United States Environmental Protection Agency
Air and Radiation
Office of Mobile Sources
EPA420-F-97-048
December 1997

NOTE: This is an unofficial text-only version of the fact sheet with no graphics. It does not meet 
EPA graphics standards. For hardcopy purposes you should use the official, fully formatted 
version with grahpics that is available either: (a) as a PDF file (which can be read using Acrobat 
Reader) located on the World Wide Web at http://www.epa.gov/omswww; or (b) by requesting a 
fax from (734) 668-4333.

Final Emissions Standards for Locomotives

The Environmental Protection Agency (EPA) is finalizing emission standards for oxides of 
nitrogen (NOx), hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM) and smoke 
for newly manufactured and remanufactured diesel-powered locomotives and locomotive engines, 
which have previously been unregulated. The new standards will achieve approximately a two-
third reduction in NOx emissions, which is equivalent to removing over thirty million passenger 
cars from the road. In addition, HC and PM emissions will be reduced by 50 percent.

History of Rulemaking
The 1990 Clean Air Act Amendments mandated EPA to establish emission standards for a variety 
of previously unregulated nonroad mobile sources. Included in those requirements was a specific 
mandate to regulate the emissions from locomotives. Current unregulated locomotives are 
estimated to contribute almost 5 percent of the total nationwide emissions of NOx, which is more 
than 10 percent of the nationwide mobile source NOx emissions. This makes locomotives one of 
the largest remaining unregulated sources of NOx emissions. Thus, this rulemaking will result in 
emissions reductions that states need to comply with the National Ambient Air Quality Standards 
(NAAQS) for ozone and PM.

Overview of Rulemaking
Since locomotive emissions have not been regulated before, it was necessary for EPA to create a 
comprehensive program, including not only emission standards, but also test procedures and a full 
compliance program. This rulemaking, which takes effect in 2000, will affect railroads, locomotive 
manufacturers, and locomotive remanufacturers.

In general terms, the overall program is similar to previously established programs for heavy-duty 
highway engines and other nonroad engines. One unique feature included for locomotives, 
however, is the regulation of the engine remanufacturing process, including the remanufacture of 
locomotives originally manufactured prior to the effective date of this rulemaking. Regulation of 
the remanufacturing process is critical because locomotives are generally remanufactured 5 to 10 
times during their total service lives (typically 40 years or more). Standards that only applied to 
locomotives originally manufactured after the effective date of the rule would not achieve 
significant emissions reductions in the near term, as those locomotives slowly replaced the existing 
fleet.

Three separate sets of emission standards have been adopted, with applicability of the standards 
dependent on the date a locomotive is first manufactured. The first set of standards (Tier 0) apply 
to locomotives and locomotive engines originally manufactured from 1973 through 2001, any time 
they are manufactured or remanufactured. The second set of standards (Tier 1) apply to 
locomotives and locomotive engines originally manufactured from 2002 through 2004. These 
locomotives and locomotive engines will be required to meet the Tier 1 standards at the time of 
original manufacture and at each subsequent remanufacture. The final set of standards (Tier 2) 
apply to locomotives and locomotive engines originally manufactured in 2005 and later. Tier 2 
locomotives and locomotive engines will be required to meet the applicable standards at the time of 
original manufacture and at each subsequent remanufacture. Electric locomotives, historic steam-
powered locomotives, and locomotives originally manufactured before 1973 do not contribute 
significantly to the emissions problem, and thus, are not included in this rulemaking.
1. HC standards are in the form of THC for diesel, bio-diesel, or any combination of fuels with 
diesel as the primary fuel; NMHC for natural gas, or any combination of fuels where natural gas is 
the primary fuel; and THCE for alcohol, or any combination of fuels where alcohol is the primary 
fuel.

In addition to the exhaust emission standards, this final rule establishes smoke opacity standards 
for all locomotives and locomotive engines.
EPA has adopted a production line testing (PLT) program that requires manufacturers and, in some 
cases, remanufacturers of locomotives to perform production line testing of newly manufactured 
and remanufactured locomotives as they leave the point where the manufacture or remanufacture is 
completed. The PLT program for newly manufactured units is based on actual testing, while the 
PLT program for remanufactured units is based on an audit of the remanufacture kitÕs installation, 
with EPA having the ability to require testing if in-use data indicates a possible problem with 
production. 

