Impact models – methods to calculate the impact of traffic
A transport supply system has several impacts, which may vary because of measures (for example the construction of a new tram line or a bypass).
- Impacts on the users of the transport supply
- Impacts on the operators responsible for providing transport supply
- Impacts on the general public, which incur costs and utility as a result of the transport supply provided
- Impacts on public transport authorities, which may be held responsible for any political shortcomings
- Impacts on the environment harmed by pollution
Users of the transport supply
Users of infrastructure for private transport are mostly car drivers and their passengers, but also non-motorized travelers such as cyclists and pedestrians. Users of public transport are public transport passengers.
Operators of the transport supply
The road network is usually operated by the state, federal states or communities and increasingly by private investors. These operators of the road network have to decide on investments for the construction and maintenance of road infrastructure. PuT operators are the transport companies and transportation agencies. In the broader sense, the PuT contractors also belong to the operators. To offer public transport service, PuT operators develop line networks and timetables from which the user can then choose connections. To organize drivers and vehicles, PuT operators develop vehicle employment plans and rosters.
Models to calculate the impact of traffic
Visum includes different models which are used to determine the impacts of given transport supply.
- Different assignment procedures make it possible to assign current or anticipated travel demand to existing or planned transport supply. The most important information of these assignment procedures are network object volumes (link volumes for example).
- The connection quality of each transport systems or for the selected demand segments is described via skims, which can be output in skim matrices (impedance matrices).
- The environmental model makes it possible to determine noise and/or pollution emissions of motorized private transport for traffic volumes in the existing or planned transport network.
- An operator model determines the operational and financial requirements of PuT supply, projection of data to analysis period or analysis horizon, as applicable, is possible. The number of required vehicles is computed by a line-blocking calculation procedure, which are necessary to be able to offer the PuT supply.

