Regulatory Announcement

EPA Proposal for More Stringent 

Emissions Standards for Locomotives 

and Marine Compression-Ignition 

Engines 

The U.S. Environmental Protection Agency (EPA) is proposing more stringent exhaust emission standards for locomotives and marine diesel engines. The proposal would significantly 

reduce harmful emissions of diesel particulate matter (PM) and 

nitrogen oxide (NOx) emissions from these engines through a 

three-part program: (1) tightening emission standards for existing 

locomotives when they are remanufactured, (2) setting near-term 

engine-out emission standards, referred to as Tier 3 standards, 

for newly-built locomotives and marine diesel engines; and (3) 

setting longer-term standards, referred to as Tier 4 standards, for 

newly-built locomotives and marine diesel engines that reflect the 

application of high-efficiency aftertreatment technology. EPA is 

also proposing provisions to eliminate emissions from unnecessary locomotive idling and is asking for comment on a concept to 

reduce emissions from existing marine diesel engines when they 

are remanufactured. This proposal is part of EPA’s ongoing National Clean Diesel Campaign (NCDC) to reduce harmful emissions from diesel engines of all types. 

Background 

Existing EPA regulations in 40 CFR parts 92 and 94 include standards for emissions 

of PM, NOx, HC and CO from locomotive and marine compression-ignition engines 

(also called diesel engines). These standards rely on engine-based technologies to 

reduce emissions. The opportunity to gain large additional public health benefits, 

as well as the similarities between these engines and highway diesel and nonroad 

Office of Transportation and Air Quality 

EPA420-F-07-015 

March 2007 
Regulatory Announcement

engines, have led us to consider additional emission controls based on the high-efficiency aftertreatment technologies that will soon be in use by highway and nonroad 

engines. 

Need to Reduce Locomotive and Marine Diesel 

Emissions 

Locomotive and marine diesel engines contribute significantly to air pollution in many 

of our nation’s cities and towns. In the coming decades, these engines are expected to 

account for an even greater share of overall emissions as other emission control programs 

take effects for cars, trucks, and other nonroad emissions sources. EPA estimates that, 

without the emission reductions from today’s proposal, by 2030 locomotive and marine 

diesel engines would contribute more than 65 percent of national mobile source diesel 

PM2.5 emissions and 35 percent of national mobile source NOx emissions, a key precursor to ozone and secondary PM formation. 

Recent air quality data show that about 157 million people live in areas that violate air 

quality standards for ground-level ozone, also called smog and about 88 million people 

live in areas that violate air quality standards from PM. These pollutants contribute to 

serious public health problems that include premature mortality, aggravation of respiratory and cardiovascular disease, aggravation of existing asthma, acute respiratory symptoms and chronic bronchitis. EPA believes that diesel exhaust is likely to be carcinogenic to humans by inhalation. Children, people with heart and lung diseases, and the 

elderly are thought to be most at risk. 

Locomotive and marine diesel emissions reductions are expected to benefit those who 

live, work, or recreate in and along our nation’s coastal areas, rivers, ports, and rail lines. 

Such reductions are expected to have beneficial impacts on visibility impairment and 

regional haze, as well as reducing crop damage and acid rain. 

Description of Engines Covered 

The proposed requirements would cover all locomotives and many marine diesel engines 

already subject to EPA emission standards, as follows: 

• Locomotives: With limited exceptions, the regulations would apply to all 

line-haul, passenger, and switch locomotives that operate extensively within 

the United States, including newly manufactured locomotives and remanufactured locomotives that were originally manufactured after 1972. The primary exception is that the new remanufacturing standards would not apply to 

the existing fleets of locomotives owned by very small railroads. 

••	 Marine Diesel Engines: The regulations would apply to newly-built marine 

diesel engines with displacements less than 30 liters per cylinder installed 

Locomotive and Marine Diesel Engines Proposed Rule 2 
Regulatory Announcement

on vessels flagged or registered in the United States. These are commonly referred 

to as marine diesel engines and are divided into three categories for the purposes of 

EPA’s standards. Category 1 are engines above 50 horsepower (hp) and up to 5 liters 

per cylinder displacement. Category 2 are engines from 5 to 30 liters per cylinder. 

Category 3 are engines at or above 30 liters per cylinder. EPA is proposing to change 

the definition of Category 1 and Category 2 engines to reflect a 7 liter per cylinder 

cut-off. 

Marine Diesel engines are used in commercial, recreation, and auxiliary power applications. Commercial propulsion applications range from tug boats to Great Lakes 

freighters. Recreational propulsion applications range from sailboats to super-yachts. 

EPA is also requesting comments on whether the Agency should tighten emission standards for certain existing marine diesel engines when they are remanufactured. Marine diesel engines at or above 30 liters per cylinder displacement are not 

included in this proposal; these engines, which are typically used for propulsion on 

ocean-going vessels, will be addressed in a separate EPA rulemaking. 

