Managed motorway

Managed motorways in the United Kingdom are motorways which use active traffic management. Their aim is to increase traffic capacity at times of peak traffic flow. They use variable speed limits and hard shoulder running at busy times. A "hard shoulder" is an inner lane which in normal times is only used for emergencies.
Active traffic management was first used in 2005. The system is now in operation on sections of the M1, M4, M6, and M42, and there are proposals for its use on sections of the M5, M25, M60 and M62. 
Benefits include smoother traffic flows, more reliable journey times, fewer road traffic collisions, and reduced noise and harmful vehicle emissions. Where only variable speed limits are used, it is called a controlled motorway.