Single lane roads?

What is the best way to use the single lane roads? I am having major trouble with trains so I want to handle truck traffic better, but when I use same way two lane roads with intersections there’s always this weird bug where an intersection will stop moving entirely and I can’t figure out why, and over time any short connections like a two way connection to a cargo station will back up enough to stop traffic too.

So how can I use single lane roads to improve things? Do they allow off and on ramps that don’t slow traffic?