Permanently signed detour route

A permanently signed detour route (also known as an emergency detour route or emergency diversion route) is a type of route which is used temporarily during special circumstances. Various areas have developed these systems as part of incident management. The purpose of these routes is to provide a detour in the event that the parent route is impassable, due to either a traffic jams, traffic collision, or road closure (for a variety of reasons). Sometimes these routes are signed as a prefixed or suffixed numbered road, making them a type of special route.

A permanently signed detour route should not be confused with a "permanent detour". The latter would be used if a particular roadway section, such as a bridge, were closed permanently.