Transportation network design considering travel time reliability

Fluctuations in roadway capacity due to non-recurrent traffic incidents is a source of uncertainty of travel time. Travel time reliability, as a transportation performance measure, which may reflect travel time uncertainty was applied to network analysis. Recently, research which applies network reliability concepts to transportation network design has been undertaken. In this study, a continuous network design problem (CNDP) with a travel time reliability constraint was formulated as a bi-level model. A simulation-based genetic algorithm with penalty method was used to obtain the optimal capacity enhancement of each link, combined with a routine which estimates travel time reliability under fluctuations of link capacity. The effect of the travel time constraint on a CNDP was analyzed through a numerical experiment using a simple network. Additionally, the effect of budget allocation and factors to be specified in the model on the results were analyzed.