Headway-based assignment: Impedance tab

In this tab you configure the parameters for the distribution of the demand to the found paths. Decide whether the calculation shall be based on perceived journey time and fare points or on perceived journey time and fare (Fundamentals: Generalized costs as impedance).

Element	Description
Impedance	The impedance of a path results from the total calculated either from perceived journey time (PCJ) and number of fare points or from perceived journey time and fare. You may enter a weighting factor for each of the addends. Below you define how the PJT is to be calculated. The number of fare points is calculated based on the input data of the corresponding network objects (Inserting fare points at network objects). The fare is based on the PuT fares defined (Defining PuT fares). Note If the impedance calculation accounts for the fare, Visum will automatically select the option Each path leg separately for the fare system's 'Fare applies to' option (Defining fare systems).
Perceived journey time PJT	The perceived journey time is the sum of different times and supplements (Fundamentals: Generalized costs as impedance). PJT = Factor • In-vehicle time • (in)direct numerical time profile item attribute + Factor • PuT-Aux ride time + Factor • Access time + Factor • Egress time + Factor • Walk time + Factor • Origin wait time, where the OWT is calculated according to a formula + Factor • Transfer wait time • direct and indirect numerical stop area attribute + Factor • Number of transfers + Boarding penalty PuT (numerical time profile item attribute) + Boarding penalty PuT-Aux (numerical transport system attribute) + Mean delay (numerical time profile item attribute) Notes You may specify a weighting factor for each of the time components (Fundamentals: Generalized costs as impedance). Using the factors (for in-vehicle time and transfer wait time) that you can select via buttons, you chose the numerical attribute (Selection of attributes). Each button label indicates the selected attribute. By default, no attribute is selected but the value 1.0 appears for factors and the value 0.0 appears for addends. As an additional factor for the In-vehicle time you may use the AddValue, for example, to consider line-specific features (e.g. preference to tram over bus). The origin wait time is calculated according to a formula which can be defined via the button. The formula can include attributes of the stop area and attributes of the time profile. The boarding penalty PuT is a time profile attribute and will be added to the perceived journey time for the boarding and for each transfer. The boarding penalty is used to model that certain lines are preferred to other lines in general. The Boarding penalty PuT-Aux is a transport system attribute. It only has an effect on transport systems of the type PuTAux. The mean delay will be added to the impedance for the boarding and for each transfer event. The mean delay is used to model the fact that certain lines (actually: time profiles) are often behind schedule at specific stops and that those lines are used less often by passengers than the theoretical data (run time, headway) would suggest.

Element

Description

Impedance

The impedance of a path results from the total calculated either from perceived journey time (PCJ) and number of fare points or from perceived journey time and fare. You may enter a weighting factor for each of the addends.

Below you define how the PJT is to be calculated. The number of fare points is calculated based on the input data of the corresponding network objects (Inserting fare points at network objects). The fare is based on the PuT fares defined (Defining PuT fares).

Note

If the impedance calculation accounts for the fare, Visum will automatically select the option Each path leg separately for the fare system's 'Fare applies to' option (Defining fare systems).

Perceived journey time PJT

The perceived journey time is the sum of different times and supplements (Fundamentals: Generalized costs as impedance).

PJT =

Factor • In-vehicle time • (in)direct numerical time profile item attribute

+ Factor • PuT-Aux ride time

+ Factor • Access time

+ Factor • Egress time

+ Factor • Walk time

+ Factor • Origin wait time, where the OWT is calculated according to a formula

+ Factor • Transfer wait time • direct and indirect numerical stop area attribute

+ Factor • Number of transfers

+ Boarding penalty PuT (numerical time profile item attribute)

+ Boarding penalty PuT-Aux (numerical transport system attribute)

+ Mean delay (numerical time profile item attribute)

Notes

You may specify a weighting factor for each of the time components (Fundamentals: Generalized costs as impedance).
Using the factors (for in-vehicle time and transfer wait time) that you can select via buttons, you chose the numerical attribute (Selection of attributes). Each button label indicates the selected attribute. By default, no attribute is selected but the value 1.0 appears for factors and the value 0.0 appears for addends. As an additional factor for the In-vehicle time you may use the AddValue, for example, to consider line-specific features (e.g. preference to tram over bus).
The origin wait time is calculated according to a formula which can be defined via the button. The formula can include attributes of the stop area and attributes of the time profile.
The boarding penalty PuT is a time profile attribute and will be added to the perceived journey time for the boarding and for each transfer. The boarding penalty is used to model that certain lines are preferred to other lines in general.
The Boarding penalty PuT-Aux is a transport system attribute. It only has an effect on transport systems of the type PuTAux.
The mean delay will be added to the impedance for the boarding and for each transfer event. The mean delay is used to model the fact that certain lines (actually: time profiles) are often behind schedule at specific stops and that those lines are used less often by passengers than the theoretical data (run time, headway) would suggest.