In message
, at
07:56:08 on Tue, 7 Feb 2012, amogles remarked:
It also means that some realistic use-cases, such as "quickly nipping
over to X to buy a Y" become single journeys, unless you have some
amazingly complex rules on doubling back. *Unless you add Oyster tap-
out to bus journeys, how would you detect "bus from home to shop, buy
thing, bus back?"

In a German style Tarifverbund, doubling back is normally allowed, as
the validity of the ticket is zone and time dependent but route
independent. However, such cases will probably be quite rare so its
better to accept them than to make the system unnecessarily
complicated because of them.

Some systems (possibly even Oyster on the tube) will look at the time
between subsequent touch *in*s to decide if it's really two separate
chargeable trips. Being out and about on buses for an hour is generally
regarded as "one trip", even if it's actually a "there and back".
--
Roland Perry