Why horizontal distance on Gravity Sewer Profiles?

[gt5879c]

I've wondered this for a while. Why do most engineers label horizontal distance on sanitary sewer profiles rather than the slope distance? I know that if you label the slope distance it will actually be the actual length of pipe, but it won't match the stationing. But is it really necessary for them to match?

 

[cvg]

it makes construction staking a lot easier...

 

[coloeng]

The actual pipe length is usually very small compared to the stationing and because you usually end up with cut pieces of pipe anyway it doesn't matter from a bidding perspective.

 

[bimr]

The pay item is generally the length of sewer installed measured along the centerline measured to the center of the manhole. That measurement is typically longer than the length of the sloped pipe. The length of the sloped pipe is only slightly longer (1-2 feet) than the horizontal measurement. The project staking is also at the surface, so measuring the sloped length is not very useful.

 

[gusongjun]

See below,

Assume the distance manhole to manhole is 180 m, slope is 1.5%, so the actual length along the profile is SQRT(180^2+(180*1.5%)^2)=180.020 m. Do you think there is a big problem with 180 m and 180.020 m?

Usually only horizontal distance is used.

 

[dicksewerrat]

And I thought we did that to confuse architects.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com