petroleum use and imports, from any induced alteration in 

the likelihood or size of disruption, or from altering the short-run flexibility (e.g., elasticity) of 

petroleum use.

In summary, the steps needed to calculate the disruption or security premium are: 1) 

determine the likelihood of an oil supply disruption in the future; 2) assess the likely impacts of a 

potential oil supply disruption on the world oil price; 3) assess the impact of the oil price shock 

on the U.S. economy (in terms of import costs and macroeconomic losses); and 4) determine 

how these costs change with oil imports. The value of price spike costs avoided by reducing oil 

imports becomes the oil security portion of the premium.

9.5.2.3.2 Cost of Existing U.S. Energy Security Policies 

The last often-identified component of the full economic costs of U.S. oil imports are the 

costs to the U.S. taxpayers of existing U.S. energy security policies. The two primary examples 

are maintaining the Strategic Petroleum Reserve (SPR) and maintaining a military presence to 

help secure a stable oil supply from potentially vulnerable regions of the world. The SPR is the 

largest stockpile of government-owned emergency crude oil in the world. Established in the 

aftermath of the 1973-74 oil embargo, the SPR provides the U.S. with a response option should a 

disruption in commercial oil supplies threaten the U.S. economy. It also allows the U.S. to meet 

part of its International Energy Agency obligation to maintain emergency oil stocks, and it 

provides a national defense fuel reserve. While the costs for building and maintaining the SPR

are more clearly related to U.S. oil use and imports, historically these costs have not varied in 

response to changes in U.S. oil import levels. Thus, while SPR is factored into the ORNL 

analysis, the cost of maintaining the SPR is excluded.

U.S. military costs are excluded from the analysis performed by ORNL because their 

attribution to particular missions or activities is difficult. Most military forces serve a broad 

range of security and foreign policy objectives. Attempts to attribute some share of U.S. military 

costs to oil imports are further challenged by the need to estimate how those costs might vary 

with incremental variations in U.S. oil imports. 

9.5.2.4 Modifications to Analysis Based Upon Peer Reviewer Comments 

As part of the peer review process, the EPA commissioned ORNL to conduct a number 

of sensitivity analyses to address the comments of the peer reviewers. Based upon the peer 

reviewer comments, key parameters that influence the “oil import” premium were assessed. 

Since not all the comments were in agreement with each other, several ranges of different 

parameters were developed for the analyses. These sensitivities used the most recent price 

forecasts and energy market trends available at the time the peer review was being conducted 

and completed, the AEO 2007 Reference Case. Thus, the results presented below are suggestive 

of how the energy security premium is influenced by alternative assumptions of key parameters 

that influence world oil markets but are not directly comparable to the oil security premiums 

used for the heavy-duty vehicle rule. A summary of the results of the sensitivity analyses 

conducted for the peer review process are shown in Table 9-7.

Deleted: existing

Deleted: energy security policies

Deleted: analysis based upon peer reviewer 

comments

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Three key parameters were varied in order to assess their impacts on the oil import 

premium: (1) the response of OPEC supply, (2) the combined response of non-U.S., non-OPEC 

demand and supply and (3) the GDP response to a change in the world oil as a result of reduced 

U.S. oil imports. The cases used updated supply/demand elasticities for non-U.S./non-OPEC 

region after considering more recent estimates than those used in 1997 study. As a result, the 

total market responsiveness is greater than previous ORNL estimates. Only relatively small 

changes to the world oil price are anticipated from a substantial reduction in U.S. demand, on 

average, about $0.70/barrel for every million barrels per day reduction in demand. In the ORNL 

framework, OPEC-behavior is treated parametrically, with a wide range of possible responses 

represented by a range of supply elasticities. Case One in below refers to the AEO 2007 

estimates of energy market trends and uses the elasticity parameters from the original 1997 

ORNL study. In Case Two, the OPEC supply elasticities range from 0.25 to 6.0 with a mean 

elasticity of 1.76. Case Three alters the distribution of the OPEC supply elasticities so that the 

mean elasticity is 2.2 instead of 1.76. With the more elastic OPEC oil supply in Case Three, the 

oil premium is lower. Alternatively, a candidate rule for OPEC strategic response behavior, 

adapted from a lead article on what behavior maximizes OPEC’s long run net revenue in a robust 

way,22

The second key parameter that was varied based upon peer reviewer comments was nonOPEC, non-U.S. demand and supply responsiveness to a change in the U.S. oil import demand 

and, hence, the world oil price. In Case Four, the mean non-U.S./non-OPEC demand and supply 

elasticities are taken to each be 0.3 in absolute value terms. When combined together, the net 

elasticity of import demand from the non-U.S./non-OPEC region is approximately 1.6. Case 

Five takes the Case Four assumptions of a more elastic OPEC supply behavior and combines 

those assumptions with the 1.6 net elasticity of import demand for the non-U.S./non-OPEC 

region. Case Six looks at the consequences of a yet higher net elasticity of import demand —

2.28 — for the non-U.S./non-OPEC region. The impact on the oil import premium is relatively 

modest.

would have OPEC responding to preserve its worldwide oil market share. This is 

presented as Case Seven. Application of this rule instead of the range of OPEC supply responses 

used leads to an estimate of the oil import premium that is between Case Two and Case Three.

