Chapter 10: Travel Networks

Travel demand is manifested in space and time and to model this one must represent the supply of transport infrastructure and services in some formal way. The most common way to achieve this is through the use of a network. This chapter deals with the concept of travel network and uses road networks, probably the most commonly used in modelling, as a starting point. The main components of a travel network are then described and the concepts of link capacity and the relationship between level-of-service and delay are explored. The chapter covers then the principles of travel assignment (the allocation of travel units to each link in the network) and considers the issues of congestion and equilibrium. The final sections of this Chapter are devoted to generalise the discussion to cover other types of networks: public transport, freight and modes different from road based ones.