Why cant there be a tube link between the top of the two northern line branches?

Question

So close, but yet so far!!!

Answer 1

Some of the station are actually very close on a real map, get out and take the bus!  You may have noticed that all the tube lines are "radial" from the centre, with the exception of the Circle Line.  The Silver Link does however perform this function in the north if you don't mind going overground.

Answer 2

If my head is correct, which it probably isn't, there is an unexploded bomb that will explode if a train goes over it. Either that or the trains would crash.

Answer 3

It was paritially built - but the outbreak of World War Two halted construction and it was never completed

Answer 4

There used to be check out this historical tube map

http://www.clarksbury.com/cdl/maps/tube4...