As of now, the yellow lines in the road can only be solid lines, like so:

It would be nice to add customization options for passing (dotted) lines for left, right, or both sides of the line per segment. Some state highways that are one-lane for both oncoming and ongoing lanes use this a lot.

Would also be helpful to have options for the yellow line to be clear, so that two-lane roads can be imitated as a one-lane roads while still technically using two-lanes. While this might be funky with intersections, this is a good easy method for allowing one-lane roads (even if they're technically two-lane) like in issue ##24 . All the user would have to do is make lane width half the size.