This is the SkylinesPlanningGuide.com's collection of raised highway bits, which helps you create highway systems with the two sides perfectly parallel.

Background: As a civil engineer in real life, it's always drived me nuts that I'm so incapable of making my highways perfectly parallel in CS. Once my OCD kicked in, I decided to create a set of ploppable freeway bits that can be snapped together like legos to build a winding highway that stays perfectly parallel. Thus, this set was created. I also have an identical set with at grade (flat) highways.

What is this?: This is my colleciton of raised highway bits for laying out highways.

What does it include?: There's three different radius sizes (Small, Medium and Large) as well as three different curve angles for each radius (22.5, 45, 90)

Layout tips: The large radius ones snap together the easiest and can be snapped together in either direction. The smaller radius ones can be a bit more difficult to snap back-to-back. If laying out multiple small radii in a row, you'll find that they will have a a tiny bit of overlap. You can delete a small segment, and re-blend back together, or do what I do and leave them slightly separated and draw in straight segments to connect them.