"John Rowland" wrote in message
...
"Sam Holloway" wrote in message
...

See this page for more on the subject :
http://www.btinternet.com/~roads/pix.../m1_oldj2.html

Thanks. The 1993 incident sort of explains why it is being kept intact,
although I don't see why it could not have been used as access from the
retail park as well.

I hadn't realised until I compared the more recent maps with a 1963 OS map
(from the time when the M1 finished at Aldenham) that the southbound slip
road is on the site of the now-disused railway line from Mill Hill East to
Edgware.

I'm not sure that I agree with the OP that the slip road would be wide
enough for two lanes of traffic. Interesting that the junction was
constructed with single-lane slip roads leading from a (presumably) 3-lane
M1 to a (presumably) 2-lane A1, rather than making the slip roads 2-lane as
you'd get at any motorway junction nowdays.