In article . 170,
Adrian wrote:
And how is the PDA + wand etc going to talk to the oyster system
in real time? Not the card; the databases and stuff in the bowels
of 55 Broadway.

Genuine question - Why would that be needed?

For many simple transactions, it isn't. I would bet that the more
complex customer-service issues would require it.

This will certainly include things like "I made a journey 2 weeks
ago and got charged the incorrect fare". Possibly even if the
journey was yesterday, or this morning, too. Or "I'd like an oyster
card please". (Ok, the mobile chap(ess) can cary the forms + blank
cards, but they can't carry many, and they won't be able to cary
'ordinary' oyster cards AND photocards AND child oysters AND customer
charter forms AND ... And it'll take them six times longer to tap
out your name and address on a PDA for later uploading than they
would take to type it on the PC, even if we exclude fun tricks like
postcode lookups).

Good comms may also be required for credit card transactions for
monthly season-ticket amounts of money. Even if not required,
there is a lower risk (read: lower cost to LuL) if they do online
checking of the card number against the merchant bad-card-number-list...
I wouldn't be suprised if the modern gripper's ticket machines do
this via a GPRS connection when they can.

Not that I'm saying that totally mobile ticket-agents aren't a good
thing; but I suspect it would be better for them to be in a ticket
office where they will be able to do more.... It's not as if there's
a shortage of counters for them to sit at - there's a shortage of
people to sit in them!

Oh, and you're underground, so wireless will be problematic.

Radio...?

It's that or IR... and I don't recomend IR ;-)

Most people wandering around on the underground seem to manage to
have comms.

Analogue voice comms has a low-bandwith requirment, and is tolerant
of noise. Data often isn't. The wavelan at home has issues with
the base station in the lounge and the laptop in the kitchen... and
that's a tiny distance compared to even simple stations.

Of course, it is a solvable problem, but it's not trivial. Read
expensive.

(as an aside, I seem to recall from somewhere that the ATM machines
that corner shops have often to their transaction processing over
GPRS or GSM. Means that deployment is "plug in a 13 amp socket",
which is nice. Certainly if you design your protocols correctly,
both the opex for this kind of thing is low (the number of bits
shipped is low), and the capex is low (it's a standard part you buy for
tuppance from the chip manufacturer)).

All this aside: I don't work in the rail industry, so my guessess
may be very wrong. However, I do know enough that even aparently
simple things like this often end up being more complex and expensive
than you expect.

--
RIP Morph (1977-2005)