Exhaust Emissions Standards 

The proposal consists of a three-part emission control. 

First, EPA is proposing to adopt more stringent standards for existing locomotives when they are 

remanufactured. These standards would take effect as soon as certified remanufacture systems are 

available (as early as 2008), but no later than 2010 (2013 for Tier 2 locomotives). EPA is also 

requesting comment on similar requirements for certain existing marine diesel engines when 

they are remanufactured. 

Second, EPA is proposing near-term emission standards, referred to as Tier 3 standards, for 

newly-built locomotive and marine engines. These standards would reflect the application of 

technologies to reduce engine-out PM and NOx emissions and would phase in starting in 2009. 

Third, EPA is proposing long-term emissions standards, referred to as Tier 4, for newly-built 

locomotives and marine diesel engines. These standards are based on the application of highefficiency catalytic aftertreatment technology and would phase in beginning in 2014 for marine 

diesel engines and 2015 for locomotives. These standards are enabled by the availability of clean 

diesel fuel with sulfur content capped at 15 parts per million, which will be available beginning 

by 2012. These marine Tier 4 engine standards would apply only to commercial marine diesel 

engines above 800 hp and recreational marine diesel engines above 2,000 hp. 

The proposal would result in PM reductions of about 90 percent and NOx reductions of about 

80 percent from engines meeting these standards, compared to engines meeting the current 

standards. The proposed standards would also yield sizeable reductions in emissions of HC, CO, 

and other air toxics. 

Locomotive and Marine Diesel Engines Proposed Rule 3 
Program Costs 

EPA estimates the annual cost of complying with the proposed program to be about $600 million in 2030. The average price in 2030 of a locomotive is expected to increase by less than 

three percent (about $49,000 per unit) as a result of the proposed standards. In the marine markets, the expected impacts in 2030 are different for engines above and below 800 hp. Increases 

in engine and vessel prices for commercial engines below 800 hp and recreational engines are 

expected to be small (less than one percent). The average price of a commercial marine diesel 

engine above 800 hp is expected to increase by about 8.5 percent for Category 1 engines and 

about 19 percent for Category 2 engines. The average price of a marine vessel using these larger 

engines is expected to increase much less, about 1 percent for vessels using Category 1 engines 

above 800 hp (about $16,000) and 3.6 percent for vessels using Category 2 engines above 800 

hp (about $142,000). The expected impacts on prices in the locomotive and marine transportation service market would be less than one percent. 

Program Benefits 

These proposed standards would result in substantial benefits to public health and welfare and 

to the environment. EPA estimates that by 2030 this comprehensive emission control program 

would reduce annual emissions of NOx and PM by 765,000 and 28,000 tons, respectively, and 

the magnitude of these reductions would continue to grow well beyond 2030. EPA estimates 

that the monetized health benefits of this rule in 2030 would be approximately $12 billion. The 

value of the benefits would be much greater than the projected program cost of $600 million per 

year. By 2030, the rule would annually prevent 1,500 premature mortalities; over 1,100 hospitalizations; 170,000 work days lost; and 1,000,000 minor restricted-activity days and other quantifiable benefits.

Regulatory Announcement

Locomotive and Marine Diesel Engines Proposed Rule 4 
Figure 1 Projected NOx Emissions (tons per year with and without the Proposed 

New Controls 

Regulatory Announcement

Figure 2 Projected PM2.5 Emissions (tons per year) with and without the Proposed 

New Controls 

Locomotive and Marine Diesel Engines Proposed Rule 5 
Regulatory Announcement

Public Participation Opportunities 

EPA welcomes your comments on this rule. Comments will be accepted for 90 days beginning 

when this proposal is published in the Federal Register. All comments should be identified by 

Docket ID No. EPA-HQ-OAR-2003-0190 and submitted by one of the following methods: 

Internet: www.regulations.gov


E-mail: A-and-R-Docket@epa.gov


Mail:


Environmental Protection Agency 

Air and Radiation Docket and Information Center (6102T) 

1200 Pennsylvania Avenue NW 

Washington, DC 20460 

Hand Delivery:


EPA West building


EPA Docket Center (Room 3340)


1301 Constitution Avenue NW


Washington, DC


A public hearing will also be held in Seattle, Washington, and Chicago, Illinois, after publication of the proposed rule in the Federal Register. Additional information about the hearing will 

be printed in the Federal Register. 

For More Information 

You can access the rule and related documents on EPA’s Office of Transportation and Air Quality (OTAQ) Web site at: 

www.epa.gov/otaq/marine.htm or www.epa.gov/otaq/locomotv.htm 

For more information on this rule, please contact the Assessment and Standards Division 


information line at: 


U.S. Environmental Protection Agency 


Office of Transportation and Air Quality 


2000 Traverwood Drive


Ann Arbor, MI 48105

Voicemail: (734) 214-4636

E-mail: asdinfo@epa.gov 

Locomotive and Marine Diesel Engines Proposed Rule 6