"Dave" wrote in message
...
Can anyone explain why some road signs have those triangle, square and
circular emblems on them? Sometimes they are empty and sometimes they are
solid colour. I would imagine that they are there for the emergency
services, but I can't understand what is what.

http://www.direct.gov.uk/en/TravelAn...endition= Web

(via
http://www.direct.gov.uk/en/TravelAn...ings/index.htm )

Diversion routes.