An integrated location and routing approach for transporting hazardous materials in a bi-modal transportation network

This article considers how best to strategically transport and route hazardous materials through a bi-modal transportation network (MMTS) consisting of road and rail links. The placement of transfer yards is also considered as well as the possibility of disruptions at those facilities. For this decision problem a two-stage stochastic programming model is formulated. The objective of the model is to minimize transportation costs and risk. As the model is intractable to solve using traditional techniques, three algorithms are proposed, namely Maximum Likelihood Sampling (MLS), Sample Average Approximation (SAA), and a combination of these two algorithms (MLSAA). Those optimization approaches have been applied to various instances to demonstrate their viability and effectiveness. Numerical testing shows that the MLSAA algorithm is superior and can solve large-scale instances

An Integrated Approach for Reliable Facility Location/Network Design Problem with Link Disruption

Proposing a robust designed facility location is one of the most effective ways to hedge against unexpected disruptions and failures in a transportation network system. This paper considers the combined facility location/network design problem with regard to transportation link disruptions and develops a mixed integer linear programming formulation to model it. With respect to the probability of link disruptions, the objective function of the model minimizes the total costs, including location costs, link construction costs and also the expected transportation costs. An efficient hybrid algorithm based on LP relaxation and variable neighbourhood search metaheuristic is developed in order to solve the mathematical model. Numerical results demonstrate that the proposed hybrid algorithm has suitable efficiency in terms of duration of solution time and determining excellent solution quality