I've used the colored pencil thing; experiment with several yellows until I got one that I could see. Never occurred to me to underline with white first, great tip DK. The white certainly works well.
For curves, I lay down paper over the road, pressing hard enough to make an imprint in the paper. Cut out to shape to both sides/edges of pavement. Measure the center and dot in the centerlines, freehand connect. Then cut down the centerline with scissors. Lay back on the road, aligning one side with the edge, center is now identified and can be followed with the colored pencils. Shift over a hair for the second line. Ends up where you want it without a fight.
I've also found the colored pencils work great for marking parking places, crosswalks, all manner of miserable highway lines. A steel coupler pin height gauge is about the right size for a lot of this as a tiny ruler.