Stochastic Flow Models with Delays and Applications to Multi-Intersection Traffic Light Control

Abstract

We extend Stochastic Flow Models (SFMs), used for a large class of discrete event and hybrid systems, by including the delays which typically arise in flow movement. We apply this framework to the multi-intersection traffic light control problem by including transit delays for vehicles moving from one intersection to the next. Using Infinitesimal Perturbation Analysis (IPA) for this SFM with delays, we derive new on-line gradient estimates of several congestion cost metrics with respect to the controllable green and red cycle lengths. The IPA estimators are used to iteratively adjust light cycle lengths to improve performance and, in conjunction with a standard gradient-based algorithm, to obtain optimal values which adapt to changing traffic conditions. We introduce two new cost metrics to better capture congestion and show that the inclusion of delays in our analysis leads to improved performance relative to models that ignore delays.1. E i : x i (t) switches from > 0 to = 0, thus ending a NEP at queue i.

Estimating the Critical Density of Road Transportation Networks using Infinitesimal Perturbation Analysis of Hybrid Systems

“…Work in transportation networks employing the SFM framework and IPA analysis including [10], [11] try to solve the traffic-light control problem for a single intersection. A recent work presented in [12] extended the aforementioned approaches to multiple intersections.…”