Dynamic transit lanes for connected and autonomous vehicles

Abstract

Transit lanes provide dedicated right-of-way to transit vehicles, but reduce the number of lanes available to other vehicles. Several studies have implemented intermittent bus lanes, which are sometimes reserved for transit but otherwise are available for general traffic. However, their efficiency suffers from the difficulties of communicating accessibility to drivers. We extend this concept by proposing dynamic transit lanes for connected autonomous vehicles, in which infrastructure continuously updates vehicles on lane accessibility. We present a cell transmission model of dynamic transit lanes in which the number of lanes available to general traffic changes in space and time in response to the presence or absence of transit vehicles. In order to extend the concept of transit signal priority in the context of connected autonomous vehicles and integrate it with dynamic transit lanes, we also modify the reservation-based intersection control system for autonomous vehicles to prioritize transit. Numerical results from small test cases show that the dynamic transit lanes and transit intersection priority allow transit to move nearly at free flow on the corridor despite congestion. Results from the downtown Austin city network using dynamic traffic assignment show that both transit and general traffic would experience significant benefits in realistic settings.