Multi-modal traffic signal control with priority, signal actuation and coordination Qing He a,b , K. Larry Head c,⇑ , Jun Ding c a Department of Civil, Structural, and Environmental Engineering and Department of Industrial and Systems Engineering, University at Buffalo, The State University of New York, Buffalo, New York, 14260, United States b Environmental and Department of Industrial and Systems Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, United States c Department of Systems and Industrial Engineering, University of Arizona, Tucson, AZ 85721, United States article info Article history: Received 19 February 2014 Received in revised form 2 May 2014 Accepted 2 May 2014 Keywords: Traffic signal control Signal optimization Multi-modal traffic control Connected vehicles v2i Transit priority Pedestrian control abstract Both coordinated-actuated signal control systems and signal priority control systems have been widely deployed for the last few decades. However, these two control systems are often conflicting with each due to different control objectives. This paper aims to address the conflicting issues between actuated-coordination and multi-modal priority control. Enabled by vehicle-to-infrastructure (v2i) communication in Connected Vehicle Systems, priority eligible vehicles, such as emergency vehicles, transit buses, commercial trucks, and pedestrians are able to send request for priority messages to a traffic signal controller when approaching a signalized intersection. It is likely that multiple vehicles and pedestri- ans will send requests such that there may be multiple active requests at the same time. A request-based mixed-integer linear program (MILP) is formulated that explicitly accom- modate multiple priority requests from different modes of vehicles and pedestrians while simultaneously considering coordination and vehicle actuation. Signal coordination is achieved by integrating virtual coordination requests for priority in the formulation. A pen- alty is added to the objective function when the signal coordination is not fulfilled. This ‘‘soft’’ signal coordination allows the signal plan to adjust itself to serve multiple priority requests that may be from different modes. The priority-optimal signal timing is respon- sive to real-time actuations of non-priority demand by allowing phases to extend and gap out using traditional vehicle actuation logic. The proposed control method is compared with state-of-practice transit signal priority (TSP) both under the optimized signal timing plans using microscopic traffic simulation. The simulation experiments show that the pro- posed control model is able to reduce average bus delay, average pedestrian delay, and average passenger car delay, especially for highly congested condition with a high fre- quency of transit vehicle priority requests. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Modern urban transportation networks involve complex traffic dynamics composed of multiple travel modes, including passenger cars, transit buses, pedestrians, bicycles, trucks, light rail, emergency vehicles, and commercial and private modes of transportation. Traffic signal control systems traditionally treat either the aggregated flow of traffic or each mode http://dx.doi.org/10.1016/j.trc.2014.05.001 0968-090X/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +1 520 621 2264; fax: +1 520 621 6555. E-mail addresses: qinghe@buffalo.edu (Q. He), klhead@email.arizona.edu (K.L. Head), dingjun@email.arizona.edu (J. Ding). Transportation Research Part C 46 (2014) 65–82 Contents lists available at ScienceDirect Transportation Research Part C journal homepage: www.elsevier.com/locate/trc