The quality-driven vehicle routing problem: Model and application to a case of cooperative logistics

Inefficient road transportation causes unnecessary costs and emissions. This problem is even more severe in fresh food transportation, where temperature control is used to guarantee product quality. On a route with multiple stops, the quality of the transported products could be negatively influenced by the door openings and consequent temperature fluctuations. In this study, we quantify the effects of multi-stop transportation on food quality. To realistically model and quantify food quality, we develop a time-and temperature-dependent kinetic model for a vehicle routing problem. The proposed extensions of the vehicle routing problem enable quantification of quality decay on a route. The model is illustrated using a case study of cooperative routing, and our results show that longer, multi-stop routes can negatively influence food quality, especially for products delivered later in the route, and when the products are very temperature-sensitive and the outside temperature is high. Minimising quality loss results in multiple routes with fewer stops per route, whereas minimising costs or emissions results in longer routes. By adjusting driving speed, unloading rate, cooling rate, and by setting a quality threshold level, the negative quality consequences of multi-stop routes can be mitigated.