OPTIMIZING CAPACITY RELIABILITY AND TRAVEL TIME RELIABILITY IN THE NETWORK DESIGN PROBLEM

Capacity reliability is concerned with the probability that the network capacity can accommodate a certain travel demand at a required level of service; while travel time reliability is concerned with the probability that a trip between a given origin-destination (O-D) pair can be made successfully within a specified interval of time for a given level of travel demand in the network. Both are useful performance measures that can describe the supplyside reliability and demand-side reliability of a road network. In this paper, we propose a biobjective reliable network design problem (BORNDP) model that explicitly considers these two interdependent reliabilities under demand uncertainty. A simulation-based multi-objective genetic algorithm (SMOGA) solution procedure, which consists of a traffic assignment algorithm, a genetic algorithm, a Pareto filter, and a Monte-Carlo simulation, is developed to solve the proposed BORNDP model. A numerical example based on the capacity enhancement problem is also presented to demonstrate the tradeoff between capacity reliability and travel time reliability in the network design problem.