In the late 1960s I used to drive down the M1 in fog every Sunday evening over the winter period. I experienced the "Break Off" thing on a couple of occasions usually in the Bedfordshire area where fog was most likely and the M1 pretty featureless. It was not very busy in those days. It certainly made my hair stand on end and I did not feel I could talk about it in case I was going bonkers.
ACW