Office of Transportation EPA420-R-05-006 

and Air Quality June 2005 

In-Use Testing Program for 

Heavy-Duty Diesel Engines 

and Vehicles 

Technical Support Document
EPA420-R-05-006 

June 2005 

In-Use Testing Program for Heavy-Duty

Diesel Engines and Vehicles

Technical Support Document 

Assessment and Standards Division 

Office of Transportation and Air Quality 

U.S. Environmental Protection Agency 
Table of Contents


CHAPTER 1: Economic Assessment 1


1.1 Overview 1


1.2 Cost Components 2


1.2.1 Fixed Costs 2


1.2.2 Variable Costs 3


1.2.2.1 General Description of Testing Scenario 4


1.2.2.2 Variable Cost Per Test 6


1.2.2.2.1 Direct Labor 6


1.2.2.2.2 Labor Overhead 7


1.2.2.2.3 Other Direct Costs 7


1.2.2.2.4 Repeat Tests 7


1.2.2.2.4 General and Administrative Overhead 8


1.2.2.2.5 Summary of Variable Cost per Test 8


1.2.2.3 Variable Cost Per Engine Family 8


1.2.2.3.1 Vehicle Incentives 8


1.2.2.3.2 Direct Labor 8


1.2.2.3.3 Travel 9 


1.2.2.3.4 Labor Overhead 10


1.2.2.3.5 General and Administrative Overhead 10


1.2.2.3.6 Summary of Variable Cost per Engine Family 10


1.3 Costs of the Program 10


i 
1.3.1 Variable Costs by Level of Testing Intensity 11


1.3.2 Total Annual Costs by Level of Testing Intensity 11


1.3.3. Total Annual Cost Point Estimate 11


1.3.4. Total Costs Over 5 and 30 Years 12


CHAPTER 2: On-Vehicle Portable Emissions Measurement Technology Review 26


2.1 Overview 26


2.2 Measurement Technologies 26


CHAPTER 3: New In-Use Testing Instrument Measurement Allowance 34


3.1 Review of NTE zone 34


3.2 Review of existing NTE allowances 34


3.3 Review of other NTE allowances 35


3.4 Discussion of the two (2) NTE measurement allowances 36


APPENDIX A: Examples of Determining the Number of Engine Families to be Tested 38


ii 
CHAPTER 1


Economic Assessment


This chapter contains our economic analysis of the costs associated with implementing a 

manufacturer-run, in-use NTE testing program for heavy-duty diesel engines and vehicles. The 

cost of the program is dependent on several key variables. One of these is the number of vehicles 

tested under the Phase 1 and 2 testing schemes. This, of course, depends on how many vehicles 

pass, or fail, the vehicle pass criteria at various points under the tiered testing procedures. Also 

important is just how each manufacturer will chose to design and conduct the test program, how 

many portable emission measurement systems (PEMS) will be purchased, and the availability of 

test vehicles. Obviously, it is difficult to project these variables for an all new program. 

However, based on our experience with in-use emissions testing, including the development and 

use of a portable emission measurement device for compliance testing, we have identified a set 

of reasonable testing scenarios that allow us to estimate the potential costs associated with the 

program. 

As part of the comments on the proposed rule, one manufacturer provided comment on a 

number of the values and assumptions used in the analysis We have considered each of these and 

revised the analysis where appropriate. In most cases these changes increased costs, leading to 

what EPA believes to be a more conservative assumption. The most notable change is our 

decision to eliminate scenario 1, and to assume all engine family testing events involve longer 

trips and overnight travel as laid out in our original Scenario 2. 

This chapter is divided into several parts. Section 1.1 contains a brief outline of the 

methodology used to estimate the associated costs is presented. Section 1.2 develops the fixed 

and variable cost components associated with the program. Section 1.3 summarizes the 

component costs into estimates of the overall cost of the program. All costs are estimated in 

Dec 2004 dollars. In most cases our estimates in 2003 were increased by 2.7 percent based on the 

CPI inflator. 

1.1 Overview 

All costs are divided into either fixed or variable cost components. Fixed costs are associated 

with the direct expense of purchasing the requisite portable emission measurement system 

(PEMS) units. Variable costs depend primarily on the number of families and vehicles tested. 

They include the direct costs for vehicle recruiting, labor for on-site testing, instrument 

calibration and maintenance, travel, data analysis, and reporting expenses. Variable costs also 

include indirect costs associated with overhead and general and administrative (G&A) expenses. 

To explore the range of possible costs, we assessed a range of costs associated with different 

testing intensities under Phase 1 or Phase 2 of the program (i.e., the amount or number of vehicle 

tests that might occur under the two phases of testing). Finally, we combined this information to 

show a range of possible costs and a single point estimate by assuming a specific mix of the 

1

above testing variables. The results are presented for all heavy-duty engine manufacturers as 

annualized costs, total costs for the first five years of the program, and costs over 30 years. 

1.2 Cost Components 

1.2.1 Fixed Costs 

Fixed costs for this program are primarily associated with buying PEMS units. Some of the 

fixed cost components have significant uncertainties associated with them. Portable 

measurement devices are already commercially available that can measure all the gaseous 

pollutants required by the program. These systems cost approximately $70,000 per unit. The 

commenter mentioned above indicated that costs were 40 percent greater, thus suggesting a cost 

of about $90,000 -$100,000 for the gaseous PEMS unit. 

Based on our experience and investment in developing portable particulate matter (PM) 

measurement technology, we estimate that systems capable of measuring both gaseous and PM 

emissions will cost an additional $30,000 per unit over our estmate for a gaseous unit alone, for a 

total of about $100,000.1 The commenter mentioned above indicated interactions with vendors 

indicating costs 3-4 times greater than EPA’s estimate for the PM unit or an additional $90,000. 

EPA has elected to very conservatively estimate costs ranging from $100,000-$180,000. Taking 

the average, we estimate the capital cost for portable measurement devices that measure both 

gaseous and PM emissions is approximately $140,000 per unit. 

As described in Chapter 2 of this document, we assume that engine manufacturers will 

initially purchase PEMS units with the capability to measure gaseous pollutants in time to 

coincide with the initiation of the pilot program during the 2005 calendar year. Add-on, modular 

devices that measure PM emissions will be purchased later in 2006 as this technology becomes 

available. Regardless of the purchasing strategy, we assume all equipment purchases occur at the 

beginning of 2005 in order to simplify the analysis. 

We estimate that portable emission measurement devices have a product life cycle of five 

years for the purposes of the program. After that time they are assumed to be replaced with 

brand new equipment. Also, we assume there is no salvage value for units that may remain in 

service for other less rigorous or less important duties after five years, although this could occur 

in some instances. Alternatively, some manufacturers may chose to replace or rebuild 

component parts of a PEMS unit rather than replace the entire unit after five years. To the extent 

this may occur, we assume such a maintenance strategy will cost approximately the same as the 

replacement strategy. The annualized cost of a single PEMS unit can now be calculated by 

using the above values and assuming a typical capital recovery rate of seven percent per annum. 

The result is an annualized cost of $34,145 per unit. 

1

 Chapter 2 contains additional information on the status and development of portable 

emission measurement systems. 

2 
The total annualized fixed cost for the program depends on how many PEMS units each 

manufacturer will purchase, the fraction of time the equipment is used for the in-use testing 

program, and the number of manufacturers subject to the requirements. Each of these cost 

components is addressed separately below. 

We assume that each manufacturer will purchase three units. We chose this number to 

illustrate the average equipment cost of the program recognizing that two units is adequate to 

perform more than the needed amount of tests for even the largest manufacturer if its program is 

designed so that testing can be conducted in an orderly, efficient manner. We recognize that 

manufacturers with a limited number of engine families may need only one unit with a backup 

unit. Manufacturers with a large number of families may prefer an additional unit for backup. 

Our final assumption in estimating the total annual fixed cost of the program is that 13 

engine manufacturers will participate in the program. This is the number of companies that 

certified heavy-duty diesel engines in the 2005 model year. The manufacturers are shown below. 

Caterpillar, Inc. 

Cummins Engine Company, Inc. 

DaimlerChrysler AG 

John Deere, Inc 

Detroit Diesel Corporation 

General Engine Products 

General Motos Corporation 

Hino Motors, Ltd. 

International Truck and Engine Corporation 

Isuzu Motors Limited 

Mack 

Mitsubishi Motors Corporation 

Volvo Powertrain Corporation. 

Using the above information, the total annualized fixed cost of the program $1,331,665, as 

shown in Table 1-1. 

1.2.2 Variable Costs 

Variable costs are grouped into two broad categories: cost per vehicle test and cost per 

family. This approach allows us to more easily account for tests that must be repeated on the 

same vehicle in order to obtain a valid test result. Repeat testing can occur in the laboratory due 

to equipment or vehicle malfunctions, and operator error. We expect that similar problems may 

occur in field testing, and assume that these issues can generally be remedied at the testing 

location. Further, a vehicle may be tested a second day under the terms of the program if less 

than three hours of non-idle operation are recorded during the first “shift day” of testing. 

