In message , at 12:03:34
on Fri, 13 Feb 2015, David Cantrell remarked:
The result - I was charged for entering and exiting at Waterloo, and
then charged again for my actual journey.
It's not an error, the system is operating as programmed. (You're a
programmer, no? Technology, including Oyster, doesn't just do it's own
random thing.)

Operating as programmed isn't the same as operating without error. If it
were then there would be no such thing as a bug.

Nor is operating as *specified* the same as operating without error. If
it were then specifications would never change.

The Oyster website says that they deliberately make this charge "to
avoid fare evasion". But I'm really struggling to think of a way of
evading fares that would involve touching in, and then touching out less
than ten minutes later at the same station. I might just about be able
to make a round trip from Waterloo to Vauxhall and back again in ten
minutes with a great deal of luck, but it's fairly obvious that the
potential costs of people avoiding that fare are far less than the
excess income generated.

It is clear to me that the specification is faulty in this case.

The failure mechanism would appear to be someone touching in, and then
touching out on a gate but failing to go through the gate. So they are
still "airside", and capable of catching a train somewhere.

This is such a fundamental fraud vector that whoever designed the system
to allow it (while penalising innocent passengers whose platform was
changed at the last minute) should be hung out to dry.
--
Roland Perry