The vehicle routing and scheduling problem has been studied with much interest within the last four decades. In this paper, some of the existing literature dealing with routing and scheduling problems with environmental issues is reviewed, and a description is provided of the problems that have been investigated and how they are treated using combinatorial optimization tools.
As the risk is a part of the objective function, it is quantified with a path evaluation function @cite_89 . This function is not additive since the probability of a release accident on a link depends on the probability of a release accident on the traveled links of the path. This important property leads to non-linear integer formulations which can not optimized using a classical shortest path algorithm. Generally approximations are needed by considering additive functions (Usually considering independent release accident probabilities on links) for obtaining tractable models.
@cite_89
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The transport of hazardous materials is an important strategic and tactical decision problem. Risks associated with this activity make transport planning difficult. Although most existing analytical approaches for hazardous materials transport account for risk, there is no agreement among researchers on how to model the associated risks. This paper provides an overview of the prevailing models, and addresses the question "Does it matter how we quantify transport risk?" Our empirical analysis on the U.S. road network suggests that different risk models usually select different "optimal" paths for a hazmat shipment between a given origin-destination pair. Furthermore, the optimal path for one model could perform very poorly under another model. This suggests that researchers and practitioners must pay considerable attention to the modeling of risks in hazardous materials transport.