Routing of hazardous materials in the presence of weather systems

Shipment of hazardous materials exposes risk to the public in case of an accident. Even though the frequency of such accidents and fatality rates are very low, such incidents are not acceptable to the public. This provides a challenge and an opportunity for quantitative analysis to make a contribution to the solution of hazardous material (hazmat) logistics problem.; Unlike traditional shortest path applications, routing decisions for hazmat, are highly sensitive to curfews, time of day constraints, location of emergency response units, and atmospheric conditions. They dynamically affect the accident probabilities, risk, equity and cost of the route(s) selected.; This study focuses on the effects of weather systems on hazmat routing and develop models for routing decisions in the presence of such systems. Existence of weather systems on the network affect the accident probability and travel speed on the links as a function of time. There are two ways to address this problem: (i) having spatially dissimilar alternate paths for shipments so that the areas affected by the weather systems could be avoided by selecting a different route, and (ii) finding the optimal route by incorporating the affects of weather systems directly into the problem.; First, the problem of finding a number of spatially dissimilar paths between an origin and a destination on a given a transportation network is considered. A critical discussion of three existing methods for the generation of spatially dissimilar paths is offered, and computational experience using these methods is reported. An alternative method, which includes the generation of a large set of candidate paths and the selection of a subset using a dispersion model, is proposed.; Second, analysis of a single link network in the existence of a dynamic weather system is done to determine the time dependent attributes of the link. This analysis is then used as a building block for the problem of finding the preferred path(s) for hazardous material transportation in the existence of weather systems. An exact algorithm and several heuristic methods are offered to solve the underlying problem.; Finally, conclusions of these procedures are summarized and issues and future research directions in the time-dependent routing of hazardous materials are identified.