Models and local search algorithms for vehicle routing with returns and time windows

A vehicle routing problem for servicing objects with the possibility of distributing work between vehicle taking into account time windows is considered. We discuss approaches to constructing integer linear programming models and their modifications. A large neighborhood search algorithm is proposed to find approximate solutions. Here an improving solution is constructed using the “destroy” and “repair” methods at each step. A series of instances with various structures are proposed, in particular demonstrating the reason of returns to objects for vehicles. The results of an experimental evaluation of models and algorithms are presented.