Prof. Dr. Herman Mawengkang conducts international cooperation research on the problem of vehicle routes. The study considers a new variant of the heterogeneous vehicle routing (VRP) problem, where each customer has a different availability window for each vehicle. Specifically, this problem includes a daily delivery trip planning application for a single vehicle, where customers can be available (served) at different times of the day.

The existing literature on heterogeneous VRPs typically distinguishes fleet (vehicle) properties such as cost or capacity, but so far, the customer availability time span is assumed to be homogeneous. To address this problem, this study proposes a hybridization approach.

For the exact method, a generalized reduced gradient method will be used, which aims to obtain a feasible solution extent. The feasible area will then be explored using the heuristic method of finding a decent environment to obtain the best viable integer solution (optimal or suboptimal)