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The Northeast has one of the most extensive public transportation networks in the United States.

Photo of a transit train.
  • Five of the 13 commuter rail systems in the United States are in the Northeast, accounting for 68 percent of the nation’s commuter rail traffic.
  • New York City and Boston have two of the nation’s largest transit systems, providing more than 8 million trips daily on buses, trains, boats, and para-transit networks.
  • Amtrak’s Northeast Corridor connects cities and towns from Maine to New Jersey and beyond. Rail often operates in densely populated urban areas where ozone levels consistently exceed the national health standard. With locomotives having useful lives of up to 40 years, programs to control emissions from trains are especially important in the Northeast.

Reducing Diesel Emissions from Transit

Nationally, more than 95 percent of public transit buses run on diesel. Northeast Diesel Collaborative partners employ the latest technologies and strategies to reduce diesel emissions from both on-road and rail commuting:

  • The entire transit bus fleets in Boston (980 buses) and New York (4,749 buses) have been replaced with cleaner vehicles or retrofitted with advanced emission control technology and switched to cleaner fuels.
  • A consortium of hospitals in Boston has retrofitted its shuttle bus fleet.
  • All of Boston’s diesel tourist trolleys have installed emission controls.
  • The Massachusetts Bay Transportation Authority (MBTA) is undertaking the first locomotive retrofit project in the nation, testing a diesel oxidation catalyst on one commuter train. The MBTA intends to retrofit 8-10 additional locomotives. In addition, all 55 commuter locomotives are already using lower sulfur diesel fuel.

Federal Regulations

Clean Diesel Trucks and Buses Rule

Emissions Standards for Locomotives:
In 2008, EPA finalized a new set of more stringent emission limits for locomotives, to be phased in over the next decade, which will result in locomotive engines that are 90% cleaner than today. This new rule also requires remanufactured locomotive engines to meet more stringent emissions standards than they were required to meet at the time of original manufacture.

State and Local Regulations

New Jersey
Emissions and Idling Controls: A3182 and SCR113, signed in September 2005, require emission controls on public transportation vehicles and garbage trucks. The law also requires installation of closed crankcase ventilation filters on school buses to reduce in-cabin emissions, as well as a study of how tailpipe emissions on school buses can affect the passenger compartment. If tailpipe emissions are found to be significant, then tailpipe emission controls will be required. The law also empowers local police to enforce idling prohibitions. In 2007, the New Jersey Department of Environmental Protection passed state regulations that operationalized the 2005 law.

Connecticut (pdf) (7.8 MB)
Clean Diesel Plan: In response to Special Act 05-07, signed into law in June 2005 by Governor M. Jodi Rell, the state Department of Environmental Protection developed a plan to reduce the impact of diesel emissions. The plan seeks to reduce fine particulate matter from diesel emissions from public transportation, school buses and construction equipment. The final report has been posted on the web at

Six of the eight Northeast states have anti-idling regulations:

Transportation Planning

In large metropolitan areas, Metropolitan Planning Organizations (MPOs) insure that expenditures for transportation projects and programs are based on a continuing, cooperative and comprehensive planning process. The US Department of Transportation requires MPOs to identify all proposed federally funded transportation improvement projects, as well as plan for the region's long-term transportation needs. Transportation projects included in these plans and programs cover various transportation modes and facilities, including transit equipment and services, roadways and bridges, bicycle and pedestrian facilities, safety improvements, and demand management programs.

Related Resources

No Escape from Diesel Exhaust: How to Reduce Commuter Exposure (Clean Air Task Force 2007) (pdf) (1.9 MB)
The Clean Air Task Force (CATF) investigated the levels of diesel particles during commutes in several cities. They found that regardless of how you get to work, there is no escape from exposure to diesel exhaust, and that pollution levels measured inside cars, buses, and trains during commutes were many times greater than levels in the outdoor air in these cities at that same time. The combined weight of scientific evidence from this CATF diesel exposure study along with the existing medical studies supports the conclusion that exposure to diesel exhaust during commutes poses a serious public health risk that needs to be addressed.