A red light
A red light is the signal for 'Stop'. When they see it drivers must stop.

A yellow light
An illuminated yellow light together with the red light also means 'Stop' and lets the road-user know that the signal for 'Proceed ahead' will directly follow.

A green light
A green light is the signal for 'Proceed ahead'.

The green light flashes four times before it changes to yellow. A green flashing light signifies the imminent end of the signal for 'Proceed ahead'.

A yellow constant light means 'Stop'. At this signal drivers of approaching vehicles must stop. Drivers who find themselves already on a junction on a constant yellow light should leave it as soon as it is possible to do so.

A flashing yellow light means 'Take care'.