Signal optimization for an isolated intersection with illegal permissive left-turning movement

摘要

Existing two-phase signal optimization models neglect the unyielding behavior of illegal permissive left-turners at intersections in many developing countries. At permitted left-turn phase warranted intersections, left-turn traffic usually needs to yield to the opposing through during permitted phasing; however, in certain circumstances such an explicit permissive left-turn yielding rule may be violated when aggressive left-turners compete with the opposing through vehicles to take the conflict point and pass through a two-phase signal-controlled intersection without yielding. Such driving behaviors, very commonly observed at urban intersections in many developing countries, have been demonstrated to have significant impact on the intersection operational performance, which has not been taken into consideration in the existing traffic signal design paradigms. This paper presents a cell-based signal optimization model for intersections without the explicit left-turn yielding rule during permitted phases. The model features its effectiveness to capture traffic dynamics and interactions between conflicting movements during permitted phases and to design appropriate signal timing plans to improve the operational performance of such intersections. Extensive experimental analyses and field validation in comparison with results from TRANSYT-7F demonstrate the promising property of the proposed model.