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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Study of Alternatives to Reduce Driver Exposure to Diesel Exhaust


To study the efficiencies of different idle reduction technologies and to compare their short- and long-term economic costs. The goal is to reduce the amount of diesel emissions that enter a truck cab and to improve air quality in the cab while a driver is resting in a sleeper berth at a truck rest stop.


Previous Federal Motor Carrier Safety Administration (FMCSA) research measured air pollution inside truck cabs and sleeping berths while vehicles were idling at a truck stop. The study found that pollution inside truck cabs exceeded the U.S. Environmental Protection Agency (EPA) National Ambient Air Quality Standards. The pollution was worse when trucks were idling. Of all the pollutants from diesel exhaust, particle matter of 2.5 microns (PM 2.5) or less poses the greatest health risks for truck drivers. Potential adverse health effects include asthma, lung cancer, cardiovascular issues, and premature death. Therefore, reducing the idling of diesel engines is a critical factor to driver health. Following FMCSA’s initial study, the Agency was determined to conduct a new study to analyze the efficiencies of idle reduction technologies for trucks and to compare their economic costs in order to reduce driver exposure to diesel exhaust and maintain driver wellness and health.


This research project focused on diesel particulate matter, which was the pollutant of concern. The following idle reduction technologies were considered: automatic shut-down/start-up systems; auxiliary power units; battery air conditioning systems; electrified parking spaces; filtering devices; fuel-operated heaters; shore connection systems; and thermal storage systems. The effort also took into account the different categories of model year engines (i.e., 1990 and earlier, 1991‒1993, 1993‒2007, and 2008 and later).


Final report compiling the results of the study.


July 2015: Kick-off meeting
October 2015: Literature review and analysis
November 2015: Proposed research methodology
December 2015: Peer review of the research methodology
December 2015: Final methodology
January 2016: Begin execution of the research methodology
September 2016: Peer review of the draft final report
October 2016: Final briefing


FY 2015: $481,078

Current Status



University of Michigan Transportation Research Institute, Texas A&M Transportation Institute, and Georgia Institute of Technology.