Dynamic submodel integration using an offer-accept discrete event simulation

Newer approaches for modelling travel behaviour require anew approach to integrated spatial economic modelling. Travel behaviour modelling is increasingly disaggregate, econometric, dynamic, and behavioural. A fully dynamic approach to urban system modelling is described, where interactions are characterized as two agents interacting through discrete events labelled as "offer" or "accept". This leads to a natural partition of an integrated urban model into submodels based on the category of what is being exchanged, the type of agent, and the time and place of interaction. Where prices (or price-like signals such as congested travel times) exist to stimulate supply and/or to suppress demand, the dynamic change in prices can be represented either behaviourally, as individual agents adjust their expectations in response to their personal history and the history of the modelled region, or with an "auctioneer" from micro-economic theory, who adjusts average prices. When no auctioneers are used, the modelling system can use completely continuous representations of both time and space. Two examples are shown. The first is a demonstration of a continuous-time continuous-space transaction simulation with simple agents representing businesses and households. The second shows how an existing model-the Oregon TLUMIP project for statewide land-use and transport modelling-can be adapted into the paradigm.