Question on sizing Culvert using FHWA HY 8 program
Question on sizing Culvert using FHWA HY 8 program
(OP)
I am currently trying to size a culvert in a FEMA Floodplain. My question is on Allowable Headwater depth and tailwater depth. I am using The FEMA floodplain Elevation as my allowable head water depth. I am interpolating the FEMA floodplain elevation around the Culvert entrance. When looking at the the output data from HY 8 I am sizing the culvert on headwater depth for that particular pipe size/shape and my design Q. I am trying to meet FEMA requirements of 0' rise. Does this seem correct?
My second question is on tailwater. I took a section 50' downstream of culvert end. This part of the stream is more typical. Should I be taking a section closer to end of Culvert?
Also, in HY 8 they ask for road data. I do not have a road just fill. Can I leave this part out?
Thanks,
Chris
My second question is on tailwater. I took a section 50' downstream of culvert end. This part of the stream is more typical. Should I be taking a section closer to end of Culvert?
Also, in HY 8 they ask for road data. I do not have a road just fill. Can I leave this part out?
Thanks,
Chris





RE: Question on sizing Culvert using FHWA HY 8 program
The 50 foot section downstream sounds reasonable, too, though you could take the section closer if you wanted to.
As for the roadway data, the software programmers seem to have assumed that all culverts are under roadways. Just define your fill data (embankment height, top widths, etc.) to ensure correct calculations.
RE: Question on sizing Culvert using FHWA HY 8 program
I guess it need that for check storm, say 100 year storm, when the road will be flooded but act as a weir for water to pass overtop. the overtop capacity is required by authority? Not sure.
RE: Question on sizing Culvert using FHWA HY 8 program