What to Do at Red and Amber Traffic Lights – UK Rules

Approaching a set of traffic lights showing red and amber together can be confusing, especially for learner drivers. Many assume the combination means “get ready to go” and begin creeping forward. The official rule, set out in the UK Highway Code, is clear: red and amber together means stop. You must stay behind the stop line until the green light appears. This short transitional phase lasts only about two seconds, but getting it wrong can lead to a driving test failure or, worse, a collision.

The UK traffic light sequence follows a fixed order: red, red and amber, green, amber, then back to red. Each phase serves a distinct purpose, and understanding every step is essential for the theory test and for safe everyday driving. This article explains what each signal means, what action you should take, and how to handle less common situations such as faulty lights or filter arrows.

The information below draws on the official Highway Code, the Traffic Signs Regulations and General Directions, and DVSA theory test guidance. No detail has been added beyond what those sources confirm.

What Does Red and Amber Showing Together Mean?

The simultaneous display of red and amber lights is a signal that the lights are about to change to green. However, the required driver action is to remain stopped. The Highway Code states that red and amber together also means stop. You must not pass the stop line until the green light shows.

Five key insights stand out from the official guidance and common theory test misunderstandings:

• Many learners confuse red+amber with a “go” signal; it actually means “stop, prepare to go” but still requires a halt.
• The red+amber phase is unique to the UK and some Commonwealth countries; drivers from other regions may not be familiar.
• Approaching a green light that has been on for a long time requires anticipation – the light may soon change to amber.
• Priority at broken traffic lights is not automatically given to one side; drivers must treat it as an uncontrolled junction.
• Reflective amber studs on the motorway indicate the left-hand edge of the carriageway, not directly related to traffic lights.

The table below summarises the actions required at each phase of the UK traffic light sequence, including green filter arrows and flashing amber at pedestrian crossings.

How Should You React to Traffic Lights That Are Changing?

Knowing what each signal means is one thing; reacting correctly in real time is another. The following subsections cover the most common scenarios drivers face when lights are transitioning from one phase to the next.

What to Do When Green Has Been On for a While

If you are approaching a green light that has been illuminated for some time, the sensible approach is to anticipate a change. Cover the brake and reduce speed slightly. The green phase typically lasts between 10 and 40 seconds depending on the junction, but the exact timing is controlled by traffic sensors and is not predictable from the driver’s seat. Being prepared for amber reduces the chance of an abrupt stop or, worse, running a red light.

What to Do When Amber Shows

A steady amber light means the signal is about to turn red. The Highway Code rule is: stop at the stop line unless the amber appeared after you had already crossed the line or you are so close that stopping might cause a collision. This is not a signal to speed up. The amber phase lasts approximately three seconds, which is long enough to stop safely if you are a reasonable distance from the line.

What to Do If the Lights Are Faulty

When traffic lights are completely out or malfunctioning, they cease to control priority. In this situation, no driver has priority by default. You must treat the junction as an uncontrolled intersection and give way to traffic from all directions, including from the right, before proceeding with caution. Be aware that drivers on other approaches may assume they have priority, so extra vigilance is necessary.

Who Has Priority When Traffic Lights Are Out of Order?

A common theory test question asks who has priority when traffic lights fail. The answer is straightforward: no one. The Highway Code states that when lights are not working, the junction becomes an uncontrolled crossroad. Drivers must proceed only when a safe gap appears in traffic from any direction.

When Traffic Lights Are Out of Order Who Has Priority?

The absence of working lights removes all signal-based priority. The rule of “give way to traffic from the right” applies, as it would at any unmarked junction. However, the AA advises that drivers should be prepared for others to assume wrongly that they have right of way. Proceed with extreme caution.

What to Do If Traffic Lights Are Broken

If you encounter a set of broken traffic lights, first check whether a police officer is controlling the junction. If so, follow the officer’s signals above all other indicators. If no officer is present, treat the junction as an uncontrolled intersection. Move forward slowly, make eye contact with other road users where possible, and be ready to stop.

How Do UK Traffic Lights Work?

Understanding how traffic lights are controlled helps drivers anticipate changes and reduces uncertainty. The standard UK sequence is fixed, but the duration of each phase varies.

How Are Traffic Lights Controlled?

