A demand segment belongs to exactly one mode. It is the link between transport supply and transport demand. As several demand segments can be defined for each mode, different types of demand can be combined in the transport model.
Demand segments can be used for differentiation among
- Person groups
Employed PrT (car drivers), Employed PuT, Students PuT, etc.
- Ticket types
For example, single fare tickets, season tickets
- Trip purposes
to work, shopping, home
- Vehicle types
For example, diesel or petrol cars
To each demand segment a demand matrix is assigned. Assignment results therefore always exist on the level of a demand segment (for example the volume for the demand segment PuT pupil transport).
In principle, it is assumed that demand matrices are available in the following units.
- PrT
in car units (CarUnits)
- PuT
in person units
For the calculation of person trips (PrT) from car units, the occupancy rate can be specified for each demand segment (Using Visum: Properties and options of demand segments).
Assignment of demand segments
In all private transport assignment procedures (User model PrT), demand segments of different PrT modes can be assigned simultaneously.
- Tribut procedure, Stochastic or Dynamic stochastic assignment
Per iteration step, a route search is carried out for each transport system, because each transport system has a transport system-specific impedance function.
- Incremental and Equilibrium assignment
The search for each demand segment is carried out individually, using the same TSys-specific impedance function. This means that volumes can be issued by demand segment. Adding the demand matrices prior to the assignment saves calculating time.
- DUE
Due to the parameterization by demand segment, the route search is always carried out by TSys.
For public transport, only the demand segments of one public transport mode can be selected for assignment calculation (User model PuT). For modeling more than one PuT mode (for example PuT-Long, PuT-Local), a separate assignment is required for each mode, as route search needs to consider different transport systems. For each demand segment, particular split parameters can be defined (see assignment parameters). This serves to model for example, deviating tolerance levels towards transfers or of specific fares due to the tariff (students, employees, pensioners).
