HEC RAS Analysis 1

[jaz2000]

Two Questions
1. When entering c-section data and press compute the program send error message "GUI..." and mentions error in STA and Elev. which do not exist in the sec?

2. The c-sections are usually taken normal to the flow line. When taking the road alignment into consideration to model multiple culverts, the alignment intersects the stream in skew angle. SO how can I model the road alignment with respect to other c-sectios. Can I change c-sections into skewed ones parallel to the road alignment? Thanks for advice?
JAZ

 

[francesca]

The culverts are going to affect flow upstream of them, so assume that the water hits the road perpendicular. Specify different downstream reach lengths for the left and right overbanks. Also be sure you've calculated your contraction and expansion reach lengths and entered them.

As for the GUI error; you'll have to be more specific. Are you running HEC-RAS on WinXP Service Pack 2? There have been some issues with that.

 

[gbam]

Modelling skewed culverts is discussed in the hydraulic reference manual. Two ways to model a skewed bridge or culvert:
1. xsec parallel to roadway and adjusted (sta coords) for skew angle by cosine of skew
2. Perpendicular to flow & model road as perpendicular as francesca mentioned.

Either way is okay, if you use the parallel to roadway method make sure your overbank lengths are true. I prefer this method over "moving" the road.