Cases Eight and Nine consider a reduced GDP elasticity, the parameter which 

summarizes the sensitivity of GDP to oil price shocks. Several reviewers suggested a lower 

estimate for this parameter. In response to their comments, a couple of cases were examined 

where the GDP elasticity was lowered to 0.032 in comparison to the original ORNL estimate of 

0.0495. As anticipated, this change lowered the oil import premium modestly. For example, 

compared with Case Four where OPEC supply is more elastic, lowering the GDP elasticity with 

respect to the world oil price reduced the oil import premium by roughly $0.40/barrel. This is 

because the GDP-dislocation component is only about one-quarter of the total premium, and 

there are offsetting changes in other components. The last case examined, Case Nine, looks at 

the consequences for the oil import premium with a reduced elasticity of GDP if OPEC attempts 

to maintain its share of the world oil market.

Clearly there is an unavoidable degree of uncertainty about the magnitude of marginal 

economic costs from the U.S. importation of petroleum, and the size of the oil import premium. 

ORNL sought to reflect this with probabilistic risk analysis over key input factors, guided by the 

available literature and the best judgment of oil market experts. Cases shown in Table 9-7 

Deleted: Table 9-7
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-30

explore some reasonable variations in the ranges of input assumptions and the mean oil premium 

estimates vary in a fairly moderate range between roughly $11 and $15/barrel of imported oil. 

On balance, Case Eight suggested a reasonable and cautious assessment of the premium value to 

ORNL, and is ORNL’s recommended case. This is based on a review of important driving 

factors, the numerical evaluations and simulations over major uncertainties, and taking into 

consideration the many comments and suggestion from the reviewers, the EPA and other 

Agencies. This recommended case, and the premium range resulting from 90 percent of the 

simulated outcomes, encompasses a wide array of perspectives and potential market outcomes in 

response to a reduction of U.S. imports.

As mentioned previously, this recommended case relied on the most recent available 

projections of the U.S. and world oil market for the next ten years based upon the AEO 2007 

Reference Case. OPEC behavior was treated parametrically, with a wide range of possible 

responses represented by a wide range of supply elasticities, from small to quite large. This 

recommended case recognized that the OPEC response is the most uncertain single element of 

this analysis. It could vary between inelastic defense of output levels, or market share, or could 

be highly elastic in defense of price, probably at the expense of longer run cartel power and 

discounted net profits. The balance between possible elastic and inelastic OPEC response was 

essentially even over a fairly wide range of elasticities. ORNL concluded that this is the best 

way to estimate OPEC behavior until greater progress can be made in synthesizing what insights 

are available from the evolving strategic game-theoretic and empirical research on OPEC 

behavior, and advancing that research. An alternative would have been to use OPEC strategic 

response behavior to maximize long-run net revenue, which may well correspond to marketshare preservation behavior (e.g., Case Seven), and a somewhat higher premium value.

Finally, ORNL’s recommended case used a GDP elasticity range, the parameter which 

summarizes the sensitivity of GDP to oil price shocks, which is reduced compared to earlier 

estimates, and compared to the full range of historically-based estimates. This helped address 

the concerns of those who either question the conclusions of past empirical estimates or expect 

that the impacts of oil shocks may well be declining.

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Table 9-7 Summary Results – Oil Import Premium Under Various Cases

($2007/BBL)

Component Statistic

1) AEO2007 Base Outlook, 1997 Study Elasticities

2) AEO2007 Base Outlook, Wider Range of OPEC Supply Elasticities

3) Case 2 with Revised Wider Range of OPEC Supply Elasticities

4) Case 2 with Updated NonOPEC Supply/Demand Elasticities

5) Case 4 plus Revised Wider Range of OPEC Supply Elasticities

6) Case 4 Variant with Wider, Higher Range of NonU.S./Non-OPEC Supply/Demand Elasticities

7) Case 6 with Applied Strategic OPEC Behavioral Rule: Maintain Market Share

8) Case 4 with Reduced GDP Elasticity

9) Case 7 with Reduced GDP Elasticity

Mean $5.57 $10.26 $8.16 $7.77 $6.52 $6.44 $9.36 $7.86 $9.42

Range ($3.60 - $8.19) ($3.10 - $21.22) ($3.12 - $19.30) ($2.94 - $13.75) ($2.90 - $13.06) ($2.69 - $11.33) ($6.69 - $12.42) ($2.94 - $13.89) ($6.72 - $12.54

