Investigating the impact of stochastic vehicle arrivals to optimal stop spacing and headway for a feeder bus route

Summary Stop spacing and service frequency (i.e., the inverse of headway) are key elements in transit service planning. The trade-offs between increasing accessibility and reducing travel time, which affect transit system performance, need to be carefully evaluated. The objective of this study is to optimize stop spacing and headway for a feeder bus route, considering the relationship between the variance of inter-arrival time (VIAT), which yields the minimum total cost (including user and operator costs). A solution algorithm, called successive substitution, is adapted to efficiently search for the optimal solutions. In a numerical example, the developed model is applied to planning a feeder bus route in Newark, New Jersey. The results indicate that the optimal stop spacing should be longer that those suggested by previous studies where the impact of VIAT was ignored. Reducing VIAT via certain operational control strategies (i.e., holding/stop-skipping, transit signal priority) may shorten stop spacing and improve accessibility.