Road signs, Road works
What does a triangle showing a workman mean?
Road works are ahead.

A red-bordered triangle showing a workman digging.
What you must do
Slow down and watch for workers, lane changes, a temporary speed limit and possible queues.
Where you will see it
On the approach to road works and maintenance.
Test yourself
The theory test asks you to recognise signs like this one. Try the road and traffic signs short test (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. The sign image is an official Department for Transport sign (Crown copyright) from Wikimedia Commons, reused under the Open Government Licence or the public domain. Always check the current Highway Code on gov.uk. Not affiliated with or endorsed by the DVSA.