The first activity begun was to Number the international roads in the UK as designated by the local area offices of the United Nations.
I started with my local one that goes from Gibralter to Greenook Primary route E05.
The only part I have done so far is on the British south coast from Gosport to the M3. Unfortunately I found I need to edit a lot of very small segements so only reached the southern end of the M3.
They aren't regulaly marked on the roads in the UK though a sign was chosen for them and the British Goverment did do a lot of leaseing at least in the past.
what you tend to find is that Motorway projects and major trunk roads (central funded and maintained) to take complementry paths to the scheme; so HGV use is still good for these roads.