A smart motorway (formerly managed motorway) is a section of motorway in Great Britain which uses active traffic management (ATM) techniques to increase capacity by use of variable speed limits and hard shoulder running at busy times. Benefits include smoother traffic flows, more reliable journey times, fewer road traffic collisions, and reduced noise and harmful vehicle emissions. The term controlled motorway is used for schemes that use variable speed limits without hard-shoulder running (for example, the M25 from J27 to J30).