Rule 255
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.
SteerTogether · Official English reference
Read rule 255
Motorways: rules 253–274
Study motorway access, joining, signals, lane discipline, overtaking and leaving the motorway.
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