problem with Length

[Anonymous]

Hello I have a problem to find out the correct distance. Drawn a horizontal line length is 1000.55 and profiling its length 1039.59
Any of them true length of the line? 

and how to know the 3D Length of profile in civil? 

THANK YOU !!

[Joe-Bouza]

The profile is reporting the horizontal distance along and alignment. If you have to have the 3d length you can set the profile type to static and list its length or explode a copy and list

[Jeff_M]

Joe's method requires the profileview vertical scale to equal the horizontal scale....

[Joe-Bouza]

Oops!

Good catch

[Anonymous]

I Create feature line from alignment and it show me the 3D length 1129.184m , and the 2D length 1001.57m , It's puzzeld me , I am very confused 

that is the file I want the real length .

[Pointdump]

Ahmad,

Welcome to the Forum. Properties shows the 3D length is indeed 1129.184m.

Dave

[fcernst]

It's puzzeld me , I am very confused 

"3D" is the Length. 

"2D" length in Civil 3D is simply the length projected on to the XY plane (Length*cos(theta)). It's a civil engineering convention.

[BrianHailey]

I think the reason why we do this is because when a long linear feature if fairly level, the horizontal (2D) length is very close the to the actual (3D) length. For example, if a pipe is put in the ground at a slope of 5% and has a horizontal length of 100m, the actual 3D length is 500.62m. If you are trying to estimate the length of a pipe to that accuracy, good luck. 

The slope of the pipe required to get an error of 1% would need to be just over 14%. At that point, it would probably be prudent to investigate the 3D length vs. the 2D length.

[Pointdump]

Brian,

"... if a pipe is put in the ground at a slope of 5% and has a horizontal length of 100m, the actual 3D length is 500.62m."

500.62 sounds kinda high. Would that be for a slope of 5% off of Vertical?

Dave

[Anonymous]

thank you very much
I am glad to be here with kind people like you.

[Anonymous]

but How i can Prove the 3D length is : 1129.184m not the 2D length 1001.57m to my consultant ?

[Jeff_M]

Show the featureline in both plan and profile. the 2d length is what you would measure in plan view which does not account for elevations. Then measure it in profile view which does account for elevation differences.

[fcernst]

Your problem is at the beginning.

See attached spreadsheet also.

[fcernst]

Actually see this attached spreadsheet.

Also using the Auto Corridor feature line is failing you for this analysis. It does not pick up all 249 PVI's

[Pointdump]

Good catch, Fred!

Dave

[fcernst]

Check..meant to say  _AeccCreateFeatureLineFromAlign

[Jeff_M]

Fred, there are a number of duplicate PVI's which the AutoFeatureline omits. So the only real issue is that the profile does not start at the alignment beginning which forces the featureline to begin at 0 elevation. Setting the profile to start at 0+000, holding the start slope, then the properties reports a 3d length of 1002.038

[BrianHailey]

---

@Pointdump wrote:

Brian,

"... if a pipe is put in the ground at a slope of 5% and has a horizontal length of 100m, the actual 3D length is 500.62m."

500.62 sounds kinda high. Would that be for a slope of 5% off of Vertical?

Dave

---

If the pipe has a slope of 5%, over 500m it will rise 25m. The actual length of the pipe would be sqrt(500^2+25^2)=500.62.

[fcernst]

Jeff,

Where are the duplicates?

[Pointdump]

Brian,

"...a slope of 5% and has a horizontal length of 100m, the actual 3D length is 500.62m."

I'm a pretty fair mathemetician. Read your post again. I was attempting to be funny.

Dave