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QTO 2D Projected Areas

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Message 1 of 27
fcernst
1080 Views, 26 Replies

QTO 2D Projected Areas

I am using QTO to get the top surface area of a stock subassembly that I have laid out at a 100% grade (1:1 H:V) with a 5 foot offset.

 

For 100' of Corridor stationing, QTO returns an area of 499.93 sqft, which is appx. equal to the 2D projected area in plan view (5'x100').

 

The requirement is to return the area using the 3D lengths of the links for quantities. The 3D length of the 1:1 top surface is 7.07'. The surface area quantity for the concrete on this side of the "concrete lined channel" is 7.07'x100' = 707 sqft.

 

The differences get more dramatic the more vertical the slope is of course. For example, wall face area calculations  by using links with a significant vertical displacement (wall height) coupled with a small offset (batter).

 

 

Capture.JPG



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
26 REPLIES 26
Message 2 of 27
BrianHailey
in reply to: fcernst

Did you try changing any of the QTO Takeoff Command Settings?

 

Brian J. Hailey, P.E.



GEI Consultants
My Civil 3D Blog

Message 3 of 27
fcernst
in reply to: BrianHailey

 

I just checked and it is set to 3D as it should be for quantities.

 

I imagine this "Length" is in the longitudinal direction for the Point Codes and Pipes though.

 

Capture.JPG



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 4 of 27
BrianHailey
in reply to: fcernst

It was worth a try...

Brian J. Hailey, P.E.



GEI Consultants
My Civil 3D Blog

Message 5 of 27
fcernst
in reply to: BrianHailey

This needs to be addressed ASAP then! 

 

I just bid a road widening project with ditch and embankment work that will have steep ditch material slopes. I bid it thinking we could generate quantities dynamically with QTO until I discovered this! Talk about budget shocker...

 

I was getting everything setup in QTO and I was really liking it. I even put Specific Weight into my SAC subassemblies for QTO to pick up and use for Tonnage calculations, and it works nicely.

 

We won't be able to use QTO if it is using 2D projectional areas for these material surface areas though. Need 3D surface area for material surface quantities. 

 



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 6 of 27
BrianHailey
in reply to: fcernst

As a possible workaround (until I can think of something better) create a surface from the links and get the 3D area of the surface.

Brian J. Hailey, P.E.



GEI Consultants
My Civil 3D Blog

Message 7 of 27
fcernst
in reply to: BrianHailey

I don't want to even go there!!!   (Thanks)

 

This needs a Hot Fix in no less than two weeks, if we don't get this figured out!!



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 8 of 27
BrianHailey
in reply to: fcernst

I just did a quick test, it also does not take into account the profile grades. I created a pretty severely graded road and it gave the same area as a perfectly flat road.

 

Perhaps something with the corridor solids tools?

Brian J. Hailey, P.E.



GEI Consultants
My Civil 3D Blog

Message 9 of 27
BrianHailey
in reply to: fcernst


@fcernst wrote:

 

I just bid a road widening project with ditch and embankment work that will have steep ditch material slopes. I bid it thinking we could generate quantities dynamically with QTO until I discovered this! Talk about budget shocker...

 


How much do the slopes on the ditches change? If they are pretty constant (it's a 3:1 slope anywhere this subassembly is being used) perhaps we can figure something out still using the QTO tools. If they vary a lot, I'm not sure what to do (other then the surfaces I mentioned before).

Brian J. Hailey, P.E.



GEI Consultants
My Civil 3D Blog

Message 10 of 27
fcernst
in reply to: BrianHailey

"I just did a quick test, it also does not take into account the profile grades. I created a pretty severely graded road and it gave the same area as a perfectly flat road."

 

Can I ask you to put in a Critical support request? I will do the same. 

 

In our municipal contracts we have to provide cost estimates at both the preliminary and final design project submittals. Then after that provide bid assistance and recommendation for payment during the construction phase.

 

Anyone else who needs to do Quantity Takeoff (QTO) and is reading this please do the same. Civil 3D needs to be able to provide these takeoffs accurately so we can promote the use of,  and be allowed to use the software in the municipal sector.



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 11 of 27
dsimeone
in reply to: fcernst

Hi folks

 

We’re interested in hearing any and all feedback on QTO or any other feature so that we can target future improvements that will make the most positive difference.

 

Specific to this… I can see the value of being able to extract 3D areas from the corridor when trying to calculate non-depth materials such as fabric, sod, seed, etc. I’ve added this to the product backlog and we’ll see what’s involved. It feels like a new “Area Computation Type” command setting similar to “Linear Computation Type” (2D or 3D) is the most logical approach. However, since we’re looking at it, I’d like some thoughts on possible project requirements…

 

  1. Should we be reporting both 2D and 3D area (and linear) values?
  2. Is 2D vs. 3D calculation consistent for both linear and area? In other words, is there a single setting that defines that both linear and area calcs will use 2D or 3D values?
  3. Are there cases where you need 2D for one type of entity and 3D for another? E.g., 3D area for daylight and 2D area for pavement?

