Last Sunday - M1 north of Luton 20mph limit

[nyt]

Last Sunday at about 10:30am on a fairly empty M1 the variable limit was reduced to 20mph. The signs said 'Oncoming vehicle'. This took place on both carriageways.

Needless to say no 'oncoming vehicle' was ever seen.

Anyone have any idea what happened. I'm guess that some numpty hit the wrong button.

[nyt]

Spare tyre said:

jumping off a motorway bridge

I suppose that it could well have been something like that. That would at least explain why both carriageways were slowed.

It did carry on for a very long distance though - at least 30mins driving time - so 10 miles I guess.