Prior to distributing the zones productions and attractions calculated in the EVA trip generation, the relations need to be weighted. For weighting, assessment types have to be defined. Assessment types are shares of the total costs of a trip, for example journey time, egress/access time, monetary costs, number of PuT transfers etc.
During EVA weighting, skim matrices are transformed per mode, per demand stratum and per assessment type by means of an evaluation function and multiplied subsequently. Exception: For the assessment type journey time, the transformed walking time (competing walking time) multiplied by a factor is subtracted from the result of the transformation. The results are listed in a skim matrix per demand segment, with the code EVA weighting (Fundamentals: EVA trip distribution and mode choice).
1. On the toolbar, click the 
Open 'Procedure sequence' window button.
The Procedure sequence window opens.
2. To the procedure sequence, at the position of your choice, add the procedure EVA weighting of the Demand model category (Setting up and starting the procedure sequence).
3. In the row of the added procedure, click the button in the Reference object(s) column.
The Demand strata selection window opens.
4. In the Select demand model list, click the demand model the demand strata belong to.
5. In the Demand stratum selection list, select the demand strata you would like to calculate the EVA weighting operation for.
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Tip: To select multiple demand strata, hold down the Ctrl key while clicking the desired entries one by one. |
6. Confirm with OK.
The demand strata selected are listed in the Reference object(s) column.
7. Make sure the added procedure is highlighted. Then, in the Operations section, click the Edit button.
The Parameters: EVA weighting window opens.
8. Make the desired changes.
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Element |
Description |
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For active OD pairs only |
If this option has been selected, EVA weighting is performed for active OD pairs only (Exception: Filter for OD pairs). |
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Exclude OD pairs connecting passive zones |
If this option has been selected, only OD pairs with at least one active zone are regarded. |
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Set all result matrices to 0 prior to calculation |
If this option has been selected, the matrix data of the matrices are set to zero prior to the calculation. |
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Consider home zone for demand strata of type 3 |
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Save result matrices to file |
Select this option to automatically save the skim matrices calculated through the procedures to the version file. Note By default, the option is not selected. For version files of previous program versions, this option is automatically deactivated. |
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Maximum number of OD pairs with negative weighting in log file |
This value specifies the detail level of the data written to the log file. If the number of OD pairs with a negative weighting is less than the value specified, the OD pairs are listed individually. If it is higher, the OD pairs are summarized. Note For this list output, select the log file output option (Specifying settings for protocol files). |
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Apply to all DStrata |
Use this button to apply the settings of the currently selected demand stratum to all demand strata with identical combinations of mode and assessment type. |
If this option has been selected, the home zone of the traveler is regarded as potential for demand strata of OD type 3. 
If this option has not been selected, the home zone is ignored.9. Click the Define assessment types... button.
The Define assessment types window opens.
10. Make the desired changes.
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Element |
Description |
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Assessment type |
List of all defined assessment types |
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Relevant modes |
Via this button, you can - by assessment type - select another mode or other modes in a separate window. Note The fields of assessment types Competing walk time and External weighting matrix can be left blank. For Journey time, all modes are always selected. |
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Create |
Use this button to create a new assessment type. You can enter a name for it in a separate window. Tip You can change the name of a user-defined assessment type by overwriting it in the respective column. |
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Delete |
Deletes the selected assessment type Note The assessment types Competing walk time, external matrix and Journey time are predefined. You cannot delete them. |
11. Confirm with OK.
The assessment type is set.
12. Make further changes in the Parameters: EVA weighting window.
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Element |
Description |
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Key |
Unique value generated by Visum for each combination of Mode, Assessment type and Demand stratum. |
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Demand stratum |
Shows the demand stratum for which you are specifying the parameters. One row per key. |
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Type (origin destination type) |
Direction of the corresponding activity pair (Properties and options of activity pairs) |
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Mode |
Shows the mode for which the evaluation is calculated. |
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Mode availability |
Via this button you can select the numerical zone attribute, that indicates the availability of the selected mode in the particular zone. The OD type of the corresponding activity pair controls whether the attribute effects the origin side and/or the destination side (Properties and options of activity pairs).
