Experimental estimation of the impact of advance time on the efficiency of a coordination plan

Abstract

The article examines the pressing issue of enhancing the efficiency of coordinated urban traffic control systems through the consideration of advance time required for the acceleration of additional vehicles accumulating in front of the stop line at successive intersections in a coordination plan. In contrast to foreign practices of implementing adaptive traffic control systems, under Ukrainian conditions, financial and infrastructural constraints dictate that coordinated signal control (green wave) remains the primary instrument for effective traffic control in cities. Existing methods for designing coordination plans do not account for the influence of additional vehicles emerging from secondary approaches to coordinated intersections, nor the time required for queues to accelerate to the speed of the main traffic flow. This reduces the overall efficiency of coordination and makes it impossible to ensure the smooth flow of vehicles along coordinated arterials. The challenge of defining and integrating advance time into coordination models remains unresolved despite numerous efforts aimed at optimizing the bandwidth of the green wave and harmonizing traffic flows speed. To provide an experimental estimate of the impact of advance time on coordination plan efficiency, a simulation model of a coordinated arterial segment was developed in the VISSIM, based on the case study presented in HCM 2016. The variable parameter of the model was advance time. Simulation results revealed that the average travel time along the arterial decreases as advance time increases up to six seconds, whereas further increases beyond this threshold lead to a sharp deterioration of traffic conditions on secondary approaches. These findings highlight that incorporating advance time into coordination plan can significantly improve the performance of primary traffic flows within the green wave. At the same time, the results emphasize the necessity of continuous monitoring of traffic demand on secondary approaches to avoid excessive delays and ensure balanced efficiency of the overall traffic control system.

Key words: traffic control, coordination plan, signalized intersections, traffic simulation, advance time, VISSIM.