This postprocessor for PrT assignments is an add-on module used to correct assignment volumes on links and turns of the forecast by means of a correction factor, which is calculated on the basis of the differences between traffic counts and an assignment, both representing the same time slice, as is described in Report 255 (National Cooperative Highway Research Program).
The procedure comprises the following steps:
1. The count values of the incoming link at the node result from totaling the turn count values for the corresponding From Link.
2. Calculate the difference between the link base count (as input by the user) and the value of the link base assignment value.
3. Calculate the adjusted link volumes as the future link assigned value + the adjustment factor.
4. Furness (balance) the new link adjusted volumes to match the counted turn volumes. The result is turns that add up to the new link volume totals, but that have the percentage split (or distribution) found in the turn counts. The Furness process is iterative.
5. The postprocessed link and turn volumes are stored in a user-specified link or turn attribute.
