Impact of Diurnal Changes in Truck Speed on Roadway Emissions Calculated with MOBILE6.2

摘要

Most on-road mobile source emissions analyses conducted for State Implementation Planinventories and project-level analysis use daily average estimates of fleet mix (vehicle milestraveled by vehicle type). However, in many cases, the fraction of traffic represented by heavytrucks is lower during the daytime, especially during peak periods, and higher at night. Roadwayoperating speeds also vary by time of day. Thus, use of a daily average estimate of fleet mix,including truck fractions, does not accurately characterize the speeds at which trucks actuallyoperate. Improving the characterization of truck activity could be important for inventory andproject-level analysis applications, since trucks contribute a large portion of on-road emissions.This paper examines the emissions impact of using changes in fleet mix to create truck-specifichourly speed distributions for use in MOBILE6.2.