Mean $2.36 $2.33 $2.34 $1.92 $1.94 $1.93 $1.89 $2.20 $2.16

Range ($0.51 - $4.66) ($0.58 - $4.57) ($0.66 - $4.61) ($0.39 - $3.75) ($0.38 - $3.84) ($0.42 - $3.70) ($0.44 - $3.66) ($0.63 - $4.07) ($0.62 - $3.96

Mean $3.83 $3.70 $3.76 $3.42 $3.45 $3.47 $3.41 $2.67 $2.64

Range ($1.06 - $6.69) ($1.04 - $6.57) ($1.06 - $6.74) ($0.92 - $6.23) ($0.94 - $6.10) ($0.92 - $6.13) ($0.87 - $6.26) ($0.90 - $4.84) ($0.87 - $4.87

Mean $6.19 $6.03 $6.10 $5.34 $5.39 $5.40 $5.30 $4.87 $4.81

Range ($2.94 - $10.01) ($2.94 - $9.75) ($2.91 - $9.85) ($2.53 - $8.69) ($2.60 - $8.62) ($2.58 - $8.92) ($2.54 - $8.74) ($2.23 - $7.85) ($2.25 - $7.77

Mean $11.75 $16.29 $14.27 $13.11 $11.90 $11.86 $14.65 $12.71 $14.23

Range ($8.04 - $15.96) ($8.10 - $27.42) ($7.90 - $25.49) ($7.26 - $19.59) ($6.96 - $18.62) ($6.79 - $17.23) ($11.03 - $18.61) ($7.07 - $19.02) ($10.76 - $18.2

Total Premium, in $/Gallon Mean $0.28 $0.39 $0.34 $0.31 $0.28 $0.28 $0.35 $0.30 $0.34

Price Reduction ($/MMBD) Mean $0.52 $1.04 $0.81 $0.75 $0.61 $0.60 $0.90 $0.75 $0.90

Economic Disruption/Adjustment CostsTotal Mid-Point

Cases

1) Based on AEO2007. Updated oil market outlook from AEO1994 Base Case to AEO2007 Base Case. Among other things, this means average crude price rises from $20.33 to $48.34. All elasticities match 1997 values. Non-U.S. elasticity of import demand = -0.2) AEO2007 Base Outlook, with wider range of OPEC supply elasticities, 0.25 to 6.0 and a mean elasticity of 1.76.3) Revise Case 2, with OPEC behavior distributed over elasticities 0 to 6, so that 25% of response is inelastic (< 1.0), mode elasticity is 2.0 (mean elasticity is 2.2 rather than 1.76)4) Updated Case 2 supply/demand elasticities for non-OPEC region with more recent estimates. Elasticity of non-U.S. demand -0.2 to -0.4, with mean and mode -0.3, non-U.S. Supply = 0.2 to 0.4, with mean and mode 0.3, implying (mode) net elasticity of impo5) Revise Case 4, with OPEC behavior distributed over elasticities 0 to 6, so that 25% of response is inelastic (< 1.0), mode elasticity is 2.0 (mean elasticity is 2.2 rather than 1.76). Net elasticity of import demand is -1.6 for the non-U.S./non-OPEC r6) Alternative to Case 4 with expanded (and higher) range of non-U.S. supply/demand elasticities. Elasticity of non-U.S. demand = -0.3 to -0.7, triangular distribution with mode -0.4 mean -0.467, elasticity non-U.S. supply = 0.2 to 0.6, mode 0.3 and m7) Applied Strategic OPEC Behavioral Rule to Case 6: Maintain Market Share (Gately 2004 paper best strategy). This rule implies that OPEC Supply elasticity matches that of all non-OPEC supply. As a result non-U.S. elasticity of import demand ranges from8) Variant on version Case 4, considered reduced GDP elasticity for future disruptions (range -0.01 to -0.054; midcase value -0.032; mean value is -0.032, reduced from mean value of -0.0495). OPECbehavior treated parametrically.9) Revise Case 7 (which applied Strategic OPEC Behavioral Rule to Case 6: Maintain Market Share (Gately 2004 paper best strategy)) with reduced GDP elasticity for future disruptions (range -0.01 to -

Table 4.B.10.2.3-1: Summary Results - Oil Import Premium Under Various Cases ($2007/BBL)

Monopsony ComponentDisruption Import CostsDisruption Dislocation Costs

Deleted: Table 9-7
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-32

9.5.2.5 The Impact of Fuel Savings on U.S. Petroleum Imports

EPA used the MOVES model to estimate the reduced consumption in fuel due to this 

proposal. A detailed explanation of the MOVES model can be found in Chapter 5 of this draft

RIA. 

