Bandwidth-Based Traffic Signal Coordination Models for Split or Mixed Phasing Schemes in Various Types of Networks

Bandwidth-based traffic signal coordination has long been an effective technique to make traffic flows within a network more efficient, smoother, and safer. Existing network bandwidth optimization models mainly focus on maximizing the bandwidth under NEMA phasing. The network bandwidth maximization under other typical phasing schemes, namely the split or mixed phasing, has not been intensively studied. To address this, a group of bandwidth-based network traffic signal coordination models is proposed for different types of traffic networks. All the proposed models can simultaneously optimize the key signal control variables, namely the phase sequences, offsets, and common cycle times. Additionally, all the developed models are formulated as mixed-integer linear programming problems, which guarantees that the global optimal solutions can be obtained using the branch-and-bound algorithm. The results of the presented index, which is defined as the absolute difference of the interference variables obtained through theoretical solutions and time–space diagrams, indicate that all the proposed models are correct. Furthermore, simulation results demonstrate that split phasing can significantly reduce the average delay time and the average number of stops compared with the existing NEMA phasing.