Why did the Watershed cross the road?

[BradOatOlsenPerformance]

Why did one water shed generation cross the road when the other did not. I would rather they not cross the road, being that stormwater that falls on the downstream side of the road will not enter the culvert, therefore the volume of water is not in the culvert. Attached photo.

[copper.chadwick]

@BradOatOlsenPerformance ,

That is a great question, to repeat it and insert the photo to help others find this as interesting as we do. Why did one water shed cross the road where the other one did not? 

I would like to investigate this, does this happen when you create all models or is it just occurring in in this one model? Would you mind zipping the models using 7Zip or another non native (not windows - seriously do not use the native windows compression methods to zip Infraworks files) compression method. Specifically the sqlite and folder with same name, then posting it here?

It almost looks like it ignores the elevated roadway?  What happens if you move your outflow marker "uphill" 100 feet?watershed.PNG

[BradOatOlsenPerformance]

This project is to design the culverts to cross a roadway. I first placed the outflow marker for the watershed....before I built the road. Then after I realized the power of Infraworks, I built the road and placed the second watershed, which remained behind the road. Also after the road, I delete the watershed that crossed the road and I then placed a new watershed....and it overflowed the road....

I'm going to guess there is some memory function that it keeps reverting back to.

[copper.chadwick · Accepted solution]

@BradOatOlsenPerformance ,

I see what you are speaking of, I think what is happening is based upon the Grid Spacing in the Create Watersheds Dialog. Decreasing the Grid spacing and then analyzing the road seemed to alleviate the issue you have demonstrated.

I tried to decrease the Grid Spacing and the Watershed considered the road as you have indicated you would like. The simplified surfaces that Infraworks analyzes when mixed with the Grid Spacing may not offer the granularity that might be better analyzed in Civil 3D and then imported into Infraworks as a surface.

As to the iterative differences between the two Watersheds, it could be based upon the larger Grid Spacing creating areas that might be "missed". Try this out and let us know how it goes.

 WatershedSmallerGrid.PNG