3

Obviously, multiple tests on the same vehicle do not directly affect other costs associated with 

testing an engine family, e.g., vehicle recruiting. Therefore, these costs are estimated separately 

in our analysis. 

Also, as noted earlier, many of the costs of the program vary by the relative availability of 

test vehicles (i.e., how difficult it is to access, instrument, and test vehicles at a job site), and the 

type and amount of travel required to conduct the test campaign (e.g., overnight versus local 

travel). In order to reasonably bracket these cost elements, we constructed two testing scenarios 

that differ in the above characteristics. These scenarios are based on our direct experience in 

conducting in-use testing of heavy-duty trucks with portable emission measurement systems 

under the 1998 consent decrees, our continued development of portable measurement systems, 

and a recently awarded EPA contract to conduct a large scale, in-use testing pilot program in 

Kansas City, Missouri for passenger cars (USEPA 2003). The two testing scenarios are 

described in the following section by first identifying some of the key elements shared by both 

scenarios and then presenting the specifics of each scenario separately. 

1.2.2.1 General Description of Testing Scenarios 

Our testing scenarios share a number of key assumptions which we believe provide a 

reasonable representation of how manufacturers are likely to design and conduct testing under 

this program. Alternatively, if an engine manufacturer decides to contract for testing services, 

we expect the service provider to similarly design and conduct the testing campaign. 

One of our most basic methodological assumptions is that field testing will usually consist of 

a multi-day campaign where a minimum of five vehicles are tested. This number was chosen for 

several reasons. First, it captures the type of back–to-back vehicle testing likely to be employed 

in order to facilitate efficient testing. Second, it represents the minimum number of test vehicles 

for Phase 1 testing under the program. Third, and finally, it simplifies the analysis when 

evaluating the potential costs of higher testing intensities associated with the maximum number 

of vehicles that may be tested under Phase 1 (10 total vehicles) and Phase 2 (20 total vehicles). 

These later testing levels are simple multiples the Phase 1 minimum testing scenario, i.e., two 

times or four times, respectively. Other key assumptions are described below. 

S Vehicle recruiting and pre-screening of prospective test vehicles will be done by 

telephone or other means prior to the test site visit. 

S All portable measurement systems will be inspected and pre-calibrated at the 

manufacturer’s facility prior to deployment in the field. 

S Field testing will be conducted by two people. One is an engineer and the other a 

qualified technician. Both are capable of installing and operating the portable 

measurement systems, screening vehicles for OBD trouble codes and MIL 

indications, performing maintenance on the portable systems, etc. The technician is 

also capable of performing all required inspections of the vehicle’s mechanical, 

4

electrical, and emission control systems; as well as performing allowable maintenance 

and the setting of adjustable engine parameters as required. 

S The test engineer and technician will coordinate their activities to optimize their 

productivity. For example, the engineer may acquire and enter a vehicle’s history and 

vital statistics into an electronic database concurrently while the technician performs 

vehicle inspection and allowable maintenance. 

S Test vehicles for an engine family are obtained from two independent sources, as 

required by the regulation. It is assumed that the sources are located relatively close 

to each other to minimize travel distances between test sites. 

S The test sites are not necessarily in relatively close proximity to a manufacturer’s 

technical center, test center, maintenance facility, or other similar location thus 

increasing personnel travel and field logistics costs. 

S In many cases test vehicles will depart and not return to the same location the same 

day, necessitating an overnight stay. 

S Field personnel have access to the test vehicles and a service location before and after 

the shift day as needed to install and remove the portable measurement devices. 

Special arrangements with the vehicle owner/operator may be necessary. 

S Two portable emission measurement systems will be deployed simultaneously during 

a test site visit when possible, i.e., two vehicles will be tested at the same time. 

S All necessary tools, spare parts, testing supplies, office supplies, etc. will be taken to 

or otherwise supplied at the site of testing to avoid unnecessary delays. 

It is also possible that test vehicles may be operated on multi-day driving routes, i.e., longhaul operation. We do not think this will be a standard practice for all vehicles/engines, but may 

happen for engines used in over the road trucks and buses. As alluded to above, we have 

incorporated this assumption into the analysis for all families. 

There are also some common on-site work activities. These categories are described below 

in their approximate order of occurrence. 

S Vehicle History/Documentation. Obtaining all relevant information not available 

prior to the field visit or verifying the accuracy of information previously obtained. 

S Vehicle Set-to-Specification. Inspecting the vehicle, performing allowable 

maintenance, and setting all adjustable engine control parameters. 

S PEMS Installation. Install the portable measurement system onboard the test vehicle. 

Warm the instrument to operating temperature, verify proper operation, perform final 

calibrations and span instruments, etc. 

S PEMS Data Acquisition. Download the measurement data set; perform on-site data 

verification and initial quality assurance; and record and store all other relevant test 

information. 

S PEMS Removal. Verify proper operation, perform post-test calibration, and remove 

system from the test vehicle. 

5

S Miscellaneous Time. Non-routine labor for repairing or replacing parts of the 

portable emission measurement systems or test vehicles, obtaining supplies not at the 

test site, etc. 

Now that the overall components of the testing scenarios have been identified, the specific 

scenario we have analyzed will be presented. We believe this is conservative since it assumes all 

families are used in overnight operation. 

Limited Vehicle Access and Overnight Travel 

Under this scenario, test vehicles are not readily available and the testing technician and 

engineer must sometimes work around a test vehicle’s normal daily work shift. This means that 

the work day for the testing personnel includes the time the vehicle is being driven over its 

normal work route. In these instances, we made a worst case assumption that the testing 

personnel remain “idle” on the job site or that they are on the vehicle, with this time charged to 

the in-use testing program. Also, the test sites are located far enough away from the 

manufacturer’s facility, or employees home base, that a single round trip to and from the job site 

and overnight travel is required. However, the sites are still close enough to one another that 

travel between the two locations is not restrictive or prohibitive. 

1.2.2.2 Variable Cost Per Test 

As described above, the cost to perform an individual vehicle test is based on a Phase 1 

testing scheme where a minimum of five vehicles must be tested. Test costs consist of direct 

labor, labor overhead, other direct costs, and general and administrative overhead. Each of these 

cost components is described below. 

1.2.2.2.1 Direct Labor 

The cost of direct labor for each scenario is estimated by applying an hourly compensation 

rate by labor category to the various activities associated with the field testing campaign. Table 

1-2 display the work flow for the scenario, broken down by activity, labor type, and number of 

hours spent preforming each activity. These depictions reflect the assumptions, work activities, 

and optimization of the work flow as described in Section 1.2.2.1. The time spent in the various 

work tasks are estimated based on EPA’s direct experience in conducting in-use testing with 

portable emission measurement devices and on the recently awarded Kansas City, Missouri test 

program. 

The test campaign is completed in five days. The lack of vehicle flexibility leads to long 

work days in this scenario. The total direct labor is 55 and 56 hours for the engineer and 

technician, respectively. 

6

We developed an hourly estimate of employee compensation from information published by 

the Bureau of Labor Statistics, Office of Compensation and Working Conditions, Employer 

Costs for Employee Compensation (BLS 2003). When increased by the CPI, Table 1-3 shows 

our estimate of $32 and $29 per hour for an engineer and technician, respectively. These hourly 

compensation rates are “total compensation,” and include wages and salaries, paid leave, 

supplemental pay, and insurance. By comparison, these labor rates compare well with the 

contract labor costs we incur in conducting our in-use testing under the consent decrees. Finally, 

we assume that labor exceeding 40 hours per week is paid as overtime, i.e., 1.5 times the normal 

hourly rate. 

For convenience, Table 1-3 also shows an hourly compensation rate for a manager using the 

same literature source as described above. This labor category will be used in Section 1.2.2.3, 

where variable costs are discussed. 

The resulting direct labor cost per test can now be calculated based on the above labor hours 

and hourly compensation rates. As shown in Table 1-4, the resulting per test cost is $773. 

1.2.2.2.2 Labor Overhead 

We assume that all direct labor is burdened at 100 percent of the total compensation rate. For 

simplicity, overtime pay is also burdened at this same overhead rate. 

1.2.2.2.3 Other Direct Costs 

A number of other costs not related to labor that are “consumed” during in-use testing include 

office supplies, DVDs, calibration gases, and fuel for the flame ionization detector (FID). Based 

on our experience with using portable measurement systems, we estimate that calibration gases 

will cost about $75 per test and all other supplies will cost about $25 per test. Therefore, we 

estimate that a total of $100 per test for other direct costs. 

1.2.2.2.4 Repeat Tests 

Some in-use tests will be voided due to operator error and test equipment malfunctions. 

