The Gateway Location Problem for Hazardous Material Transportation

This paper introduces a new combinatorial optimization problem, arising in the framework of risk mitigation strategies for hazardous material routing. The strategy consists of imposing check points along the routes, so called gateways, and forcing each carrier to detour by a specific gateway on its route from origin to destination. Each carrier will select the minimum cost detour by the assigned check point, according to a rationale behavior. The problem faced by the administrator is to select the location of a given number of check points on the network, and to select which check point has to be assigned to each carrier, so that carrier responses will minimize total risk. We provide a bilevel multicommodity flow formulation for this problem, and we show how to reformulate it as a single level MILP by exploiting linear duality. Computational results on realistic instances taken from the literature assess the efficacy of the gateway based strategy.