Evaluation of Transition Methods of the 170E and 2070 ATC Traffic Controllers after Emergency Vehicle Preemption

Abstract

Modern traffic signal control systems provide emergency vehicle preemption (EVP) capabilities using advanced sensors and communication technologies. While EVP strategies have been widely implemented by urban transportation management agencies, few research efforts have studied the transition methods employed after EVP operations. This paper presents comprehensive evaluations of EVP transition operations, considering both exit phase control and transition methods under three different traffic volume conditions. The research employed hardware-in-the-loop simulation, which provides a more realistic evaluation environment because it incorporates actual signal controllers into the simulation. The evaluation results at a coordinated-actuated signalized intersections in Northern Virginia indicated that: (1) performance measures varied significantly depending on the EVP transition methods; (2) shortway in the 170E controller and smooth in the 2070 ATC controller generally outperformed the other transition methods; and (3) the use of exit phases—available in the 2070 ATC controller—provided significant benefits over the 170E controller.