Route selection is the process by which travelers determine which set of roadway links they will follow to reach their destination. This is affected in important ways by how trip cost is calculated:
- Travel time—By default, simulation models typically consider travel time as the only factor affecting route selection. While this works for small networks, it can create issues in large networks, as routes with significantly different lengths can have similar travel time due to differences in speed limits and the effects of traffic control. Considering travel time alone can push a substantial portion of travelers to choose a longer route.
- Travel distance—The trip cost calculation can be refined by adding travel distance as a factor. This tends to prevent vehicles from choosing longer “sightseeing” routes.
| Route selection based solely on travel time | Route selection considering travel time and distance |
- Traveler preferences—A further refinement is to factor in traveler preferences. For freeway and arterial trips with similar travel times, motorists tend to prefer using the freeway and may be willing to travel extra distance to stay on a freeway. In addition, HOV vehicles have an extra incentive to use HOV lanes.
Further details on route choice modeling can be found in the AMS Phase 2 presentation.