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Locomotive engines are significant contributors to air pollution in many of our nation's cities and ports. Although locomotive engines being produced today must meet relatively modest emission requirements set in 1997, they continue to emit large amounts of nitrogen oxides and particulate matter (PM), both of which contribute to serious public health problems.

In May 2004, as part of the Clean Air Nonroad Diesel Rule, EPA finalized new requirements for nonroad diesel fuel that will decrease the allowable levels of sulfur in fuel used in locomotives by 99 percent. These fuel improvements will create immediate and significant environmental and public health benefits by reducing PM from existing engines.

In March 2008, EPA finalized a three part program that will dramatically reduce emissions from diesel locomotives of all types -- line-haul, switch, and passenger rail. The rule will cut PM emissions from these engines by as much as 90 percent and NOx emissions by as much as 80 percent when fully implemented.

This final rule sets new emission standards for existing locomotives when they are remanufactured--to take effect as soon as certified systems are available, as early as 2008. The rule also sets Tier 3 emission standards for newly-built locomotives, provisions for clean switch locomotives, and idle reduction requirements for new and remanufactured locomotives. Finally, the rule establishes long-term, Tier 4, standards for newly-built engines based on the application of high-efficiency catalytic aftertreatment technology, beginning in 2015.

This page provides general and technical information on the locomotive rulemakings that affect railroads, locomotive manufacturers, and remanufacturers.

NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.

Regulations and Guidance

See the electronic Code of Federal Regulations (e-CFR) for the full text of current regulations that apply to locomotives. The documents related to the rulemaking that established these provisions are available below.

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For more information, please email EPA's Assessment and Standards Division (asdinfo@epa.gov) or call the Assessment and Standards Division voicemail at 734-214-4636.

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This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
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