A SIMHEURISTIC FOR THE STOCHASTIC TWO-ECHELON CAPACITATED VEHICLE ROUTING PROBLEM

Two-echelon distribution systems are very common in last-mile supply chains and urban logistics systems. The problem consists of delivering goods from one depot to a set of satellites usually located outside urban areas and from there to a set of geographically dispersed customers. This problem is modeled as a two-echelon vehicle routing problem (2E-VRP), which is known to be computationally difficult to solve. This paper proposes a solution approach based on optimization-simulation to solve the 2E-VRP with stochastic travel times. For the objective function, this paper considers the minimization of travel times. The efficiency of the solution approach is analyzed against the solution of the deterministic counterpart, which is solved using both exact and approximation approaches. The impact of adding stochastic travel speeds as part of the objective function is evaluated through simulation. Experiments are run using real data from several convenience stores in the city of Bogota, Colombia.