A Stochastic Programming Approach For Variable Message Signs Location Problem For Freeway Networks

With the rapidly growth of car ownership and traffic demand,various traffic problems are becoming increasingly serious.Highway traffic accidents have attracted considerable attention because of their sudden occurrence and high casualty rate.Variable message signs(VMS),as a common means of traffic guidance,have important applications in expressway traffic management system.To alleviate the congestion of freeway caused by accidents,this paper aims to optimize the location of VMS and the type of information release on the VMS to achieve the reasonable distribution of traffic flow on the road network and to improve the efficiency of traffic system.Focusing on accidents scenarios,we propose a heterogeneous VMS location problem based on a stochastic model of accidents on a freeway network.We consider both gantry and cantilever mounted VMS that display both passive and active real-time messages.The problem is formulated as a two-stage stochastic programming model.The first-stage model determines the location and type of VMS installation.The second-stage evaluates the performance of VMS location solutions by minimizing travelers’ travel time and penalty for misleading guidance.The model is reformulated as a large-scale 0–1 mixed integer linear programming(MILP)problem,which is difficult to get accurate solutions by traditional methods.The Benders decomposition method is utilized to decompose the model into master problem and sub-problem,and the exact solution of model is obtained with high efficiency.The Nguyen-Dupuis and Sioux-Fall networks are used to verify the effectiveness of the proposed models.The numerical experiments show that the VMS location model based on different accidents conditions has extraordinary adaptability for different road network.And the results can provide practical guidance to freeway administrators.Based on the scenario of portable variable message signs,this paper presents the research problem of the co-use of portable and fixed variable message signs,establishes the stochastic planning model and verifies it with Nguyen-Dupuis road network.The examples show the effectiveness of the model.When the accident has strong randomness,the use of portable variable message signs can greatly reduce the cost of intelligent guidance system.