Design and Evaluation of Impact of Traffic Light Priority for Trucks on Traffic Flow.

摘要

Current traffic light control systems treat all vehicles the same. Trucks however have different dynamics than passenger vehicles. They take a longer distance to stop, have lower acceleration rates, have bigger turning rates that cause bigger traffic disturbances consume more fuel and pollute more. These dynamic differences create delays at intersections that affect the travel time of all vehicles involved and may have a negative effect on the environment if not taken into account by traffic control systems. In this report the authors consider the problem of taking into account the presence of trucks in controlling the traffic lights at intersections with the objectives of minimizing delays for all vehicles involved and reducing pollution. The problem was motivated from the observation that in many cases it is better for all vehicles involved to extend the green cycle in order to have a heavy truck cross instead of forcing it to stop and restart again. The system is similar to the bus priority system that currently operates in many cities except that in the case of trucks the objective involves benefits for all vehicles than just the trucks involved. We proposed two different controllers for the truck signal priority problem: a neural network-based controller and one based on integrated priority strategies. The first controller is based on the use of a neural network approach to model the vehicle delays by distinguishing between different classes of vehicle and the use of optimization to reduce the vehicle delays by properly controlling the lights. The controller is adaptive since the delay prediction model is updated once new data is obtained from the infrastructure. The second controller is similar to the bus priority traffic light approach and uses a combined passive and active strategy in order to minimize delays. The similarity with bus priority is that it gives priority to trucks in certain situations if such an action benefits the overall system. In the case of bus priority the objective is to give priority to busses without optimizing for the delays of all vehicles involved. Both controllers have been evaluated using a microscopic traffic flow model for a single intersection and a network of intersections.