Based on a detailed analysis of differences in fuel consumption, petroleum imports, and 

imports of refined petroleum products and crude oil among the Reference Case, High Economic 

Growth, and Low Economic Growth Scenarios presented in AEO 2009, NHTSA and EPA 

estimate that approximately 50 percent of the reduction in fuel consumption resulting from 

adopting improved fuel GHG standards and fuel economy standards is likely to be reflected in 

reduced U.S. imports of refined fuel, while the remaining 50 percent would be expected to be 

reflected in reduced domestic fuel refining. Of this latter figure, 90 percent is anticipated to 

reduce U.S. imports of crude petroleum for use as a refinery feedstock, while the remaining 10 

percent is expected to reduce U.S. domestic production of crude petroleum. Thus, on balance, 

each gallon of fuel saved as a consequence of improved fuel heavy-duty GHG standards and fuel 

economy standards is anticipated to reduce total U.S. imports of crude petroleum or refined fuel 

by 0.95 gallons.I

Based upon the fuel savings estimated by the MOVES model and the 95 percent oil 

import factor, the reduction in U.S. oil imports from this rule are estimated for the years 2020, 

2030 and 2040 (in millions of barrels per day (MMBD)) in Table 9-8 below.

 

Table 9-8 U.S. Oil Import Reductions Resulting from the Heavy-Duty Vehicle Rule in 2020, 2030 and 2040

(in MMBD)

2020 2030 2040

0.177 0.357 0.463

For comparison purposes, Table 9-9 shows the U.S. imports of crude oil in 2020 and 

2030 as projected by DOE in the Annual Energy Outlook 2010.

Table 9-9 Projected U.S. Imports of Crude Oil in 2020 and 2030

J

(in MMBD)

2020 2030

8.54 8.69

 

I

This figure is calculated as 0.50 + 0.50*0.9 = 0.50 + 0.45 = 0.95. J AEO 2010, EIA, Table 127, Projected United States Imported Liquids by Source to 2030.

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9.5.2.6 Energy Security Benefits of this Proposed Program 

Using the same methodology as the peer reviewed model, but updating the analysis using 

AEO 2010 world oil price values and the estimated fuel savings from the rule using the MOVES 

model, EPA has calculated the energy security benefits of the rule for the years 2020, 2030 and 

2040. Since the Agency is taking a global perspective with respect to valuing greenhouse gas 

benefits from the rule, only the macroeconomic adjustment/disruption portion of the energy 

security premium is used in the energy security benefits estimates present below. These results 

are shown below in Table 9-10.

Table 9-10 U.S. Energy Security Benefits of the Heavy-Duty Vehicle Rulemaking in 2020, 2030 and 2040

(in millions of $2008)

2020 2030 2040

$479 $1,117 $1,526

9.6 Summary of Benefits and Costs

In this section, the agencies present a summary of costs, benefits, and net benefits of the 

proposal. Table 9-11 shows the estimated annual monetized costs of the proposed program for 

the indicated calendar years. The table also shows the net present values of those costs for the 

calendar years 2012-2050 using both 3 percent and 7 percent discount rates.

K

Table 9-11 Estimated Monetized Costs of the Proposed Program (Millions of 2008 dollars)

 In this table, the 

aggregate value of fuel savings is calculated using pre-tax fuel prices since savings in fuel taxes 

do not represent a reduction in the value of economic resources utilized in producing and 

consuming fuel. Note that fuel savings shown here result from reductions in fleet-wide fuel use. 

Thus, they grow over time as an increasing fraction of the fleet meets the 2018 standards.

a

2020 2030 2040 2050

NPV, YEARS 

2012-2050, 3%

DISCOUNT 

RATE

NPV, YEARS 

2012-2050, 7%

DISCOUNT 

RATE

Truck/Tractor 

Costs $2,000 $1,900 $2,200 $2,500 $42,100 $22,500

Fuel Savings 

(pre-tax) -$8,100 -$19,000 -$28,100 -$35,400 -$352,300 -$152,600

Quantified 

Annual Costs -$6,100 -$17,100 -$25,900 -$32,900 -$310,200 -$130,100

a Technology costs and fuel savings for separate truck segments can be found in Chapter 7.

 

K For the estimation of the stream of costs and benefits, we assume that after implementation of the proposed MY 

2014-2017 standards, the 2017 standards apply to each year out to 2050.

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-34

Table 9-12 presents estimated annual monetized benefits for the indicated calendar years. 

The table also shows the net present values of those benefits for the calendar years 2012-2050 

using both 3 percent and 7 percent discount rates. The table shows the benefits of reduced CO2

 In addition, these monetized GHG benefits exclude the value of reductions in non-CO

emissions—and consequently the annual quantified benefits (i.e., total benefits)—for each of 

four SCC values estimated by the interagency working group. As discussed in Section 8.5, there 

are some limitations to the SCC analysis, including the incomplete way in which the integrated 

assessment models capture catastrophic and non-catastrophic impacts, their incomplete treatment 

of adaptation and technological change, uncertainty in the extrapolation of damages to high 

temperatures, and assumptions regarding risk aversion. 

