On Fri, 17 Nov 2006, Peter Frimberley wrote:

On Thu, 16 Nov 2006 22:02:31 +0000, Dave Arquati
wrote:

John Rowland wrote:
alex_t wrote:

There's also a nice picture of the MonoMetro as it passes down
Liverpool Street. But they only give 10% chance for that one, sadly.

I have never seen a "top suspended" monorail like the one in that video
though. Doesn't such a design make it massively more complex, in that
the trains have to be so much stronger to hang from something rather
than just sit there on a concrete beam?

Er, no. Rather than supporting N tonnes on a rail beneath them, they have
to support N tonnes on a rail above them. The difference will be that a
bottom-rail system is in compression, while a top-rail system is in
tension, which are completely differnt types of load. However, i believe
that common engineering materials, like steel and carbon fibre, perform
better in tension than compression, although IANAengineer. If that's true,
it would mean top-rail systems could be lighter.

It's certainly going to make the track bed harder to get through,
because the pylons will have to be so much higher, and it'll be more
difficult to integrate track and buildings. For instance the Sydney
monorail goes through the middle of the odd building (some of which were
there before they built it) and is just sitting on top of the building
walls (no doubt strengthened), top-hung must be way more challenging to
poke through existing structures or tight spaces.

Will it? You need exactly the same sized hole through buildings, just with
the rail at the top rather than the bottom.

tom

--
It is better to create badly than to appreciate well. -- Gareth Jones