Simulated Annealing Approach For The Vehicle Routing Problem With Synchronized Visits

In this paper, we consider a vehicle routing problem in which customers have to be visited by two different vehicles in a certain order. The first vehicle has to visit n customers to pickup or deliver empty containers, while the second has to deliver ready-mixed concrete by pouring it into the previously delivered containers. This problem is a vehicle routing problem (VRP) variant involving synchronized visits and temporal precedence constraints.We propose an ILP formulation and a simulated annealing algorithm to minimize the total travel times of both vehicles, and we provide experiments that show very satisfying results.