Comparisons of Discretionary Passenger Vehicle Idling Behavior by Season and Trip Stage with Global Positioning System and Onboard Diagnostic Devices

This study addresses the comparisons of discretionary passenger vehicle idling by using field data collected from 20 volunteers in Vermont. Each volunteer participated in two 2-week data collection periods, one in the summer and one in the winter. Overall, 15.6% of vehicle-operating time was spent idling, consistent with the limited existing data on this topic. In addition, the paper describes a processing method used with an in-vehicle Global Positioning System and onboard diagnostic data that allows discretionary idling at the start and end of trips to be separated from the in-travel idling related to traffic or traffic control. Discretionary idling accounted for more than 6.5% of vehicle operating time. Discretionary winter idling events were found to be longer than summer idling events and, for idling events greater than 60 s, trip-start idling was found to be longer than trip-end idling. Both of these results reaffirm previous findings suggesting that there are opportunities for behavioral changes to reduce idling. The method used to extract discretionary idling is promising for widespread use and large sample data collection efforts. This method will be critical for the many communities that lack robust idling data when considering the costs and benefits of idling behavior change initiatives.