Other tests will be repeated if less than three hours of non-idle vehicle operation are recorded 

during the first day of testing. At our National Vehicle Fuel and Emissions Laboratory in Ann 

Arbor, Michigan, we experienced a test void rate for laboratory-based, non-research testing of 

approximately four percent over the last two years. We expect a somewhat higher void rate for 

field testing. Also, as noted, some tests will be repeated do to the three hour non-idle 

requirement. Overall, we assume a combined repeat test rate of 10 percent for this analysis. 

7

1.2.2.2.5 General and Administrative Overhead 

Certain costs are incurred for common or joint objectives and therefore cannot be 

identified specifically with a particular project or activity. We assume these general and 

administrative costs to be 6.5 percent of all other costs. 

1.2.2.2.6 Summary of Variable Cost per Test 

Table 1-5 summarizes the various direct cost elements described above. As shown, the 

resulting total variable costs per test are $1,928. 

1.2.2.3 Variable Cost Per Engine Family 

As with the previous section, the cost per engine family is based on a Phase 1 testing scheme 

where a minimum of five vehicles must be tested. This overall cost is composed of a number of 

individual expenses such as paying the test vehicle’s owner/operator an incentive, recruitment, 

travel, instrument pre-calibration, data analysis, and reporting. Each of the cost elements are 

described below. 

1.2.2.3.1 Vehicle Incentives 

We generally offer a vehicle’s owner an incentive in the form of a government bond and free 

vehicle repairs as part of our in-use test programs. Sometimes the owner cooperates without 

such an incentive, as most often occurs in our in-use testing under the consent decrees. For the 

purposes of this analysis, we assume that a cash incentive of $150 per vehicle will be paid to the 

owner by the engine manufacturer. This is the average cost of the incentive, with some owners 

being offered more some less, and some cooperating without an incentive. Therefore, the total 

incentive for an engine family tested under the Phase 1 minimum requirements is $750. 

1.2.2.3.2 Direct Labor 

Each engine family will incur costs in three main labor categories: vehicle recruitment, 

instrument pre-calibration, and data analysis and reporting. We expect that manufacturers will 

rely heavily on their existing customer relationships to recruit appropriate test vehicles from 

fleets or individual owners. Alternatively, they will create new lines of communication with their 

customers. A significant amount of pre-screening and vehicle history will also be associated 

with vehicle recruitment. We assume that with a heavy emphasis on existing customer 

relationships and data bases, recruiting the requisite five test vehicles will average about $300 per 

engine family. 

Prior to being deployed in the field, each portable measurement system will be carefully 

examined at the manufacturer’s facility to ensure proper operation. Based on our experience 

8

with portable emission measurement systems, we estimate that pre-calibrating each unit will 

require 0.5 and 1.5 hours of engineer and technician time, respectively. Using the total 

compensation rates previously described in Table1-4, this would cost $60 per unit. Since it is 

assumed that testing will be conducted using two portable systems, the total direct labor cost for 

pre-calibrating the instruments is $120 per engine family. 

The last category of direct labor per engine family is primarily for final data analysis and 

quality assurance (beyond that which is conducted in the field), reporting results, and archiving 

information. We assume that engine manufacturers will develop a number of automated methods 

to perform many of these functions to minimize labor requirements. Our direct labor estimates 

are basically taken from another EPA report that was prepared to support a new pilot program 

aimed at developing new in-use data collection methods for nonroad diesel-powered equipment 

(USEPA 2004). That program will also collect, analyze, and report emissions data using portable 

emission measurement systems. For the purposes of this analysis, we doubled the time per test 

for managerial oversight, since the original estimate was developed to reflect an emission factor 

style program, while the in-use program potential compliance implications. 

Table 1-6 presents the estimated labor hours for each data analysis and reporting activity, the 

cost per test, and the cost per engine family. The cost per test is based on a labor rate of $32 per 

hour for an engineer and $48 per hour for a manager. These labor classifications and 

compensation rates were previously discussed in Section 1.2.2.2 and presented in Table 1-3. The 

total cost of post-data analysis and reporting is estimated to be $751 per engine family. 

The resulting total direct labor for the three categories described above is $1,171 per engine 

family. 

1.2.2.3.3 Travel 

As discussed above, we assume the test sites are located far enough away from the 

manufacturer’s facility, or employees home base, that a single round trip to and from the job site 

and overnight travel is required. More specifically, we assume that commuting at the beginning 

and end of the work week is four hours one way for a total of eight hours. Again, using the total 

compensation rates previously presented in Table 1-4 of $32 and $29 per hour for an engineer 

and technician, respectively, the travel-related direct labor cost with 100% overhead is $976 per 

engine family. 

The vehicle expenses consist of the round trip travel to the testing locations described above, 

and daily travel to and from the test sites as well as itinerant travel, e.g., lunch and dinner. The 

round trip travel expense associated with the eight hours of commuting time is estimated by 

using an assumed average speed of 50 miles per hour and a mileage fee of $0.40 per mile. The 

result is $160. The itinerant travel distances are assumed to be 30 miles for Day 1 and 45 miles 

9

each day for the next three days, or a total of 165 miles. Using the assumed vehicle 

reimbursement fee, this amounts to $226. 

This scenario requires overnight travel. There will be approximately four days of full per 

diem expenses and a partial day of meals on the fifth day (Table 1-3). We assume it costs $100 

per night for lodging and $40 per day for meals. This results in per diem expenses of $1200 for 

the full week. Combining this with the travel-related labor of $976 nd the vehicle cost of $226 

from above, the total travel cost is $2,402 per engine family. 

1.2.2.3.4 Labor Overhead 

We assume that all direct labor is burdened at 100 percent of the total compensation rate. 

1.2.2.3.5 General and Administrative Overhead 

We assume general and administrative expenses to be 6.5 percent of all other costs. 

1.2.2.3.6 Summary of Variable Cost per Engine Family 

Table 1-7 summarizes the various cost elements discussed above. As shown, the resulting 

total variable costs per engine family are $5,851. 

1.3 Costs of the Program 

Now that the basic fixed and variable cost inputs have been developed, we will use that 

information to identify a range of total annual costs for the program. This range reflects the 

testing scenario, as described in Section 1.2.2.1, and three different levels of testing intensity that 

may occur under the Phase 1 and 2 requirements, which are described below. We will also 

develop a single point estimate of the program’s annual cost. Finally, we will use this point 

estimate to present total costs for the first five years of the program, and costs over 30 years. 

These costs are presented for the entire industry. 

The first level of testing intensity is the minimum number of vehicles that must be tested 

under Phase 1 of the program to demonstrate if a designated engine family passes the NTE 

criteria, i.e., five vehicle tests per family. This is the basis upon which the variable cost 

components were developed in Section 2.1, and is referred to as Phase 1 minimum. The second 

level of testing is the maximum number of vehicles that could be required under Phase 1, i.e., 10 

vehicle tests per family. This is referred to as Phase 1 maximum. The third level of testing is a 

worst case where a manufacturer must complete Phase 2 testing for an engine family. At its 

maximum, Phase 2 requires up to 20 vehicle tests per family. This is referred to as Phase 2 

maximum. 

10

Overall, our methodology for estimating the costs associated with the three testing levels is 

simple. We assume that a manufacturer will complete each level of testing in discrete steps. For 

example, after completing Phase 1 minimum, the test results for the engine family will be 

thoroughly evaluated at the manufacturer’s technical center. If one or more of the vehicles do not 

pass the testing criteria, the manufacturer is assumed to return to the field to continue testing five 

more vehicles, i.e., Phase 1 maximum. For the purposes of this analysis, this means that the 

variable cost of Phase 1 maximum testing is twice the cost of performing Phase 1 minimum 

testing. Similarly, the variable cost of Phase 2 maximum, i.e., 20 vehicles, is twice the cost of 

Phase 1 maximum, i.e., 10 vehicles. The fixed cost of testing is constant for each of the three 

testing intensities, since the cost of purchasing the portable measurement systems does not 

change with the number of tests performed. 

1.3.1 Variable Costs by Level of Testing Intensity 

As noted above, fixed costs do not change by the number of tests performed, although 

variable costs do vary by testing intensity. Therefore, the first step in estimating the range of 

annual costs is to determine variable cost per family for each of the testing levels. This is 

presented in Table 1-8. 

The next step is to find the range of annual costs for all manufacturers, i.e., all engine 

families. Under the program, we may generally select up to 25 percent of an engine 

manufacturer’ families for testing each year. In the 2005 model year, there were 71 heavy-duty 

diesel engine families certified. Hence, we may select up to 18 engine families per year. Using 

this value, the resulting range of annual costs for all manufacturers is shown in Table 1-9. 

1.3.2 Total Annual Costs by Level of Testing Intensity 

Table 1-10 summarizes the fixed and variable cost estimates and presents the total annual 

cost for each testing level. The low end of the range is about $1.6 million per year for Phase 1 

minimum, and the high end of the range is $2.1 million for Phase 2 maximum. 

