Generating static routes from assignment

You can convert the current state of the dynamic assignment and thereby also the paths found and their congestions into a Vissim model with static routes. This Vissim model can be used without the dynamic assignment module.

Vehicle inputs and routing decisions are generated based on the contents of the path file *.weg, the cost file *.bew and the total demand of matrices.

Note: Ensure that for the dynamic assignment, the simulation time is a whole number, frequently the evaluation interval. Otherwise the path and cost files can be incomplete because you save data per evaluation interval.

To generate routing decisions and vehicle inputs the following data is used:

• The path volumes last saved to the path file (Volume (new) attribute, vehicles that departed within the time interval)
• The total origin volume of zones in the OD matrices

Where:

• For each origin parking lot, one vehicle input is generated for each time interval resulting from it whose traffic volume corresponds to the total of path volumes in the path file.
• Next, the traffic volumes of all origin parking lots of a zone are multiplied with a common factor. Their sum then corresponds to the total origin volume of this zone in the matrix or matrices.
• For each parking lot a static routing decision per group of vehicle types is generated, which has an identical path selection behavior in the dynamic assignment, e.g. with the same weighted parameters for the costs, the same accessible road network and the same parking lot selection parameters. The relative volume for each route corresponds to the route volumes from the path file.
• Vissim selects the next higher number available, respectively, for the numbers of the generated vehicle input and the generated routing decisions.

The vehicle compositions are generated from the overlapping of all vehicle compositions allocated to matrices. Vehicle compositions (combination of vehicle type - desired speed) with a relative share < 0.001 (0.1 %) pare not taken into consideration.

If in your Vissim network, the link on which a destination parking lot is placed is connected to additional links via connectors, vehicles will use the connectors and links after static routes have been generated and will remain in the Vissim network.

1.  Select from the menu Traffic > Dynamic Assignment > Create Static Routing from Assignment.

The Create Static Routing window opens. The settings are only available during the run time of Vissim and are not saved.

2.  Make the desired changes:

Element	Description
Limit number of routes	All paths are converted to static routes. All path volumes are defined based on the relative distribution of routes. For each decision section, the absolute and the relative minimum volume as well as the number of routes per destination section are compared with the set parameters. Thereby the number of generated static routes is reduced. All routes, which do not fulfill the criteria, are deleted with their volumes. Decision sections are not deleted, even when all routes on a decision section are deleted.
rel. min. Volume	The static route is deleted if the following applies for the relative volume: Relative volume in each time interval < current relative minimum volume Value range [0.00 to 1.00], Default: 0.05, two decimals If the rel. min. Volume = 0.00, no generated static routes are discarded due to this criterion. Relative volume in time interval = absolute volume in time interval /Sum of volumes for all routes of the respective time interval If the sum of volumes of all routes of a routing decision in a time interval is 0, this time interval is evaluated as if the relative volume was greater than the relative minimum volume.
Abs. Min. Volume	The static route is deleted if the following applies for the absolute volume: Absolute volume in each time interval < current absolute minimum volume Value range [0 to 999 999 999], Default value: 2, integer If the Abs. Min. Volume = 0, no static route generated is discarded because of this criterion.
max. number of routes (per destination)	All the routes from the start section to the destination section are taken into consideration. For each decision section, the number of routes to destination sections is specified. Multiple destination sections of a routing decision, which are located closely to each other on a link (tolerance ± 1 m), are regarded as one single destination section. If the number of routes per destination section is > current Max. no. of routes, then the routes with the smallest time interval volume sums are removed. If a very unlikely value is entered, for example, 999,999, no static routes are generated because this criterion is discarded. Value range [0 to 999 999 999], Default value: 10, integer

3.  Click on OK.

Create static routing is started.