On Sun, 13 Sep 2009, Mark Brader wrote:

Tom Barry:
One other benefit of double-deck trains, by the way, is shorter train
lengths for the same capacity (which saves money on station lengths,
but not in the capacity of escalators etc.). That's at the expense of
dwell times, though, unless you do something really clever like having
double-height platforms with doors on the upper deck too (I like the
sound of that, actually).

J.R. Stockton:
At busy stations, there can be a lower-deck platform on one side of the
train and an upper-deck platform on the other side.

Tom Anderson:
Has this actually been done anywhere? Can i see pictures?

The upper deck would have to have doors that open about 8-10 feet (2.5-3
m) above rail level. Which means that if those doors ever opened
outside a station, someone could fall out and break their neck. I find
it hard to believe that safety authorities anywhere would accept that.

Much as they wouldn't accept the idea of trains driven by computers, or
without guards on board? As with those examples, it's a matter of building
enough safeguards into it that it's safe. Perhaps the doors could be built
to only open once a positive physical interlock with a platform was
established, a bit like a space station docking port. Of course, the you
have the question of whether the benefit-to-cost ratio of the system with
the necessary safeguards included would still be greater than one.

It's different for elevators, because the elevator shaft provides
protection. I used to work in a building with double-deck elevators. If
you worked on an even-numbered floor, to get there you boarded from the
ground floor. For odd-numbered floors you'd take the escalator to the
basement concourse to catch the elevator.

(As this was in Canada, the ground floor was also floor 1, which
seems to break the pattern; but floor 2 only existed in the lobby
area and was not served by the main elevators. Going back down,
you'd just have to take whichever deck arrived,

Wouldn't that always be the same for a given floor? Or did the lifts not
follow the synchronisation pattern on the way down?

and wouldn't have a choice of whether you arrived at the ground or
basement level.

Ah, they didn't, then. Interesting!

Both decks had buttons for all floors they could reach; they just didn't
all work when you were on the ground or basement. So trips between
floors above ground were generally like using a normal elevator.)

Even going up? Or did upward trips divide into two classes, those carrying
people up from floors 0 and 1, where synchronisation was maintained (at
least at the floors to which people from 0/1 were going), and those which
were purely aerial, where it wasn't?

tom

--
I now have a problem with tomorrow. -- Graham