1.3.3. Total Annual Cost Point Estimate 

Our point estimate assumes the overall program will reflect the average of weighted at 80 

percent of the Phase 1 minimum average cost, 10 percent of the Phase 1 maximum average cost, 

and 10 percent of the Phase 2 maximum average cost. This reflects our belief that most of the 

engine families will be designed and built in full conformance with the applicable NTE 

standards. But also that the program will identify some level of potential nonconformance. 

Table 1-11 summarizes the Phase 1 minimum and Phase 2 maximum costs from the previous 

table for convenience and presents our point estimate of the total annual cost for all 

manufacturers. The point estimate is $1.68 million per year. 

11

1.3.4. Total Costs Over 5 and 30 Years 

We developed an estimate of the total program costs over both 5 and 30 years using the 

annual point estimate costs from Table 1-12 and a discount rate of seven percent per annum. As 

shown, the 5 year cost is about $6.89 million and the 30 year cost is about $20.85 million. 

12

Chapter 1 References 

1. U.S. Environmental Protection Agency. 2003. Characterizing Exhaust Emissions from 

Light-Duty Gasoline Vehicles in the Kansas City Metropolitan Area. ERG. EPA Contract 

Number GS-10F-0036K. Office of Transportation and Air Quality, Assessment and Standards 

Division, Ann Arbor, Michigan. Awarded February 2004. 

2. Bureau of Labor Statistics. 2003. Employer Costs for Employee Compensation-June 2003. 

USDL: 03-446. U.S. Department of Labor, Washington, D.C. 

3. U.S. Environmental Protection Agency. 2004. Mobile Source Emission Factors: 

Populations, Usage and Emissions of Diesel Nonroad Equipment in EPA Region 7. Agency 

Form Number 0619.11, Supporting Statement, Part A. Office of Transportation and Air Quality. 

March 2004. EPA Edocket No. OAR-2003-0225-0003. 

13

Table 1-1. Total Annualized Fixed Costs1 

Cost per 

PEMS Unit 

($) 

Annualized cost 

of PEMS Unit 

($) 

Annual Cost per 

Manufacturer 

($) 

Number of 

Manufacturers 

(#) 

Total Annual 

Cost 

($) 

140,000 34,145 102,435 13 1,331,655 

1

 2004 dollars. 

14

Table 1-2. Limited Vehicle Access and Overnight Travel


Day 1 Day 2 Day 3 Day 4 

Activity Hrs 

Labor 

Type Activity Hrs 

Labor 

Type Activity Hrs 

Labor 

Type Activity Hrs 

Labor 

Type A

Travel 4 B1 

V1, V2 Warm-Up 1 T 

V4 Set-toSpec 1 T V5 Set-to- Spec 1 T Trav

V1, V22 

History 2 E 

Shift Wait Time 8 B V4 History 1 E V 5 History 1 E 

V1, V2 Setto-Spec 2 T V3 Set-to- Spec 1 T V4 Install V3 Warm 1.5 B V5 Install 1.5 B 

V1, V2 Install 3 B V3 History 1 E 

Shift Wait Time 8 B 

Shift Wait Time 8 B 

Misc. Time 1 B 

V1, V2 Data Acquisition 1 B 

V3, V4 Data Acquisition 1 B V5 Remove .75 B 

V1, V2 Remove 1.5 B 

V3, V4 Remove 1.5 B 

V5 Data Acquisition .5 B 

V3 Install 1.5 B Misc. Time 1 B Misc. Time 1 B Misc. Time 1 B 

Totals 10 T 15 T 14 T 13 T 

10 E 14 E 14 E 13 E 

1 T=Technician, E=Engineer, B=Both 2 V = Vehicle (identifier). 

15

Table 1-3. Labor Compensation Rates


BLS Category1 In-Use Testing Category 

Total Compensa

($/Hour) 

Technical3 Engineer 

Precision Production, Craft, and Repair4 Technician Executive, administrative, and managerial5 Manager 

1 BLS 2003, inflated by 2.7%.
2 Total compensation includes wages and salaries, paid leave, supplemental pay, and insurance. Rounded to the nearest whole 2003 dollars.
3 Table 11, Private industry, goods-producing and service-producing industries, by occupational group; All workers, goods-proindustries; White-collar occupations; Professional specialty and technical.
4 Table 11, Private industry, goods-producing and service-producing industries, by occupational group; All workers, goods-proindustries; Blue-collar occupations; Precision production, craft, and repair.
5 Table 11, Private industry, goods-producing and service-producing industries, by occupational group; All workers, goods-prindustries; White-collar occupations; Executive, administrative, and managerial. 

16

Table 1-4. Direct Labor Costs Per Vehicle Test 1


(Based on Phase 1 Minimum Five Vehicle Tests per Engine Family)2


Labor Rate 

Type 

Hours Per Family (5 tests) 

Hourly Compensation 

($ per hour) 

Total Cost 

($/5 tests) 

Eng 

ineer Technician Engineer Technician 

Regular 40 40 32 29 2440 

Overtime2 15 16 48 44 1424 

Total -- -- -- -- 3864 

1 2004 dollars.
2 Based on Phase 1 testing five vehicles.
3 Overtime paid for work exceeding 40 hours/week at 1.5 times the regular pay rate. 


17

Table 1-5. Variable Costs Per Test Vehicle1 

($/test) 

Scenario 

Direct 

Labor2 

Labor 

Overhead3 

Other Direct 

Costs4 

Voided 

Tests5 

General and 

Administrative6 Total 

773 773 100 165 118 1,928 

1

 2004 dollars. 2

 See Table 1-4. 3

 100 percent of direct labor. 4

 General supplies, PEMS maintenance, calibration gases, FID fuel, etc. 5

 Assumes 10 percent of tests are void (i.e., 0.10 * (direct labor, labor overhead, and other direct costs)). 6 6.5 percent of all costs. 

18

Table 1-6. Post-Test Data Analysis and Reporting Variable Cost Per Family1

Activity 

Hours/Test 

(hrs)2 

Cost/Test 

($) 

Cost Per En

($/5 T

Manager Engineer Manager Engineer Manager En

QA Measurements 0.056 3.0 2.69 96.00 13 Load Database 0.056 0.278 2.69 8.90 13 Analysis, Write Report, Archive 0.056 1.167 2.69 37.34 13 Total 0.168 4.445 8.07 142.24 40 

1 2003 dollars. 2 See USEPA 2004. 

19

Table 1-7. Summary of Variable Costs Per Engine Family1

($/family) 

Direct Labor 

Labor 

Overheard2 Incentive Travel 

General and 

Administrative3 

1,171 1,171 750 2402 

1 2004 dollars. 2 100% of direct labor. 3 6.5% of all costs. 

20

Table 1-8. Summary of Variable Costs Per Engine Family by Level of Testing Inte

($) 

Phase 1 Minimum2 Phase 1 Maximum3 Phase 

Scenario 

Vehicle 

Testing5 

Engine 

Family Total 

Vehicle 

Testing5 

Engine 

Family Total 

Vehicle 

Testing5 

E

F

9,640 5,851 15,491 19,280 5,851 25,131 38,560 

1 2004 dollars.
2 Phase 1 minimum = 5 test vehicles.
3 Phase 1 maximum = 10 test vehicles.
4 Phase 2 maximum = 20 test vehicles.
5 Cost per vehicle from Table 1-5 multiplied by the number of vehicles tested.


21

Table 1-9. Total Annual Variable Costs for All Manufacturers by Level of Testing In

($) 

Scenario 

Phase 1 Minimum2 Phase 1 Maximum3 Phase 2 

Cost 

Per 

Engine 

Family 

# 

Families 

Per 

Year5 Total 

Cost 

Per 

Engine 

Family 

# 

Families 

Per 

Year Total 

Cost 

Per 

Engine 

Family 

Fa

15,491 18 278,838 25,131 18 452,358 44 

1 2004 dollars.
2 Phase 1 requires that a minimum of 5 test vehicles.
3 The maximum number of vehicles tested in Phase 1 is 10.
4 The maximum number of vehicles tested through Phase 2 is 20.
5 25% of a total of 71 engine families certified in the 2005 model year.


22

Table 1-10. Total Annual Costs for All Manufacturers by Level of Testing1


Intensity


($ Thousands)


Scenario 

Phase 1 Minimum2 Phase 1 Maximum3 Phase 2 Maximum4 

Fixed 

Cost 

Variable 

Cost Total 

Fixed 

Cost 

Variable 

Cost Total 

Fixed

 Cost 

Variable 

Cost Total 

1,332 279 1,611 1,332 452 1,784 1,332 799 2,131 

1

 2004 dollars. 2

 Phase 1 minimum = 5 vehicle tests. 3 Phase 1 maximum = 10 vehicle tests. 4

 Phase 2 maximum = 20 vehicle tests. 

