Bridge Waterway

Creation Mode: Draw Line on Terrain (not allowed on scenarios with start time > 0)

Purpose and Effect: Allows users to provide waterway lines for use with the Bridge action to model bridges. Each Bridge action requires one waterway line that crosses the bridge polygon on two opposite sides, representing the flow axis beneath the bridge. By default, the system uses river lines from shape files (see Exploiting River Lines and Bank Polygons) or from the River Line action for this task. Manually drawn waterway lines are only needed when these lines are inaccurate (e.g., blue line shown below) or missing.