On 29 Jun, 08:52, DRH wrote:
On Jun 29, 8:34 am, (Neil Williams)
wrote:



On Sat, 28 Jun 2008 23:42:54 +0100, Paul Corfield

wrote:
Your final option - updated coding on first entry - is correct. All
tickets and smartcards are updated whenever there is a valid transaction
at a ticket vending or validation device.

Except National Rail barriers, surely? I was fairly sure they were a
read-only technology. Or is it just understood that they'll probably
end up used on the Tube first anyway, otherwise they'd have probably
been bought from a mainline ticket office instead?

Similarly, does a Tube barrier write to a NR-encoded Travelcard?
Again, I thought it couldn't.

Neil

--
Neil Williams
Put my first name before the at to reply.

I believe both NR and LUL use the same encoding system. NR/LUL
barriers have to write (time and point of entry, etc) to the magstripe
even for ordinary singles, to prevent "passback" (a ticket being
handed back over the barrier for a second passenger to use)

Thats easily bypassed - carry a magnet , go through the barrier , wipe
the stripe with said magnet , pass back to mate who then goes to bloke
at gate and looks innocent saying his ticket doesn't work. Bloke
checks ticket, shrugs shoulders and lets mate through. This would
probably work 99% of the time without the magnet but sometimes they
used to check the ticket with a machine.

B2003