A critical element in the success of this locomotive program is ensuring that manufacturers and 
remanufacturers produce locomotives that continue to meet emission standards beyond certification 
and production stages, during actual operation and use. EPA is adopting an in-use compliance 
program with two distinct components. The first program requires the manufacturers and 
remanufacturers to test representative locomotives from all engine families using the Federal Test 
Procedure (FTP). This testing will occur between 50 and 75 percent of useful life. Actual repair in 
the event of a determination of noncompliance or recall action, however, will apply to all 
locomotives of that family, regardless of whether the locomotives have exceeded their useful lives. 
Second, EPA is requiring that Class I railroads annually test a sample of their locomotives which 
have met or exceeded their useful lives, also using the FTP.

EPA has adopted averaging, banking and trading (ABT) provisions to allow manufacturers and 
remanufacturers the flexibility to meet overall emissions goals at the lowest cost, while allowing 
EPA to set emissions standards at levels more stringent than they would be if each and every 
engine family had to comply with the standards. ABT is also designed to encourage early 
introduction of cleaner engines, which will secure emissions benefits earlier than would otherwise 
be the case.

EPA has adopted regulations that will codify and clarify Clean Air Act preemption of certain state 
and local requirements relating to the control of emissions from new locomotives and new 
locomotive engines. This preemption was included in the Clean Air Act because of the inherent 
interstate nature of the railroad industry. Moreover, EPA believes that a strong federal program that 
addresses manufacturing, remanufacturing and in-use compliance is the best way to achieve the 
necessary emissions reductions.


Health and Environmental Benefits
Emissions from diesel-powered locomotives, such as NOx, HC, and PM, contribute to air 
pollution in both urban and rural areas, and have significant health and environmental effects. NOx 
is a major component of smog and acid rain. NOx emissions combine with HC in the atmosphere 
to form ground-level ozone, the primary constituent of smog. Ozone is a highly reactive pollutant 
that damages lung tissue, causes congestion, and reduces vital lung capacity, in addition to 
damaging vegetation. Acid rain damages buildings and crops, and degrades lakes and streams. 
NOx also contributes to the formation of secondary PM, which causes headaches, eye and nasal 
irritation, chest pain, and lung inflammation. Environmental impacts of PM include reduced 
visibility and deterioration of buildings. 
The primary focus of this rulemaking is on reducing NOx and PM emissions, although there are 
also reductions in HC and CO. NOx emissions from locomotives will be reduced by 60 percent by 
2040, compared to 1995 baseline levels. This would be almost 650,000 metric tons per year. Most 
of these reductions will come early in the program (e.g., 41 percent reduction by 2010), due to the 
standards that apply to pre-2000 locomotives when they are remanufactured. In addition to the 
NOx benefits, the final rule will provide some PM benefits through the Tier 2 standards. A PM 
reduction of 46 percent is expected by 2040, compared to 1995 baseline levels. This reduction is 
over 12,000 metric tons per year, and amounts to over one percent of national PM emissions from 
mobile sources. 


Flexibility For Industry
The final rule codifies the Clean Air ActÕs preemption of state and local emission requirements, 
which is intended to prevent inappropriate burdens on interstate commerce. The flexibility provided 
by ABT lowers the costs to manufacturers and makes it easier to meet the technological challenges 
posed by the new standards. EPA is also exempting the smallest railroads from compliance with 
the Tier 0 standards, with some restrictions, and is providing a phase-in of the standards for small 
manufacturers.


Cost of New Program
EPA estimates that the lifetime cost per locomotive will be approximately $70,000 for the Tier 0 
standards, $186,000 for the Tier 1 standards and $252,000 for the Tier 2 standards. Lifetime cost 
components consist of initial equipment costs; remanufacturing costs; fuel economy costs; and 
certification, production line and in-use testing costs. The average annual cost of this program is 
estimated to be $80 million per year. This would be about 0.2 percent of the total freight revenue 
for railroads in 1995. The average cost-effectiveness of the standards is expected to be about $163 
per ton of NOx, PM and HC.
For More Information
The final rule and other documents on locomotives are available electronically from the EPA 
Internet server at:

http://www.epa.gov/OMSWWW/locomotv.htm

Document information is also available by contacting Russ Banush at:

U.S. Environmental Protection Agency
2565 Plymouth Road
Ann Arbor, MI 48105
(734) 668-4333