Features that cause rerouting

There are multiple simulation features that allow routing at simulation time. They are described in the following:

Routing triggered by the vehicle

This type of routing works by assigning a rerouting device to some or all vehicles. Details are given at Demand/Automatic_Routing.

Incomplete Trips and Flows

This is a special case of the above method. Vehicles with incomplete routes automatically receive a rerouting device and are rerouted once when entering the network. In some scenarios this is a practical one-shot-approach to route assignment that avoids time-consuming iterative assignment.

Alternative Route Signage

This is a location based method for triggering rerouting and is described at Simulation/Rerouter.

TraCI

Using the methods change target or reroute rerouting is triggered for the specified vehicle.

Alternative Destinations

By using <rerouter>-definitions, vehicles can be routed to alternative destinations. A different method is to use traffic assignment zones (TAZ). This allows vehicles to change their destination to the best alternative from a list of potential destinations.

Travel-time values for routing

By default, the route with the least travel time is chosen. The following order of steps is taken to retrieve the travel time for each edge (If one step fails due to lack of data, the next step is taken):

1. The vehicle retrieves it's individual data storage. This can be set and retrieved using the TraCI vehicle methods change edge travel time information and edge travel time information.
2. The global edge weights loaded using option --weight-files are retrieved.
3. The global edge weights (set and retrieved via TraCI) using the TraCI edge methods change edge travel time information and edge travel time information.
4. The minimum travel time (length/allowedSpeed) is used.

Special cases

• When rerouting with the rerouting device the travel time always comes from another data storage which is updated continuously with a configurable averaging procedure. The parameters for this updating strategy are user definable. It is also possible to set the device travel time directly via TraCI.
• When using the TraCI method rerouteTraveltime from the python TraCI library, the command supports an additional boolean parameter currentTravelTime (default True). When this parameter is set to True, the global edge weights are replaced by to the currently measured travel times before rerouting. To replicate this behavior with other TraCI clients, all edges in the network must be called with change global travel time information using the value of current travel time. Note that the travel time values which are set in this way are used for the full duration of the simulation unless updated again.

Routing by effort

When setting the option --weight-attribute, additional routing efforts are read according to the specified attribute. These are only used when calling the TraCI function reroute by effort. The assumed efforts along a vehicles route are are time-based values and the time is computed based on the travel time values described above.