Deriving Local Operating Distributions to Estimate Transit Bus Emissions Across an Urban Network

Abstract

In a 6-week data collection campaign, instantaneous bus speeds and ridership data were collected onboard 96 buses operating over 3,700 road links. Emissions were estimated by using the Motor Vehicle Emission Simulator 2014 version (MOVES2014). The effects of bus type and passenger load were explicitly accounted for in the emissions estimation process. The resulting emissions figures exhibit networkwide variations across different time periods, directions, land uses, passenger ridership figures, and transit service. Per passenger emissions data highlight the importance of considering onboard passenger weight in the estimation process. These results are relevant to transit planners who are evaluating plans to modify or introduce bus routes. This study also demonstrated a process in which local operating mode distributions were generated and specific drive cycles were developed for different average speeds and then were embedded into the MOVES2014 database. A validation test suggested that emissions figures derived using the locally developed operating mode distributions were better than and largely different from the emissions figures obtained using the MOVES default distributions. These embedded drive cycles could be useful when instantaneous speed information is unavailable, especially when developing a regional inventory for bus emissions in Montreal, Canada.