You may find some use in this guide I’ve written on curvature: FP1's Guide to Building Curvature in Studio
A combination of SBS/F3X and Gapfill can result in decent curving slopes, employing a method similar to what is shown in the screenshot. I rotated the parts using the circle as the pivot point, to keep the distance between each segment the same. If you need the road to be smoother, you can add more segments and decrease the distance between each one.
For the screenshot, I rotated each part by 15 degrees and raised each segment by 1 stud. The red lines show which edges you would gapfill between, and the initial rectangle parts can be deleted afterwards.
You would need to follow the same process but with separate parts for your yellow and white lines, to match the curvature.