I've done that myself it's pretty easy. You might want to opt for no-traffic roads and not connecting them to active roads, meaning those with traffic. If you connect them to traffic-enabled roads, the no-traffic roads will have cars running on them. If you want to try this, I recommend the YARN-like roads, or modified YARN roads to disable the traffic. These are thick enough so the track doesn't float to high above the roads which happens with other road-track combinations.
John