Traffic assignment models simulate the interaction of demand and supply on a transportation network. These models allow calculation of performance measures and user flows for each supply element (network link), resulting from origin–destination (O-D) demand flows, path choice behavior, and the mutual interactions between supply and demand. Assignment models combine the supply and demand models described in the previous chapters; for this reason they are also referred to as demand–supply interaction models. More specifically, as seen in Chap. 4, path choices and flows depend on generalized path costs; moreover, demand flows themselves are generally influenced by path costs in choice dimensions such as mode and destination. Furthermore, as seen in Chap. 2, link and path performance measures and costs generally depend on flows as a result of congestion. There is therefore a circular dependency among demand, flows, and costs; assignment models represent this dependency. Figure 5.1 illustrates the general modeling framework. Assignment models play a central role in comprehensive transportation system models because their outputs describe the state of the system, or rather, the mean state and its variation. Assignment model outputs, in turn, are inputs required for design and/or evaluation of transportation projects.
Basic Static Assignment to Transportation Networks. (Chapter 5)
CANTARELLA, Giulio Erberto;
2009-01-01
Abstract
Traffic assignment models simulate the interaction of demand and supply on a transportation network. These models allow calculation of performance measures and user flows for each supply element (network link), resulting from origin–destination (O-D) demand flows, path choice behavior, and the mutual interactions between supply and demand. Assignment models combine the supply and demand models described in the previous chapters; for this reason they are also referred to as demand–supply interaction models. More specifically, as seen in Chap. 4, path choices and flows depend on generalized path costs; moreover, demand flows themselves are generally influenced by path costs in choice dimensions such as mode and destination. Furthermore, as seen in Chap. 2, link and path performance measures and costs generally depend on flows as a result of congestion. There is therefore a circular dependency among demand, flows, and costs; assignment models represent this dependency. Figure 5.1 illustrates the general modeling framework. Assignment models play a central role in comprehensive transportation system models because their outputs describe the state of the system, or rather, the mean state and its variation. Assignment model outputs, in turn, are inputs required for design and/or evaluation of transportation projects.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
