On Sun, 27 Mar 2005, Richard J. wrote:

John Rowland wrote:
"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.

How can you have steps or a lift when the pier is afloat, rising and
falling by up to 7 metres twice a day?

The lift would have to have a variable top or bottom point. I've never
come across a lift like this, but i don't see why it couldn't be done.

There are a couple of ways you could do the steps. The first would be to
have the steps fixed to the bank, so that the bottom ones are sometimes
underwater, and have the pier slide up and down the steps (ie diagonally).
This would be pretty simple, but would mean the steps would be a bit
muddy. Perhaps a cunning mechanism on the lip of the pier could clean them
up as it descended. The other would be to have flexible steps - so that
when the tide was higher, they were shallower and flatter, perhaps even
becoming a flat walkway at high tide.

Getty any of that past the HSE, though ...

tom

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