Headway-based assignment: Basis tab

If this option has been selected, the assignment is carried out.

If this option has not been selected, the assignment is not carried out.

Note

You may, for example, just calculate skim matrices.

If this option has been selected, the service frequency is calculated by OD pair. The service frequency by OD pair can be displayed in the Service frequency column of the Paths > OD pairs PuT list.

If this option is selected, the skim matrices selected in the Skim matrices tab are calculated (Calculating PuT skims).

If this option is selected, the assignment is calculated with a proportional distribution of the transport demand across the connectors (Fundamentals: Distribution of the travel demand to PuT connectors).

Notes

If you want zones to be accounted for with proportional distribution during the assignment, set the SharePuT attribute to 1 (yes). For the origin and/or destination connectors of these zones, you need to specify shares (Connectors: Basis tab).

If this option has been selected, certain path attributes in lists are no longer defined clearly, e.g. access time.

Via these two entries you may restrict the calculation to the demand for the destination zones with the selected numbers. Thus only the selected columns of the demand matrix will be assigned.

Notes

If both entry fields are empty, Visum will assign the entire demand matrix.

If only a single zone number is entered, Visum will use this value as the upper or lower limit respectively (half-open interval).

These limiting entries apply to the assignment and skim matrix calculation. In addition, the restrictions selected via the Analyzed OD pairs apply.

In the list box, you can specify the data you want to use for the assignment procedure: All, Only active OD pairs, Only active destination zones, Only pairs of active zones.

Note

The setting specified for the OD pairs analyzed might differ from the setting for skim matrix calculation.

If a restricting zone interval has been set for assignment, this will reduce the number of analyzed OD pairs even more.

Only that part of the timetable and transport demand that falls within the period defined here will be taken into account for assignment.

Note

If a calendar is used, you need to select a weekday or a date (Selecting a calendar ).

The headway-based procedure calculates the headway by line or gains the headway from a time profile attribute. Using this headway data, a path search including choice is performed. Additionally, you may subdivide the analysis time interval into time slices, with different parameter settings per time slice (Fundamentals: Headway calculation).

Note

Note that a headway of zero is not allowed and will cause the assignment to be aborted.

Per time interval from the mean wait time according to timetable

The headway results from the time expected until the next departure of the succeeding line according to its timetable.

Per time interval from the mean headway according to timetable

The headway results from the temporal length of a time slot divided by the number of vehicle journeys in this slot.

Constant from time profile attribute

If the timetable information is not essential due to dense headways or if there is no timetable data available, the headway per time interval can be read from any attribute.

Note

For the headway, you should select an attribute of the type Time period or Precise duration.

The defined time intervals are displayed in tabular form. Number and labels of columns depend on the selected Calculation mode and whether a calendar is used.

Date or Weekday

Via the selection list you select the day when the time interval starts.

Note

This column is only shown if you use a calendar (Selecting a calendar ).

Time

Start time of the time interval

Double-click in the selected cell to edit the value.

Headway input attribute

Click the button to open an attribute selection window (Selection of attributes). Here you define per time interval the time profile attribute from which the headway is calculated.

Notes

This column is only available if you have selected Constant from time profile attribute under Calculation mode.

Here, only numerical attributes are provided.

We recommend using user-defined attributes.

Headway output attribute

Click the button to open an attribute selection window (Selection of attributes). Here you define for each time interval in which time profile attribute the calculated headways are saved.

Notes

This column is only provided if one of the Per time interval from... options has been selected for Calculation mode.

Here, only editable numerical attributes are provided.

We recommend using user-defined attributes.

Via this button, you add a new time interval.

Notes

The new interval is automatically added after the currently selected interval. The start time of the new time interval is placed between the two neighboring time intervals.

Double-click the selected cell to edit the time.

The time intervals are automatically adjusted to the current settings in the Assignment time interval section.

• By default, the first time interval starts at 0.00 a.m. If the start of the assignment time interval is edited, this moment in time is adjusted automatically.
• User-defined time intervals that lie completely outside of the current assignment time interval are highlighted in red.