What should you do?
Slow down and keep a firm grip on the steering, especially on two-wheelers or when towing.
How to recognise it
Yellow diamond with a black road profile topped by a row of irregular bumps.
Common confusion
Very similar to the series of bumps or hollows sign; both call for lower speed over an irregular surface.
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.
