Speed bump help

So, im new to the game and i was wondering if anyone could help me edit some speed bumps into a map with a highway, or something along those lines. any help would be appreciated!

 

1. Press F11
2. Go to the Scene Tree
3.
4. Click 'art'
5. Look around in these folders until you find it.

Hope this helped!

 

You can try my map if you want https://www.beamng.com/resources/feel_the_bumps.2707/