Chapter 17: Urban Freight Tour Models: State of the Art and Practice

The main objective of this chapter is to provide a comprehensive overview of empirical findings and models that focus on urban freight tours. In doing so, the chapter provides background information; reviews the research literature; classifies the tour models in simulation, hybrid, and analytical models; discusses strengths and weaknesses of a sample of key models; and concludes with a statement of chief findings.

Keywords: Freight demand model; tour model; urban freight

The phenomena that create freight demand are very different, and more complex, than the ones observed in passenger demand. To start with, freight demand is the result of the economic interactions of the multiple agents that participate in supply chains, including producers, shippers, carriers, freight forwarders, warehouses, receivers, as well as the public agencies that regulate various aspects of the system. In the context of this chapter, however, the role of producers and shippers is subsumed into the supplier, which is assumed to undertake the functions of producing and shipping the goods. The multiplicity of agents leads to a situation in which proper modeling of the freight demand process requires consideration of how their interactions shape freight demand. However, since considering all these interactions is a practical impossibility due to the mathematical intractability of the resulting models, and lack of data about the interactions, simplifications are warranted. For that reason, the bulk of the research focuses on producers, shippers, carriers, and receivers as they play the key roles. Adding even more complexity to the mix, these interactions are governed by the tactical and strategic business considerations required to survive and thrive in an environment of market competition. The fact that producers, carriers, and receivers compete with others of their kind in a market, influences their behavior because they have to take into account what the competition would do (as opposed to optimizing their operations in isolation of others). Disregarding the effects of market competition is likely to lead to results that do not reflect the realities of urban freight markets.