How to drive safely on smart motorways

June 25, 2025

Smart motorways use technology to control the flow of traffic, reduce congestion and improve journey times. However, these roads have proved highly controversial in recent years.

The rollout of smart motorways across the UK was paused in 2022, then halted altogether a year later. The then-prime minister, Rishi Sunak, cited a lack of public confidence in the roads, which have been blamed for a number of road accidents and deaths, as one reason for his decision.

However, are still 375 miles of smart motorways in the UK, so understanding how they work is important – both for your own safety and that of others.

These are the three types of smart motorway that you may encounter:

Dynamic hard shoulder: where the hard shoulder is temporarily opened up to traffic
All-lane running: where the full width of the road is usable, with emergency refuge areas alongside
Controlled motorway: with three or more lanes, a hard shoulder and variable speed limits

Read our separate advice guide to discover more about the pros and cons of smart motorways.

Safer driving on smart motorways

National Highways, which manages the motorway and A-road network in England, has the following advice for motorists driving on a smart motorway:

Never drive in a lane closed by a red ‘X’. Not only is it illegal, you will endanger the lives of other motorists and anyone who might be working in the closed lane.
Keep to the speed limits shown on the signs. National Highways uses sensors and cameras to monitor traffic volumes, with limits set accordingly.
A hard shoulder is always identified by a solid white unbroken line. If there’s no speed limit displayed above it or a red ‘X’ is displayed, do not use it except in emergency.
A broken white line indicates a normal running lane.
If the hard shoulder is being used as an extra lane, use the designated emergency areas for emergencies.
If your vehicle experiences difficulties, exit the motorway immediately.
If you break down, put your hazard lights on.
Most breakdowns are preventable. Keep your car maintained, check your tyres and ensure you have enough fuel for your journey.

In an emergency or breakdown

If you are unable to exit the motorway, follow these steps:

Use an emergency area. These are marked with blue signs with an orange SOS telephone symbol.
If you can leave your vehicle safely, contact National Highways using an emergency telephone at the roadside. Alternatively, call 0300 123 5000 from your mobile phone.
If you can’t get to an emergency area, move to the hard shoulder (where available) or as close to the nearside of the road as possible.
Consider exiting the vehicle via the nearside door and waiting behind the safety barrier.
Switch on your hazard lights and side lights. Do not use a warning triangle.
Contact your breakdown provider, such as the AA or RAC.

What does the red ‘X’ mean?

A red ‘X’ means you must stay out of a lane that is closed to traffic. It might be displayed on an overhead gantry or on large signs next to the motorway.

It’s illegal to drive in a lane closed by a red ‘X’ sign. You could receive a fixed penalty of up to £100 and three points on your driving licence. More severe penalties and a court appearance could follow in some cases.

What about variable speed limits?

National Highways might impose a variable speed limit at busy times, but these can also be automatically triggered by sensors that monitor traffic flow.

The speed limit is displayed inside a red circle and is legally enforceable. If no limit is displayed, the national speed limit of 70mph on a motorway applies.

Speed cameras are in operation on the smart motorway network and the police are responsible for enforcing speeding offences.