Comparison of mathematical modeling approaches for heterogeneous fleet vehicle routing problem

The vehicle routing problem has been a frequently studied area in the literature in recent years. It also plays a significant role in real-life problems. Solving vehicle routing problems significantly reduces transportation costs, while also preventing time losses through the efficient planning of routes. When the routes are properly determined, both the number of vehicles and the amount of fuel used by the vehicles can be minimized. In this way, companies can perform more efficient deliveries with fewer vehicles and save on operational costs, such as fuel, during these deliveries. In the thesis, capacitated and heterogeneous fleet problems were selected. Three alternative mathematical models were developed for these problems. The models prepared include a two-index approach, a machine scheduling based approach, and a three-index approach. These three different models were adapted to the Lingo program (Lingo 2025 (Lindo Systems)). Of the models used in the thesis, two are existing models from the literature, while one was developed as part of the thesis work. In the conclusion section of the thesis, the outputs obtained from the program were compared.