Hello,
We tend to use culverts instead of bridges (energy equation) for most applications, simply because they seem to give more realistic results in terms of their backwater effect.
For example, for a normal motorway bridge with zero constriction (we only put it into the model because there is a possibility that the soffit level may be reached in a 1 in 200 year event) we get a backwater effect of +1.5 m even though the water level is well below the soffit level. I have observed the same effect in all other models, even from other consultants (so this should hopefully exclude a mistake from our side).
Have you had similar experience? It is difficult to explain to the client why we use a culvert instead of a bridge to model this kind of large structures, because culverts are often interpreted as small structures with lots of flow constriction.
Thanks.
