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Problem: Routes travel the wrong way on one-way streets with the Network Analyst extension

Description

When performing a network analysis with the Network Analyst extension, the resulting route travels the wrong way on streets known to be one-way.

Cause

Possible causes to this problem:

  • The network analysis layer is not configured to use a one-way attribute restriction.
  • There is no one-way attribute restriction defined in the network dataset.
  • The evaluator defined for the one-way attribute restriction is incorrect.

Solution or Workaround

The most common solution is to change the properties of the network analysis layer to use the one-way attribute restriction.

  1. In ArcMap, open the properties for the network analysis layer and click the Analysis Settings tab. Check the one-way attribute in the restrictions list.
  2. If there is no one-way attribute in the analysis layer's restrictions list, the underlying network dataset does not have a one-way attribute restriction. Create this attribute as follows:
    1. In ArcCatalog, navigate to the network dataset and open its properties. Click the Settings tab.
    2. Create a new attribute with a name such as 'OneWay' for type 'Restriction'.
    3. Click Evaluators and set up the appropriate evaluator for the one-way attribute based on the underlying data. This is usually a field evaluator.
  3. Rebuild the network dataset after making this change, and before performing analysis.
  4. If there is already a one-way attribute defined for the network dataset, and it is specified as restricted in the analysis layer but it is still traveling the wrong way, then the evaluator was defined incorrectly. Modify the evaluator to have the appropriate expression based on the underlying data and rebuild the network dataset.
Note:
It is possible to verify the attributes' restrictions are set correctly using the Network Identify tool in ArcMap.