Site Improvement Material Density Takeoff Calc

How do you get a Site Improvement Material to calculate shrink/swell factors in a Takeoff Report? When I have 20% shrink on the select fill in a building pad material layer it does not calculate it.

The Site Improvement Quantities are not adjusted by Shrink / Swell factors. The only way that I know you can do this is in the material in TBC MSI Manager create an alternative unit called Shrunk YD3 for the materials that you are using and put in 1 cubic Yard = 0.75 Shrunk YD3 so that when you run the report it shows the actual CY and the Shrunk YDS

In reality, if you have an area of 100 yds2 and you have a material 12" thick then you have 100*1/3 CY i.e. 33.33 CY of Fill required. If the material is shrinking by 25% then you need 33.33/0.75 i.e. 44.44 CY of loose fill to generate the compacted 33.33 CY.

For Site Improvements it was decided to give you the raw CY and let you determine how you wanted to handle this - to generate the number on the report to show this use an alternative measurement unit where 1 cubic yard = 1/.75 = 1.33 Loose Yds3

and then it will report as follows

Hope that this helps

Thank you Alan. May I ask; Being that “Earthen (Select)” materials are defined as:

“Earthen materials (other than [those defined for mass earthworks] Earthen (select) materials may include mined or processed materials, such as limerock, cement treated base, crushed gravel, or extraordinarily high-bearing capacity soils acquired from off site due to the contribution that they can make specifically toward building the stabilized subgrades associated with pavements, or other area-based site improvements.”

I’m a little confused on why there is an option to input shrink/swell values for select materials? Where/when are these values used in calculation?


I looked into this to summarize this for you yesterday and this is what I came up with

Takeoff Reports - Shrink / Swell is only used in the Earthworks that uses the Earthen Category Materials. The Earthen Select Category used in Site Improvements, Shrink / Swell is not used - all reports work the same way

Utility Takeoff reports - Shrink / Swell is only used in the Earthworks that uses the Earthen Category. The Earthen Select Category used in backfill for trenches, Shrink / Swell is not used - all reports work the same way

Corridor Earthworks report - Shrink / Swell is only used in the Earthworks that uses the Earthen Category. The Earthen Select Category used in Material Layers of eg Road Bed are not affected by Shrink and Swell properties

Corridor Mass Haul - Same as Corridor Earthworks Reports

So based on this review, I do not see anywhere in TBC that Earthen Select Materials that have Shrink / Swell properties defined are affected by Shrink / Swell in any reports that are currently being generated. My guess is that they were put in there thinking that at some point they would be used but that was never implemented in any report generation. The only Materials that are affected by Shrink Swell are the Earthen Materials and the Shrink / Swell properties are used in all reports where an Earthen Material is being Cut and used as Placed Fill.

I always use the original Takeoff Report - while the other reports (Earthworks Summary and Custom Takeoff Report look prettier I don’t trust all of the numbers that they generate). The original Takeoff report always gets the numbers right in my experience. In this review, both the Earthworks Summary and the Custom Takeoff reports failed to apply the Shrink / Swell Numbers correctly to Imported Soil Fill for a simple Fill Only Takeoff where the Fill is defined as Import Soil. The Takeoff report provided the correct numbers.

As I mentioned yesterday, TBC does as follows

Earthworks Materials (that are natively in your strata layers of existing ground) will be defined as Earthen Materials and will be affected by Shrink and Swell factors because you Cut them on site, Haul Them On Site and Place them on Site or Waste the materials. The thinking of the software is that the Cut Materials will typically Expand for Haulage and then when Placed will be Compacted / shrunk in the Fill. So if an Earthen Material like Soil has a Loose Haulage Factor of 20% and a Shrinkage Factor of 10% then 100CY of Cut will become 120 CY in the Truck and 90 CY in the Compacted Fill. When you compute the Fill Required that is a Compacted Fill Number so if you need 85 CY of Fill then you would have a 5 CY Excess in this situation.

Note Rock typically gets bigger when Excavated for both Haulage and Compacted Fill so its Shrinkage can be -10% (i.e. it gets bigger not smaller than the native Cut qty))

If you are importing material, and you are bringing in e.g. 10 CY per Truck - this will be Loose Fill, if the Import Soil has a Loose Haulage Factor of 0% and a Shrink Factor of 20% then 100 CY of Imported Loose Material will become 80 CY in the compacted Fill or if you need 100 CY of Compacted Fill this will be 100/0.8 of Loose Import that is required ie 125 CY. I validated this by creating a simple Takeoff where it has all Fill in Earthworks and then I set the MSI Earthen Material Import Soil to 0% Loose Haulage and 20% Shrinkage and it generated me an Earthworks Volume of 105423 as a deficit that needed 131779 of Loose Haul Material of the Import Soil Material Type (My Shrink Factor was 20% and Loose Haul Factor was 0%). so that works as expected. I did the calcs using the Takeoff Report - This was correct, however I also did the same calc with the Earthworks Summary Report and that did not get the calcs correct - it did not apply the Inverse Shrinkage to the Fill Needed. The Custom Takeoff Report also got the numbers wrong and did not apply the Inverse Shrinkage to the Fill Needed from Import…

