What should you do?
Check your mirrors, ease off and be prepared to move slightly right or slow down to let others through safely.
How to recognise it
Yellow diamond with two vertical lines where the left line bends inwards towards the right.
Common confusion
Easy to mix up with road narrows from right; look at which line bends to know which side loses width.
Explanation written by the My Driving Test editorial team using the Department of Transport Traffic Signs Manual conventions and the RSA Rules of the Road.
