In this tutorial, we’ll walk through how to create a grading group in Civil 3D that forms a runoff along the side of an embankment. This workflow is extremely common when you’re building ditches, pond berms, roadside grading tie ins, drainage swales, and other drainage control surfaces.
This post is geared for beginners — but this exact workflow is the same approach used every day in professional site development and transportation grading work.
Step 1 — Open the Grading Creation Tools
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Go to the Home tab
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Locate the Create Design panel
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Click the Grading dropdown
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Select Grading Creation Tools
Civil 3D will open the Grading Tools toolbar.
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Step 2 — Create a New Grading Group
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Click Set the Grading Group
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Name it: Ditch Drainage
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Turn ON Automatic Surface Creation
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Choose Volume Surface
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Comparison Surface: EG
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Click OK
Step 3 — Verify Surface Settings
Civil 3D will now open a Create Surface dialog.
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Keep the default name
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Style can remain Standard (unless you have ditch-specific styles)
Step 4 — Assign Your Criteria Set
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Select the Criteria Set button
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Choose the ditch criteria set previously created
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Select: Distance at -6%
This tells Civil 3D to create a grading that runs 10’ horizontally outward at a 6% downward slope.
Step 5 — Pick the Feature Line & Build the Grading
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Click the Create Grading button
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Select the feature line (in the demo: AB)
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Click on the side above that line
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Apply to the Entire Length
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Distance = 10 ft
Hit Enter — grading is generated.
That diamond shape symbol you now see represents a grading object.
Step 6 — Manage Selection Visibility
If clicking selects the grading instead of the feature line:
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Right-click the grading → Send to Back
This will help when adjusting the feature line later.
Step 7 — Verify Your Geometry
Use Linear Dimension:
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Distance: ~10 ft
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Slope: -6%
Your ditch runoff grading is complete.
Final Notes:
Grading groups are one of the fastest methods to model short runoff tie-ins, ditch backs, low berms, ponds, and swale transitions. Once you master criteria sets + groups, you’ll design faster with less editing and far less manual corridor manipulation.
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