When you are working with Subgrades, the materials are mostly imported materials (Earthen Select) (Concrete, Asphalt, Aggregate, Sand, Gravel, Rip Rap etc.) and the reports all generate the compacted volume required. I agree that you are bringing in Loose Volume material and you have to compact it in place so if you need 100 CY of Compacted Material and that material comes in loose and shrinks by 20% from the loose state then you have to take the subgrade material numbers and divide them by the shrinkage factor ie 100/0.8 = 125 in this example. This applies to Site Takeoff, Corridor Earthworks and Mass Haul and Utility Takeoff (Trench Backfills) The reports are all consistent with this regard, and apply no Shrink and Swell factors regardless of what is defined in the MSI Manager. Because they are not typically being excavated on site, there is no Native Cut Volume inside the project to use as a start point that gets bulked up to Loose Haulage state before getting compacted in the placement area, so TBC just reports the quantity of Placed Compacted Material Required (It does not show these as Imported Materials either). Agreed that this is extra work for you to review the reports generated and then compute the Imported Loose Material required.

The only times that this will be an issue is if you are excavating eg Rock and then using that as a subgrade Material. In this case you have an Earthen Material Rock that you are Excavating and maybe Crushing to create an Aggregate and then using the Aggregate as an Earthen Select Material to place in a subgrade adjustment. In this case The Rock Cut is computed and it may have a Loose Haulage Factor and a Shrink / Swell Factor (for use in an Earthworks scenario, however if you intend to use all or part of that material generated for Aggregate, then you will want to set that Earthen Material to be of Type Ordinary Soils and then Set the material to have a % Usable as fill so that the remainder is “wasted” so that it can be used via the crusher to create a volume of Aggregate that will satisfy the Subgrade requirements. The aggregate Requirements in this scenario would be for a compacted Fill, so if the need is 100 CY and the Aggregate shrinks by 20% when Compacted then you need 125 CY of Loose Material out of the Crusher to meet the need. In this case you would need to compute the Rock Generated from Cut and the Aggregate Needed for Compacted Fill and then do the math to compute the amount of Rock that needs to be wasted (and not used for Earthworks Fill) so that you can crush and use it for aggregate

So eg

Take 500 CY of Native Rock

You need 200 CY of Compacted Aggregate for a pad

If the Rock gets 20% bigger in Haul and is still 10% bigger in Compacted Fill (-10% Shrink)

If 1CY of Native Rock creates 1.2 CY of Compacted Crushed Aggregate then you need 200/1.2 of Native Rock to meet the needs of the pad = 166.67 CY of Native Rock

If the Aggregate Shrinks by 15% in compacted Fill then the 200 CY need of Compacted Aggregate will be 235.29 CY of Loose Haul from the Crusher

That leaves 500 - 166.67 CY of Native Rock for the Earthworks Fill which is 333.33 CY or 66.67% of the original Native Rock being generated

So I would edit the Rock Earthen Material, Set the properties to Ordinary Soils and set the % usable for fill to 66.67

This will then generate 333.33 *1.1 CY of Compacted Fill = 366.66 CY for the Earthworks Requirements

The 166.67 CY of “Wasted Rock” can then be used to create the 200 CY of compacted Aggregate for the building pad

My recommendation to Trimble is that if the Shrink Swells of Earthen Select Materials are not used anywhere that they be hidden for now in the MSI Manager until such a time as they are used, unless I have missed something here in my review. If anybody knows of anwhere that the Earthen Select Materiual Shrink / Swell numbers are being applied, please let me know so I can amend this post.


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Thank you for taking the time to look into and explain your findings Alan, they are consistent with my experiences. It’s really unfortunate that TBC doesn’t seem to have any interest in improving the operability and customizability of Takeoff Reporting. I spend a lot time reformatting reports to make them as digestible and concise as possible. I think that time could be reduced or eliminated with some improvement of TBC reporting tools that never seem to come.

Our volumes Manager command is our first step towards solving this issue - I think it is a good start - it has some way to go to give people what they need for full Takeoff but it is 100% on the right track. It is good today for any type of Surface to Surface volume with boundaries i.e. Stockpiles, Progress Qtys, Earthwork Volumes and can be used with Takeoff Surfaces to generate results for key elements like

Topsoil Strip

The Boundary Management and Grouping makes it ideal for subdivided volumes on sites split into phases or work areas, and the fact that it stores all the results in the project file and also tabulates all the results as drawing elements directly is a huge time saver.

Probably not what you wanted to hear, however just know that we are working on it.