Photo: Josh Withers / Pexels. Illustrative photograph.
This guide is for learner drivers in Great Britain who want the Highway Code’s “Light signals controlling traffic” section in one place: what each traffic light means, where flashing red lights are used, how motorway signals work and what lane control signals tell you. Steady lights tell you when to stop and go; flashing red means you MUST stop; a red X over a lane means you MUST NOT drive in it.
Key facts
- Red, and red with amber: stop. Do not go until green shows.
- Amber on its own: stop at the stop line unless you have already crossed it or are too close to stop safely.
- Alternating flashing red lights: you MUST stop. They are used at level crossings, lifting bridges, airfields, fire stations and similar places.
- Red X (motorway or lane control signal): you MUST NOT carry on in that lane.
- Penalty: failing to comply with traffic light signals is endorsement code TS10, 3 penalty points.
Traffic light sequence: what each light means
In Great Britain the sequence runs red, red and amber, green, amber, then red again.
| Light | Meaning | What you do |
|---|---|---|
| Red | Stop | Wait behind the stop line on the carriageway. |
| Red and amber | Stop | Do not pass through or start until green shows. |
| Green | You may go if the way is clear | Take special care if you are turning left or right, and give way to pedestrians who are crossing. |
| Amber | Stop at the stop line | Go on only if amber appears after you have crossed the stop line, or you are too close to stop safely. |
| Green arrow (with the full green) | Filter | You may go in the direction of the arrow if the way is clear, whatever other lights are showing. |
White light signals at some junctions are for trams only. Rule 300 says they give instructions to tram drivers, not to you. More on that in driving alongside trams.
The MUST rules at traffic light junctions (Rules 175 to 178)
- Rule 175: you MUST stop behind the white stop line unless the light is green.
- Rule 176: you MUST NOT move forward over the white line while red shows. On green, only go if there is room to clear the junction safely or you are turning right. If the lights are not working, treat it as an unmarked junction and go with great care.
- Rule 177: a green filter arrow controls a filter lane only. Do not enter that lane unless you are going the way the arrow points, and give cyclists in particular time and room to get into the right lane. The arrow releases only that lane and direction: if it lets the left-turning car beside you go while your ahead signal is still red, stay behind your line.
- Rule 178 (advanced stop lines): when the lights are amber or red you MUST stop at the first white line. If you have already crossed the first line when the light turns red, you MUST stop at the second line. Do not block the cyclists’ box at other times. When the lights go green, give cyclists ahead of or beside you time and room to move off before you turn.
The legal references for these rules are the Road Traffic Act 1988 section 36 and the Traffic Signs Regulations and General Directions. For turning right and box junctions at lights, see road junctions explained.
Worked example: amber as you approach
The light changes from green to amber as you approach. You are not yet over the line and can pull up with normal, firm braking, so you stop. If amber had appeared as your front wheels crossed the line, or stopping would have needed harsh braking with a car close behind, you would continue. Planning ahead (a light that has been green for a while may change) makes this decision easier. Being late or impatient is not part of the exception, and speeding up to beat the change is exactly what the rule is meant to stop.
Flashing red lights: level crossings, fire stations and bridges
Alternating flashing red lights mean you MUST stop. Apart from level crossings, you will see them at lifting bridges, airfields and fire stations, where they stop traffic so emergency vehicles can get out.
At a controlled level crossing (Rule 293):
- A steady amber light comes on first. Keep going if you have already crossed the white line when it appears; otherwise stop.
- When the red lights flash you MUST stop behind the white line.
- If the red lights keep flashing after a train has passed, you MUST wait, because another train is coming.
Barriers, user-worked gates and what to do if you break down on the tracks are covered in level crossings explained.
Flashing amber: pelican crossings
A flashing amber light after red at a pelican crossing means you MUST give way to pedestrians still on the crossing. If it is clear, you may go with caution (Rule 196). Puffin, toucan and equestrian crossings have no flashing amber phase and work like normal traffic lights (Rule 199). See pedestrian crossings for the full set.