23

Table 1-11. Total Annual Cost Point Estimate for All Manufacturers1 

($ Thousands) 

Phase 1 Minimum Phase 2 Maximum Phase 2 Maximum 

Fixed Variable Fixed Variable Fixed Variable Fix

Scenario Cost Cost Total Cost Cost Total Cost Cost Total Co

1,332 279 1,611 1,332 452 1,784 1,332 799 2,131 1,

1 2004 dollars. 2 Assumes a 80/10/10 split between Phase 1 minimum, Phase 1 maximum, and Phase 2 maximum, respectively. 

24

Table 1-12. Total Program Cost Over 5 and 30 Years1


(Based on Point Cost Estimate)


(thousands of $)


Years Annualized Fixed 

Costs 

Annual Variable 

Costs 

Total Annual 

Costs 

2005-2034 1332 348 1,680 

30 Year NPV in 2005 16,530 4319 20,849 

1st 5 Year NPV in 

2005 5461 1423 6,888 

1

 2004 dollars. 

25

CHAPTER 2


On-Vehicle Portable Emissions Measurement Technology Review


2.1 Overview 

With respect to measurement equipment, we already have equipment available to measure 

gaseous emissions on-vehicle using the test procedures proposed for this program, and we believe 

that PM emissions measurement equipment will be available as needed. 

In the NTE standard we have already taken into account the variation in emissions due to 

varying engine operation and ambient conditions. In addition, in this proposal, we have taken into 

account the measurement tolerances of on-vehicle measurement systems. 

Given the very active interest in portable measurement equipment in the rest of the industry, 

and given lead time, we believe that measurement equipment will be widely available well ahead of 

time so that this program will be fully implemented for all regulated emissions–including PM–by 

2007 and 2008. For the 2005-2006 gaseous emission pilot program, equipment is already available 

for total hydrocarbons, carbon monoxide, and NOx that measure emissions at the concentrations 

associated with 2007 and later model year NTE standards. In 2004, units were introduced that 

measure NMHC, although some extra work is being instituted to verify the accuracy and precision of 

these new systems. For the 2006-2007 PM pilot program, and we also believe that PM emissions 

measurement equipment will be available. This chapter discusses this measurement technology and 

summarizes research results. Chapter 3 discusses the new emissions measurement allowance and 

cooperative test program that will comprehensively evaluate both gaseous and PM portable 

emissions measurement systems prior to the initiation of the fully enforceable in-use testing program. 

2.2 Measurement Technologies 

We expect that several complete systems will be commercially available in the 2005-2007 

timeframe that will be capable of performing the measurements needed to determine whether or not a 

vehicle passes an on-vehicle emissions test. At a minimum, any such measurement system must 

include individual analyzers and sensors that can quantify the following parameters: 

1. Regulated emissions concentrations in exhaust: 

a. Oxides of nitrogen, NOx. 

b. Carbon monoxide, CO (and carbon dioxide CO2). 

c. Non-methane hydrocarbons, NMHC. 

d. Particulate mass, PM. 

2. Exhaust flow rate. 

3. Engine operation: 

a. Speed. 

b. Torque. 

26

c. Coolant temperature and intake manifold temperature and pressure. 

4. Ambient conditions: 

a. Temperature. 

b. Dewpoint. 

c. Altitude. 

In this section we describe the measurement technologies that we expect to be used to quantify 

these parameters. If these technologies are properly applied, we believe that they are acceptable for 

measuring emissions on-vehicle. Note too that we also allow for the use of alternate technologies 

according to §1065.10. 

1. Regulated emissions concentrations in exhaust. Emissions concentrations need to be 

measured to determine brake-specific emissions. 

a. NOx measurement technology. We typically accept NOx measured as the sum of NO and 

NO2 since conventional engines and aftertreatment systems do not emit significant amounts of other 

NOx species. NO may be measured either by a chemiluminescence detector (CLD) or a nondispersive ultra-violet (NDUV) detector. NO2 may be converted catalytically to NO and detected by 

a CLD, or it may be detected directly via NDUV. NDUV and CLD are already available as 

components of complete on-vehicle emissions measurement systems, and they already have been 

performing well in on-vehicle applications. For example, a recent study by the California Air 

Resources Board (CARB) indicated that for 27 heavy-duty diesel chassis dynamometer tests, an 

NDUV-based on-vehicle system reported NOx emissions within 4.6 % of the current NOx standard, 

as compared to laboratory measurements.(1) We are currently studying NDUV analyzer 

performance with a 2002 light-heavy duty diesel (LHDD) on a chassis dynamometer. Our results so 

far indicate that the NDUV-based system reported NOx within 3.1 % of our laboratory, prior to a 

5000-mile cross-country road test that we conducted. After running the NDUV-based system for the 

entire road test–with no failures, the vehicle was returned to the laboratory, and the NDUV-based 

system reported NOx emissions within 3.9 % of our laboratory. The manufacturer of the NDUVbased system has also indicated that several engine manufacturers have evaluated their system, and 

their results from 11 HDDE FTP tests indicate Nox emissions were reported within 4.4 % of the 

current standard in engine manufacturer’s laboratories. (1) 

b. CO (and CO2) measurement technology. Since we first regulated CO, non-dispersive infrared (NDIR) detector technology has been used for measuring CO and CO2 in laboratory applications. 

Many laboratory NDIR analyzers have a moving part called a chopper-wheel to pulse infra-red light 

through the exhaust gas sample. The pulsing light is used to alternately detect the CO and CO2 

concentrations and then the dark-current of the NDIR detector. This is done to maintain accuracy, but 

the moving chopper-wheel is not durable under the high vibration environment of on-vehicle testing. 

However, new NDIR analyzers have been commercialized that electrically switch the infra-red light 

source on and off. These new NDIR analyzers are already commercially available in complete onvehicle emissions measurement systems, and they have been performing well in on-vehicle 

27

applications. For example, a recent study by the California Air Resources Board (CARB) indicated 

that for 27 heavy-duty diesel chassis dynamometer tests, an NDIR-based on-vehicle system reported 

CO emissions within 0.7 % of the current CO standard (2.1 % for CO2), as compared to laboratory 

measurements.(1) We are currently studying NDIR analyzer performance with a 2002 light-heavy 

duty diesel (LHDD) on a chassis dynamometer. Our results so far indicate that the NDIR-based 

system reported CO within 1.0 % of our laboratory (1.1 % for CO2), prior to a 5000-mile crosscountry road test that we conducted. After running the NDIR-based system for the entire road 

test–with no failures, the vehicle was returned to the laboratory, and the NDIR-based system reported 

CO emissions within 7.1 % of our laboratory (2.2 % of the current CO standard) and 4.7 % for CO2. 

The manufacturer of the NDIR-based system has also indicated that several engine manufacturers 

have evaluated their system, and their results from 11 HDDE FTP tests indicate CO emissions were 

reported within 0.5 % of the current standard in engine manufacturer’s laboratories (3.55 % for 

CO2).(1) 

c. NMHC measurement technology. The flame ionization detector (FID) has been the 

measurement technology of choice for hydrocarbon measurements since the late 1950s. The FID has 

been used as a detector in liquid and gas chromatography systems for individual hydrocarbon 

speciation and quantification. It is used because of its response to a broad range of hydrocarbons, its 

inherent stability and its remarkably linear response from very high levels to very low levels of 

hydrocarbons. Because the FID responds to a very broad range of hydrocarbons, we chose to set our 

initial hydrocarbon standard based on the FID response to the total hydrocarbons (THC) in engine 

exhaust. Later, by allowing for the subtraction of methane (CH4) from THC, we set non-methane 

hydrocarbon (NMHC) standards based on the FID’s response to all non-methane hydrocarbons in 

engine exhaust. Because the FID has a range of response factors for all of the hydrocarbons that it 

detects, and because the mixture of hydrocarbon species in engine exhaust changes as a function of 

engine operation, fuel, and aftertreatment systems, the FID’s response to NMHC in engine exhaust is 

characteristic to hydrocarbon measurement via FID technology alone. This makes it almost 

impossible for other hydrocarbon detector technology to equivalently detect engine exhaust NMHC. 

Fortunately, FIDs have been adapted for on-vehicle use. These new FID analyzers are already 

commercially available in complete on-vehicle emissions measurement systems, and they have been 

performing well in on-vehicle applications. For example, a recent study by the California Air 

Resources Board (CARB) indicated that for 27 heavy-duty diesel chassis dynamometer tests, a FIDbased on-vehicle system reported THC emissions within 2.8 % of the current NMHC standard, as 

compared to laboratory measurements.(1) We are currently studying FID analyzer performance with 

a 2002 light-heavy duty diesel (LHDD) on a chassis dynamometer. Our results so far indicate that the 

FID-based system reported THC within 7.8 % of our laboratory after running the FID-based system 

for a 5000 mile road test–with no failures, (2.4 % of the current NMHC standard). The manufacturer 

of the FID-based system has also indicated that several engine manufacturers have evaluated their 

system, and their results from 11 HDDE FTP tests indicate THC emissions were reported within 1.3 

% of the current NMHC standard in engine manufacturer’s laboratories.(1) 

28

d. PM measurement technology. PM measurement has been traditionally conducted by 

depositing diluted exhaust PM on a sample filter and then weighing the filter in a PM measurement 

laboratory before and after testing to determine the net mass gain due to PM. 

