As a white road marking, it is so widely authorised for particular locations or authorities in England that there is a DfT drawing of it: NP545RM. You can see it in this area-wide authorisation for Milton Keynes for example: link.
It has also been authorised for individual places in Scotland, which implies that there’s no Scotland-wide authorisation. The official list (without drawings unfortunately) is here.
Many authorities put down a coloured road marking, presumably without authorisation, but it usually looks dreadful after a couple of years.
I’m sure this has been asked before – probably by me…
There’s a Scottish version of a document wherein there’s a note that the Scottish ministers at some point allowed a blanket authorisation to use the Diagram 545 symbol and surrounding triangle as a road marking.
Can anyone point me in the right direction as to where to find this my mind is blank?
Also, does anyone have an AutoCAD detail or a working drawing for said symbol?