Bandwidth Maximization Approach for Displaced Left-Turn Crossovers Coordination under Heterogeneous Traffic Conditions

Abstract

As one of the UAIDs (unconventional alternative intersection designs), DLTs (displaced left-turn crossovers) have been presented to mitigate traffic congestion. Although, qualitatively and quantitatively isolated UAIDs outperform their conventional counterparts, there is no simplified procedure to consider the DLTs coordination. Hence, this research investigates the coordination of consecutive DLTs under heterogeneous traffic conditions. To achieve the optimal coordination and provide an efficient coordination control, a bandwidth maximization progression approach was used. Seeking the optimal offset for each pair of consecutive intersections to guarantee the green bandwidth waves along the coordinated corridor, a mixed-integer linear program was adopted. The optimization problem was formulated and solved based on the standard branch-and-bound technique. As a real-world study case, data of three typical intersections located in an arterial corridor in Cairo, Egypt was used. PTV-VISSIM as a microsimulation platform was employed to simulate and evaluate the different signal timing plans. However, to represent the heterogeneous traffic characteristics as close as possible to the reality, different simulation parameters were tuned and validated carefully. The results emphasized the undoubted improvement of coordinated DLTs by different operational performance indices. The total travel time, average delay, the number of stops per vehicle were obviously improved.