Multistate supernetwork approach to modelling multi-activity,multimodal trip chains

Least-costs path finding methods belong to the standard toolkit of geographical information science and allow one to assign trips with known origin and destination to a transport network. An extension of the network representation is proposed that allows one to model complete trip chains (tours) that may involve multiple transport modes and multiple activities, as a least-cost path through the network. The extension is based on the notion that link costs may change as a consequence of activity and vehicle choices during the tour. The extended network or supernetwork contains as many copies of the network as there are possible activity–vehicle states and additional state transition links to interconnect them. In this way, not only the generalized link cost function, but also the start and end points of a path can be defined state dependently. A least-cost path through a multistate network defines an optimal sequence of travelling, transferring, parking, conducting activities and dropping off products of activities. An application shows how a multistate network can be constructed and used to assess the impacts of network design variables on path choice.