A green filter arrow pointing left indicates that traffic turning left may proceed, even if the main light is showing red or amber.
Filter lights help manage traffic flow smoothly at complex busy junctions.
What this sign means
When illuminated, the green arrow grants priority to vehicles turning left in the direction indicated.
It indicates that opposing or conflicting traffic flows are currently stopped by red signals.
What to do when you see it
When the left green filter light illuminates:
Key steps:
- You may proceed to turn left, even if the main central signal is red.
- Check for pedestrians who may be crossing the side road you are entering.
- If you are not turning left, remain stopped behind the stop line.
How this sign is tested
Questions assess whether candidates understand that filter arrows permit directional movement regardless of the main signal state.
You may also be tested on positioning in multi-lane junction approaches.
Common mistakes
Remaining stationary when intending to turn left because the main light is red, delaying traffic behind.
Blocking the left-turn filter lane when intending to travel straight ahead.
Test yourself on this one
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Practise road sign questionsFrequently asked questions
Can I turn left on a green arrow if the main light is red?
Yes, the filter arrow gives you permission to turn in that direction.
What if I am in the filter lane but want to go straight?
You should not be in a dedicated filter lane unless turning in that direction, as you will obstruct other drivers.
Do I have absolute priority when the arrow is green?
You have priority over junction traffic, but you must still watch for crossing pedestrians.