You can determine a user-defined PrT skim which concatenates the attributes of traversed network objects. By means of the user-defined skim, you can count the traversed POIs (gas stations, for example) or 'count locations' by OD pair. You may also link a unique attribute (AddValue1, for example) of various traversed network objects.
For this, the direct and indirect numerical attributes of links, connectors, turns, main turns, and restricted traffic areas are provided for selection. Attributes of nodes and main nodes can be included in the skim calculation as follows:
- As Via Nodes of turns (without From Nodes or To Nodes)
- As From Nodes of links (without To Nodes)
- As To Nodes of links (without From Nodes)
- As Via Nodes of turns plus connector nodes (all nodes included)
- As connector nodes
Real values can be calculated. You may also use user-defined numerical attributes.
Setting parameters for the user-defined PrT skim
1. From the Calculate menu, choose General procedure settings.
The General procedure settings window opens.
2. In the navigator, select PrT settings > Skims.
The table of skims appears.
3. In the Settings for specific skims section, click the Parameters button.
The window User-defined skim PrT opens.
4. Click the button of the desired network object type.
5. Make the desired changes.
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Element |
Description |
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Coefficient |
Factor, the source attribute is multiplied by. Note To make the coefficient on the right available, select an operational sign. |
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Attribute |
Source attribute, whose value enters the formula. Use the button to select an attribute (and a subattribute, if available). Direct and indirect attributes of the source network object type are provided. The selection is done in a separate window (Selection of attributes). Notes The source attribute on the right is only available if you have selected an operational sign. If you do not select a source attribute, the value 1.0 is used instead. |
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Op. |
Operational sign of a mathematical operation that includes two terms (for example, AddValue 2 + AddValue 3). Use the drop-down list to select an operational sign. |
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Via this button, you add a new line to the formula. If you insert several rows, the values are summed up. |
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Via this button, you remove the bottom row. |
6. Confirm with OK.
The window closes, the settings for the selected network object type are stored.
7. If applicable, click the button for any other network object type in the window User-defined skim PrT to take the particular attribute data into consideration for the user-defined skim calculation, and repeat step 6) and step 7).
The settings for further network object types are stored.
8. Confirm with OK in the window User-defined skim PrT.
The parameters for the calculation of the user-defined skim have been set.
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Note: Take the given units for impedances into consideration for the choice of the coefficients: Length in Meters and Time in Seconds. |
