An Optimization Model for the Integration Design of Signal Timing Plan and Lane Allocation Pattern at Signalized Intersections

An Optimization Model for the Integration Design of Signal Timing Plan and Lane Allocation Pattern at Signalized Intersections


W Ma, Citilabs, Inc., US



With increasing traffic on major roads controlled by traffic signals, many problems have become common, specifically during periods of peak demand. In most urbanized settings worldwide, drivers have become accustomed to undesirable congestion and excessive delay. For traffic engineers and transportation researchers, signal timing and lane allocation are most important settings at signalized intersections to control the operation. Efficiently operated traffic signals and reasonably designed lane markings can reduce congestion and bring about significant payoffs in time and energy benefits. Nowadays, it is difficult to widen existing roads or build new roads in urban areas to improve the service of traffic networks. Better utilizing the existing traffic facilities is the only reasonable answer to most of the traffic congestion problems. The need for efficient traffic signal operation and lane allocation has never been more important.

The design of signal timing plan and lane allocation pattern should be complementary to each other. An efficient signal timing plan should be based on a reasonable lane allocation pattern, and vice versa; otherwise, it would not really help to improve the operation service. Existing research works have been concentrated on signal optimization, where several models have been developed such as delay-based models and bandwidth-based models. On the other hand, research on the optimization of lane allocation is quite limited. Few researches have been addressed on an integration design of signal timing and lane pattern.

This paper proposed an optimization model for the integration design of signal timing and lane pattern at signalized intersections. A Genetic Algorithms (GA) model is developed and validated with the Cube transportation software suites. The decision signal variables including cycle length, phase durations, phase sequence and permitted movements; the decision lane allocation variables including number of exclusive lanes and shared properties for each movement. A full optimized intersection design can be generated according to the assigned traffic flows and geometric properties at the intersection. A set of constrains are set up to guarantee feasibility of the optimal signal timing and lane pattern design. Examples are given to demonstrate the rationality and efficiency of the proposed model.


Association for European Transport