"Richard J." wrote in message
...

To accommodate tides of 7 metres or more, you would
need ramps totalling 90 - 100 metres long (to limit maximum
gradient to the DfT guideline maximum of 1 in 12),
and sufficient of them to cope with large passenger
flows. It's not impossible, but it's a significant constraint
on the design, and may limit potential capacity just
because the piers would take up so much room.

You could have a narrow zigzaggy ramp (or even a lift?) for the few, and
wide steps for the many.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes