High Quality Content by WIKIPEDIA articles! A concurrency, overlap, or coincidence in a road network is an instance of one physical road bearing two or more different highway, motorway, or other route numbers. When it is two freeways that share the same right-of-way, it is sometimes called a common section or commons. Road enthusiasts often use the term multiplex -- as well as the more specific duplex and triplex -- to refer to such instances although those type are the more common instances.