trevHCS:
The environmental one makes sense since they often have “air monitoring” around the northbound J28 M1 and also a 60 limit. Not sure why there’d be any dodgy air around there unless its because of the long hill.56 in a 50 - I’m not going to be the one to test that against these signs. In theory most do have a 10% allowance, but that’s discretionary not a requirement and it seems the 70 limits set on these are very tight tolerance. I’ve also been doing 50mph (49 on the sat nav) and had someone pass me very slightly faster and they get flashed, so suspect they’ve reduced the 10% on many. No idea if it results in an NIP ultimately, but don’t want to find out.
Same here, I just trundle along at 50 in lane 1 and watch the antics of the pallet network bods (amongst others) in lane 2 (and sometimes 3!) as they sit 6’ off the bumper of the small hatchback who has the temerity to observe the posted limit.