HecRas 6, bridge modeling

[AnaHP]

Hi,
I started to work with Ras6 by adding a bridge to one of my old models. I followed up the procedure explained in the manual but I end up getting wrong results.
In my model, the flow doesn’t go through and/or over the bridge but it goes around it no matter what method I use for bridge calculations (attached image). Any idea what is going on?
Also, I realized that after a few trial I might be able to have flow going through the bridge, but when I rerun the model, it goes back to the previous wrong results.

Thanks for your help in advance,
Ana

[GF]

Hi,
Are you tryning to model a bridge in 2d Area?
If yes, are you working in SI units?

[sdonnan]

Hi,

I have been having the same issue and I think it is a bug.

I’ve tried countless iterations (including SI and US units) to try and get it working but nothing helps. Interestingly, I started to create bridges in the existing example project of Bald Eagle Creek. It worked fine in there provided I was using the existing terrain within the model. I could delete everything (except the terrain), create a new 2d flow are, new boundary conditions and new bridges and they worked fine. Once I deleted the terrain however and replaced it with something else (or even the same terrain added back in) any structures begun to act like a dam again.

Hoping they are able to fix this soon as this function would be very useful for a current project! Sorry I couldn’t be any more help.

[Péter]

I agree, I also suspect it is a bug. I can see that if the project is in SI, the HT curves for the bridge are generated with wrong elevation values. The values of all curves I got were under the terrain and so practically not allowing water to flow over the terrain, under the bridge. I did not find a way to manually edit the HT curves, so sent a report about it to HEC.
An interesting test if someone has time for that would be to convert the project (and not just switch to) to US units, securing correct HT-curve elevations, and converting back after the simulation.

[sdonnan]

Well, the good news is that I reported the issue and they got back to me saying they were aware of it and will be releasing a new beta this week or next that should rectify this issue.

[Author]

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