Dave Larrington wrote:

Don't have to walk though Rotherhithe Tunnel [spelt right this time].
On-road cycling is possible and allowed - just not very good.

True, but the OP said "south from the Isle of Dogs", which I took to
mean the Greenwich foot tunnel. The Rotherhithe tunnel can by no
stretch of the imagination be said to go south from the Isle of Dogs.

My imagination obviously stretches a long way.

Woof.

Yap.

~PB