Modeling Bus Priority Using Intermodal Dynamic Network Assignment-Simulation Methodology

This article presents a modeling framework that represents bus priority at signalized intersections in the context of its potential network-level and intermodal effects. The model incorporates bus priority within an intermodal dynamic traffic assignment simulation model. It dynamically assigns travelers to different modes and routes in the network according to prevailing traffic conditions, which result from applying a certain network control/bus priority scheme. The model considers changes in traffic conditions as a result of (1) drivers’ route choice adjustments due to changes in traffic signals settings and (2) modal shifts by travelers to take advantage of improved transit service. Three different bus priority strategies are considered: phase (green) extension, red truncation, and phase advance. A set of simulation experiments is performed to compare these strategies using two different assignment scenarios: single-mode assignment and intermodal assignment. The results of these experiments highlight the importance of considering reassignment and potential modal shifts in evaluating traffic network performance under different control schemes, especially when these schemes are expected to affect the modal split in the network such as bus priority.