Assessing the reduction of empty backhauls using transshipment points

Further reducing empty running by trucks is clearly an important source of efficiency for transportation companies, as well as a valuable way to decrease their carbon footprint. The Pickup and Delivery Problem (PDP) aims at selecting routes such that the distance travelled empty is as short as possible, given a set of transportation requests. In this context, the driving time constraint may be a key factor since it restricts the number of possible routes for each vehicle. To overcome this time constraint, an opportunity is for vehicles to drop or swap their trailer at intermediary transshipment points. In this paper, we evaluate the benefits of using transshipment points in the PDP to reduce the length of the empty backhauls, and we study how the driving time constraint affects those benefits. For this, we apply a MIP model for the PDP integrating transshipment points, and conduct computational experiments comparing the results with a classical PDP. We find that indeed, when driving time is constraining, enabling transshipment points seems to be of interest (up to 25% more reduction in the distance travelled empty)