 

Thanks in advance

Dave Simeone

Senior Product Manager – AutoCAD Civil 3D




Dave.Simeone

Product Line Manager, Autodesk Infrastructure Products
Message 12 of 27
Neilw_05
in reply to: dsimeone

Hi Peter,

 

I hope your request for input includes other aspects of QTO besides corridors.

 

If so I'd like to mention another problem: we can't extract quantities for certain items within a range. For example it is common practice to summarize quantities on a per sheet basis. As far as I know we cannot do that with pipes using QTO. It only computes a pipe length if it's ends are within the extents of the sheet.

Neil Wilson (a.k.a. neilw)
AEC Collection/C3D 2024, LDT 2004, Power Civil v8i SS1
WIN 10 64 PRO

http://www.sec-landmgt.com
Message 13 of 27
Cadguru42
in reply to: dsimeone


@Anonymous wrote:

Hi folks

 

We’re interested in hearing any and all feedback on QTO or any other feature so that we can target future improvements that will make the most positive difference.

 

Specific to this… I can see the value of being able to extract 3D areas from the corridor when trying to calculate non-depth materials such as fabric, sod, seed, etc. I’ve added this to the product backlog and we’ll see what’s involved. It feels like a new “Area Computation Type” command setting similar to “Linear Computation Type” (2D or 3D) is the most logical approach. However, since we’re looking at it, I’d like some thoughts on possible project requirements…

 

  1. Should we be reporting both 2D and 3D area (and linear) values?
  2. Is 2D vs. 3D calculation consistent for both linear and area? In other words, is there a single setting that defines that both linear and area calcs will use 2D or 3D values?
  3. Are there cases where you need 2D for one type of entity and 3D for another? E.g., 3D area for daylight and 2D area for pavement?

 

Thanks in advance

Dave Simeone

Senior Product Manager – AutoCAD Civil 3D


I don't know of a single case where the 2d length would be used over a 3d length for quantities use. Quantities should reflect the real world which is 3d. The only time I can think of using a 2d area over a 3d area would be for slope, ROW, drainage, etc. easements, which QTO doesn't do anyway. 

 

That's just what we would use, though. There very well could be others who would need the 2d length/area. 

C3D 2022-2024
Windows 10 Pro
32GB RAM
Message 14 of 27
fcernst
in reply to: dsimeone

Hi Dave,

 

QTO is a great conceptual implementation, once again leveraging the power of the Corridor modeling system. It has two problems however:

 

  1. Implements an incorrect surface area alogrithm by returning a "2D projected area" for its "Item Area" value.
  2. It is producing Pay Item Formula errors.

This goes way beyond just "seeing value" in computing surface area, it is the correct procedure to get accurate quantities. We desperately need the surface area returned for the "Item Area" value in QTO.

 

We use Corridors today in our Civil design work, we are 3D, so now we can deliver accurate quantity estimates, without being embarassed by the Contractor in front of the client in meetings with our 2D planimetric engineering cost esitmates. Contractors have never regarded engineering estimates as a serious undertaking in determining the amount of material it takes to complete the project. They have their own methods.

 

Now we have the opportunity to deliver more realistic quantity estimates (and expectations) for our clients. This will also help us in our Recommendation for Contractor Payment services we are obligated to perform by contract.

 

Imagine the errors induced using the 2D projected area in my typical cross section below for my surface materials:

 Capture.JPG

 

 

The Pay Items are integrally related and connected to our Corridor objects. They reside in the Corridor code set styles we use and are entered directly in the Corridor Properties window. The Civil 3D Help advocates and instructs on the use of Pay Items with Corridors.

 

Why would Autodesk consider using an algorithm in QTO that uses projected area for a 3D Corridor modeling object?

 Capture2.JPG

 

 

Consider the induced error in payment for this lined channel from a recent support request:

 

(this could be any material: seeded areas, sod, geo-fabic, riprap, topsoil, gravel, base course, pavers, etc.):

 

Use QTO to get the top surface area of a stock subassembly that I have laid out at a 100% grade (1:1 H:V) with a 5 foot offset.

 

For 100' of Corridor stationing, QTO returns an area of 499.93 sqft, which is appx. equal to the 2D projected area in plan view (5'x100'). The correct requirement is to return the area using the 3D lengths of the links for quantities. The 3D length of the 1:1 top surface is 7.07'. The surface area quantity for the concrete on this side of the "concrete lined channel" is 7.07' x 100' = 707 sqft.

 

This is a difference of 207 sqft of concrete per 100 lineal feet of channel per side, resulting in 2*207 = 414 sqft of total difference in concrete per 100 lineal feet of the channel. The differences get more dramatic the more vertical the slope is of course, as a function of 1/Cos(theta). 

 

Brian Hailey reports the following: "I just did a quick test, it also does not take into account the profile grades. I created a pretty severely graded road and it gave the same area as a perfectly flat road."

