Creating and Organizing Grading Groups in Civil 3D

Setting up Grading Entities and Automatic Surface Creation in Civil 3D

Explore the process of grading within Civil 3D, focusing on the creation and application of grading groups. Understand how grading entities must be organized and the steps to create an automatic surface based on your grading groups.

Key Insights

  • In Civil 3D, grading is organized through a dropdown located in the home tab of the ribbon bar. It includes options for grading creation tools, creating grading infill, and creating grading groups.
  • All grading entities in Civil 3D need to be organized inside of grading groups. Prior to working with the grading creation tools, it's recommended to create the grading group first.
  • When creating an automatic surface, tessellation spacing and tessellation angle determine the definition of your surface. Choosing smaller numbers results in a more defined surface, while larger numbers lead to a less defined surface.

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Now that we've prepped our parcels with their specific pads, we're ready to start talking about grading, grading objects, and grading groups. Inside of Civil 3D, grading has its own dropdown.

It's up here in the Home tab of the Ribbon bar, right under Grading. So there are three options inside of Grading. We have the option for Grading Creation Tools, Create Grading Infill, and Create Grading Groups.

All of your Grading entities inside of Civil 3D need to be organized inside of Grading Groups. And so even though you can click on Create Grade or Grading Creation Tools, and then if you don't have a Grading Group, Civil 3D will prompt you to create one, I think it's good practice.

If you intend to start working on a Grading Group that hasn't been created yet, you should go ahead and create the Grading Group before you start working in the Grading Creation Tools. So I'm gonna go ahead and select Create Grading Group. From here, I'm gonna be given the option of what I want the name for the Grading Group to be.

All of these Grading entities are gonna be associated with my Dev Main corridor. So I'm gonna go ahead and call this DevMainGrad. From here, I could give it a description.

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I'm not gonna go ahead and do that. I'm gonna move on to the next option, which is automatic surface creation. Whether or not you check this box, Civil 3D can or won't create an automatic surface based on your Grading Groups.

I'm gonna go ahead and check it to have it create an automatic surface. I'm gonna go ahead and use the group name, DevMainGrad, as my surface name. I'm gonna specify the surface style as Design Topo.

And then we have these options of tessellation spacing and tessellation angle. Tessellation spacing and tessellation angle are basically how Civil 3D will interpret your Grading Group into a surface. Tessellation spacing sets how many breaklines are placed into your surface based on your Grading Group, or how few of them are placed in it, or how far apart they’re spaced.

The important thing to note is that the smaller the number you choose for tessellation spacing and tessellation angle, the more detailed your surface will be. And the larger the spacing or the larger the angle, the less detailed your surface will be. I am fine with 10 feet for the tessellation spacing and three degrees for the tessellation angle.

So I'm gonna go ahead and leave these as they are. I am not going to check this volume-based surface option. Civil 3D can create a volume-based surface for you.

If you select this option, you would set the base surface for your volume-based surface. I am not going to create that. So I'm gonna go ahead and leave it unchecked and click OK.

Civil 3D is now going to prompt me to create my surface. Because I already prompted it to automatically create this surface, it has now filled in the name of DevMainGrad. It has also set the style as Design Topo, as I indicated in the previous window.

So I'm gonna go ahead and click OK. What Civil 3D has now done is it has created my DevMainGrad surface. It has also created my DevMainGrad Grading Group.

If you don't have these expanded out, Grading Groups are found under Sites. They're found under the specific sites, so under our DevMain, and then under Grading Groups. Same thing with the surface.

It's under Surfaces, and then here’s our DevMainGrad surface that’s being built from our DevMainGrad Grading Group. So what I'm gonna go ahead and do now is save this drawing, and then I'll meet you in the next video.

photo of Michael Kinnear

Michael Kinnear

Civil 3D Instructor

Mike is a Civil Engineer and a member of the American Society of Civil Engineers. He brings a wealth of experience working on transportation engineering and site development projects that involve working with Civil 3D, AutoCAD, and MicroStation. Mike is an avid hiker and enjoys spending time with his family in the local Cuyamaca and Laguna mountains.

  • Autodesk Certified Instructor (ACI)
  • Autodesk Certified AutoCAD Civil 3D Professional
  • Civil 3D
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