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Smart motorway signs: red X, speed limits and emergency areas

On some motorways, overhead signs and signals change to manage traffic: they close lanes, set speed limits and, on some stretches, open the hard shoulder as an extra lane.

This guide explains what each signal means and what the Highway Code says you must do.

By , founder and editorPublished

Drafted with AI from the Highway Code and Department for Transport sources, then checked and approved by Bikash Thapa. How we write guides

Smart motorway signals: a red X for a closed lane, an arrow to move to the next lane, an advised speed and a closed hard shoulder

The short version

  • A red X, with red flashing lights, means the lane is closed. You must not drive in it.
  • A speed limit shown in a red circle is mandatory. A speed shown without a red circle is advice for the conditions.
  • Where the hard shoulder can be used as a lane, you may only drive on it when a speed limit is shown above it.
  • Emergency areas are marked by blue signs with an orange SOS telephone symbol. Use one if you break down and can reach it.
  • If a sign shows all lanes closed, the road is closed: do not go beyond it or use the hard shoulder to get round it.

Red X: a closed lane

A red X is the most important smart motorway signal. It means something is in the lane ahead: a broken-down vehicle, an incident or people working.

  • Red flashing light signals and a red X on a sign identify a closed lane in which people, stopped vehicles or other hazards are present. You must follow the instructions on signs in advance of a closed lane to move safely to an open lane, and you must not drive in a closed lane.

    The Highway Code, Rule 258

  • A sign will tell you when the lane is no longer closed, by displaying a speed limit or the word END.

    The Highway Code, Rule 258

  • Lane and road closures indicated by red flashing lights are enforced by the police.

    The Highway Code, Rule 258

  • Where red flashing light signals and closure of all lanes are shown on a sign, the road is closed. You must not go beyond the sign in any lane or use the hard shoulder to avoid the closure unless directed to by a police or traffic officer.

    Know Your Traffic Signs, p. 105

Variable speed limits

Overhead signs can lower the speed limit to keep traffic moving or to protect people ahead. Look at whether the number has a red circle.

  • You must not exceed a speed limit displayed within a red circle on a sign.

    The Highway Code, Rule 261

  • Where variable speed limit signs are mounted over individual lanes or at the side of the motorway and the limit is shown in a red circle, the limit is mandatory. Speed limits not shown in a red circle are the maximum speeds advised for the prevailing conditions.

    Know Your Traffic Signs, p. 104

The hard shoulder as a lane

On some motorways the hard shoulder is opened as an extra lane when traffic is heavy. The signs above it tell you whether you may use it.

  • Where present, you must not use a hard shoulder except in an emergency or if directed to do so by the police, traffic officers or a traffic sign.

    The Highway Code, Rule 269

  • Where the hard shoulder is used as an extra lane, a red X or a blank sign above it means you must not use it except in an emergency. You can only use it as an extra lane when a speed limit is shown above it.

    The Highway Code, Rule 269

Emergency areas and breakdowns

Where there is no hard shoulder, or it is used as a lane, emergency areas give you a safer place to stop.

  • Where the hard shoulder is being used as an extra lane, emergency areas are provided for use in an emergency. They are marked by blue signs with an orange SOS telephone symbol and may have orange surfacing.

    The Highway Code, Rule 269

  • If you need to stop because of a breakdown or incident, try to stop in a place of relative safety. On motorways and other high-speed roads the safest place to stop is a service area; other places include lay-bys and emergency areas.

    The Highway Code, Rule 275

  • If you cannot get out of your vehicle, or have not stopped near a free emergency telephone, call 999 immediately and ask for the police, or press your SOS button if your vehicle has one.

    The Highway Code, Rule 275

Test yourself

Check you can tell these signs apart with the Motorway Signs Quiz: 10 questions, with an explanation after each answer.

Take the Motorway Signs Quiz

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Sources

Checked against these sources and reviewed by Bikash Thapa, full UK driving licence holder. Last reviewed 13 October 2026. This guide explains the rules in our own words; for the full rules, see The Highway Code. How we source and check content

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