What does a red triangle with an exclamation mark mean?
A hazard ahead that has no specific sign of its own. A small plate underneath usually says what it is.
A red-bordered triangle pointing up with a black exclamation mark.
What you must do
Slow down and read the plate. Be ready for the hazard it describes.
Where you will see it
Anywhere an unusual hazard needs flagging, such as a queue, an event, or a temporary danger.
Test yourself
The theory test asks you to recognise signs like this one. Try the road and traffic signs quiz (with an easy and a hard set), or read the signs revision notes. Source: Know Your Traffic Signs.
Other common road signs
Meaning based on Know Your Traffic Signs and The Highway Code under the Open Government Licence v3.0. The sign image is our own simplified rendering for learning. Always check the current Highway Code on gov.uk. Not affiliated with or endorsed by the DVSA.