This technique has been applied to on-vehicle testing by one on-vehicle emissions 

measurement system manufacturer. This system was tested by the California Air Resources Board 

(CARB) versus a chassis dynamometer laboratory.(2) Thirty-three tests were run on two different 

heavy-duty trucks, and one of the trucks was equipped with a PM trap. The 33 emissions results 

were collected over five different test cycles for each truck. For the current-technology truck, onaverage, the on-vehicle system reported PM results within 0.6 % of the standard when compared to 

laboratory results. For the trap-equipped truck, on-average, the on-vehicle system reported PM 

results where the difference between the on-vehicle and laboratory was 38 % of the 2007 standard. 

However, because the trap-equipped truck was emitting PM at only 44 % of the 2007 standard 

(according to laboratory results), the 38 % error of the on-vehicle system would not have caused any 

false indication of a failure (i.e. 44 % + 38 % = 82 %). Furthermore, neither the laboratory nor the 

on-vehicle system were equipped to sample PM according to our specifications for measuring PM 

from engines that meet the 2007 PM standards. These specifications were tailored to reduce 

variability in this type of PM measurement. 

These filter-based results demonstrate that accurate on-vehicle PM measurement technology is 

already commercially available for the current level of PM emissions, and it demonstrates that 

proportional sampling of PM on-vehicle is commercially available today. However, we do not 

expect filter-based methods to be used for conducting NTE tests in the field. This is because for 

NTE testing, PM emissions must be quantified for several individual NTE events, which would 

require many filters and a means to switch these filters in an automated way. No such system is 

commercially available or in development to our knowledge, and we believe that such an automated 

system might be cumbersome on-vehicle. 

We are currently evaluating more automated technologies for quantifying PM mass on-board. 

These automated technologies detect the inertia of particulate mass (PM) by accelerating it via 

vibration, rather than detecting its weight due to the acceleration of Earth’s gravity. These inertial 

technologies include the Tapered Element Oscillating Microbalance (TEOM) and the Quartz Crystal 

Microbalance (QCM). Since these technologies are compact, they are suitable for on-vehicle 

applications. And since they impart greater acceleration upon PM versus Earth’s gravity, they are 

more sensitive than a laboratory microbalance. They also eliminate the need to transport PM sample 

filters to a PM measurement laboratory for pre- and post-weighing. Researchers at West Virginia 

University have compared QCM and TEOM technologies versus laboratory PM measurements on a 

heavy-duty diesel engine, and they showed that for seven repeats of EPA’s heavy-duty FTP, the 

TEOM and QCM can quantify PM within 5 % of a traditional microbalance at current emissions 

standards.(3) 

29

These results demonstrate that this automated on-vehicle PM measurement technology is 

already commercially available today. However, conducting NTE tests in the field poses additional 

challenges. Namely, quantification of PM over sampling intervals as short as 30 seconds has yet to 

be demonstrated. Additionally, because PM equilibration is required before and after each NTE 

event, the time it takes to equilibrate PM mass after an NTE event might prevent sampling all or part 

of the next NTE event. Although these prototype systems are commercially available, more work is 

needed to demonstrate their accuracy in the lab and in the field. 

Also, we are currently investigating the sources of error in the laboratory PM measurement of 

trap-equipped engines. When we initially compared the TEOM and QCM versus laboratory PM 

measurements from trap-equipped engines, we discovered that the laboratory results were very 

sensitive to sampling conditions. This is due to the fact that PM from a trap is mostly semi-volatile 

matter, such as high-molecular weight hydrocarbons and dilute sulfuric acid. These PM constituents 

can exist either as a gas or as PM, depending upon dilution conditions, pressures, temperatures, and 

PM collection media. It is important to note that the TEOM uses a different type of media than the 

lab, and the QCM uses a platinum substrate to collect PM. Within our current specifications for 

sampling post-trap PM, two different acceptable laboratory filter media give results where one is 

four times that of the other.(4) We believe that this difference is from a combination of gaseous 

hydrocarbons adsorbing onto one filter, while PM hydrocarbons are stripped off of the other filter. 

We are currently supporting a Coordinating Research Council study to resolve these laboratory PM 

measurement issues, and we expect that results from this study, which should be available before the 

end of 2004, will allow us to more accurately compare the TEOM and QCM to laboratory 

measurements of trap-equipped diesels. Based on the results of this study, we will select a single 

filter material specification for laboratory PM measurement. We expect that such a specification will 

resolve most of the current issues with post-trap PM measurement in the laboratory. Furthermore, 

based on this study, we will likely specify an on-vehicle PM sampling dilution rate and ratio, along 

with the on-vehicle equilibration pressure, temperature and humidity for PM samples. By specifying 

these sampling conditions, we can help assure that PM measurement on-vehicle will be sufficiently 

equivalent to laboratory PM measurements–even at our most stringent PM standard. 

2. Exhaust flow rate. In a CVS laboratory the entire volume of engine exhaust is diluted and 

then measured. Since this is impractical for on-vehicle emissions measurement, the raw exhaust 

flow rate must be measured. We are aware of four commercially available technologies for onvehicle exhaust flow measurement. One has been developed and patented by us, and it is based on 

an averaging Pitot tube (Patent No. 6,148,656). This technology is commercially available because 

we have licensed the technology to two on-vehicle emissions measurement system manufacturers. 

Another technology uses a hot-wire anemometer to measure the flow of ambient air induced by a 

sub-sonic venturi placed in the raw exhaust. A third technology uses a heated hot-wire anemometer 

directly in the exhaust. A fourth technology measures a known proportion of raw exhaust flow via 

the laboratory CVS technique. It’s proportionality is maintained with the total raw exhaust flow by 

balancing certain partial flow pressures with the exhaust tailpipe and ambient pressures. All of these 

techniques have been demonstrated to be within 5 % of the true exhaust flow, and two of these 

30

techniques were used to measure the flows required to achieve the gaseous and PM measurement 

results indicated in the previous section (1,3). 

3. Engine operation. Certain engine parameters are required to calculate emissions or to 

determine whether or not an engine is operating in the NTE zone. Other parameters are used to 

determine if an EGR-equipped engine is sufficiently warmed-up for NTE testing. These parameters 

may be measured directly using the technologies described below. However, if the engine 

manufacturer determines that an engine’s Electronic Control Module (ECM) accurately quantifies 

these parameters, the manufacturer may rely on ECM values for these parameters. 

a. Speed. Engine crankshaft speed is required to determine whether or not an engine is 

operating within the NTE zone. Engine speed also may be used to determine engine power for 

emissions calculations. We have used magnetic flux detectors attached to the housing of an engine’s 

belt-driven alternator to measure engine speed. Other on-vehicle emissions measurement system 

manufacturers detect alternator voltage ripple frequency. These signals are calibrated to actual 

engine speed during each engine installation with a portable reference tachometer. 

b. Torque. Engine torque is required to determine whether or not an engine is operating within 

the NTE zone. Engine torque also may be used to determine engine power for emissions 

calculations. Engine torque may be measured directly by installing and calibrating a strain gage on 

the drive shaft. We also allow torque determination using fuel flow, as calculated via carbonbalance, in combination with engine speed and an estimated brake-specific fuel consumption. For 

details, refer to §1065.650, which is being revised in a companion final rule to this notice. 

c. Coolant temperature, intake manifold temperature, and intake manifold pressure. These 

three parameters are used to determine whether or not an EGR-equipped engine is sufficiently 

warmed-up for NTE testing. These can be measured with standard thermocouples and automotive 

pressure transducers, which can be mounted into coolant and intake system caps or plugs. 

4. Ambient conditions. Ambient conditions are used to calculate emissions or to determine if 

ambient conditions are within limits for NTE testing. These parameters may be measured directly 

using the technologies described below, or if the engine manufacturer determines that an engine’s 

Electronic Control Module (ECM) accurately quantifies these parameters, the manufacturer may rely 

on ECM values for these parameters. 

a. Temperature. We have used thermistor-based and thermocouple-based ambient temperature 

sensors for this purpose. Either technology is sufficient for this temperature measurement. These 

sensors are rugged because they are commonly used in remote weather station applications, however 

these sensors must be shielded from heat from the sun and heat from the engine to achieve accurate 

ambient temperature readings. 

31

b. Dewpoint. We have used thin-film capacitor-based ambient dewpoint sensors for this 

purpose. This technology is sufficient for this dewpoint measurement. These sensors are rugged 

because they are commonly used in remote weather station applications. 

c. Altitude. We have used Global Positioning System (GPS) technology to measure altitude. 

We have used this technology cross-country as part of a complete on-vehicle emissions measurement 

system, and it measured altitude accurately. 

