Defining Multiple Openings for HEC-RAS Bridge Modeling

In GeoHECRAS, the Multiple Openings data panel of the Bridge & Culvert Data dialog box allows the user to define stagnation points for the multiple opening roadway crossings. This article describes how to use the Multiple Openings data panel.

Follow the steps below to use the Multiple Openings data panel:

Select the Multiple Openings option from the Roadway Crossing Specifications dropdown combo box of the Bridge & Culvert Data dialog box.
The Multiple Openings data panel will be displayed.

The following sections describe how to interact with the Multiple Openings data panel of the Bridge & Culvert Data dialog box.

Opening Stagnation Specifications

This section provides a table that is used to define the stagnation stations for multiple bridge and/or culvert openings at a roadway crossing. A maximum of 7 rows are provided because HEC-RAS supports a maximum of 7 openings at a single roadway crossing. Any combination of bridges, culvert groups (a group of culverts is considered to be a single opening), and conveyance areas (an area where water will flow as open channel flow, other than a bridge or culvert opening) can be defined. Conveyance areas can only be located on the far left or right of the roadway crossing.

Openings must be defined in order from left to right while looking in the downstream direction. In addition to establishing the number and types of openings, the user must also define a left and right stagnation station for each opening. Stagnation stations are used to establish limits for each opening at which flow separates (on the upstream side) from one opening to the next adjacent opening. Stagnation stations between bridges and/or culvert groups can overlap, and the HEC-RAS software will attempt to determine the actual stagnation station within this area of overlap. However, conveyance area stagnation stations must be set to fixed locations, they are not allowed to overlap other opening stagnation stations.

The table contains the following entries:

Opening Type: This column contains a read-only dropdown entry that allows the user to select the type of opening that the stagnation stations are to be defined for. By default, the Blank entry is set in the table column. The Opening Type column consists of three additional types of dropdown options: Conveyance, Culvert, and Bridge.
Upstream Left Station (ft): This entry defines the leftmost stagnation station for the upstream face of the roadway crossing. A […] pick button can be used to select the station from the roadway crossing cross section plot.
Upstream Right Station (ft): This entry defines the rightmost stagnation station for the upstream face of the roadway crossing. A […] pick button can be used to select the station from the roadway crossing cross section plot.
Downstream Left Station (ft): This entry defines the leftmost stagnation station for the downstream face of the roadway crossing. A […] pick button can be used to select the station from the roadway crossing cross section plot.
Downstream Right Station (ft): This entry defines the rightmost stagnation station for the downstream face of the roadway crossing. A […] pick button can be used to select the station from the roadway crossing cross section plot.

Duplicate Opening Stagnation Station

In this section, the user can copy the stagnation points from upstream cross section to downstream cross section (or vice versa) by clicking on the [Copy Upstream to Downstream] or [Copy Downstream to Upstream] button.