M27 junctions 4 to 11: smart motorway

Latest updates

• 29 June 2022

  Upgraded motorway now open

  This week we’re changing the speed limit between junction 4 and 11, which marks the lifting of the final restriction on the upgraded section. It means you can now drive at national speed limit.

  If you’ve been using the road recently you’ll know all four lanes of the upgraded carriageway were open and the speed limit was 60mph. Drivers were kept at a lower maximum speed limit while we adjusted the technology which detects stopped vehicles. We continue to make adjustments but our testing shows we can now increase maximum speed on the upgraded section.

  Thank you to everyone for your co-operation and understanding during this phase. Routine operational checks of the system continue. 

  All motorways, with or without a hard shoulder, are designed and operated with drivers centrally in mind, to be easy and straightforward to drive on. The technology currently used on smart motorways, all focussed on drivers, is a system of inter-related features creating a layering effect. These include:

  • Variable speed limits to help keep traffic moving, reducing frustrating stop-start traffic and making journeys quicker 
  • Clearly signed and orange-coloured emergency areas set back from the road and with telephones linking directly to our control rooms 
  • Detection systems to monitor traffic for changes in flows 
  • Stopped Vehicle Detection (SVD) technology which can identify a stationary vehicle, typically within 20 seconds
  • CCTV cameras that our operators are able to move and zoom to monitor and manage congestion and incidents, where notified. The system has the ability to see 100% of the carriageway Signs and signals to provide information to drivers which can alert them to hazards ahead
  • Red X signals to close lanes to other traffic when a stopped vehicle is identified 
  • Enforcement cameras to deter the minority who break speed limits and ignore Red X signals 

  If drivers get into difficulty between junctions 4 and 11, they will be able to use one of 23 places to stop in an emergency. There is a place to stop in an emergency every 1.27 miles on average, which includes 13 new emergency areas. We will consider retrofitting additional emergency areas on this stretch at a later date.

  With the fourth traffic lane open and in use the capacity on this vital route along the south coast between Portsmouth and Southampton will be boosted by a third.

  If you’d like to know more about the main features of smart motorways, and advice and guidance on safer driving and what to do in an emergency, visit our new ‘Driving on motorways’ hub. 

  What’s still to be done

  We’ll be continuing with some final activities, information about any closures will be available here.