32

Chapter 2 References 

1. “On the Road to Clear Skies: Semtech-D For On-highway Heavy-duty Diesel Applications.” 

SAE Government/Industry Meeting May 13, 2003, Andrew Reading, Sensors Incorporated. 

2. “Validation of the RAVEM Ride-along Vehicle Emissions Measurement System.”, Final 

Report June 19, 2001, Christopher Weaver, Engine, Fuels, and Emissions Engineering. 

3. “Evaluation of TEOM and QCM Technology for Particulate Mass Measurement”, ETH 

Conference on Nanoparticle Measurement, Zurich, August 2001, David Booker, Mridul Gautam, 

West Virginia University. 

4. “Particulate Mass Measurements of Heavy-duty Diesel Engine Exhaust Using 2007 CVS 

PM Sampling Parallel to QCM and TEOM.”, Final Report No. 08.06129 September 30, 2003, Imad 

A. Khalek, Ph.D., Southwest Research Institute. 

33

CHAPTER 3


New In-Use Testing Instrument Measurement Allowance


Before discussing the basis for the new measurement allowances for on-vehicle emissions 

measurements, it is instructive to review the restricted engine operation that the NTE zone covers, 

the list of other NTE allowances that we already have finalized, and other allowances that we 

propose elsewhere in this notice. 

3.1 Review of NTE zone 

On October 6, 2000 we published Not-To-Exceed (NTE) rules and regulations for heavy-duty 

diesel engines (65 Fed. Reg. 59895); effective for engines starting with model year 2007. NTE 

provisions were also incorporated into the regulations promulgated shortly thereafter requiring 

further reductions in emissions from heavy duty engines (66 Fed. Reg. 5001 January 18, 2001). 

Briefly, the NTE provisions specify brake-specific averaging periods as short as 30 seconds, and 

under these provisions testing is restricted to a limited region of engine operation. Namely, when all 

of the following conditions are simultaneously met for at least 30 seconds, an NTE event is 

generated. Note however, that if an aftertreatment system were to regenerate during this time, the 

minimum time under which all of these conditions must be met would increase to at least twice the 

regeneration interval: 

1. Engine speed must be greater than 15% above idle speed. 

2. Engine torque must be greater than or equal to 30% of maximum torque. 

3. Engine power must be greater than or equal to 30% of maximum power. 

4. Vehicle altitude must be less than or equal to 5500 feet. 

5. Ambient temperature must be less than or equal to 100 degrees F at sea level to 86 degrees F 

at 5500 feet. 

6. Brake-specific fuel consumption (BSFC) must be less than or equal to 105 % of the 

minimum BSFC if an engine is not coupled to a multi-speed manual or automatic transmission. 

7. Engine operation must be outside of any manufacturer petitioned exclusion zone. 

8. Engine operation must be outside of any NTE region in which a manufacturer states that less 

than 5% of in-use time will be spent. 

9. For EGR-equipped engines, the intake manifold temperature must be greater than or equal to 

86-100F, depending upon intake manifold pressure. 

10. For EGR-equipped engines, the engine coolant temperature must be greater than or equal to 

125-140 degrees F, depending on intake manifold pressure. 

11. Engine aftertreatment systems’ temperature must be greater than or equal to 250 degrees C. 

3.2 Review of existing NTE allowances 

As part of these rules, we also finalized several compliance allowances with respect to meeting 

the Not-To-Exceed (NTE) standard. At that time we did not finalize any NTE allowances that were 

34

to specifically account for any differences between the quality of laboratory measurements and onvehicle measurements. Note that we did finalize the following NTE allowances: 

1. We allowed for the use of the family emissions limit (FEL) to which an engine was 

certified, rather than using actual emissions standard as the NTE standard. This allowance accounts 

for any differences in the engine’s certified emissions and the actual emissions standard when 

comparing on-vehicle emissions to laboratory certified emissions. 

2. We allowed for NTE multipliers of 1.25x and 1.5x times the engine’s certified emissions, 

depending upon the level of the engine’s certified emissions compared to the standard. This 

multiplier allowance accounts for any differences in engine operation and/or ambient conditions 

when comparing on-vehicle emissions to laboratory certified emissions. 

3. We allowed for rounding of the compliance limit after multiplying the engine’s certified 

emissions by 1.25x or 1.5x. Therefore, when an engine is certified at 0.01 g/hp-hr PM, this rounding 

effectively increases the 1.5x multiplier to 2.0x. This allowance creates an NTE compliance limit 

with the same number of significant figures as the emissions standard. This allows for a pass/fail 

determination with the same number significant figures when comparing on-vehicle emissions to 

laboratory certified emissions. 

4. For NOx emissions, we allowed an additive allowance of 0.10, 0.15, or 0.20 g/hp-hr, based 

on an engine’s model year, its certified emissions, and vehicle accumulated mileage. This additive 

allowance accounts for any differences in the performance of the first an in-use-aged NOx emissions 

control systems (including the engine and aftertreatment systems) when comparing their on-vehicle 

emissions to laboratory certified emissions. 

5. For PM emissions, we allowed an additive allowance of 0.01 g/hp-hr, based on an engine’s 

model year and its certified emissions. This additive allowance accounts for any differences in the 

performance of the first an in-use-aged PM emissions control systems (including the engine and 

aftertreatment systems) when comparing their on-vehicle emissions to laboratory certified emissions. 

3.3 Review of other NTE allowances 

As discussed elsewhere in this notice we also proposed additional NTE allowances for 

demonstrating compliance with this program. These allowances are based upon our settlement 

agreement with engine manufacturers. These include the following allowances: 

1. We are allowing vehicles to meet the vehicle pass criteria for this program even though up 

to 10 % of the time-weighted NTE events exceed the applicable NTE threshold. For model years 

2007 through 2009, however, none of these NTE exceedances can be greater than to 2x the NTE 

threshold. In the case of NOx emissions certified at or below 0.50 g/hp-hr–for model years 2007 

35

through 2009, we are allowing these NTE exceedances to occur up to a threshold of 2.00 g/hp-hr. 

After model year 2009, there will be no upper limit to these individual NTE exceedances. 

2. Elsewhere in this notice we are proposing that we would not require further testing of an 

engine family under this program even though a fraction of engines within that engine family failed 

to meet the vehicle pass criteria – even after applying all of the allowances discussed above. 

3.4 Discussion of NTE measurement allowances 

We have agreed to work co-operatively with engine manufacturers and the California Air 

Resources Board on a test plan to determine data-driven measurement allowances. The experimental 

methods and procedures specified in the test plan for determining, modeling, and comparing each of 

the various components of measurement error are designed to generate statistically robust 

data-driven measurement allowances for each of the gaseous emissions, namely NOx, NMHC, and 

CO. We have also agreed to develop a similar cooperative test plan for the determination of a PM 

measurement allowance. 

As detailed in the gaseous emissions test plan, which is contained in the record for this 

rulemaking, we have an agreement with engine manufacturers and the California Air Resources 

Board on what components of measurement error are intended to be covered by the measurement 

allowances. Agreed upon sources of error include differences in emissions concentration 

measurements, differences in exhaust flow measurements, differences in PEMS environmental 

conditions, and differences in torque measurement versus inference of engine torque based on 

electronic control module (ECM) signals. We have agreed upon exploring the following 

environmental conditions effects on PEMS: ambient temperature and pressure, shock and vibration, 

electromagnetic radiation, and ambient hydrocarbons. We have also agreed that the test plan will 

comprehensively explore the sources of error that might arise because torque is not measured in-use, 

but rather it will be inferred from other signals from an engine’s ECM. Specifically, lab measured 

torque versus ECM-derived torque will be compared over the following different conditions: 

different engine speeds and torques, different ambient pressures, temperatures, and humidities, 

different intake air and exhaust restrictions, and different charge air cooler temperatures. 

Furthermore, engine manufacturers are allowed to submit supplemental information regarding the 

effects of non-deficiency AECDs on the accuracy and precision of ECM-derived torque. 

The test plan’s measurement allowances will be calculated in a manner that subtracts lab error 

from PEMS error. Specifically, the lab error associated with measuring heavy-duty engine emissions 

at stabilized steady-state test points within the NTE zone, sampled over 30-second durations utilizing 

Part 1065 compliant laboratory emissions measurement systems and procedures will be subtracted 

from the PEMS error associated with measuring heavy-duty engine emissions utilizing PEMS over 

30-second transient NTE sampling events under a broad range of ambient and environmental 

conditions. This subtraction will yield "PEMS minus laboratory" measurement allowances. 

