The Lateral Structures layer is used to locate the centerline of hydraulic structures run parallel to the river course and are used to connect a river reach to another river reach or 2D Flow Area. The lateral structure should be created in the downstream direction along the edges of cross sections. When a new lateral structure is created a dialog will be prompt the user to enter a Node Name, the Width for the structure and provide a Description, if desired.
The lateral structure's River, Reach, and River Station is automatically computed based on evaluating the upstream end point of the structure and finding the river station location between the two bounding cross sections. Information for the Weir/Embankment Data Editor is extracted from the Terrain layer. Elevation data will be filtered based on the Elevation Point Filtering tolerance set in RAS Mapper Options.
Lateral Structure information will need to be completed in the Lateral Structure Data Editor.
Lateral structures can have Culvert Barrels, Gate Openings, Rating Curve Outlets, and Outlet Time Series. Each are defined by selecting the corresponding layer and drawing a line in the direction of flow across the structure. The line will then determine the structure it belongs to. The Gate Opening Editor is very similar to the Culvert Barrel Editor. For Rating Curves and Outlet Time Series you are prompted for a name. Additional data will be need to be entered in the appropriate editors in HEC-RAS to complete the data.
While Culvert Barrels specified at a Bridge may be have an inlet and outlet in close proximity of the structure (just upstream and downstream), culvert barrels can be created going from any 2D cell to another, so long as they intersect the lateral structure. This will allow the user to define the inlet and outlet location at location in the computational meshes that are the true low-elevation collection points. The terrain elevation at the inlet and outlet of the culvert barrel or gate opening must be lower than the invert elevations provided.