MIG wrote:

The extension ticket in the paper travelcard case is £4, generally
more than PAYG for the whole journey. So, in fact, you have to get out
of the train, go to the exit, touch in, go back and wait for another
train.

The main problem with the combination of paper tickets and Oyster in
London is in my opinion the decision to have the card readers on
gates/platforms but not on the trains, so there is no way to touch
in/touch out without leaving the trains which leads to this problem.
There are also specific rules at some places which often leads to
confusion, it is not in all cases clear simple-to-understand logic
behind the "touching" people are supposed to do at interchanges such as
Winbledon NR/tube/tram or between tube/DLR at Bank.

There is a similar smart card system being introduced in western Sweden
where I live and one of the big differences I have noticed is that here
the card readers are always on the vehicle (on the bus, tram, train,
boat etc). We only have season tickets on smart cards right now here but
it is said that within a few months pre-pay value will be introduced too
and that it will always require touch-in when boarding any public
transport vehicle and touch-out when leaving it, no matter if it happens
to be a bus, train or something else. There will be no special rules of
validating on special card readers on platforms when changing trains or
interchanging between train/tram or something like that. It is always
the same rules, touch-in and touch-out on the vehicle you are using.
That said, I still think that the London model is better in many ways,
especially I find it quite reasonable to not require touch-out on buses
(it will be very interesting to see if that rule will really work here).

--
Olof Lagerkvist
ICQ: 724451
Web: http://here.is/olof