Defining and performing Matrix correction

For Matrix correction, select the desired origin-destination matrix, the count data source and the path attributes. The count data must be available as numeric link attributes, vehicle class specific subattributes of the attribute count data or as user-defined attributes.

1.  Ensure that at least one OD matrix containing demand data has been defined (Modeling traffic demand with origin-destination matrices).

2.  Ensure that dynamic assignment has been performed and a Path file is available.

3.  Specify the source of your count data:

• To use the count data of a numeric link attribute (default setting), make sure that the desired data is available in the link attribute.
• To enter count data for a specific link and access it via the Count data attribute, in the Links list, show the vehicle class-specific subattribute of the Count data attribute. Then, in the row of the respective link, enter the values.
• To access count data via a user-defined attribute, define the attribute according to your requirements (Using user-defined attributes).

4.  On the Traffic menu, click > Dynamic Assignment > Matrix Correction.

The Matrix correction window opens.

5.  Make the desired changes:

Element	Description
Input and output matrix	Number and name of OD-matrix whose values you want Matrix correction to correct based on selected count data and volumes.
Counts for links:	Shows the link attributes selected. The count data of a link is made up of the total of the selected attributes.
	Opens the window Links: Select attribute: Select the desired numeric link attributes and/or subattribute of the Counted data attribute. The data of the selected attributes are used as target values during Matrix correction. Under the Counted data attribute, you can select the desired vehicle class. If you have created user-defined attributes, you can select them as well.
Volumes on paths:	Shows the path attributes selected. The volume of a path is made up of the total of the selected attributes.
	Opens the Paths: Select attribute: Select the desired numeric path attributes, for example Volume (new).

6.  Click the Execute button.

If no paths are available, Vissim will read in the Path file. Based on OD-matrix data, selected count data of links and paths and scaling factors, Vissim calculates new values for the OD-matrix. The scaling factors cannot be changed.