Turns indicate whether turning is permitted at a node and what time penalty has to be considered for PrT transport systems.
- For private transport systems, time penalty and capacity can be specified which describe the impact of the intersection on the network performance. Turns are considered for PrT transport systems during assignment.
- For public transport systems turning prohibitions are considered during the construction of a line route and during transport system-based PuT assignment.
- Turns representing a change of direction are important for PuT line blocking.
When inserting a link, Visum creates all theoretically possible turns at both nodes of the link and uses the default values from the user-defined turn standards.
For example, at a four-way intersection, there is a total of 16 turns (4 right turns, 4 straight ahead, 4 left turns and 4 U-turns).
Each turn is described by the following elements:
- A list of permitted/not permitted transport systems
- PrT capacity
- PrT time penalty
- Is change of running direction
For each turn, the transport systems have to be specified which may use this turn. A turn differentiates permitted and blocked transport systems.
|
Permitted public transport systems |
The turn can be used when constructing the line route. |
|
Permitted PrT transport systems |
The turn can be used for the assignment taking the PrT capacity and the PrT time penalty into account. |
|
Blocked transport systems |
Prohibited turns |
Per default, the following rule applies when you insert a new turn:
- All turns are open to all transport systems that are allowed on both the "from link" and the "to link". This also applies to u-turns.
- An exception are the PuTWalk transport systems: These are not automatically incorporated into the transport system set of turns.