2

GHG emissions (CH4, N2O, HFC) expected under this proposal. Although EPA has not 

monetized the benefits of reductions in non-CO2 GHGs, the value of these reductions should not 

be interpreted as zero. Rather, the net reductions in non-CO2

Table 9-12 Monetized Benefits Associated with the Proposed Program (Millions of 2008 dollars)

GHGs will contribute to this rule’s 

climate benefits, as explained in Section III.F of the preamble. 

2020 2030 2040 2050

NPV, YEARS 2012-

2050, 3% DISCOUNT 

RATEA

NPV, YEARS 2012-

2050, 3% DISCOUNT 

RATEA

Reduced CO2 Emissions at each assumed SCC valueb

5% (avg SCC) $200 $700 $1,200 $1,700 $8,600 $8,600

3% (avg SCC) $900 $2,300 $3,600 $4,900 $44,000 $44,000

2.5% (avg SCC) $1,500 $3,500 $5,300 $7,100 $74,600 $74,600

3% (95th 

percentile) $2,800 $7,100 $10,800 $14,800 $134,100 $134,100

Energy Security 

Impacts (price 

shock)

$500 $1,100 $1,500 $1,800 $19,800 $8,700

Accidents, Noise, 

Congestion -$200 -$400 -$500 -$600 -$7,500 -$3,400

Refueling Savings $100 $100 $200 $200 $2,500 $1,100

Non-CO2

Non-GHG 

Impacts c,d

GHG 

Impacts and n/a n/a n/a n/a n/a n/a

Total Annual Benefits at each assumed SCC valueb

5% (avg SCC) $600 $1,500 $2,400 $3,100 $23,400 $15,000

3% (avg SCC) $1,300 $3,100 $4,800 $6,300 $58,800 $50,400

2.5% (avg SCC) $1,900 $4,300 $6,500 $8,500 $89,400 $81,000

3% (95th percentile $3,200 $7,900 $12,000 $16,200 $148,900 $140,500 a Note that net present value of reduced CO2

b Section 8.5 of the RIA notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for Average SCC 

at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.F also presents these SCC estimates.

emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used to 

calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG emissions 

expected under this proposal (see RIA Chapter 5). Although EPA has not monetized changes in non-CO2

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GHGs, 

the value of any increases or reductions should not be interpreted as zero.

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9-35

d Non-GHG-related health and welfare impacts (related to PM2.5 and ozone exposure) were not estimated for this 

proposal, but will be included in the analysis of the final rulemaking. 

Table 9-13 presents estimated annual net benefits for the indicated calendar years. The 

table also shows the net present values of those net benefits for the calendar years 2012-2050 

using both 3 percent and 7 percent discount rates. The table includes the benefits of reduced 

CO2

Table 9-13 Monetized Net Benefits Associated with the Proposed Program (Millions of 2008 dollars)

emissions (and consequently the annual net benefits) for each of four SCC values 

considered by EPA. 

2020 2030 2040 2050 NPV, 3% NPV, 7%

Annual Costsa -$6,100 -$17,100 -$25,900 -$32,900 -$310,200 -$130,100

Monetized Annual Benefits at each assumed SCC value

5% (avg SCC) $600 $1,500 $2,400 $3,100 $23,400 $15,000

3% (avg SCC) $1,300 $3,100 $4,800 $6,300 $58,800 $50,400

2.5% (avg SCC) $1,900 $4,300 $6,500 $8,500 $89,400 $81,000

3% (95th percentile) $3,200 $7,900 $12,000 $16,200 $148,900 $140,500

Monetized Net Benefits at each assumed SCC value

5% (avg SCC) $6,700 $18,600 $28,300 $36,000 $333,600 $145,100

3% (avg SCC) $7,400 $20,200 $30,700 $39,200 $369,000 $180,500

2.5% (avg SCC) $8,000 $21,400 $32,400 $41,400 $399,600 $211,100

3% (95th percentile) $9,300 $25,000 $37,900 $49,100 $459,100 $270,600 a Note that negative costs represent savings rather than costs.

EPA also conducted a separate analysis of the total benefits over the model year lifetimes 

of the 2014 through 2018 model year trucks/tractors. In contrast to the calendar year analysis 

presented in Table 9-11 through Table 9-13, the model year lifetime analysis shows the impacts 

of the proposed program on vehicles produced during each of the model years 2014 through 

2018 over the course of their expected lifetimes. The net societal benefits over the full lifetimes

of vehicles produced during each of the five model years from 2014 through 2018 are shown in 

Table 9-14 and Table 9-15 at both 3 percent and 7 percent discount rates, respectively. 

