The more important quality metric than “roughness” is infrastructure/safety. A multi lane road shouldn’t cross another one in a flat traffic light intersection

The more important quality metric than “roughness” is infrastructure/safety. A multi lane road shouldn’t cross another one in a flat traffic light intersection. That risks T-collisions if someone runs a red light. It’s pretty cheap to keep roads smooth if you skimp on making separated lanes, safe multilevel junctions and roundabouts in every intersection.