What does Highway Code Rule 255 say?

Rule 255 (Motorway signals (rules 255 to 258)) Signs and signals (see ‘Light signals controlling traffic’) are used to warn you of hazards ahead. It is advisory guidance rather than law, but you are still expected to follow it and an examiner can mark a fault if you do not.

Is Rule 255 the law or just guidance?

Rule 255 is advisory, it does not use “MUST” or “MUST NOT”, so it is not directly enforceable as a standalone offence. You are still expected to follow it, and ignoring it can contribute to a careless- or dangerous-driving charge and to faults on your test.

How is Rule 255 tested on the driving test?

Motorway rules feature on Pass Plus and motorway lessons rather than the standard L-test, but the same lane discipline, joining technique and overtaking habits are assessed on dual carriageways during the practical and the independent-driving section.

What are the common mistakes related to Rule 255?

The faults examiners most often record around this part of the Code are: joining without matching the traffic speed, forcing other drivers to brake; hogging the middle lane instead of returning left after overtaking; leaving too small a following distance at high speed. Rehearsing the safe habit during lessons is the most reliable way to avoid them.

Highway Code · Rule 255

Highway Code Rule 255

Motorways (253 to 274). Advisory guidance you are expected to follow.

Motorways
Advisory rule
OGL v3.0

What the rule says

Advisory

Rule 255 (Motorway signals (rules 255 to 258)) Signs and signals (see ‘Light signals controlling traffic’) are used to warn you of hazards ahead. For example, there may be an incident, fog, a spillage or road workers on the carriageway which you may not immediately be able to see.

Rule text reproduced verbatim from the official Highway Code (Crown copyright) under the Open Government Licence v3.0, see the attribution at the foot of this page.

In plain English

Stripped of the formal wording, Rule 255 comes down to one idea: rule 255 (Motorway signals (rules 255 to 258)) Signs and signals (see ‘Light signals controlling traffic’) are used to warn you of hazards ahead. It is advice rather than law, but examiners and the courts still treat it as the expected standard of safe driving.

It belongs to the motorways part of the Code, the habits a confident, considerate driver builds until they are automatic. The aim is not to memorise the sentence word for word, but to understand the hazard it protects you from, so you apply it without having to think when it counts.

If you are learning, treat this rule as one piece of a connected set rather than an isolated fact. The related rules below sit in the same section and reinforce each other, reading them together is how the motorways part of the Code starts to feel like common sense rather than a list to revise.

Because this is advisory rather than legal, no one will fine you for the rule alone, but ignoring it can still count against you in a careless-driving case, and it will cost you faults on the test. Either way, the safe move is to build the habit early, while a driving instructor can correct it, rather than relearning it under test pressure. That is exactly what the practice routes and coaching in the DriveRoutes app are designed to help with, turning the rules below into the way you naturally drive.

Why rule 255 matters on the road

High-speed roads leave very little margin for error: a late lane change or a misjudged join at 70 mph develops far faster than the same mistake in town. Building disciplined habits here protects you and everyone travelling at speed nearby.

Common faults examiners record

In the motorways part of the Code, the faults most often written on the marking sheet tend to be the same handful. Knowing them in advance is the quickest way to drive them out of your own habits:

Joining without matching the traffic speed, forcing other drivers to brake.
Hogging the middle lane instead of returning left after overtaking.
Leaving too small a following distance at high speed.

On the day

On the day, applying Rule 255 is about doing the safe, deliberate thing slightly earlier than feels necessary: read the situation in good time, observe fully, and act smoothly. The examiner is looking for planned driving, not perfection, and good habits formed in lessons carry you through.

Quick checklist

Read the situation early and plan your response.
Observe fully before you commit to anything.
Keep your speed suitable for the road and conditions.

Related Highway Code rules

Rule 255, your questions

: Rule 255 (Motorway signals (rules 255 to 258)) Signs and signals (see ‘Light signals controlling traffic’) are used to warn you of hazards ahead. It is advisory guidance rather than law, but you are still expected to follow it and an examiner can mark a fault if you do not.

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