NSGAII enhanced with a local search for the vehicle routing problem with time windows and synchronization constraints
Abstract
In the field of Home Health Care (HHC), the vehicle routing problem with time windows, synchronization, and precedence constraints (VRPTW-SP) involves finding the lowest-cost set of routes to visit patients requesting one or more services in a specific time window and during a fixed time service. Each patient has preference weights associated to the vehicles who are available to provide the requested service. To solve the problem, different variations for multi-objective met a-heuristic based on the Non-dominated Sorting Genetic Algorithm (NSGAII) are proposed. The considered objectives are the minimization of travel costs and the maximization of patients preferences. This problem was solved in a previous work as a single-objective variant, despite the conflicting nature of these two criteria. Numerical results are presented for instances with up to 73 patients. Metrics such as spacing, hyper-volume and the number of non dominated solutions are used to measure the quality of solutions.