Learning Dirt Quantities

Volumes can be generated from surfaces. Look into surface creation to find a tutorial to fit your specific need.

Average End Areas are mainly for roadway elements. Remember that depending on the cost associated with the dirt/property etc. area density coverage can play a major role in your volume computations. Working with the DOT's, we use more Average End Area since it is easier to compare to specific areas for quality assurance and verification of the same along a specific pathway. Defferent softwares do not have this specific computation method included. MicroStation's InRoads does, this is a widely used DOT software.

AzClif

Do not forget how compact the material is too.

Cheers,

Derek

Thanks, Gentlemen. It all helps on my path to enlightenment. I haven't had much luck with either the Help Section or Tutorials in Civil 3D, but I'll try again. YouTube usually has tons of good stuff, but it's fairly quiet on the subject of dirt calcs.

I've heard the term "Average End Area" before. I guess it's a particular method of calculating volumes. How many ways are there, and how do you determine the best method?

Dave

Create a base surface and a surface of your stockpile or detention pond. Then compare the two to get your volumetrics. Most programs allow calculations above or below an elevation also. They will also allow you to apply a shrinkage or swell factor if needed. I have used TGO and LDD for these types of calculations. My fellow coworkers use mircostation, terramodel, and C3D. Any decent survey program will do volume calculations, it is just a matter of taking the time to learn the method to the madness . Have someone check your numbers with another program. Provide them the breaklines and mass points.

Civil needs a surface of the pile, and a base surface to compare it. There is a tutorial on it within civil 3d,but ignore the quantity take off. Sorry I can't be specific, not at the work computer right now.

Average end area is where you take cross sections through the project. You calculate areas of cut and fill (or in the old days plot on paper and buggy with a planimeter).

Say you have adjacent sections 50' apart. One is 500 sf and the other is 1000 sf. The average end area is 750 sf time 50 equals 3750 cf divided by 27 for cy. Do this for adjacent sections and add up volumes. A mass diagram is a table that has cut areas and fill areas in the case where you have both cuts and fills.

The absolute best training I have ever received for anything in C3D has been from talking to Mike Carris and subscribing to his TSC365 service. He has many videos on youtube. I have sent him several of my C3D files with a list of questions and he makes a personal video showing me how to fix things in my own drawing on the video. His group has also made videos over each section of the C3D user manual with great instruction.

But the solution to your question would be to have multiple surfaces and have the program calculate the volume from the surfaces. The video I watched by Mike Carris was really well informed.

Good Luck,
I'm not a C3D Guru, But I do know someone who is....

https://www.youtube.com/user/mcarris

Thanks all! I love this forum.

I've bookmarked Mike Carris' YouTube channel, but at $600 I'll save him for desperate times. 🙂

Comparing two surfaces sounds easy at first blush, but I haven't done much with surfaces. So I'll go over that chapter again in my books. Keeping the points separated from the two comparison surfaces is the first thing I'll need to work on. Then there's the "volumes dashboard" and "sample lines." It's gonna be a long week!

Dave

The main thing is - don't trust the answers the software is spitting out.

Step back and think..does this make sense? Always have an alternate method to use as a check, even if it's only a rough check assuming some simple shapes x length.

I wouldn't get caught up in the whole compaction issue. Give the contractor in-place quantities and let them worry about how much the material shrinks/swells...loose vs. compacted, ect. Just make sure they are aware of what your giving them.

Most contracts are written to avoid disputes about quantities arising from compaction issues.

Way we used to do it by hand was to topog the stock pile. Establish contours at one foot intervals and then use the techniques of average end area using the area within the contour lines rather than cross sections. Probably programing available to do that or you could just use your existing software to determine the area of each contour. With that area, a little averaging and addition you could compute the volume.

Be aware the average end area method is only mathematically correct on straight alignments. In curves, the "outside the curve" volumes are overestimated and the "inside the curve" volumes are underestimated. The error can become large with small radius curves and steep hillside roadwork.

The average end area method is popular with DOTs because they build roads (mostly) and it's easily calculated; everybody gets the same answer.

> Way we used to do it by hand was to topog the stock pile. Establish contours at one foot intervals and then use the techniques of average end area using the area within the contour lines rather than cross sections. Probably programing available to do that or you could just use your existing software to determine the area of each contour. With that area, a little averaging and addition you could compute the volume.

That used to be called the "layer cake" method.

I remember reading about that method several years ago @ RPLS.com and had forgotten about it. Thanks for the reminder.

With the huge cost of Civil 3D, I think it ought to be easy to figure volumes. Not only should it do the calcs for me, it should also walk my dog out to whiz on the lawn. 😀

Dave

I came across a YouTube channel, CAD1Webinars, which publishes webinars when I was trying to learn more about surfaces and quantities in Civil 3D. The two videos I watched about surfaces are very informative. Surface creation and Volumes, about an hour each.

Thanks, Ralajer! That is exactly what I was looking for.

Dave