What should you do?
Use it only in an emergency or breakdown, and stay alert when rejoining traffic.
How to recognise it
A white panel with a red fire extinguisher, a black telephone and the letters SOS above a blue lay-by diagram.
Common confusion
It is for emergencies, not routine rest stops like a regular lay-by.
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.
