Attributes for calculating costs as a basis for path selection
1. On the Traffic menu, click > Dynamic Assignment > Parameters.
The Dynamic Assignment: Parameters window opens.
2. Select the Cost tab.
3. Make the desired changes:
Element | Description |
---|---|
Time interval for edge travel times in path search |
Time interval of which the smoothed edge travel times shall be used:
|
Cost for path distribution with Kirchhoff |
Calculation procedure used as a basis to calculate costs for path selection if you have selected Stochastic assignment (Kirchhoff) or Equilibrium assignment for the distribution model. Existing volumes Volume (old) are not taken into account:
For links with multiple lanes, the Measured path travel times option produces more accurate results than the Sum of edge travel times option: In both cases, Vissim determines the average travel times on the edges of the paths. However, the average edge travel time is less significant when travel times on an edge before a node strongly differ for different following edges, e.g. because right turn traffic in the node is congested but straight-on traffic is flowing. Therefore, Vissim does not use the sum of the average edge travel times when using option Measured path travel times, but the smoothed total travel time of all vehicles that reach the destination parking lot if at least one path travel time is available from a previous simulation run. In an overloaded network, it makes sense to use measured path travel times only, as the total of estimated edge travel times in congested areas may result in completely unrealistic total times. |
Selecting smoothing method for travel times:
In the Files tab, the Store costs option must be selected. If the Write evaluations option is not selected, the smoothing of travel times is not performed. Instead, for each simulation run, the costs listed in the cost file *.bew are used. The smoothing method is not relevant if you have selected equilibrium assignment (Attributes for path selection). |
4. Confirm with OK.
Superordinate topic:
Controlling dynamic assignment
Information on editing:
Controlling iterations of the simulation