Tip The attribute value should lie between 0 and 1. Thereby 0 means "not available" and 1 means "100 % available". |
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Capacity utilization |
Via this button you can select the numerical zone attribute, that indicates the maximum share a structural property may be utilized. Example: For the activity pair Home-Shopping you may define to which extent the available retail sales area on the destination side may be utilized. The OD type of the corresponding activity pair controls whether the attribute effects the origin side and/or the destination side (Properties and options of activity pairs).
Tip The attribute value should lie between 0 and 1. Thereby 0 means "no capacity utilization" and 1 means "100% capacity utilization". |
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Assessment type |
Display of the assessment type the weighting is calculated for. The assessment types are selected via the Define assessment types button. |
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Gen. Costs |
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SkimMat / ZoneAttr / LinComb |
Click this button to specify the values used for cost calculation.
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Transformation type |
In the list box, click the weighting function type for transformation (Fundamentals: EVA trip distribution and mode choice). |
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a, b, c |
You can edit the parameters of the weighting function in the cells (Fundamentals: EVA trip distribution and mode choice). Note If you select No transformation as the function, these parameters are grayed out. Tip Alternatively, you can edit the parameters under Graph (Viewing and editing the curve progression of the weighting function). |
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Max. imp. |
Threshold for impedance Notes If the impedance exceeds the threshold for an assessment type, the overall weighting is set to 0. Blank entry permitted (no upper limit for the impedance). |
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PKF |
Factor for the competing walk time (Fundamentals: EVA trip distribution and mode choice) Note The factor is regarded for the assessment type Journey time. |
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Graph |
View the curve progression of the weighting function in a separate window and edit it, if necessary (Viewing and editing the curve progression of the weighting function) |
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Comparison |
Show the curve progression of the weighting function for each mode simultaneously in separate windows. If required, select a mode to edit it (Viewing and editing the curve progression of the weighting function for all modes). |
13. Confirm with OK.
14. Execute the procedure (Executing procedures in the procedure sequence).
EVA weighting is calculated. The calculation results are saved per demand stratum to a skim matrix.
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Tip: You can show and edit the skim matrices (Managing, showing and analyzing matrices) |
Viewing and editing the curve progression of the weighting function
1. Make sure that the Parameters: EVA weighting window is open (Calculating EVA weighting).
2. For the desired demand stratum, click the corresponding Graph button.
The Function graph window opens and the curve progression of the utility function is shown with the currently set parameters a, b, and c.
3. In the Range section, you may edit the scaling of the x axis and the y axis, if applicable.
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Element |
Description |
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X Min |
Minimum value for x-axis (negative values allowed) |
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X Max |
Maximum value for x-axis |
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Y Min |
Minimum value for y-axis (negative values allowed) |
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Y Max |
Maximum value for y-axis |
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Apply |
Click this button to use the entered values for the graph and to update the curve progression. |
4. Edit the weighting function parameters a, b, and c in the Parameters section, if applicable.
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Tip: Alternatively, you can change the parameters directly in the table of the Parameters: EVA weighting window. |
5. Click the Apply button.
The entered parameter values are applied to the graph and will thus update the curve progression.
6. Confirm with OK.
Viewing and editing the curve progression of the weighting function for all modes
1. Make sure that the Parameters: EVA weighting window is open (Calculating EVA weighting).
2. For the desired demand stratum, click the respective Comparison button in the All modes column.
The Function graph window opens; for each mode, the curve progression and the weighting function with current a, b, and c parameter settings are displayed.
3. In the color legend to the right, click the color of the particular mode.
The curve of this mode is highlighted for processing.
4. In the Range section, you may edit the scaling of the x axis and the y axis, if applicable.
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Element |
Description |
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X Min |
Minimum value for x-axis (negative values allowed) |
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X Max |
Maximum value for x-axis |
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Y Min |
Minimum value for y-axis (negative values allowed) |
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Y Max |
Maximum value for y-axis |
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Apply |
Click this button to use the entered values for the graph and to update the curve progression. |
5. Edit the weighting function parameters a, b, and c in the Parameters section, if applicable.
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Tip: Alternatively, you can change the parameters directly in the table of the Parameters: EVA weighting window. |
6. Click the Apply button.
The entered parameter values are applied to the graph and will thus update the curve progression.
7. Confirm with OK.
