Flow direction in a trace network

In a trace network, understanding the direction of flow along a network edge is essential when performing traces. The direction of flow in the trace network is managed by a system-maintained network attribute that is created for all line features that participate in the network.

Set and display flow direction

When the network topology is enabled, the direction of flow is established with the digitized direction of the line feature and is stored in the network attribute. You can update the direction of flow using the Set Flow Direction geoprocessing tool at the feature or feature class level. Flow can be specified with digitized direction, against digitized direction, or as indeterminate.

The Display Flow Direction command on the trace network's Data tab allows you to visualize the flow of resources in your network through a flow direction layer that displays flow arrows for network edge features in the current extent of the active map.

To learn more, see Set the flow direction and Display flow direction.

Work with flow direction

Tracing analytics rely on the flow direction set in the network attribute to determine directionality in traces. Changes to the flow direction of a line impact the results of upstream, downstream, and shortest path traces.

Flow direction for features are reset to their default value when they are validated using either the Validate command or Validate Network Topology tool. The Disable Network Topology tool drops the network attribute where the flow direction is stored. This is re-created when the network topology is reenabled. To maintain information for lines that are configured to flow against digitized direction or with indeterminate flow, it is recommended that you create an attribute to track how flow should be set for the features.