New Methodology to Calculate Unblocked Reliability to Assess Road Network Operation Performance

Abstract

This paper presents a new methodology to calculate unblocked reliability of a road network. Unblocked reliability analysis is used to assess the operation performance of a road network at peak hour in order to support the decision-making involved in road network planning. A four-level model of road network unblocked reliability (link, path, Origin-destination pair and whole network) is shown to assess the operation performance of each level of the road network. A method of sensitivity analysis is provided to determine the priority of the road section in the planning scheme. However, the most difficult task in unblocked reliability analysis is how to find a route choice pattern, namely, which routes are selected and how proportions of Origin-destination flows are loaded on these used routes between every Origin-destination pair. In order to resolve this problem, a new traffic assignment method is proposed in this paper based on the Frank-Wolf algorithm. This algorithm not only can find the link flows but can also solve the route choice pattern, which satisfy the User Equilibrium criterion. The proposed methodology is applied to solve the goal of traffic demand control and the necessary road capacity when a road network is improved to the expected operation performance. The proposed methodology provides a useful tool to assess the operation performance of a road network at several levels of road capacity and traffic demand, and can be used to evaluate various road network planning and to design a reliable road network system.