Lately, I’ve been seeing quite a few questions on the Civil 3D discussion group regarding volumes and quantities. Volumes can be pretty straightforward, but individual material quantities can be a bit more in-depth. Following the link will hopefully illustrate this process a bit better.
First of all, you have to have a sample line group of you want to calculate quantities. It should go without saying that you have to sample the materials that you want to calculate the quantities of – if they’re not sampled, you can’t include them in any calculations. That seems to be a sticking point with some people, so I’ll repeat it:
YOU HAVE TO SAMPLE THINGS THAT YOU WANT TO USE FOR CALCULATING MATERIALS.
To make sure my materials work, I always start with a corridor. To make sure that I have something other than just a singular layer of asphalt, I typically use the LaneOutsideSuper subassembly for my lanes. This gives me 4 potential layers of materials, known as Pave1, Pave2, Base, and Subbase. Do you know how figured out which layer was which on this subassembly? I went to the subassembly help file for that particular one – the help files for subassemblies are absolutely phenomenal.
Once my corridor is built, I build two surfaces from my corridor. My first surface is the roadway top surface – that’s the one that I want to show contours for in my finished plan, and is built from the Top link. My second surface is what I consider to be my working surface, and is called my roadway datum surface. It is calculated from the very bottom (or datum) of my corridor and is used for earthwork quantities. To make the quantities more accurate, I also create a boundary around both surfaces, typically from the Daylight feature line.
Once my surfaces are created, I create my sample line group (SLG.) In that SLG, I sample 4 items: my existing ground surface, my corridor top surface, my corridor datum surface, and my corridor itself. All of the typical styles are applied with one exception – I don’t want to see my datum line, so I assign it a null style.
Next, I create my sample lines as I normally do, and may even create some section views to see what’s going on. Once that’s done, I compute materials using the Earthworks criteria. I specify my EG as the existing ground, and my corridor datum surface as the datum surface, as shown below:
Once that’s done, I simply click OK. I’m done, right? Well, no, there’s other stuff to add, but I can’t do it there. What I have to do now is go right back into that same command. There’s no “edit materials list” command, but using the Compute Materials command on the same SLG brings up a window that lets us either edit our current materials or add new ones. Well, that sound like what we want to do, so let’s look at that dialog box:
This allows me to change the cut and fill factors for my soil shrinkage and expansion, and a nice shiny button in the upper left allows me to add new materials. If I change my Data Types from Surface to Corridor Shapes, you can see the different materials available for materials display:
If I want quantities of each material in my corridor, I simply have to add each one as a new material in my list. The problem is that if I click the Add New Material button and then try to add a corridor shape, I get this nice error message:
This one threw me a bit until I looked at the new material and saw that the material type was set to cut. If I click in that box, I get a pulldown that allows me to select Structures, as shown below:
Once I select the Material Quantity Type as Structures, I can then go and add each one, remembering to change the name of each material for easy sorting later.
Now that I’ve done that, I can go create my material tables. The first one will be a total earthworks table, and then one for each of my corridor materials.
So I hope that de-mystifies the secrets of quantities. There are a few nuances to remember, and know that your corridor has to be modeled correctly before you can calculate quantities with any form of accuracy.