On 2013\01\15 11:53, Roland Perry wrote:
In message , at 11:24:03 on
Tue, 15 Jan 2013, David Walters remarked:
davros.org lists Marble Arch as having a fixed stairway.

That confirms my recollection (a stairway alongside one of the
escalators, but not at the same angle so it's succession of half a dozen
steps, landing etc)

Is that a safety thing? If you slip you will stop at the next landing
rather than tumbling all the way to the bottom. It seems rare to find
very long unbroken flights of stairs.

It's because the natural 'angle' of escalators and stairs are different,
due to the different step dimensions. The landings are needed to keep
the two in synch.

I think you might have put the cart before the horse... I think the step
size of escalators is deliberately different to the step size of steps
in order to ensure that a flight of escalators and multiple flights of
steps with landings can occupy the same shaft.