Cut-Fill Volumes

[kapted]

I have read the previous topics with the same main idea but I need someone to help me understand something.

I know how to generate cut-fill volumes, but I was suspicious of my findings so I had someone redo the numbers by hand. My number for cut was only 14,250 cubic meters and my co-worker's number was 30,000 cubic meters.

To make a long story short - I trust his figure because I broke up my entire surface (700'x700') into areas (4: 200'x700' & 2: 65'x700') and when I added all the separate areas I was close to his number.

Is there a setting in Civil 3D that I missed to tell the computer to tighten up the calculations, or something?

Thanks.

Ted

[Anonymous]

Hi Ted,
Do you have any holes in your tin's? Import the contours and boundaries for
the volume surface and see if it has any anomalies in it.
Anyway, when I come up with numbers that are off, nine out of ten times it's
because a spike or a hole or some sort of a glitch in the surfaces that I
didn't notice before running the numbers.

I do a lot of volume calcs in C3D and LDDT, and I'm not aware of a setting
that's goofed up my numbers yet, it's been the operator (my) error every
time. As much as I hate to admit it.
[It's unfathomable, I know what I'm doing!!! Who? Me? Make a mistake?
Neverrrrrr, my ego doesn't allow mistakes? I'm infallible, just ask me! -
LOL]

In the interest of quality control, the first time I run a volume calc, I
always run it as a volume surface (as opposed to going to
surface>utilities>volume... ), so I have a chance to inspect it, and
convince myself that I'm getting a believable number.

Volumes calcs are rather picky about holes and spikes in the tin. Applying
surface boundary (outer/show/hide) has an effect of creating a hole in the
surface, as far as the volume calculation is concerned. Masking doesn't
appear to affect the volume calc, but it seems to give the visual effect
only.

Did you and your coworker work off the same comparison surfaces, or did you
each create your own? This one seems to be a less likely scenario, but, did
you check your units?

wrote in message news:5264676@discussion.autodesk.com...
I have read the previous topics with the same main idea but I need someone
to help me understand something.

I know how to generate cut-fill volumes, but I was suspicious of my findings
so I had someone redo the numbers by hand. My number for cut was only 14,250
cubic meters and my co-worker's number was 30,000 cubic meters.

To make a long story short - I trust his figure because I broke up my entire
surface (700'x700') into areas (4: 200'x700' & 2: 65'x700') and when I added
all the separate areas I was close to his number.

Is there a setting in Civil 3D that I missed to tell the computer to tighten
up the calculations, or something?

Thanks.

Ted

[kapted]

Thanks for responding Connie.

I am new to this game, but I do not see any holes or spikes. I believe that my existing surface is good. The contours look good and no conflicts.

My co-worker worked off a plotted version of my drawing, so his contours and mine were exact (if that's what you were getting at).

What's the largest area that you've worked with? My co-worker and I think that the size of the area has something to do with my "challenge". Theory - one junior surveyor we used at one point had his grid spacing for points too far apart and AutoCAD actually missed a small hill that we ended up leveling. I am wondering if the volume calc.s (created internally) make a grid that is spread to much for the area I specify, therefore it is unable to extrapolate the exact rise or dip in the surface that may be caught in a more tighter grid. Make sense, or did I lose you?

I am attaching a portion of the site plan used. It is a 24x36 plot, metric scale of 1:500.

Thanks.

Ted

[kapted]

Thanks for your help Connie, I just discovered the HUMAN ERROR (like you said, What me!? make an error, unthinkable).

It is almost embarrassing to mention. My existing surface is OK, it was my finished surface that was flawed. I created my finished surface with only a minimum number of points, I had to insert my grid into the surface to create a more accurate model.

I can rest now.

Thanks.

Ted

[Anonymous]

That darn human factor, gets us every time, doesn't it?
I'm glad you found what happened and how to fix it, that's what really
counts in the end.
Good job :)!

As for the sizes of the projects, I work on huge ones. My last one had 15
million cubic yards of dirt to be moved around...

wrote in message news:5265248@discussion.autodesk.com...
Thanks for your help Connie, I just discovered the HUMAN ERROR (like you
said, What me!? make an error, unthinkable).

It is almost embarrassing to mention. My existing surface is OK, it was my
finished surface that was flawed. I created my finished surface with only a
minimum number of points, I had to insert my grid into the surface to create
a more accurate model.

I can rest now.

Thanks.

Ted

[Anonymous]

Hi,

I'm having a similar problem. My values in LDT are not corresponding with my cut/fill values in Civil 3D. What do you mean you added your grid to your finished surface? How do I add it?
Any help would be appreciated. Thanks.

[kapted]

I created a grid - 25m x 25m (approx.) and at each grid crossing I added a point. I had to calculate the point elevations "by hand" because the final surface layout had slopes. Once the grid was done, I generated a new cut-fill calculation.

I do however think that I was correct all along, the one aspect that I probably didn't think of was the fact that the existing land slopes, so calculating a cut-fill on a sloped surface is different than calculating cut-fill on a piece of land that is truly flat.

I hope that this helps.

Ted