Motorway signals: what each one tells you
These signals are also used on some other high-speed roads, not just motorways.
| Signal | Meaning |
|---|---|
| Red X | Do not go further in this lane. |
| Diagonal arrow | Change lane. |
| Reduced visibility ahead | Slow down and be ready for fog or similar. |
| Lane ahead closed | Move out of the lane shown as closed. |
| Advisory speed | Temporary maximum speed advised, sometimes with an information message. |
| Speed limit in a red circle | Temporary mandatory maximum speed limit. It may come with a message such as do not enter or proceed in the left lane. |
| End | End of the restriction. |
Flashing amber and flashing red on motorways (Rules 257 and 258)
- Flashing amber: a hazard ahead. Slow down, be ready for it, and only speed up again once you pass a signal that is not flashing, a national speed limit sign or “END”, and it is safe.
- Flashing red with a red X: a closed lane, with people, stopped vehicles or another hazard in it. You MUST follow the signs to move to an open lane and MUST NOT drive in the closed lane. The lane is open again when a sign shows a speed limit or “END”.
- All lanes closed: red flashing lights over every lane with a closure sign means the road is closed. You MUST NOT go past the sign in any lane, or use the hard shoulder, unless a police or traffic officer tells you to.
- A speed limit shown inside a red circle is mandatory: you MUST NOT exceed it (Rule 261).
Red X enforcement and emergency areas on smart motorways: see smart motorways and red X signals. All the signs are illustrated on our motorway signs guide.
Lane control signals
Lane control signals sit above individual lanes and apply only to traffic facing them.
| Signal | Meaning |
|---|---|
| Green arrow | The lane is open to traffic facing the sign. |
| Red X | The lane is closed to traffic facing the sign. |
| White diagonal arrow | Change lanes in the direction the arrow points. |
Rule 256 explains the difference between a single sign covering all lanes and lane-specific signals: read the one above your lane.
Common questions
Can I go through on amber?
Only if amber appeared after you crossed the stop line, or you were too close to stop safely. Otherwise amber means stop.
What happens if I go through a red light?
It is endorsement code TS10, 3 penalty points, and Annex 5 of the Highway Code lists a maximum fine of £1,000 with discretionary disqualification. Within two years of passing, 6 points cancels your licence under the New Drivers Act.
The lights are stuck on red or not working. What do I do?
If they are not working at all, treat the junction as unmarked and go with great care (Rule 176). The Highway Code does not give permission to go through a red light because it seems stuck, so wait for green or for a police or traffic officer’s direction.
Do I have to stop for flashing red lights at a fire station if nothing is coming out?
Yes. Alternating flashing red lights mean you MUST stop, whether or not you can see a fire engine.
Is a speed on a motorway gantry a legal limit?
If the number is inside a red circle, yes, it is mandatory. A number without the red circle is advisory.
Can I drive in a lane with a red X if it looks empty?
No. You MUST NOT drive in a closed lane, even if you cannot see why it is closed. The hazard may be out of sight, and emergency services use closed lanes to reach incidents.
Practise these for your theory test in the road and traffic signs topic, and see the basics with pictures in traffic lights and signals. In Northern Ireland, check the NI Highway Code (see NI vs GB differences).
Back to the main guide: Learning to Drive in Great Britain.
Sources
- Department for Transport, “The Highway Code: Light signals controlling traffic” (gov.uk)
- Department for Transport, “The Highway Code: Using the road (159 to 203)” (gov.uk)
- Department for Transport, “The Highway Code: Motorways (253 to 274)” (gov.uk)
- Department for Transport, “The Highway Code: Road works, level crossings and tramways (288 to 307)” (gov.uk)
- Department for Transport, “The Highway Code: Annex 5. Penalties” (gov.uk)
- GOV.UK, “Penalty points (endorsements): Endorsement codes and penalty points” (gov.uk)