"Robin" wrote in message
...
It's not the technology that important here but the fare structure.

There are several other metro areas using exactly the same technology
where there is no opportunity for a systematic overcharge to occur.

Could you unpack that for me please? I'm not really into these things but
ISTR being told in HK, Tokyo and Melbourne that one had to use the card
in *and* out to get the lowest fare. Does it not follow if there is
anything other than a flat fare?

Other systems in use:

1) South Sweden - The system assumes the minimum journey length unless the
user manually sets a longer journey at the start. If starting on a bus then
you have to tell the driver to do this, but if starting on a train you do
this at the automatic machines. You are now on trust not to go outside the
selected zones upon pain of fine if caught (just like LT really). This is
definitely the same basic technology as London.

2) Helsinki - The same except that as there are only three zones the user
can also select outer zones at the machine. This is a proximity card, but I
don't know who supplies it.

3) Lisbon - There are only two zones here and you tell the system how many
zones you want to travel by having two cards (one loaded for one zone and
the other for two), of course most people only ever make one or the other
and don't actually have two cards. Again, this is a chip card but I don't
know who supplied it

tim