Network design problem considering system time minimization and road safety maximization: formulation and solution approaches

This paper discusses the network design problem (NDP), solved for travel time minimization and road safety maximization. Similarly to other NDP models, the model is formulated as a bi-level multi-objective optimization problem. The estimation of the system time benefit and safety benefit is performed using previously developed methods. Two different approaches are applied and discussed for solving the problem: the constrained multi-objective optimization and the multi-objective genetic algorithm. Both approaches are tested on a real-size network, using a large set of candidate projects. The paper presents a discussion regarding the different optimal solutions obtained, emphasizing the relative attractiveness of the candidate projects.