On Thursday, 7 November 2013 13:50:38 UTC, Neil Williams wrote:

1. No unresolved journeys. The way I would work this is the same way as many other systems do it, such as Singapore - touching in charges the maximum Oyster single fare to the card that could apply from that station (subject to cap if appropriate for London), and touching out refunds back the difference back to the journey you actually made. If you don't touch out, you don't get it back, tough. That is powerful motivation, and far, far less complicated.

Failure to touch in and touching out would do the same thing. Maximum fare that could apply to that station would be charged. Or in the case of National Rail, an automatic Penalty Fare.

Neil