Use your browser's 'back' button to return directly to the previous page. Centroids-- Imaginary points within zones from which all departing trips are assumed to originate and at which all arriving trips are assumed to terminate. Cordon Line-- An imaginary line that denotes the boundary of the study area. Friction Factor-- A mathematical factor that is used to describe the effort that is required to travel between two points. Link-- An element of a transportation network that connects two nodes. A section of roadway or a bus route could be modeled as a link. Modal Choice Analysis-- The process used to estimate the number of travelers who will use each of the available transportation modes (train, car, bus) to reach their destination. Nodes-- Nodes are points at which links terminate. Links may terminate at destinations or at intersections with other links. Routes-- Pathways through a network. Routes are composed of links and nodes. Study Area-- The region within which estimates of travel demand are desired. Trip-- The journey between one point and another. Trip Assignment Analysis-- The process used to estimate the routes (for each mode) that will be used to travel from origin to destination. This process yields the total number of vehicles or passengers that a particular route can expect to service. Trip Distribution Analysis-- The process used to determine the number of produced trips from each zone that will be attracted by each of the remaining zones. Trip Generation Analysis-- A data collection and analysis process that is used to estimate the number of trips that each zone will produce and attract. Urban Growth Boundary (UGB)-- An imaginary boundary that encloses all of the land that is expected to be developed at some point in the future. Utility Function-- A mathematical function that expresses the advantages and disadvantages of a particular transportation mode. Zones-- Regions within the study area that contain homogenous land uses and can be described accurately by only a few variables.