The supply data of a transport network are described in a network model consisting of various network objects. To describe the transport supply, Visum distinguishes between the following network object types:
- Nodes and main nodes
- Links
- Turns and main turns
- Zones and main zones
- Zone connectors
- Territories
- Paths and paths sets
- Stops with stop areas and stop points (PuT)
- PuT lines with line routes, time profiles, and main lines
- System routes (PuT)
The network model also contains the following data:
- Operational data on PuT vehicles and on public transport operators
- Points of Interest (POIs), count locations, detectors,
- Territories for precise PrT and PuT indicator calculations (with user-defined territory boundaries)
- GIS objects, which are active within the network only during a Personal Geodatabase connection
Visum provides different kinds of network objects:
- Point objects are defined by means of co-ordinates.
- Line objects have a spatial course.
- Polygonal objects are point objects with a spatial extent. They are modeled by means of a centroid and a boundary polygon (Managing boundaries of polygonal network objects).
Network objects are described by means of attributes. You can enter the values of some attributes; other attribute values are calculated (Managing attributes).
Network processing modifies the properties of the transport network. This may produce different indicator values and assignment results.
|
Notes: As long as you modify only attribute data of network objects, for example, the length of a link, the current assignment result will not be initialized, even though a new calculation of the assignment might produce a different result. In the case of modifications to the network structure, a current assignment result is deleted. Inserting, deleting, or renumbering a network object as well as merging nodes, splitting zones or links, and aggregating zones are changes to the network structure. PuT assignment results are kept if new zones and connectors are inserted. |