Table 9-14 Monetized Costs, Benefits, and Net Benefits Associated with the Lifetimes of 2014-2018 Model 

Year Trucks (Millions of 2008 dollars; 3% Discount Rate)

2014MY 2015MY 2016MY 2017MY 2018MY SUM

Monetized Costs

Technology Costs -$1,300 -$1,300 -$1,500 -$1,600 -$2,000 -$7,700

Monetized Benefits at each assumed SCC value

Pre-tax Fuel Savings $6,100 $6,400 $7,200 $10,700 $11,900 $42,300

Energy Security $400 $400 $400 $600 $700 $2,500

Accidents, Noise, Congestion -$300 -$300 -$300 -$300 -$300 -$1,400

Refueling Savings $200 $200 $200 $200 $200 $1,100

Non-CO2

Non-GHG Impacts a,b

GHG Impacts and n/a n/a n/a n/a n/a n/a

Reduced CO2 emissions at each 

assumed SCC value

5% (avg SCC) $200 $200 $200 $300 $300 $1,200

3% (avg SCC) $600 $600 $700 $1,000 $1,200 $4,100

2.5% (avg SCC) $1,000 $1,000 $1,100 $1,600 $1,800 $6,500

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-36

3% (95th percentile) $1,900 $2,000 $2,200 $3,200 $3,500 $12,800

Monetized Net Benefits at each assumed SCC value

5% (avg SCC) $5,300 $5,600 $6,200 $9,900 $10,800 $38,000

3% (avg SCC) $5,700 $6,000 $6,700 $10,600 $11,700 $40,900

2.5% (avg SCC) $6,100 $6,400 $7,100 $11,200 $12,300 $43,300

3% (95th percentile) $7,000 $7,400 $8,200 $12,800 $14,000 $49,600 a The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG emissions 

expected under this proposal (see RIA Chapter 5). Although EPA has not monetized changes in non-CO2

b Non-GHG-related health and welfare impacts (related to PM

GHGs, 

the value of any increases or reductions should not be interpreted as zero. 

2.5 and ozone exposure) were not estimated for this 

proposal, but will be included in the analysis of the final rulemaking. 

Table 9-15 Monetized Costs, Benefits, and Net Benefits Associated with the Lifetimes of 2014-2018 Model 

Year Trucks (Millions of 2008 dollars; 7% Discount Rate)

2014MY 2015MY 2016MY 2017MY 2018MY SUM

Monetized Costs

Technology Costs -$1,300 -$1,300 -$1,500 -$1,600 -$2,000 -$7,700

Monetized Benefits at each assumed SCC value

Pre-tax Fuel Savings $4,500 $4,500 $4,900 $7,000 $7,500 $28,400

Energy Security $300 $300 $300 $400 $400 $1,700

Accidents, Noise, Congestion -$200 -$200 -$200 -$200 -$200 -$900

Refueling Savings $200 $200 $200 $200 $200 $900

Non-CO2

Non-GHG Impacts a,b

GHG Impacts and n/a n/a n/a n/a n/a n/a

Reduced CO2 emissions at each 

assumed SCC value

5% (avg SCC) $200 $200 $200 $300 $300 $1,200

3% (avg SCC) $600 $600 $700 $1,000 $1,200 $4,100

2.5% (avg SCC) $1,000 $1,000 $1,100 $1,600 $1,800 $6,500

3% (95th percentile) $1,900 $2,000 $2,200 $3,200 $3,500 $12,800

Monetized Net Benefits at each assumed SCC value

5% (avg SCC) $3,700 $3,700 $3,900 $6,100 $6,200 $23,600

3% (avg SCC) $4,100 $4,100 $4,400 $6,800 $7,100 $26,500

2.5% (avg SCC) $4,500 $4,500 $4,800 $7,400 $7,700 $28,900

3% (95th percentile) $5,400 $5,500 $5,900 $9,000 $9,400 $35,200 a The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG emissions 

expected under this proposal (see RIA Chapter 5). Although EPA has not monetized changes in non-CO2

b Non-GHG-related health and welfare impacts (related to PM

GHGs, 

the value of any increases or reductions should not be interpreted as zero. 

2.5 and ozone exposure) were not estimated for this 

proposal, but will be included in the analysis of the final rulemaking. 

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Regulatory Impact Analysis 

9-37

References

1 American Transportation Research Institute, An Analysis of the Operational Costs of Trucking, December 2008

(Docket ID: EPA-HQ-OAR-2010-0162-0007). 

2 Transport Canada, Operating Cost of Trucks, 2005. See http://www.tc.gc.ca/eng/policy/report-acgoperatingcost2005-2005-e-2-1727.htm, accessed on July 16, 2010 (Docket ID: EPA-HQ-OAR-2010-0162-0006). 

