DEVELOPMENT OF A SCOOTER-VEHICLE MIXED TRAFFIC SIGNAL OPTIMIZATION MODEL FOR URBAN ARTERIALS

Abstract

Despite the popularity of using scooters as one of the primary transportation modes in many developing countries, design guidelines or software for arterial signals accommodating heavy scooter-vehicle mixed flows are not available yet to date. Traffic professionals, suffering from the insufficient research on this subject, often have no choice but to apply existing signal models or simulation programs, developed mainly for passenger-car traffic flows, for intersections plagued by scooters’ complex lane-changing and filtering maneuvers. Hence, the purpose of this research is to address such imperative needs with a signal optimization model for arterials experiencing heavy scooter-vehicle mixed flows. The first part of this research is to conduct field observations on the complex interactions between scooter and vehicular flows from their discharging during a green phase to the formation/dissipation of stop queues at the downstream intersection. Based on the statistical analysis results, this study has further developed a series of concise formulations to illustrate the behavior of mixed traffic flows, including the estimation of discharging rates, lane choice decision, speed evolution, propagation to join the stop queues, and the filtering process by scooters. The second part of this research presents a simulation-based signal optimization model for arterials experiencing heavy scooter-vehicle flows. The proposed model consists of a macroscopic simulation and a signal optimization module, where the former, developed from empirical studies, functions to capture the interactions between the scooter and vehicular flows. The latter offers a specially-designed objective function and an algorithm to search for the optimal signal plan and arterial offsets, based on the complex traffic evolution patterns estimated with the simulation module. This study is expected to yield the following contributions: • Development of a scooter-vehicle mixed traffic model with respect to the evolution of mixed traffic flows from discharging, propagation, to the formation of queues at the downstream intersections. • Design of a signal optimization model for arterials experiencing heavy scooter-vehicle flows, which can account for their complex interactions in the evolution and filtering process.