36

The error model developed in the test plan will not subtract any laboratory accuracy or 

precision determined from laboratory measurements of transient 30-second NTE events. However, 

such transient 30-second NTE data will be collected by laboratory measurement instruments during 

testing. Based on comments we received regarding the ability to conduct NTE testing in a 

laboratory, this data will be analyzed to determine whether or not we are correct in our belief that 

Part 1065-compliant engine dynamometer laboratories can accurately and precisely measure transient 

NTE events as short as 30 seconds. If not, we have agreed with engine manufacturers and the 

California Air Resources Board on a separate process to address this situation, should it arise. If 

results show that the lab 95th percentile transient 30-second NTE error is greater than the lab 99th 

percentile steady-state 30-second NTE error, then EPA, CARB, and EMA would agree to the 

following: 

a. EMA will work with EPA and CARB to optimize laboratory NTE measurement specifications 

and procedures. This work will primarily be in the form of participating in and supporting joint 

laboratory NTE test procedure development efforts and meetings. 

b. EPA would intend to issue a guidance document and/or propose changes to Part 1065 to reflect 

any optimized specifications and procedures for laboratory NTE testing as a result of those efforts and 

meetings no later than the end of calendar year 2008. 

We are confident that based on the results of the test plan, we will be able to determine emissionsspecific, brake-specific, additive, data-driven measurement allowances for NOx, NMHC, and CO with 

sufficient lead-time for engine manufacturers to prepare for the 2007 fully enforceable program for 

gaseous emissions. 

As noted above, we intend to develop a similar test plan for determining a PM measurement 

allowance, and we are confident that we will be able to determine data-driven measurement allowances 

for PM with sufficient lead-time for engine manufacturers to prepare for the 2008 fully enforceable 

program for PM emissions. 

For measurement allowances in the interim before the test plans are completed, we have finalized 

generous emissions-specific, brake-specific, additive measurement margins. Based on the correlation 

studies detailed in the previous section of this document, we believe that these interim measurement 

allowances provide considerable margin for error based on the existing information on the accuracy of 

existing PEMS units. 

37

APPENDIX A: Examples of Determining the Number of Engine Families to be


Tested


This appendix contains a few examples showing how many engine families EPA may designate 

for testing each year under the in-use, manufacturer-run program. More specifically, they illustrate 

how we would calculate the maximum annual number of engine families for more complex cases 

where the four-year average annual cap and 25 percent per year limit might apply to a manufacturer 

with four or more engine families, all of which have annual production volumes more than 1,500 

units. 

The multi-step methodology is identical regardless of number of engine families a 

manufacturer has in these cases. The steps are discussed below and illustrated in Tables A-1 through 

A-3. 

Step 1. For the calendar year in which we are testing (the evaluation year), identify the number 

of engine families produced in the model year corresponding to that calendar year and each of 

the three preceding model years. 

Step 2. Divide by 4 the number of engine families produced in the model year corresponding 

to the evaluation year and round the result to the nearest whole number using the rounding 

convention specified by the National Institute of Standards and Technology (NIST 1995).2 The 

result is the 25 percent annual limit on the number of engine families that potentially may be 

designated for testing in the evaluation year. 

Step 3. Sum the engine families identified in Step 1 to determine the total four-year engine 

family production. 

Step 4. Divide by 4 the total four-year engine family production from Step 3 and round the 

result to the nearest whole number using the rounding convention specified by the National 

Institute of Standards and Technology (NIST 1995). The result is the four-year average cap on 

the number of engine families that may be designated for testing in the evaluation year. 

Step 5. Subtract the number of engine families we have required to be tested under this 

program over the past three years from the four-year average cap. The result is the four-year 

average annual cap. 

2

 Under the rounding convention contained in this reference, when the first digit discarded 

is exactly five, the last digit retained should be rounded upward if it is an odd number, but no 

adjustment made if it is an even number. 

38 
Step 6. Select the lower of the rounded four-year average annual cap from Step 5 and the 

rounded 25 percent annual limit from Step 2. The result is the maximum number of engine 

families that may be designated for testing in the evaluation year. 

As noted, Tables A-1 through A-4 illustrate the procedure described above. They also show 

that the actual number of engines which may be designated in any year never exceeds the four-year 

average annual cap, and may be less for some years, especially for the initial model year of testing, 

i.e., 2007. 

39

Table A-1. Example of Engine Family Selection for One or Two Families Per Y

Inputs 

Model Year 04 05 06 07 08 09 10 11 12 # Certified Families 1 1 1 1 1 1 2 2 2 4-Year Total Families (3 preceding years + current year) 

4 4 4 5 6 7 

4-Year Ave. Cap (simple) 1.00 1.00 1.00 1.25 1.5 1.75 4-Year Ave. Cap (NIST 811 rounded) 

1 1 1 1 2 2 

25% Annual Family Limit (simple) 

0.25 0.25 0.25 0.25 0.50 0.50 

25% Annual Family Limit (NIST 811 rounded) 

0.0 0.0 0.0 0.0 0.0 0.0 

Calculations 4 -Year Ave. Cap (from above) 

1 1 1 1 2 2 

25% Annual Family Limit (from above) 

0.0 0.0 0.0 0.0 0.0 0.0 

# Tests Allowed/Year 1 0 0 0 2* 0* (4 Year Cap Applied?) (no) (yes) (yes) (yes) (no) (yes) 

#Tested/4 -Year Ave. 1/1 1/1 1/1 1/1 2/2 2/2 Annual Cap (% Tested) (100) (100) (100) (100) (100) (100) 

* Alternatively, one family could have been tested in any two of the four years shown. 

40 
Table A-2. Example of Engine Family Selection for Six or Seven Families Per Y

Inputs 

Model Year 04 05 06 07 08 09 10 11 12 1# Certified Families 6 6 6 6 6 7 7 7 7 4-Year Total Families (3 preceding years + current year) 

24 24 25 26 27 28 

4-Year Ave. Cap (simple) 6.00 6.00 6.25 6.5 6.75 7.00 4-Year Ave. Cap (NIST 811 rounded) 

6 6 6 6 7 7 

25% Annual Family Limit (simple) 

1.50 1.50 1.75 1.75 1.75 1.75 

25% Annual Family Limit (NIST 811 rounded) 

2 2 2 2 2 2 

Calculations 4 -Year Ave. Cap (from above) 

6 6 6 6 7 7 

25% Annual Family Limit (from above) 

2 2 2 2 2 2 

# Tests Allowed/Year 2 2 2 0 2 2 (4 Year Cap Applied?) (no) (no) (no) (yes) (no) (no) 

#Tested/4 -Year Ave. 2/6 4/6 6/6 6/6 6/7 6/7 Annual Cap (% Tested) (33) (67) (100) (100) (86) (86) 

41

Table A-3. Example of Engine Family Selection for 10 Families Per Year


Inputs


Model Year 04 05 06 07 08 09 10 11 12 13 # Certified Families 10 10 10 10 10 10 10 10 10 10 4-Year Total Families (3 preceding years + current year) 

40 40 40 40 40 40 40 

4-Year Ave. Cap (simple) 10 10 10 10 10 10 10 4-Year Ave. Cap (NIST 811 rounded) 

10 10 10 10 10 10 10 

25% Annual Family Limit (simple) 

2.5 2.5 2.5 2.5 2.5 2.5 2.5 

25% Annual Family Limit (NIST 811 rounded) 

2 2 2 2 2 2 2 

Calculations 4-Year Ave. Cap (from above) 

10 10 10 10 10 10 10 

25% Annual Family Limit (from above) 

2 2 2 2 2 2 2 

# Tests Allowed/Year (4-Year Cap Applied?) 

2 

(no) 

2 

(no) 

2

 (no) 

2

 (no) 

2 

(no) 

2

 (no) 

2

 (no

# Tested/4-Year Ave. Annual Cap (% Tested) 

2/10 

(20) 

4/10 

(40) 

6/10 

(60) 

8/10 

(80) 

8/10 

(80) 

8/10 

(80) 

810 

(80

42

Table A-4. Example of Engine Family Selection for 9, 10, or 14 Families Per Y

Inputs 

Model Year 04 05 06 07 08 09 10 11 12 1# Certified Families/Year 9 9 9 9 9 10 10 10 10 4-Year Total Families (3 preceding years + current year) 

36 36 37 38 39 40 

4-Year Ave. Cap (simple) 9.00 9.00 9.25 9.50 9.75 10.00 14-Year Ave. Cap (NIST 811 rounded) 

9 9 9 10 10 10 

25% Annual Family Limit (simple) 

2.25 2.25 2.50 2.50 2.50 2.50 

25% Annual Family Limit (NIST 811 rounded) 

2 2 2 2 2 2 

Calculations 4-Year Ave. Cap (from above) 

9 9 9 10 10 10 

25% Annual Family Limit (from above) 

2 2 2 2 2 2 

# Tests Allowed/Year 2 2 2 2 2 2 (4-Year Cap Applied?) (no) (no) (no) (no) (no) (no) 

# Tested/4-Year Ave. 2/9 4/9 6/9 8/10 8/10 8/10 10Annual Cap (% Tested) (22) (44) (67) (80) (80) (80) 

43

 Appendix References 

1. National Institute of Standards and Technology. 1995. Guide for the Use of the International 

System of Units (SI), NIST Special Publication 811, 1995 Edition. U. S. Department of Commerce. 

44