You may only wait in the area marked with a cycle (the cycle box at traffic lights) in very limited situations.

Direct answer

  • The cycle box is reserved for cyclists when the traffic lights are red; other vehicles must normally stop at the first stop line, not in the box.
  • You may wait in the cycle-marked area only if:
    1. You have already crossed the first stop line when the signal changes to amber/red and stopping before the box is no longer possible or safe, so you must stop at the second line inside the box.
2. You are following specific local rules that legally allow entry (for example, if signs/markings explicitly permit it), though this is unusual and still should not obstruct cyclists.

What you should do in normal driving

  • Treat the cycle box as cyclists’ space : always stop at the first line if the light is red or about to change and the junction ahead is not clear.
  • Do not enter or wait in the cycle area just because it is empty; the space is for cyclists who may arrive after you stop.

Why this rule exists

  • The marked cycle area gives cyclists a visible, protected position ahead of motor traffic so they can set off first and are easier to see when turning.
  • Blocking that area forces cyclists to squeeze alongside vehicles or wait in blind spots, which increases collision risk, especially with larger vehicles.

TL;DR: Wait in the area marked with a cycle only if you have already passed the first stop line and the lights change so you must stop at the second line; otherwise, always stop behind the first line and keep the cycle box clear for cyclists.

Information gathered from public forums or data available on the internet and portrayed here.