Highway Code: signals, traffic lights and traffic signs

Signals, traffic lights and traffic signs tell every road user what to do, what to expect and what is forbidden. Council taxi and private hire knowledge tests regularly test the meaning of common signs and the exact traffic light sequence. This note explains the shape and colour system, the light signals, the signals given by authorised persons, and the signs used where trams run.

How signs work: shapes and colours

Know Your Traffic Signs explains that there are three basic types of sign, and each type has its own shape:

Shape	What it does	Colour rules
Circle	Gives orders	Red rings or circles tell you what you must not do; blue circles give a positive (mandatory) instruction, such as "turn left", or show a route only for particular traffic, such as buses and cycles only
Triangle	Warns	All triangular warning signs have a red border
Rectangle	Informs	Blue rectangles are used for information signs except on motorways, where blue is used for direction signs. Green rectangles show direction signs on primary routes. White rectangles show direction signs on non-primary routes, or are used as plates with warning and regulatory signs

Two signs break the shape rules so that they stand out:

• The "STOP" sign is an eight-sided (octagonal) shape. You must stop behind the transverse line on the road and only move off when the way is clear.
• The "GIVE WAY" sign is an upside-down triangle. You must give way to traffic on the major road. The same message is often painted on the road as broken lines with triangles.

Key fact: Circles give orders, triangles warn, rectangles inform. A red circle prohibits; a blue circle instructs.