Smart motorways

The new name for actively managed motorways

‘All lanes running’ motorways have variable speed limits, no hard shoulder, and emergency refuge areas every 2.5km

‘All lanes running’ motorways have variable speed limits, no hard shoulder, and emergency refuge areas every 2.5km

Blue signs and ‘M’ prefixes aside, for a little over 50 years the term ‘motorway’ for most people has meant a dual carriageway with a 70mph speed limit, hard shoulders on either side for the entire length and emergency telephones every 1.5km.

We got variable speed limits on the western side of the M25 as early as 1995 but things really started to change in 2006 when a stretch of the M42 became a fully flexible ‘controlled’ motorway - it has a hard shoulder which can be opened and closed, variable speed limits, lane control, overhead gantries, and emergency refuge areas.

In 2013 the Highways Agency (now Highways England) started using a new term, 'smart motorway', to describe a range of different designs of actively controlled motorway some of which have no hard shoulder at all.

Different types of smart motorway

Controlled motorway

A controlled motorway is one with multiple lanes, variable speed limits and a hard shoulder for use in emergencies only.  (e.g. western section of M25)

Hard shoulder running

Some sections of motorway have a variable speed limit and a hard shoulder that can be opened as a running lane at busy times. Overhead signs tell drivers when the hard shoulder may be used and when it must not.  (e.g. M42 J7-9, M4 J19-20, M5 J15-17)

All lanes running

This is the standard for all new smart motorway schemes started from 2013 on.  All lanes running motorways have variable speed limits, no hard shoulder, and emergency refuge areas every 2.5km. (e.g. M25 J23-27, M25 J5-6/7)

Highways England regional control centres use CCTV cameras and variable message signs to manage smart motorways. Depending on the type of motorway, speed restrictions can be set and lanes closed in the event of an incident or congestion.

Overhead and large nearside information signs are used to warn drivers about queuing traffic and speed limits as well as being used to close lanes and divert traffic in the event of an incident.

The most important feature of the new smart motorways is the Red X sign used to show when a lane is closed due to an incident or obstruction.

Don't ignore the red X

Don't ignore the red X

A red X means lane closed

If a red X is displayed you must not proceed further in the lane indicated – driving in a red X lane is dangerous and can lead to prosecution.

Variable speed limits

Besides using the red X to close individual lanes, active traffic management of smart motorways also uses variable speed limits (70, 60, 50, 40) to try to maintain traffic flow when volumes are high or for safety reasons to protect an incident. This could be anything from a breakdown or crash to staff working at the roadside or to allow a vehicle to safely rejoin lane 1 from a refuge area.

New digitial speed cameras are being used more and more to enforce these variable speed limits on smart motorways.  Though clearly signed, the cameras are smaller and less visible than the more familiar 'yellow box' cameras. They are grey and mounted discreetly to the side of the road but are nevertheless capable of monitoring all four lanes.

Many incidents will be cleared very quickly so it's inevitable that some drivers will experience a reduced speed limit but see no obvious reason for it.

This combination of 'hidden' camera enforcement and lower speed limits for sometimes no obvious reason could turn driver opinion against smart motorways, and the AA would like to see more use of variable message signs to explain the reason for reduced speed limits, both before and after any incident.

Breakdown advice

If you break down on a motorway without a hard shoulder, try to use an emergency refuge area, motorway service area or leave at the next junction.

If you can't then try and get the vehicle off the carriageway, if it is safe to do so.

If there is no choice but to stop in a live lane;

  • use hazard warning lights
  • if you are in the left hand lane and it is safe to do so, exit the vehicle via the left hand door and wait behind the barrier if possible.
  • if you can't exit the vehicle, do not feel it is safe to do so or there is no other place of relative safety, stay in the vehicle. Keep your seat belt on and dial ‘999’.

Emergency Refuge Areas (ERA)

Read more about what to do if you break down

On a smart motorway you will find 'Emergency Refuge Areas' at regular intervals rather than a continuous hard shoulder.

Operators in the Regional Control Centre (RCC) won't be alerted automatically whenever a vehicle enters or leaves an ERA but if you have to stop you will see signs in the ERA instructing you to contact the RCC (using the SOS phone) when you stop and before you leave. Operators will then be able to monitor your vehicle using CCTV.

Rule 276 of the Highway Code describes what you should do following a breakdown on the hard shoulder of a conventional motorway: "Before you rejoin the carriageway after a breakdown, build up speed on the hard shoulder and watch for a safe gap in the traffic".

ERA's are only short lay-bys, not long enough to allow you to build up sufficient speed before rejoining lane 1, so before leaving the ERA you must contact the Regional Control Centre and they will either dispatch a Highways England Traffic Officer and/or set signs and signals to assist your safe exit.

If you're driving and a red cross appears above lane 1 it could be to allow a slow moving vehicle to rejoin the carriageway from an ERA.

How safe are smart motorways?

Overall motorways carry 21% of traffic but account for just 5.4 % of fatalities which makes them safer than other types of roads.

Despite the fact that 85%* of AA members agree that hard shoulders help to make motorways safer, according to Highways England analysis smart motorways with all lanes running (no hard shoulder) and MIDAS queue protection system** give a safety benefit (reduced risk of injury collisions) of about 19% compared with the baseline of a traditional dual 3-lane motorway with continuous hard shoulders.

MIDAS alone when incorporated into a traditional motorway layout (e.g. western side of M25) gives a safety benefit of around 10% though it is only works when there is a detectable traffic flow so is not, for example, effective at protecting a lone breakdown in a live lane at night when traffic is light.

By contrast the safety risk on all purpose trunk roads (dual carriageways with no hard shoulder or emergency refuge areas) is around 9% higher than on traditional motorways.

At the other end of the scale, the risk of injury collisions on the M42 pilot with Active Traffic Management and emergency refuge areas/gantries every 500m is 68% lower than on a traditional 3-lane motorway with continuous hard shoulders.

(updated 13 April 2016)


*AA-Populus motoring panel survey in July 2015 (29,267 respondents)

**MIDAS = Motorway Incident Detection and Automatic Signalling. Inductive loops detect the volume and speed of traffic and send data automatically to the local cotrol centre and to overhead variable message gantries in the form of pre-set messages.