Its very helpful in an emergency..
I had another very similar situtation to the obstruction when a cars bumper had fallen off and was straddling the 2nd and 3rd lanes of the M1 near wakefield, you could see cars swerving as you come up to the asecent.
after i passed it i called the police and told the woman that i didnt know what junction i was at, but norhtbound on the M!. but i told her that i was at the Junction where the West Yorkshire Police Traffic HQ is.. and she thought that was in Sheffield...
Wakefield = West, Sheffield = South :nutter: