Analysis of different risk models for the hazardous materials vehicle routing problem in urban areas

The distribution of hazardous materials in urban areas is an important tactical and strategic decision problem. Reducing the transportation risk and increasing the traffic safety is also an important indicator for a sustainable transportation. For the last four decades, a multitude of approaches for risk assessment and modelling have been proposed. However, the majority of these approaches are focusing on different adaptations of shortest path problems. Risk modelling for routing and distributions problems, like the vehicle routing problem (VRP) have received far less attention, especially when the vehicle load is varying during a trip. This paper investigates how different factors are influencing the risk values and the outcomes of the hazardous materials vehicle routing problem (HMVRP). As foundation for the HMVRP, the path generation between the customer and the depot nodes in realistic urban road networks is considered. The influence of the fleet size is investigated. Different risk models are compared, with a special focus on the comparison of classical load-independent risk models with load-dependent risk models. Additionally, the tradeoff between risk minimization and the minimization of travelled distance is investigated. The results show, that these factors can have strong impact on the outcomes and lead to different "optimal" solutions.