Ponding Calculations

[Ramz7887]

I'm having trouble figuring out how to produce these numbers and then apply them to the plan view.

I made a profile view of the existing street section. It is a 1525' straight strech of roadway. The existing flow line is at a .25% grade. The new FL will be .9% for 200' then is will decrease to -.4% with a 20' vertical curve in the middle. These intervals will continue for the length of the section.

I plotted these elevation changes on the plan view and constructed a 1.8' elevation conture line from the curb face. I came up with with calcs by taking the change in elevation at each station, minus the gutter elevation(.13') and then dividing by the the slope from the gutter to center line which is 2%.

The curb is .5' high, from the bottom to the lip of the concrete gutter is .13', then there is the 31.5' length to the CL at a 2% grade.

Thanks

 

[LHA]

What are you trying to do? If you want to find the flow capacity, FHWA's HEC-12 will give you all the info you need. Or are you trying to make contours and spots on plan view?

Engineering is the practice of the art of science - Steve

 

[francesca]

Consult the drainage manual of which ever authority you're designing the road for.

 

[Maury]

The Federal Highway Administration's URBAN DRAINAGE DESIGN MANUAL (HEC 22) explains design procedures for gutter flow.

 

[Ramz7887]

If you want to find the flow capacity, FHWA's HEC-12 will give you all the info you need. Or are you trying to make contours and spots on plan view?


Both. Is there any spot online where I could look at the HEC-12?

 

[Ramz7887]

I found a pdf. of HEC-12 but not I need to figure out how to calc the contour spots.

 

[runoff]

Unfortunately, you might have to do it the old fashion way. Measure through autocad the distance between the two points and solve for the unknown (i.e. the elevation needed). Consult the local authority and the manuals, as francesca recommended. They might have mandated slopes for road ways etc.. For example, a given road in an area I designed for could not have a slope greater than 12% for fire code issues. Anyway, I think you are on the right track.

 

[Ramz7887]

Thanks everyone for your help.