Any advice on adding an actual road model to topo mesh?

You’re welcome, James!

Watch this tutorial to see the differences (Artisan or Sandbox Smoove)

And for boulders, you can create them from a cube or an icosahedron

boe-09b

boe-09a

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Instant Roads is certainly the best I have found

My process is designed to be quick and intuitive. It follows roughly the steps of Chuck Vali’s “Instant Road Nui” (which I also use and recommend), but this one is simpler.

Step 1:
Draw straight lines through the terrain, representing the Centreline (or one edge) of the road/path:


(I’ve added some gradient labels to it, so that I can check the levels/grades and adjust the various points until they are roughly okay).

Step 2:
Smooth the Edges into a curve. You can use extensions for this, but I just use the Arc tool.


You can check the horizontal and vertical curves and adjust as required (you don’t want to use curves with radius that’s too tight).

Step 3:
Make a 2d cross-section profile of your road, including all the bits you need to color in later. They need to have some vertical steps (even tiny ones) so that the edges are extruded. It can be complex. Here I’ve even drawn some kerbs and markings. Tip: Use Streetmix.Net to help figure out the dimensions.

Step 4: Carefully locate the “profile” onto the curve. It needs to be centered and perpendicular. Use Upright Extruder (free extension) to build the 3d form of the road.

Step 5:
Tie the road in to your terrain. There are several methods for doing this. I tend to use Sandbox Tools to start with, then I will manually model retaining walls etc if required. I used a very simple mesh for my surface so this looks rather blocky…but it could be complicated.

Step 6:
Colors and stuff.

This whole process may take 5-10 minutes, so it’s something that you can rough in and then re-create later if you change your mind. You can use Sandbox tools to push and adjust the road but it’s not recommended for more complex road cross sections.
You can also use some of those edges (eg kerb edge) to place streetlights, trees and other stuff.

If i need to model an intersection, what I will do is model that as a 3d object and place it (or overlay it) into the terrain and adjust its levels manually. Then I will tie my road centrelines into that intersection (i.e. i will use the intersection as a sort of starting point).

If you need to adjust Cut-to-fill or earthworks batters and retaining walls, then I suggest using a much simpler road first, then making it more detailed by editing the Profile.
Sketchup 2022 file example:
terrain and road example.skp (1.0 MB)

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Thank you @AK_SAM ! This is a very nice guide. I’m sure I missed the “5-10 minutes” part in my previous attempts. I was using the 5-10 hours technique… but I’m learning. I’m going to do a few more from scratch to learn some of the other tools demonstrated in this thread. Goal: get end results like what the posters here are getting. Thanks again.

Thanks for everybody’s input. As usual, there are 100 different ways to create what you want.

I used the follow me tool to create the curbs with some contour following techniques from SU Landscape Lesson and Soap Skin Bubble for the asphalt to get the raised center for drainage.

Now I am going to try to clean up these topo contours.

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