Most traffic lights in the UK use sensors embedded in the road surface or cameras to detect approaching vehicles. These sensors adjust the timing of the green phase to match traffic flow. At less busy times, a green light may appear quickly after a vehicle arrives. During peak hours, the cycle timings are often longer to accommodate higher volumes. The Traffic Signs Regulations and General Directions 2016 set out the legal framework for all traffic light installations in Great Britain.

What Is the Traffic Light Sequence in the UK?

The sequence is: red, red and amber, green, amber, red. This cycle repeats continuously. The red+amber phase is always two seconds. The amber phase lasts three seconds. The red and green phases vary in length depending on traffic detection and junction design.

Where Would You Find Reflective Amber Studs on a Motorway?

Reflective amber studs on a motorway mark the left-hand edge of the carriageway, adjacent to the hard shoulder. They are not directly related to traffic lights but are sometimes grouped with traffic light questions in theory test preparation. The National Highways colour guide explains that white studs separate lanes, red studs mark the left edge of the main carriageway, amber studs indicate the hard shoulder edge, and green studs denote slip road entry or exit points.

What Is the Traffic Light Sequence in the UK?

The following timeline lists each phase of the standard UK traffic light cycle in order, with typical durations and the required driver action at each step.

1. Phase 1 – Red (variable, typically 20–30 seconds): Stop behind the stop line. Wait until the next phase.
2. Phase 2 – Red + Amber (2 seconds): Remain stopped. Prepare mentally to move but do not release the brake.
3. Phase 3 – Green (variable, typically 10–40 seconds): Proceed if the junction is clear. Give way to pedestrians crossing.
4. Phase 4 – Amber (3 seconds): Stop unless you have already crossed the stop line or are too close to stop safely.
5. Phase 5 – Red (repeat): Cycle returns to phase 1.

This sequence is standardised across the UK under the Traffic Signs Regulations and General Directions. The exact timings may differ at individual junctions due to traffic sensors and local configuration.

What Is Certain and What Remains Unclear About Traffic Light Rules?

Why Does the Red and Amber Phase Exist in the UK?

The red and amber phase is a transitional warning that the lights are about to turn green. It gives drivers a brief moment to prepare to move off without the need to watch the red light constantly. This two-second phase reduces hesitation when the green appears, helping traffic flow more smoothly at junctions. It also provides a clear distinction from a single amber light, which signals an imminent stop rather than an imminent go. For a comprehensive understanding of traffic light rules, consult our A-level periodic table guide.

This topic appears in the UK driving theory test under the “Rules of the Road” section. The official sources are the Highway Code (Rules 109 and 175–177) and the Traffic Signs Regulations. The red+amber phase is often misunderstood as a suggestion to start moving, which is why theory test questions stress that it remains a stop signal. Official DVSA practice tests include multiple-choice questions on this exact point.

Beyond the theory test, understanding the sequence helps drivers react more calmly and predictably at junctions. The UK system is designed to minimise ambiguity: every colour combination has one clear meaning, and there is no phase in which a driver is expected to guess what to do next.

Where Can You Find the Official Rules About Traffic Lights?

The most authoritative source for traffic light rules in the UK is the Highway Code, published by the Driver and Vehicle Standards Agency (DVSA) and available on GOV.UK. Rules 109 and 175–177 cover the meaning of each light signal and the actions required. The legal framework behind traffic light installations is the Traffic Signs Regulations and General Directions 2016.

“Red and amber together means the lights are about to change to green. You must stop and wait behind the stop line until the green light shows.”

UK Highway Code, Rule 176 (adapted)

“Amber means ‘stop’ unless you have already crossed the stop line or are so close that stopping might cause a collision.”

UK Highway Code, Rule 109

“If traffic lights are out of order, treat the junction as an uncontrolled junction and give way to traffic from the right.”

UK Highway Code, Rule 177

What Should You Remember About Traffic Light Rules?

The single most important rule for UK traffic lights is that red and amber together means stop, not go. Only a green light gives you permission to proceed, and even then only when the junction is clear. Learning the full sequence – red, red+amber, green, amber, red – and practising the Mirror-Signal-Manoeuvre routine at every approach will help you stay safe and pass the theory test. For more detail on each phase, see the UK traffic light sequence – full explanation.

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