Passenger Waiting Strategies for Overlapping Bus Routes

Transit passengers in many urban areas must deal with overlapping bus routes with some routes sharing common stops. Such a passenger can decide either to board an arriving bus or wait for a faster bus---one which will have a shorter in-vehicle travel time. The purpose of this paper is to clarify this route-choice problem using mathematical formulations of passenger waiting times. First an analysis of previous research is carried out based on a field-verified formulation between the variance and the mean of the bus headway and on two headway distribution families. Second, probabilistic mathematical formulations are developed, and an interpretation of the problem is presented. In this second part, overlapping routes are categorized as slow or fast routes, and the proportion of passengers selecting each type of route is derived. The results concerning the route-choice strategies show that an optimal strategy might be to disregard an arriving slow bus. In this case the passenger should wait for a fast bus while disregarding slow buses arriving in the meantime. The results concerning the two route categories show that the intuitive rule in which passengers board the routes in proportion to their frequencies is not a good approximation in all cases, and it can be revised in accordance with this analysis. In addition, this research constructs a framework to consider further aspects of passenger behavior at urban bus stops.