What Is a Smart Motorway?
Ellie Dyer-Brown, 8 months ago
3 min read
- Car ownership
FixMyCar explains what smart motorways are and how they affect drivers.
Smart motorways have been a hot topic over the past decade, and a controversial one, too. Like them or loathe them, it pays to be aware of how they operate and how they differ from conventional motorways because, despite the government scrapping plans to build more of them, several are already in use across the country.
Contents:
What is a smart motorway?
Smart motorways are designed to be extremely efficient owing to the traffic management methods they use to reduce congestion and increase capacity.
Usually, this involves using the hard shoulder as a regular lane and implementing variable speed limits.
Smart motorways were designed by Highways England to manage traffic while minimising environmental impact. However, as we’ll discuss later on in this article, they have certainly come under fire thanks to safety concerns.
There are three main types of smart motorway:
‘All lane running’ schemes
‘Dynamic hard shoulder’ schemes
‘Controlled motorway’ schemes
‘All lane running’ smart motorway schemes
In ‘all lane running’ schemes, there is no longer a hard shoulder; instead, there is an extra lane that will only be closed to traffic if there is an accident.
If an accident does happen, one or more lanes could end up being closed. This is always signalled by a red X that will appear on an overhead gantry or a sign at the edge of the road. When you see a red X, exit that lane as soon as you can; failing to do so is not only dangerous but illegal.
Signs are also used to show the speed limit which varies depending on the level of traffic.
‘Dynamic hard shoulder’ schemes
During the busiest parts of the day, the hard shoulder is opened up to ease congestion, and this is indicated by overhead signs.
Again, overhead signs display the speed limit which varies depending on the volume of traffic.
‘Controlled motorway’ schemes
Controlled motorways still have a traditional hard shoulder with three lanes or more. However, these lanes are subject to a variable speed limit which is displayed by overhead signs. The national speed limit applies if a speed limit is not indicated above.
How do smart motorways prevent traffic bunching?
Smart motorways prevent long queues and congestion by using variable speed limits. Some of them also control the traffic flow by opening up the hard shoulder as a regular lane.
Smart motorway signs
On smart motorways, a red X always signals that a lane is closed and should not be used.
Sometimes, red X signs need to be implemented in advance of an incident to provide access for emergency vehicles, so even if you can’t see why a lane is closed, it’s important that you don’t use it.
Where are smart motorways UK?
There are over 236 miles of smart motorway in the UK.
M1 - Junctions:16-19, 24-25, 28-31, 32-35a, 39-42, 10-13, 6a-10, 23a-24, 25-28, 31-32
M3 - Junctions: 2-4a
M4 - Junctions: 4-5 interchange
M5 - Junctions: 4a-6
M6 - Junctions: 2-4, 11a-13, 16-19, 4-5, 5-8, 8-10a, 10a-11a
M20 - Junctions: 3-5, 5-7
M23 - Junctions: 8-10
M25 - Junctions: 5-7, 23-27, 2-3, 7-10, 10-16, 16-23, 27-30
M42 - Junctions: 3a-7, 7-9
M60 - Junctions: 8-18
M62 - Junctions: 18-20, 10-12, 25-30
Are smart motorways dangerous?
There are a number of valid concerns about smart motorways. Some drivers have expressed worry about road safety thanks to the variable speed limits, which could require them to slam on their brakes to slow down in time.
In response, Highways England clarified that there is a slight lag between when the speed limit is changed and when cameras start enforcing the new limit. However, this can be as little as ten seconds, which fails to reassure many motorists.
Many people feel that motorways without a permanent hard shoulder are unsafe, and a YouGov poll in 2021 found that the majority of motorists agree. Currently, the furthest distance between emergency laybys is 1.5 miles, which, in the eyes of many, is too far to be safe.
In 2023, the government confirmed that plans to create more smart motorways had been scrapped owing to a lack of public confidence in them.
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Written by Ellie
Ellie is FixMyCar's Content Writer. She has over three years of experience writing about cars and regularly collaborates with automotive experts to provide trustworthy advice for drivers in a language they understand. Her work has been featured in Yahoo! Finance, iNews, The Daily Express and The Sun. She has a BA in English literature and an MA in creative writing from Durham University. Outside of work, Ellie follows F1 and eagerly awaits Ferrari's next era of dominance in the sport. She drives a Suzuki Swift.