 

 

Problem #2

 


Here is a statement today from Lisa Pohlmeyer, who I have found to be a very accomplished user and mentor to the group, that sums up this problem very eloquently. My summary follows:

 

 Capture3.JPG

 

 

Summary:

We need these two problems with QTO addressed ASAP, as we have purchased the software under the context that QTO would not have these defects. This affects crucial project deadlines and previous man-hour budget appropriations, with cost implications.



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 15 of 27
fcernst
in reply to: dsimeone

"I’ve added this to the product backlog"

 


Dave,

 

Can you please clarify what this statement means?

 

My research this week has shown people have been hollering about QTO since about 2009?

 

Thanks

Fred



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 16 of 27
dgorsman
in reply to: dsimeone

If Civil3D was done as work-for-hire, I'd be checking the contract - its usally understood that area isn't a projected 2D value.  Unfortuneately the program is explicitly sold as-is with no guarantee it will meet the needs of the end user, and any shortcomings may or may not be adressed.  So the request for feedback *is* appreciated, and I hope the resulting posts contain enough information on workflow and data to point the developers in the right direction with all deliberate speed.

 

I recognize that solving this problem could be technically complex and may take some time (diagnosis and planning alone could take most of the two work-weeks requested earlier).  It would be helpful if there was further feedback from AutoDesk once the development team has had a chance to look at it, so we can know in general terms if this is considered something they can start work on.  Specific details or scheduling isn't important, as I know future release content cannot be commented on, just a "Yes, its possible, and its something we are looking at" or "Its very complex, it may have to wait for a future release".

----------------------------------
If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.


Message 17 of 27
AllenJessup
in reply to: dsimeone

Dave,

 

I just wanted to add my agreement that  a 3D computation of quantities is absolutely the correct way. The example of a trapezoida, concrete lined, channel is probably perfect. If the walls are tall and relatively steep, the concrete quantity would be vastly different if based only on the 2D footprint.

 

When this was done by hand it would have been based on cross-sectional area computed by average end area. I can't understand why calculating if from a corridor would be any different.

 

If you're doing quantities on a simple, relatively flat, road. You might not have enough of a difference for a contractor to quibble over. But in any other case you'll be paying out a lot of extras if you that short on your quantities. Oh, the contractor will know you're short. Some of them might mention it - but you did it on your computer using Civil 3D so it must be right. Other contractors wont say anything but will bid cheap on the quantities they agree with and then bit high on those they think you're short on. That can lead to a big extra payment on those items.

 

So please. Give this a high priority. I, like others, have projects in the pipeline that this will make a huge difference on. I'll be very embarrassed if I have to tell our Engineers that the quantities will have to be calculated by hand after telling them that all this can now be done by the program.

 

Allen Jessup



Allen Jessup
Engineering Specialist / CAD Manager

Message 18 of 27
AllenJessup
in reply to: dgorsman


dgorsman wrote:

 

I recognize that solving this problem could be technically complex and may take some time (diagnosis and planning alone could take most of the two work-weeks requested earlier).


Yes. It will take some time. But the information is there. Before 2014 as an add on and included in 2014 is the ability to create solids from corridors. This is for 3d rendering. But it shows that the underlying calculations are there. The big hurdle will be to get that reflected in the QTO.

Allen Jessup



Allen Jessup
Engineering Specialist / CAD Manager

Message 19 of 27
troma
in reply to: fcernst

OK, I've never used QTO, never even glanced at it.  But I've been following the various conversations with interest.  There is a thought that's bugging me, but I need to put it out there cautiously because I really haven't got a clue what I'm talking about.  So here goes:

 

Is there anything like an 'expression' or formula available in QTO?

Are the slope of the link and the 2D area generated by the link available in the 'expression'?

 

Because if so, then the 3D area could be calculated by some trigonometry.

 

Or if the 'volume by 2D area' is available along with the slope, the same formula would convert that into 'volume by 3D area'.

 

I don't want to ruffle any feathers here by sticking my nose into something I don't understand, but I had to throw that out there.


Mark Green

Working on Civil 3D in Canada

Message 20 of 27
dsimeone
in reply to: dsimeone

Fantastic feedback on all of this..  Greatly appreciated.

 

One thing I want to be clear about is that the Pay Item / Takeoff system is not intended as a way to calc material volumes. It's really about counting things, getting linear distances and area totals. Not that it wouldn't make sense for material volumes to also come out of the same system... Certainly something to look at for the future.

 

Material volumes are done via the sample line-based material totals. Note that there are changes to this in R2014 to provide a bit more flexibility and usability. A lot of the improvements came from the perspective of organizations doing construction supervision (aka, needing very accurate material volumes - either from surfaces or from corridor shapes).

 

Another approach that you should try is to create corridor solids from key shapes in the corridor. Then use the AutoCAD "Mass Properties" (Massprop) command to list out the volume. This works very well on complidated shapes. The solids are also a good way to QA your model (not saying traditional things like sections and surfaces are bad... looking at the 3D solids, however, makes it instantly clear of there are issues).

 

Really interesting feedback - thanks again.

 

Dave S




Dave.Simeone

Product Line Manager, Autodesk Infrastructure Products

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