The Vehicle Routing Problem with Occasional Drivers and Time Windows

In this paper, we study a variant of the Vehicle Routing Problem with Time Windows in which the crowd-shipping is considered. We suppose that the transportation company can make the deliveries by using its own fleet composed of capacitated vehicles and also some occasional drivers. The latter can use their own vehicle to make either a single delivery or multiple deliveries, for a small compensation. We introduce two innovative and realistic aspects: the first one is that we consider the time windows for both the customers and the occasional drivers; the second one is the possibility for the occasional driver to make multiple deliveries. We consider two different scenarios, in particular, in the first one multiple deliveries are allowed for each occasional driver, in the second one the split delivery policy is introduced. We propose and validate two different mathematical models to describe this interesting new setting, by considering several realistic scenarios. The results show that the transportation company can achieve important advantages by employing the occasional drivers, which become more significant if the multiple delivery and the split delivery policy are both considered.