Chapter 10: Endogenous Shipment Size in Freight Mode Choice Models: Theory and Empirical Testing

One of the research questions in freight demand modelling is how to improve the representation of logistics choices underlying the decision of the mode of transport. On theoretical grounds it is already widely accepted that the choice of shipment size influences the choice of mode. Mostly due to a lack of data, however, there have been few attempts to empirically test the quality of this relationship. In this chapter we propose a model for the choice of mode of transport in which the costs of transport follow the logic of economics of shipment size choice. We specify a discrete choice model where the generalized cost depends on transport distances, mode abstract values of time and continuous shipment sizes. The model is estimated on observations of about 10,000 individual shipments from the French ECHO survey. The results show that mode choice is strongly consistent with the economics of shipment size choice. Possibilities for the further extension and application of the model lie in simultaneous mode and shipment size choice, in network based choice where modes interact and in geographically specified models.