In message , at 12:04:38 on Mon, 17
Dec 2012, tim..... remarked:
It needs fixing such that if you over-run the
timeout the next touch in, if it is at a station that is a possible
part of
an OSI, closes the previous journey and opens a new one.

Unfortunately it has to close the previous touch in/out. That's why
it's non trivial to solve. But it can't be impossible

The simplest suggestion, which I mentioned long ago, would be to either
add a facility to the ticket machines to "close my journey NOW", or
simpler (but more expensive) have a "close my journey NOW" validator
somewhere on the concourse.

I see no reason why the concept of OSI needs to be such a secret and you
could have dumbed-down signs saying something like:

"Finished your journey? Touch the purple validator to ensure you
are charged the correct fare".

If you wanted the general public to avoid the problem.
--
Roland Perry