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The hidden dangers of smart motorways

Sarah Tooze
Written by  Sarah Tooze
Alicia Hempsted
Reviewed by  Alicia Hempsted
5 min read
Updated: 20 Jun 2024

At least 79 people have been killed on smart motorways and many people have spoken out about safety concerns. What makes them dangerous, and what should you do if you breakdown on a smart motorway?

The UK Government has put a stop to any new smart motorways being built but they still make up about 10% (about 400 miles) of England’s motorway network. So what exactly is a smart motorway, where are they and are they safe?

What are smart motorways?

Smart motorways are designed to provide extra capacity on some of the busiest and most congested sections of motorway, without building or widening existing lanes. To do this ‘smart’ technology is used to control the speed and flow of traffic and, in some cases, the hard shoulder of the motorway is turned into an extra lane.

There are three types of smart motorway:

All lane running (ALR)

The hard shoulder is permanently converted to a live lane. ALR motorways use technology to detect if a vehicle has stopped in a live lane and have emergency refuge areas with emergency roadside telephones at intervals along the road.

Dynamic hard shoulder (DHS)

The hard shoulder temporarily becomes a live lane at peak times of congestion. Electronic signs and signals show drivers when to use this lane and a maximum speed limit of 60mph is set. Like ALR motorways, DHS motorways have emergency refuge areas.


These have a permanent hard shoulder and use variable mandatory speed limits to control the speed and flow of traffic. Overhead electronic signs display messages to drivers, such as warning of an incident ahead.

Where are smart motorways?

Smart motorways are on some parts of England’s motorway network, which is managed by a government-owned company National Highways (formerly Highways England).

The smart motorway concept was first trialled on the M42 in 2006 and the first ALR smart motorway opened on part of the M25 in 2014. Since then, the number of smart motorways has increased and stretches of smart motorway are now on the M1, M3, M4, M5, M6, M20, M23, M25 M27, M40, M42, M56 and M62 (see map here).

Are smart motorways safe?

Motorways in general are the safest roads to travel on and National Highways says that the latest data (published in its Smart motorways stocktake third year progress report) shows that, overall, in terms of serious or fatal casualties, smart motorways are “our safest roads”.

However, at least 79 people have been killed on smart motorways and in the past five years seven coroners have called for them to be made safer.

Some MPs have also repeatedly spoken out against smart motorways. In June 2016, a Transport Committee report advised the Government that it should not proceed with ALR schemes, citing “major safety concerns”.

In 2019 the then Transport Secretary Grant Shapps commissioned a review, which led to an 18-point improvement plan. But the safety of smart motorways was called into question again following a Transport Committee inquiry in 2021.

The Government agreed with the recommendations of the Transport Committee’s report to pause the rollout of ALR smart motorways until five years of safety and economic data was available for schemes introduced before 2020. The Government also announced it would invest £900 million to improve safety on ALR motorways.

Then in April 2023, the Government announced it was removing new smart motorways from its road-building plans, including 11 schemes which had already been paused and three which were earmarked for construction due to “financial pressures and lack of confidence felt by drivers”.

Loved ones of those killed on smart motorways and motoring organisations like The AA and The RAC want the Government to go further and abolish existing smart motorways too.

The AA says that this is a major plank of its Motoring Manifesto and is supported by 81% of drivers.

It points out that live lane breakdowns are “incredibly dangerous” and that there is twice the likelihood (40%) of breaking down in a live lane on ALR than on a conventional motorway (20%).

Concerns have also been raised about the technology used on smart motorways after a BBC Panorama Freedom of Information request discovered that between June 2022 and February 2024 there were 392 reported incidents where smart motorway technology lost power.

A traffic officer for National Highways who works on smart motorways told Panorama he had lost confidence in the technology used to detect broken down vehicles because he had seen it fail too many times.

National Highways said in response that when power loss does occur it only impacts “a small area and not a whole scheme”, that it is meeting the 98% target for the detection of stopped vehicles, and that it ensures any staff concerns are “listened to and they are fully supported in their roles”.

It said that reinstating hard shoulders would “remove vital road capacity; congestion would increase significantly with the potential consequence of drivers choosing less safe roads away from the motorway network”.

The AA disagrees, claiming that more than a third of drivers don’t use the inside lane due to fear of a broken-down vehicle ahead and any incident leads to “severe congestion and delays for emergency service getting to the scheme of crashes”.

“Reinstatement (of the hard shoulder) should come with the instigation of strict lane discipline campaigns to maintain capacity,” it says.

What to do if you break down on a smart motorway

National Highways’ advice if you break down on a smart motorway is leave at the next junction or service area if you can.

If that’s not possible, move to the nearest emergency area and get yourself and any passengers out of the vehicle via the passenger door, and get behind the safety barrier where there is one, and if it is safe to do so, and on to the verge, and call for help.

If your vehicle stops in live traffic and you can’t get into the left hand lane or you can’t exit your vehicle to get to a place of safety, stay in your vehicle, keep your seatbelts and hazard warning lights on and call 999 immediately. Or if your vehicle has an SOS button, press it and ask for the police, who will then alert National Highways.