"Tim Roll-Pickering" wrote in message
...
Just noticed on Wikipedia that originally it was hoped to take the
Northern Line beyond Morden and onto what's now the Thameslink loop to run
down to Sutton - see
http://en.wikipedia.org/wiki/Morden_...ailway_station

How far apart are the lines now and what would, other than line capacity,
carriage size and cost, would prevent such a connection being made today?

Nothing has changed. The lines are as close together now as they
were when the rail line was built in 1930 (the underground line was
completed in 1926).

The track at the underground depot almost touches the National
rail line, except that it is 20 feet below it.

There's no technical reason why they couldn't be joined, just
financial and operation ones.

tim