The data model for EVA also comprises demand object types (Demand objects) relevant for other models, such as the additional demand object type structural property. Compared to the standard-4-stage model, these demand objects have some additional attributes in the EVA model. These attributes have an effect on EVA trip generation (EVA trip generation).
Activities and activity pairs
In the EVA model activities and activity pairs have the following additional attributes.
|
Type of demand object |
Attribute and range of values |
Meaning |
|
Activity |
IsHomeActivity bool (0,1) |
The value of 1 specifies the activity representing the road user’s home. Just one activity can be specified as such. The attribute influences the default setting of the OrigDestType attribute for the type of demand object of Activity pair. |
|
Activity pairs |
OD type {1, 2, 3} |
1 = Origin activity is home activity 2 = Destination activity is home activity 3 = neither origin nor destination activity are home activity |
|
Activity pair |
Joint coupling of demand strata |
Consideration of coupling across demand strata under constraints Calculate separately: The constraints apply per demand stratum Origin together for all demand strata: The constraints apply to all demand strata on the origin side of this activity pair Destination together for all demand strata: The constraints apply to all demand strata on the destination side of this activity pair Joint double binding: The constraints apply to all demand strata on both the origin and destination side of this activity pair |
Table 43: Demand object types in the EVA demand model
Structural properties
Structural properties are used to measure the zone attractiveness as origin or destination of a journey. They, for example, include sales floor areas or the number of school places. Structural properties are very simple demand objects, their only attributes are a code and a name. Instead, you could also use user-defined zone attributes. However, defined as structural properties, they better reflect their role in the demand model.
To each structural property SP defined in the demand model the numerical zone attribute ValueStructuralProp(SP) in which the values of the structural property per zone can be filed is created automatically.
Demand strata
Demand strata, too, have several additional properties, particularly in connection with their constraints. Moreover, demand strata refer to an activity pair having an origin-destination type. Since that type determines the treatment of the demand strata in the different operations and therefore is referred to frequently, it is called the origin-destination type of the demand stratum itself below.
|
Attribute |
Meaning and range of values |
|
Origin structural property codes |
Parameters specifying the structural potential of the demand stratum on the origin side. Range: set of structural properties |
|
Destination structural property codes |
Parameters specifying the structural potential of the demand stratum on the destination side. Range: set of structural properties |
|
Balancing (Balancing on the user interface) |
Value 1 specifies the demand stratum in which the differences between total origin and destination traffic are absorbed during balancing. Just one demand stratum can be marked as such, it has to be of origin-destination type 3. Range: bool (0, 1) |
|
Quantity as potential |
1 = productions or attractions also define the structural potential (attractiveness) of the zone for the demand stratum. 0 = productions or attractions have to be kept as constraint during Trip distribution, but do not reflect any attractiveness. Instead all zones show the same structural potential. Range: bool (0, 1) |
|
Marginal totals type origin (Constraint Orig. on the user interface) |
Type of constraint on origin side. For origin-destination type 1 it is always hard, in all other cases variable. Range: {hard, weak, elastic, open} |
|
Marginal totals type destination (Constraint Dest on the user interface) |
Type of constraint on destination side. For origin-destination type 1 it is always hard, in all other cases variable. Range: {hard, weak, elastic, open} |
|
Marginal totals min factor origin constant (CF OMin Constant on the user interface) |
1 = ConstraintMinFactorOrig is constant, i.e. zone-independent. The value of the ConstraintMinFactorOrig attribute of the demand stratum is applicable. Select this option if the factor for the lower limit of the productions is equal for all zones. 0 = ConstraintMinFactorOrig is zone-dependent. The value of the ConstraintMinFactorOrig(DStr) zone attribute is applicable. This option makes sense if you want to use the individual lower limits. This attribute can only be edited if the factor has not been determined by the selected type of constraint. Range: bool (0, 1) |
|
Constraints max factor origin constant (CF OMax constant on the user interface) |
As above for the upper limit on origin side Range: bool (0, 1) |
|
Constraints min factor destination constant (CF DMin constant on the user interface) |
As above for the lower limit on destination side Range: bool (0, 1) |
|
Marginal totals max factor destination constant (CF DMax constant on the user interface) |
As above for the upper limit on destination side Range: bool (0, 1) |
|
Constraints min factor origin (CF OMin on the user interface) |
Factor for the lower limit of the productions if ConstraintMinFactorOrigConstant = 1 This attribute can only be edited if the factor has not been determined by the selected type of constraint. Range: floating point number ≥ 0 |
|
Constraints max factor origin (CF OMax on the user interface) |
As above for the upper limit on origin side Range: floating point number ≥ 0 |
|
Constraints min factor destination (CF DMin on the user interface) |
As above for the lower limit on destination side Range: floating point number ≥ 0 |
|
Constraints max factor destination (CF DMax on the user interface) |
As above for the upper limit on destination side Range: floating point number ≥ 0 |
Table 44: Properties of the demand strata in the EVA demand model
Zones
Due to the definition of the objects of the demand model several zone attributes are created.
|
Attribute |
Subattribute |
Meaning and range of values |
|
Balance factor production |
Demand stratum |
Weighting of demand stratum productions This value can be included in and recalculated during trip distribution. |
|
Balance factor attraction |
Demand stratum |
Weighting of demand stratum attractions This value can be included in and recalculated during trip distribution. |
|
Constraints min factor origin |
Demand stratum |
Factor for the lower limit of the productions if ConstraintMinFactorOrigConstant = 0 This attribute can only be edited if the factor has not been determined by the selected type of constraint. Range: floating point number ≥ 0 |
|
Constraints max factor origin |
Demand stratum |
As above for the upper limit on origin side Range: floating point number ≥ 0 |
|
Constraints min factor destination |
Demand stratum |
As above for the lower limit on destination side Range: floating point number ≥ 0 |
|
Constraints max factor destination |
Demand stratum |
As above for the upper limit on destination side Range: floating point number ≥ 0 |
|
Number of persons |
Person group |
Number of inhabitants of the person group in zone Range: integer ≥ 0 |
|
Structural property value |
Structural property |
Value taken by the structural property in zone Range: floating point number ≥ 0 |
|
Mobility rate |
Demand stratum Person group |
Specific traffic demand of a person group for the demand stratum. Only effective if MobilityRateConstant(DStr) = 0 in the procedure parameters of EVA trip generation. Range: floating point number ≥ 0 |
|
Production rate |
Demand stratum Structural property |
Production rate of structural property for the demand stratum on origin side. Only effective if ProductionRateConstant(DStr) = 0 in the procedure parameters of EVA trip generation. Range: floating point number ≥ 0 |
|
Attraction rate |
Demand stratum Structural property |
As above for destination side Range: floating point number ≥ 0 |
|
Study area factor home |
Demand stratum Person group |
Remaining share of home trips of the person group for the demand stratum. Only effective if StudyAreaFactorHomeConstant(DStr) = 0 in the procedure parameters of EVA trip generation. Range: floating point number ≥ 0 |
|
Study area factor origin |
Demand stratum Structural property |
Effective share of the structural property for the demand stratum (on origin side). Only effective if StudyAreaFactor ProductionConstant(DStr) = 0 in the procedure parameters of EVA trip generation. Range: floating point number ≥ 0 |
|
Study area factor destination |
Demand stratum Structural property |
As above for destination side Range: floating point number ≥ 0 |
Table 45: Zone attributes for the EVA demand model
