Dwell Time Estimation with Consideration of Bus Bunching

Dwell time has been generally accepted as a major factor causing bus bunching, but there is seldom any research on the effect of bus bunching on dwell time. In previous research, the bunched buses were generally considered from the same bus route; however, there are cases where the bunched buses come from different bus routes. In this research, bus bunching at a bus stop is defined as buses stuck together at the stop, no matter whether from the same bus route or different bus routes. To test and verify the effect of bus bunching factor and different passenger demand variables on dwell time, two groups of regression models for dwell time estimation were proposed, with or without considering bus bunching factor. Using manual collected data, comparisons were made among models in the same group to measure the effect of different passenger demand variables on dwell time estimation, and between the corresponding models from the two different groups to identify the effect of bus bunching factor on dwell time estimation. The results show that bus bunching does have a significant effect on dwell time. When a vehicle is bunched with its previous vehicle at a bus stop, the overall dwell time of its followed vehicles could increase by 4.223 to 6.225 seconds. The regression results also suggest that the sum or the maximum of boarding and alighting passengers has a more significant effect on dwell time than the number of boarding or alighting passengers.