Every so often you might see a small, square green sign, bordered in yellow, with the initials PCD. The initials stand for Pollution Control Device and there are several signs on the M6, M61 and M65 ...

It's worth mentioning that not all UK motorway signs are green; sometimes they're blue - another soothing colour. Since the video was posted, it has garnered over 55,800 likes and 4,400 shares.

Drivers have been issued an urgent warning over a 'little-known' motorway sign with a hidden meaning. Millions of people use A roads without noticing crucial blue signs, known as "driver location ...

Amber speed limit signs on motorways are actually advisory (stock image) Backlash sees 20mph speed limit dropped on some roads in Wales Motorists aged 50 and over issued warning over Highway Code ...