AutoCAD Civil 3D General

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Registered: ‎07-09-2010
Message 1 of 7 (575 Views)

which C3D QTO approach - compute materials, Corridor Code PayItems, or Volumes

575 Views, 6 Replies
08-09-2011 01:16 PM

How does the 'Compute Materials' QTO function differ from the 'Corridor Properties/Code/Code Set Style/Link|Point/PayItem' QTO function - I understand that the measurement is obtained using a different approach - I'd like to know why one method is used over another method? They both appear to provide the quantity for the same ACAD model object?


Also, same question for the 'Volumes' QTO function - I understand this function is only for volume difference between two surfaces but the Corridor Code payItem and Compute Materials documentation appears to say they also compute difference of surface volumes, but I do not see where you define the comparison surface so doubt this is correct and I must misunderstand the authors.

Forest Peterson,; build-sheet
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Message 2 of 7 (570 Views)

Re: which C3D QTO approach - compute materials, Corridor Code PayItems, or Volum

08-09-2011 01:37 PM in reply to: granite07

I think the corridor quantities are for linear feet (Points) and area calcualtions (Links). The Compute Materials QTO function is for volumes of materials (shapes) from the corridor. If you create a material criteria for surfaces you can use them in the Comput Materials.


I don't think the QTO functions are user friendly. I despise having to run it more then once for each material group. It really needs a dialog box interface to let the user run multiple reports from one place.



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Message 3 of 7 (525 Views)

Re: which C3D QTO approach - compute materials, Corridor Code PayItems, or Volum

08-10-2011 08:14 AM in reply to: christopher

That sounds like the actual truth of C3D but was it intended the QTO would report volumes too?


In the corridor properties code tab, payItems can be assigned to the link and point code set style codes. The links are 2D and the Points are lines, but the links can also be 3D if a volume unit of measure is designated in the payItem file. For the subassembly.MedianFlushWithBarrier with a specified Pave1 depth .951' the QTO report found the correct CY volume of 156.96CY; there is more to this specific test documented here but ultimately the reported volume is correct for the assumptions imbbedded in the C3d sourceCode.


The question: While Autodesk intended the QTO function to report volumes, in reality it has unresolved issues so the Compute Material should actually be used for volumes and QTO only used only for 2D and lines?


I was going to report volumes using QTO but I'd rather avoid any issues with this if Compute Material is a cleaner approach.

Forest Peterson,; build-sheet
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Message 4 of 7 (509 Views)

Re: which C3D QTO approach - compute materials, Corridor Code PayItems, or Volum

08-10-2011 06:15 PM in reply to: granite07
I went to the web link you gave. Some nice stuff! In this part of country where I come from, we still use a tape measure to do work. Research is a good thing, moving dirt is another. It is just that simple! We compact dirt to about 95% standard proctor. Is the dirt you are calculating within 10% error of expansion or contraction? Or to be diplomatic "contigency"? How are the soils parameters changing every 500 feet? Well let us talk about volume! "Eat what you can, can what you cannot" You have to separate theory from practice.
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Message 5 of 7 (502 Views)

Re: which C3D QTO approach - compute materials, Corridor Code PayItems, or Volum

08-10-2011 06:51 PM in reply to: granite07

I have absolutly no idea what it is you are trying to say or do, but I noticed on your link you set up your "model space units to inch"


Civil3d does not work in inch units - it works in decimal feet of meter.

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People) Civil 3D 2012 & 2013
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Message 6 of 7 (496 Views)

Re: which C3D QTO approach - compute materials, Corridor Code PayItems, or Volum

08-10-2011 08:20 PM in reply to: granite07

Thank you for pointing out the issue with inch msu - I am well aware of this.


Also, good adice about earthwork. I was an earthwork engineer with the Granite Construction Heavy Construction Division on a large design-build project. The equipment manager retired unexpectedly so I was also the equipment manager for a regional comapny sized fleet. I can appreciate what you are saying and it is under control.

Forest Peterson,; build-sheet
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Posts: 342
Registered: ‎07-09-2010
Message 7 of 7 (476 Views)

Re: which C3D QTO approach - compute materials, Corridor Code PayItems, or Volum

08-11-2011 01:19 PM in reply to: granite07

Civil 3D has three quantity takeoff functions, "volumes", "compute materials", and "takeoff" by payItem


As I understand it:

  • "volumes" quantifies bank and embank from a surface comparison
  • "compute materials" quantifies corridor volume from corridor code link surfaces and shapes
  • "takeoff" by payItem quantifies length, area, and volume, by associating a payItem to corridor code link surfaces (area of link or the product of link area with a defined subassembly depth attribute for volume)

When is "takeoff" by payItem used for volume in place of "compute materials"?


Also, a note on earthwork shrink and swell - haul truck factors for computing bank and embank volumes - this is vastly more significant than the compaction shrink. Unless you complete a laser scan or can survey a square earthwork object with clean edges, you have no clue what your actual volumes are in bank, loose, or embank units. And, scales were made to be tampered with and teamsters were made to eat lunch and add an extra tick mark to their time cards. Last, this is assuming you can even track what type of haul trucks you are running and the actual fill factor for the trailers by material type. The fill is done when it is filled and the excavation is done when the hole is there - how much was it? It was that much, who cares we are working on something else today, I also understand the field mentaility out where it counts.

Forest Peterson,; build-sheet

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