HEC RAS Bridge Modeling Issues 1

[Crystalct1]

I have a situation where the 10-year flow just begins to overtop the roadway. There is a roadway sag on the right side of the bridge with a lowest low point (BU and BD low point) at 11.69. Computed water surface just downstream of bridge (section 2) is 11.67.

HECRAS is telling me that my computations for the bridge default to energy (I turned on pressure/weir for high flow) since the bridge is submerged. I know that my higher flows will always default to energy when the WSE is like a couple feet above the roadway elevation - no problem. But this profile is not even submerging the deck downstream a little yet. The bridge output tells me that minimum weir elevation is 11.96. That seems to correspond to another centralized low point closer to the structure on the upstream side. But even so - the WSE is not above any of those minimum weir elevations.

Any ideas as to why HECRAS is defaulting to energy for submergence when the deck is not actually submerged? And what can I do to change it?

 

[Callin]

Can you post an image of the profile and cross sections at the bridge?

I have been dealing with a similar situation, but with about 3 feet of submergence over the roadway. What is your flooding depth? A few tenths?