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Exhaust emissions from transit buses have long been a concern for air quality officials. Agencies have been investing millions of dollars in advanced and clean fuel technologies to reduce emissions from their bus fleets. Generally, the only information available about the emission characteristics of these vehicles comes from expensive engine- and chassis-dynomometer tests. Relatively little is known about actual on-road performance, especially as vehicles age. To help fill this void, M.J. Bradley and Associates has been working with the Massachusetts Bay Transportation Authority (MBTA) in Boston to develop an emissions inspection and maintenance (I/M) program for heavy-duty vehicles.
The MBTA is the nation's 5th largest mass transit system. In addition to operating subway, trolley and commuter rail service, the MBTA operates 1,000 forty- and sixty-foot urban transit buses in fixed route service on approximately 190 routes throughout greater metropolitan Boston.
M.J. Bradley & Associates, working with a team of consultants, evaluated several options for cost-effective emissions testing and designed the procedures for implementing an enhanced I/M program. The project involved significant community outreach with a Project Advisory Committee overseeing the effort. The final project report recommended that the MBTA use remote sensing technology as a screening tool to identify high emitting buses, and a Portable Emissions Monitoring System (PEMS) to diagnose certain engine problems.
Having completed the evaluation phase of the project, the MBTA is now in the process of implementing the program throughout its fleet, including quarterly emissions fleet screening of every bus housed at each of the eight MBTA bus garages to identify buses with higher than normal emissions and a program to repair buses identified as high emitters. M.J. Bradley and Associates continues to be involved in this effort.