Hey Chris,
I have heard before that its okay to model a culvert as a bridge, if there is a large opening when compared to the deck thickness. Do you think a 12′ span x 9′ rise RC Box culvert with 2 ft thick deck is a good candidate for this concept? Also, how would one recognize when to model one, or the other? Is there some threshold of Span vs Deck as a cutoff between the two?
Background on the project:
Existing condition is a bridge, ~11.5′ span. Proposed is the RC box culvert mentioned above. Steep channel >5% with flat area (from scour) local to the structure. Using mixed flow regime due to the flat area and flow wanting to transition to sub-critical at the structure.
When the proposed conditions are modeled as a culvert, we see WSE increases downstream of the structure. When modeled as a bridge, we see decreases downstream.
If you don’t think this culvert is a good candidate to model as a bridge, do you have any suggestions to reduce the proposed water surface downstream of the bridge?
Thanks!