Reactive Route Guidance

Reactive route guidance refers to systems which generate guidance based on current traffic conditions. A system with reactive route guidance is simulated in TMS as follows:

1. The average travel time for each link in the network is updated periodically (e.g. every 5 minutes) based on speed measured by the surveillance sensors or the actual speed probe vehicles experienced in the link during the last time period.
2. For every eligible path, the travel time from each link to the destination of the path is recalculated based on the updated link travel times.
3. The shortest paths from each link to every destination in the network are also computed based on the updated link travel times, using a modified version of the label correcting shortest path algorithm).
4. Drivers who have access to the updated information choose routes and make en-route decisions based on the updated path travel times or shortest path tables.