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October 16, 2017   |   Diesel Technology Forum

Policy Insider

The Fast Track to Clean Air with Clean Diesel Locomotives

New Tier 4 locomotives are already at work around the country to reduce emissions and improve efficiency and performance.

Rail transportation is vital to the U.S. economy. Freight train engines rely almost exclusively on diesel and haul roughly one-third of the freight in the U.S. Commuters in cities across the country rely on America’s railroads every day.

The diesel industry and rail manufacturers continue to invest resources and make strides toward producing the cleanest train technology possible. Diesel engine technology in railroad locomotives has advanced dramatically in recent years to meet the stringent U.S. EPA Tier 4 emissions standards. Tier 4 compliant engines significantly reduce emissions of particulate matter (PM) and oxides of nitrogen (NOx) to near zero levels. Relative to previous emissions standards, Tier 4 compliant engines reduce emissions by over 95 percent for most agricultural and construction equipment and just over 86 percent for much larger applications like locomotives and marine vessels.

This new technology can also be used to replace or repower California’s largest and oldest locomotive engines and would yield immediate and significant NOx benefits at the lowest cost per ton, compared to electrification and other as-yet commercially widespread technologies.

States are gearing up now to decide how to invest their share of the $2.9 billion VW Environmental Mitigation Trust and applying VW settlement funds and carbon auction revenue to rapidly reduce emissions of oxides of nitrogen (NOx) that contribute to ground level ozone, or smog. The emission reductions from replacing just one of the oldest locomotive engines removes 37,602 lbs. of NOx a year and is equivalent to replacing 29 older trucks or removing 30,000 cars from the road for one year.

Big Engine Locomotives

New Tier 4 locomotives are already at work around the country to reduce emissions and improve efficiency and performance.

At Metrolink, a Southern California commuter rail service, a new Tier 4 clean diesel F125 locomotive, built by Caterpillar, Inc., will begin taking passengers in late October. By next year, Metrolink will have placed 40 new locomotives in service, nearly replacing its entire fleet of 55. When all 40 are running, it will mean the equivalent of removing the annual emissions of 31,320 vehicles on roadways, Metrolink estimated.

Amtrak recently unveiled 33 new higher-speed passenger locomotives that were manufactured by Siemens at its manufacturing hub in Sacramento, CA and powered by a Midwest-made 4,400 horsepower Cummins QSK95 diesel engine.

These new locomotives meet the highest federal environmental standards, meaning a 90 percent reduction in emissions and a reduction in fuel 

Diesel hybrid innovations are offering even more fuel savings and reduced emissions. MTU combines a diesel engine and an electric motor and battery storage in the newly developed MTU PowerPack battery system. The hybrid system converts braking power into electricity which is then stored in the battery pack, giving operators fuel savings as high as 25 percent, much lower emissions, quieter trains and shorter journey times.


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Ezra Finkin
Director, Policy

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