Traffic lights and officers' signals: understanding who may proceed

Who the signal addresses and which instruction prevails

Before interpreting a light, establish whether it controls your lane and intended manoeuvre. A signal at the side may govern all vehicles on the carriageway; an illuminated arrow applies only to the direction shown; an overhead signal may refer to one particular lane. A pedestrian, bicycle or public-transport symbol identifies the users for whom the signal is intended.

When an officer gives a clear direction, follow it even if a traffic light or sign says something different. If the officer is not directing traffic, follow the working light. With a failed or abnormal signal, proceed very slowly with particular care and use any duplicate lamps that still work; with flashing amber only, travel at moderate speed and obey priority rules and other signs. Even on green, do not enter a blocked junction.

Red, amber and green vehicle signals

A red light requires the vehicle to stop before the stop line or, where no line exists, without entering the controlled junction or crossing. Green permits only the directions allowed by signs and road markings. Drivers must still yield to pedestrians and cyclists who also have permission to cross; when turning, they must also yield to vehicles from the right and to traffic already on the road they are joining. Green does not guarantee clear space beyond the junction.

Steady amber warns that red is imminent. A driver who can stop safely must do so; one already too close to halt without danger proceeds carefully and clears the junction promptly. Accelerating merely to cross the line defeats the purpose of amber. While waiting, leave crossings unobstructed and move only when the light governing your manoeuvre changes.

• Red: stop before the controlled point
• Steady amber: stop unless it is no longer safe to do so
• Green: permission to move, not absolute priority

Arrows, lanes and separately controlled directions

Illuminated arrows separate movements that do not necessarily receive permission together. A green arrow permits only the direction shown, an amber arrow warns that this permission is ending, and a red arrow prohibits it. The driver must be in the appropriate lane before the line and cannot rely on a signal given to another direction to cross the junction.

On reversible or dynamically managed lanes, a red cross above a lane closes it; a downward green arrow marks it as open; and a flashing oblique amber arrow requires users to leave it towards the side shown. Because these signals can change with traffic, check the signals above your lane throughout the managed section. A lane that was open on a previous journey may be closed now.

Flashing lights and special situations

Flashing amber is not the same as steady amber before red. It marks a point to be approached at moderate speed and with particular care; when it replaces the normal signal cycle, it does not by itself give priority. Drivers must use the displayed priority signs and check for vehicles, pedestrians or cyclists that may cross their path.

Flashing amber lights beside pedestrian or bicycle symbols draw attention to crossings affected by a turning movement. Alternately flashing red lights, used at level crossings and other temporarily closed passages, require a stop. At a level crossing this command applies even if a half-barrier still appears raised, because the warning lights and physical barriers may operate in a timed sequence.

Pedestrians, bicycles and public transport

Pedestrian and cycle signals use recognisable symbols to show which users they apply to. Green allows a crossing to begin with due care; amber tells those who have not started to wait and those already crossing to complete the movement; red prohibits starting. A turning driver must still inspect crossings and cannot infer which light pedestrians or cyclists are seeing solely from the colour of the vehicle signal.

Signals for scheduled public-transport vehicles use their own symbols and govern only the vehicles for which they are intended; they do not give ordinary traffic permission to proceed. A green-wave indication also has a narrow purpose: it recommends a speed, within the legal limit, likely to meet a succession of green signals. It changes neither legal limits nor the need to adapt to the road and maintain a safe following distance.

Understanding an officer's gestures

When an officer holds both arms horizontally, road users facing the officer's front or back must stop. Those seeing the officer from the side may proceed carefully in a direction parallel to the arms. A useful reminder is to imagine the body as a barrier: chest and back close the way, while the sides open it. Other arm movements may authorise a turn or call only certain vehicles forward.

One arm raised vertically announces a general stop, much like the amber phase: road users who can stop safely do so, while those already in the junction clear it. A prolonged whistle may stop all traffic to let emergency vehicles pass or, in other circumstances, order an offender to stop. When faced with a stop paddle, gesture or direct instruction, slow down enough to understand it, avoid sudden manoeuvres and carry out only the instruction clearly received.

Roadside checks and identifying authorised personnel

Personnel exercising road-policing functions may direct traffic, order a vehicle to stop and inspect drivers and vehicles within their legal powers. When they are not in uniform, they must make their official capacity identifiable in the prescribed manner. When an officer orders you to stop, slow down, pull over at the first safe place and wait for the next instruction: do not brake abruptly in the carriageway or ignore the order while searching for a more convenient place.

During a check, the driver cooperates, presents the prescribed personal and vehicle documents and allows the required inspections. This duty is distinct from carrying emergency equipment such as a high-visibility garment or warning triangle: those items may also be checked, but serve a different purpose. Remaining calm, avoiding sudden movements and asking for clarification when an instruction is not understood reduces misunderstandings and makes the check safer for everyone.