Shockwave-Based Queue Length Estimation Method for Presignals for Bus Priority

This paper presents a shockwave-based method for estimating queue length associated with presignals for bus priority. Both queue length at presignals and main signals arc estimated by the proposed method. In this study, we first analyze traffic operations with the implementation of presignals for bus priority using shockwave theory. On this basis, queue length at presignals and main signals are estimated for eight cases in which a bus arrives at different times during a traffic signal cycle. Detailed comparisons of queue length estimated by shockwave theory and that obtained by a cellular-automaton-based simulation are made from the shape of the fundamental diagram (triangular and concave), areas (upstream of the presignal and between the presignal and the main signal), bus arrival scenarios (bus is not present and bus is present), and bus arrival times (during the red presignal and during the green presignal). Simulation experiments show that the proposed shockwave-based method is effective in estimating queue length associated with presignals for bus priority in all cases. The efforts are made to provide the basis for evaluating the performance of intersections with presignals for bus priority implemented and designing sorting area for presignals for bus priority. (C) 2018 American Society of Civil Engineers.