Tour-based model

The tour-based model is based on the assumption that external activities cause mobility. In the following examples previously defined activities are being used (Activities, activity pairs, activity chains).

An activity chain describes a sequence of typical activities during a person's day. An example would be: Home – Work – Shopping – Home (HWOH). Such a sequence of activity pairs implies trips, in this example here three different trips: HW, WO, OH. The average mobility program of persons is described by activity chains for the tour-based model.

You can find the demand object activity chain attributes in the general description of the demand objects (Activities, activity pairs, activity chains).

Some changes in the demand objects, which are especially necessary for the tour-based model, are described below.

Note: In a Visum-tour-based demand model, a demand stratum is specified by exactly one person group (e.g. E+c) and one activity chain (e.g. HWOH). In the other demand models, several person groups can be assigned to one demand stratum.

Changes to activities in the tour-based model

Each activity from the activity chain, apart from the home activity, has to be assigned to exactly one structural property, whose value flows in as target potential into the trip distribution.

The following table shows examples for activities and respective structural properties.

Activity	Structural property	Structural property value = target potential
Work ('W')	Jobs	Number of jobs
Home ('H')	Homes	Number of homes
Shopping ('O')	Shopping possibilities	Retail sales floor
Recreation ('R')	Recreational facilities	Number of mentions of the zone as recreation destination in a household survey
School ('S')	School places	Number of school places (up to 18 years)
Vocational school ('V')	Vocational school places	Number of vocational schools
Primary school ('P')	Primary school places	Number of primary school places
University ('U')	University places	Number of university places

Table 69: Examples of activities and their structural properties

You can specify whether a possible destination-binding can be considered for trip distribution, per activity. If desired, a constraint for the destination side (for example hard, weak, elastic, open) can be defined analog to the EVA demand model using two real-valued factors ConstraintMinFactorDest and ConstraintMaxFactorDest. Depending on the constraint on origin and destination side, the doubly-constrained trip distribution is calculated for each activity transfer. If destination binding is used, you can also also specify whether you want the demand to be distributed across all demand strata. This means that the structure size is maintained, but that it is not important which person group people belong to. The allocation to a person group is an output of the demand model.

This results in the following new attributes:

Type of demand object	Attribute and range of values	Meaning
Activity	StructuralPropertiesCodes Range: set of structural properties	Reference to the activity relevant structural properties
Activity	ConstraintDest Range: bool {0, 1}	Destination-sided coupling during trip distribution (yes / no). Home activity always =1.
Activity	ConstraintMinFactorDest / ConstraintMaxFactorDest Range: floating point number ≥ 0	Factor for the lower or upper limit of the constraint on destination side if ConstraintDest = 1. For home activity, both factors are always = 1.0.
Activity	Joint coupling of demand strata Range: bool {0, 1}	Distribution of the destination potential across all demand strata with the activity jointly or individually (only for destination-bound binding)

Table 70: Activity attributes in the tour-based model

Changes to activity pairs in the tour-based model

The tour-based model offers a hourly calculation of the demand. This calculation requires as input, proportional time series which are defined separately per activity pair and person group.

This results in the following new attribute:

Type of demand object	Attribute and range of values	Subattribute	Meaning
Activity pairs	TimeSeriesNo Range: set of standard time series (Time series)	Person group	Reference to a standard time series, which has to be proportional

Table 71: Attribute of an activity pair in the tour-based model