The procedures SBA (Simulation-based dynamic assignment (SBA)), DUE (Dynamic User Equilibrium (DUE)) and dynamic stochastic assignment (Dynamic stochastic assignment) allow you to model time-dependent transport supply. In Visum, time-varying attributes are used for this purpose. Time-varying attributes only affect these assignment procedures.
Otherwise time-varying attributes override the valid value of an attribute with a deviating value for a certain amount of time. They can thus model, for example the impact of tidal flow lane allocation or transient road works.
Time-dependent attributes can be assigned to the following network objects.
- Links
- Turns
- Main turns
- Node
- Main nodes
For these network objects, only specific attributes can be time-varying, and the deviating value of the attributes is not relevant to all procedures. The Table 27 gives an overview of which attributes can be time-varying in which assignment procedures.
* = With time-varying attributes, links may only be closed, but not opened.
The example in Table 28 illustrates the effect of time-varying attributes using the example of the Dynamic Stochastic assignment. The upper image shows the volumes and the capacity PrT on the links in time period from 5 am to 7 am. The lower image shows the volumes and the capacity PrT in the time period from 7 am to 9 am (a constant time series has been used here to simplify the comparison of both conditions, so that the traffic supply is the same in both of the time intervals).
