Mitigating Excessive Idling of Transit Buses

In recent years much media attention has been paid to research developments related to three types of diesel vehicles: school buses, long-haul trucks, and transit buses. Transit bus emissions studies often gain attention because the public wants to know whether transit agencies are spending public dollars efficiently and with concern for public health. The public health and environmental effects of transit bus idling and strategies to mitigate idling practices need to be understood. Most transit bus idling is considered nondiscretionary and occurs while a bus is stuck in traffic or making a stop along its route. However, in some scenarios transit buses idle unnecessarily. Although many solutions exist to limit idling, these solutions have not garnered much interest from transit agencies, researchers, or lawmakers. This paper will review the causes and effects of transit bus idling and examine the potential costs and benefits of using idling reduction technologies and policies on the bus fleet of a large metropolitan transit agency in the Midwest to limit fuel consumption and emissions. The paper is organized as follows: Economic, environmental, and health effects of diesel emissions are discussed in the introductory section, as is current anti-idling public policy. The research methodology is described, and causes of excessive bus idling at the Chicago Transit Authority in Illinois are discussed, as are potential solutions. Idling reduction technologies are examined to determine which provides the greatest economic and environmental benefit for the lowest cost. The paper concludes with specific recommendations for the Chicago Transit Authority.