3 Graham and Glaister, “Road Traffic Demand Elasticity Estimates: A Review,” Transport Reviews Volume 24, 3, 

pp. 261-274, 2004 (Docket ID: EPA-HQ-OAR-2010-0162-0005). 

4 Winston, C. (1981). The welfare effects of ICC rate regulation revisited. The Bell Journal of Economics, 12, 232-

244 (Docket ID: EPA-HQ-OAR-2010-0162-0021).

5 Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles; National Research 

Council; Transportation Research Board (2010). Technologies and Approaches to Reducing the Fuel Consumption 

of Medium- and Heavy-Duty Vehicles. ("The NAS Report") Washington, D.C., The National Academies Press. 

Available electronically from the National Academy Press Website at http://www.nap.edu/catalog. See also 2009 

Cambridge Systematics, Inc., Draft Final Paper commissioned by the NAS in support of the medium-duty and 

heavy-duty report. Assessment of Fuel Economy Technologies for Medium and Heavy Duty Vehicles: 

Commissioned Paper on Indirect Costs and Alternative Approaches (Docket ID: EPA-HQ-OAR-2010-0162-0009).

6 Friedlaender, A. and Spady, R. (1980) A derived demand function for freight transportation, Review of Economics 

and Statistics, 62, pp. 432–441 (Docket ID: EPA-HQ-OAR-2010-0162-0004).

7 Christidis and Leduc, “Longer and Heavier Vehicles for freight transport,” European Commission Joint Research 

Center’s Institute for Prospective Technology Studies, 2009 (Docket ID: EPA-HQ-OAR-2010-0162-0010). 

8 Christidis and Leduc, 2009.

9 Winebrake, James and James J. Corbett (2010). “Improving the Energy Efficiency and Environmental 

Performance of Goods Movement,” in Sperling, Daniel and James S. Cannon (2010) Climate and Transportation 

Solutions: Findings from the 2009 Asilomar Conference on Transportation and Energy Policy. See 

http://www.its.ucdavis.edu/events/2009book/Chapter13.pdf (Docket ID: EPA-HQ-OAR-2010-0162-0011)

10 Winebrake, J. J.; Corbett, J. J.; Falzarano, A.; Hawker, J. S.; Korfmacher, K.; Ketha, S.; Zilora, S., Assessing 

Energy, Environmental, and Economic Tradeoffs in Intermodal Freight Transportation, Journal of the Air & Waste 

Management Association, 58(8), 2008 (Docket ID: EPA-HQ-OAR-2010-0162-0008).

11 Cambridge Systematics, Inc.. 2009.

12 Northeast States Center for a Clean Air Future, Southeast Research Institute, TIAX, LLC., and International 

Council on Clean Transportation, Reducing Heavy-Duty Long Haul Truck Fuel Consumption and CO2 Emissions, 

September 2009. See http://www.nescaum.org/documents/heavy-duty-truck-ghg_report_final-200910.pdf

13 These estimates were developed by FHWA for use in its 1997 Federal Highway Cost Allocation Study; see

http://www.fhwa.dot.gov/policy/hcas/final/index.htm (last accessed July 21, 2010).

14 See Federal Highway Administration, 1997 Federal Highway Cost Allocation Study, 

http://www.fhwa.dot.gov/policy/hcas/final/index.htm, Tables V-22, V-23, and V-24 (last accessed July 21, 2010). 

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Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Economic and Social Impacts

9-38

15 See Table 4. Last viewed on September 9, 2010 at http://ostpxweb.dot.gov/policy/Data/VOTrevision1_2-11-

03.pdf. Note that we assume the value of travel time is constant out to 2050, which is a conservative assumption 

since it is likely this value will increase due to income growth in the future.

16 Passenger vehicle fuel dispensing rate per EPA regulations, last viewed on August 4, 2010 at 

http://www.epa.gov/oms/regs/ld-hwy/evap/spitback.txt

17 U.S. Bureau of Economic Analysis, U.S. International Transactions Accounts Data, as shown on June 14, 2010.

18 U.S. Department of Energy, Annual Energy Review 2008, Report No. DOE/EIA-0384(2008), Tables 5.1 and 

5.13c, June 26, 2009.

19 Leiby, Paul N. "Estimating the Energy Security Benefits of Reduced U.S. Oil Imports," Oak Ridge National 

Laboratory, ORNL/TM-2007/028, Final Report, 2008.

20 Leiby, Paul N., Donald W. Jones, T. Randall Curlee, and Russell Lee, Oil Imports: An Assessment of Benefits and 

Costs, ORNL-6851, Oak Ridge National Laboratory, November, 1997.

21 Peer Review Report Summary: Estimating the Energy Security Benefits of Reduced U.S. Oil Imports, ICF, Inc., 

September 2007.

