Vehicle routing problems (VRP) [72, 50, 186] represent one of the most investigated combinatorial optimization problems [134], due to the problem complexity and their potential impact on real-world applications especially in logistics and supply chains. The basic VRP involves constructing a set of closed routes from and to a depot, each serviced by a vehicle of certain capacity. In each route, a vehicle delivers the required demand in an ordered list of tasks for customers. The objective is to minimize the total distance, satisfying the capacity for all customers on each route. In some problem variants the number of vehicles used is also minimized. More details of the problem models and benchmark datasets are given in Appendix B.3.