Traffic Signals: Lights, Arrows and Flashing Warnings
The standard sequence
Traffic lights follow a fixed order: red, red-and-amber, green, amber, red. Red means stop behind the stop line. Red-and-amber means prepare but do not move. Green means proceed if the way is clear. Amber means stop unless it is unsafe to do so - it is not an invitation to accelerate.
Filter arrows and lane signals
A green arrow permits movement only in the direction shown, and you may proceed even if another aspect is red, provided the arrow applies to your lane. Red arrows prohibit that movement. Lane-control signals (red crosses or green arrows above lanes) override normal lane use.
Flashing signals
A flashing amber at a pelican-style pedestrian crossing usually means give way to pedestrians on the crossing and proceed only when clear. Flashing red at a railway crossing means stop and proceed only when it is safe and the signal permits. A single amber flashing light on a vehicle or barrier warns of a hazard, not a right to proceed blindly.
Pedestrian and special signals
Pedestrian signals govern pedestrians, not vehicles. At signals operated by police, the officer's directions override the lights.
Traps
Questions love the phrase “if safe”. Green does not guarantee safety: you must still check for vehicles clearing the junction, cyclists and pedestrians. Another trap is treating amber as “go faster” rather than “stop if you can do so safely”.
Rule of thumb: Green means go if clear; amber means stop if you can; red means stop, full stop. Never enter a junction you cannot clear.
Worked example: Your light turns green, but a pedestrian is still crossing and a car is clearing the junction. You wait: green grants permission, not priority over hazards already in the junction.