22 Gately, Dermot 2004. "OPEC's Incentives for Faster Output Growth," The Energy Journal, 25(2):75-96, "What 

Oil Export Levels Should We Expect From OPEC?" The Energy Journal, 28(2):151-173, 2007

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Chapter 9: Other Economic and Social Impacts

9-1
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Small Business Flexibility 

Analysis

1

Chapter 10: Small Business Flexibility Analysis

The Regulatory Flexibility Act, as amended by the Small Business Regulatory

Enforcement Fairness Act of 1996 (SBREFA), generally requires an agency to prepare a

regulatory flexibility analysis for any rule subject to notice-and-comment rulemaking

requirements under the Administrative Procedure Act or any other statute. This requirement 

does not apply if the agency certifies that the rule will not have a significant economic impact 

on a substantial number of small entities.

The following discussion provides an overview of small entities in the heavy-duty 

vehicle and engine market. Small entities include small businesses, small organizations, and 

small governmental jurisdictions. For the purposes of assessing the impacts of the rule on

small entities, a small entity is defined as: (1) a small business that meets the definition for 

business based on the Small Business Administration’s (SBA) size standards (see Table 

10-1); (2) a small governmental jurisdiction that is a government of a city, county, town, 

school district or special district with a population of less than 50,000; and (3) a small 

organization that is any not-for-profit enterprise which is independently owned and operated 

and is not dominant in its field. Table 10-1 provides an overview of the primary SBA small 

business categories potentially affected by this regulation.

Table 10-1 Primary Small Business NAICS Categories Affected by this Rulemaking

NAICS CODES1 DEFINED BY SBA AS A 

SMALL BUSINESS IF LESS 

THAN OR EQUAL TO:2

Engine Equipment Manufacturer 333618 1,000 employees

Automobile Manufacturer 336111 1,000 employees

Light Truck and Utility Vehicle 

Manufacturer

336112 1,000 employees

Heavy-Duty Truck Manufacturer 336120 1,000 employees

Motor Vehicle Body Manufacturing 336211 1,000 employees

We compiled a list of engine manufacturers, vehicle manufacturers, and body 

manufacturers that would be potentially affected by the rule from the EPA database for engine 

certification, Ward’s Automotive Database, and the M.J. Bradley’s Heavy Duty Vehicle 

Market Analysis. We then identified companies that appear to meet the definition of small 

business provided in the table above based on the number of employees based on company 

information included in Hoover’s. Based on this assessment, the agencies identified the 

following:

• two tractor manufacturers3 which comprise less than 0.5 percent of the total 

heavy-duty combination tractors in the U.S. based on Polk Registration Data 

from 2003 through 2007;

4

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Regulatory Impact Analysis 

2

• ten chassis manufacturers5 less than 0.5 percent of the total heavy-duty 

combination tractors in the U.S. based on Polk Registration Data from 2003 

through 2007;

6

• three heavy duty engine manufacturers

and

7

The proposed exemption from the standards established under this proposal would 

have a negligible impact on the GHG emissions and fuel consumption reductions otherwise 

due to the standards. 

which comprise less than 0.1 percent 

of total heavy-duty engine based on 2008 and 2009 model year engine 

certification data submitted to EPA for non-GHG emissions standards.

EPA has not conducted an Initial Regulatory Flexibility Analysis for this proposed

rulemaking because we are certifying that the rule would not have a significant economic 

impact on a substantial number of small entities. EPA is exempting manufacturers, domestic 

and foreign, meeting SBA’s size definitions of small business as described in 13 CFR 

§ 121.201. EPA will instead consider appropriate GHG standards for these entities as part of 

a future regulatory action. 

To ensure that EPA and NHTSA are aware of which companies would be exempt, the 

agencies propose to require that such entities submit a declaration to EPA containing a 

detailed written description of how that manufacturer qualifies as a small entity under the

provisions of 13 CFR § 121.201. 
Heavy-Duty GHG and Fuel Efficiency Standards NPRM: Small Business Flexibility 

Analysis

3

References

1 North American Industry Classification System

2 According to SBA’s regulations (13 CFR Part 121), businesses with no more than the listed number of 

employees or dollars in annual receipts are considered “small entities” for RFA purposes. 

3 The agencies have identified Ottawa Truck, Inc. and Kalmar Industries USA as two potential small tractor 

manufacturers

4 M.J. Bradley. Heavy Duty Vehicle Market Analysis. May 2009.

5 The agencies have identified Lodal, Indiana Phoenix, Autocar LLC, HME, Giradin, Azure Dynamics, 

DesignLine International, Ebus, Krystal Koach, and Millenium Transit Services LLC as potential small business 

chassis manufacturers.

6 M.J. Bradley. Heavy Duty Vehicle Market Analysis. May 2009.

7 The agencies have identified Baytech Corporation, Clean Fuels USA, and BAF Technologies, Inc. as three 

potential small businesses