Using CVIS to process the concurrent signal priority requirements: A cooperative optimization model and its hardware-in-the-loop field tests

Various signal priority models have been proposed for different types of special vehicles (e.g. emergency vehicles or buses). However, they are generally difficult to be compatible for each other and fail to be used in one road network. In this paper, a cooperative optimization model is proposed to process concurrent priority requirements in traffic signal control. First, the standard of the priority requirements is unified so as to enable the concurrent processing. And a signal optimization model is proposed to coordinate the conflicting requirements. The strategy relies on real-time location and speed adaption of vehicles provided by CVIS (cooperative vehicle infrastructure system). A HIL (hardware-in-the-loop) field test was conducted to evaluate the developed strategy and the results are encouraging.