How To Grade a Parking Lot Using Civil 3D

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Setting up the Kerb Lines:

1. Inspect polylines: We will be converting the front of kerb polylines into feature lines. Add a radius to any missing sections. If you are creating a loop, ensure the first vertex is in the middle of a straight section; having the first vertex at the start and end of a curve can cause issues. You can easily move the vertex using the break command.
2. Convert these lines to feature lines. Use an appropriate feature line style. Use the Name feature to ensure each line is named something like “Kerb <Next Counter>”. Organize them into a site for drawing tidiness and add elevation.
   

Model the Kerb Corridor:

1. Insert a kerb subassembly.
2. (Optional) Exaggerate the height for easy checking, remember to return the kerb to the design height.
3. Mirror the assembly: Often, kerb lines will be going in different directions. You could reverse the lines, but I find using a mirrored assembly easier.
4. Add a corridor using the kerb feature lines as baselines. Adjust the frequency to make corners smooth. Use a mirrored assembly if corridor regions are going the wrong way.
5. Check the corridor.
   
   

Model the Surface:

I often use a “vacuum form” style workflow to generate my proposed surface.

1. Draw a boundary around the proposed site.
2. Convert the boundary line into an alignment. You can use a feature line, but he prefers using an alignment for this workflow.
3. Add a profile to the alignment. He usually draws a profile that closely matches the existing ground.
4. Add a new subassembly with a single marked point and give the marked point a name, such as “boundary.”
5. Add a corridor, using the alignment as the baseline and the boundary marked point as the assembly.
6. Extract the feature line from the corridor.
7. Create a new surface.
8. Add the boundary feature line to the surface as a breakline.
9. You can increase the number of triangles in the surface by increasing the frequency of the corridor.
10. Add a boundary to the surface if needed. You can offset the boundary alignment by 1m and add the polyline boundary as a destructive boundary.
    
    

Add Kerb to the Surface Model:

1. Extract feature lines from the kerb model using a naming template. Add these feature lines to a new site to keep them separate.
2. Add the feature lines to the proposed surface.
   
   

Add Centreline:

You can use the same workflow as above by drawing an alignment, proposed profile, boundary marked point, and feature line workflow. You can swap the marked point for the disk channel if needed. Either way, model the centerline and add it to the proposed surface.

Tidy polylines

Move first vertex away from corner or curve for lopped lines

Convert polylines to feature lines, make sure you name them correctly

Make a pair of kerb subassemblies, set the height very big to start to make it easier to check the corridor is set up correctly

Check corridor, make sure no regions are running backwards

A single marked point. This can turn an alignment and profile into a feature line

Draw a quick boundary profile, usually following existing ground. You can use existing ground if there are no gaps in the data.

Add a corridor, use marked point assembly and bounday alignment and profile, extract the feature line.

Add boundary feature line to proposed surface.

Adjust frequency of boundary corridor if needed.

Extract feature lines from kerb corridor

Always name your feature lines!

Add kerb corridor feature lines to proposed surface

Add centre line alignment

Draw a quick centre line profile. No doubt you will be adjusting this throughout the project.

Draw a corridor again for the centreline. You can just add it to the kerb corridor.

Exact feature line from centreline corridor, add this feature line to the proposed surface

End result.

C3DChallenge 3- Grading Parking Lots.dwg

C3DChallenge 3- Grading Parking Lots MK.dwg