The national speed limit has been restored between junctions 4 and 8/9. This marks the lifting of the final restriction on the upgraded M4 between junctions 4 and 12.
A section between junctions 3 and 4 in West London will remain at 60mph to help manage air quality in the area, and to manage traffic into London; our upgrade of the road and calibration of the technology here is complete.
You’ll have seen between junctions 3 and 8/9 all 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 have now increased the maximum speed on the upgraded section but we continue to make small adjustment to the technology and routinely check the system.
If drivers get into difficulty between junctions 3 and 8/9, they will be able to use one of 16 new emergency areas, bringing the total of emergency areas on the M4 between junctions 3 and 12 to 34. In total there are 59 places to stop in an emergency, including retained sections of hard shoulder between junctions and on junction slip roads, every 1.3 miles on average.
We use a system of inter-related features and technology on upgraded motorways which 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 which provide drivers with information that alerts 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
Some lane and slip road closures will take place overnight for the next few weeks while we remove temporary traffic management associated equipment.
This is the final section of this major upgrade to open on one of the busiest stretches of motorway in the country. We’re looking forward to real improvements it will bring to more than 130,000 journeys every day. We would like to thank you for your co-operation and understanding during this phase and during the roadworks that we started in 2018.
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 ‘Driving on motorways’ hub.
Thank you
Best Regards
Community Relations Team
Balfour Beatty VINCI | M4 3 to 12 motorway upgrade
Email: m4j3-12@bbv-jv.com
Working on behalf of National Highways
National Highways Customer Contact Centre: 0300 123 5000