The system will have a record of you entering at one station, but no record of an exit.
Will that result in a charge or other problem?
(On the London Underground, it would result in a charge, as the system is designed to assume you exited somewhere but somehow managed to leave without tapping out.)
One thing that surprised early Oyster users on LU was that the new system knew about routes. If you live in Zone 3 and you travel to a Zone 3 station on the far side of London, you could buy a weekly paper ticket that's not valid in Zone 1, and it'd let you in (in Zone 3 it's valid) and out (in Zone 3 again, it's valid) despite your train passing straight through Zone 1. However after switching to Oyster weekly the computer would look at these journeys and go, er - no, the sane routes use Zone 1 so a ticket needs Zone 1 validity...
On day one there was no noticeable symptom. But if your Oyster only had a season ticket for outer Zones and your route was via Zone 1 the system had surcharged you, and when you tried to travel the next day the Oyster has negative balance, you can't use it until you pay off the excess. This infuriated some travellers, when in reality they had actually been cheating (presumably in most cases without realising) previously.
Today Oyster can actually track if you insist on taking the long route, you tap pink validators at key interchanges you'd need to pass through to do your slower and less central route avoiding Zone 1, and the system will go OK, fair enough, you really did go the long way so keep your money. I expect very few people do this.
I doubt this. Even as a child I knew that a travelcard must be valid for all the zones you travel through. Of course, if challenged, someone knowingly cheating would claim they didn't realise.
> you tap pink validators at key interchanges
> you'd need to pass through to do your slower
> and less central route avoiding Zone 1"
Wow! I had no idea this was a thing. I moved away from London in 2010, and now I'm curious to know whether this was implemented before or after I left.
I used this frequently at some point, but it is now so long ago I can't remember where. Especially with many London Overground routes, it's not necessarily slower.
You’re correct. When you try to enter next the turnstile will error out with “see agent”. That’s when they fix your card and peel the sticker off. Which highlights the total ridiculousness: they’re asking riders to see an agent twice!
In this particular context by the way (enter and exit same station, assume you just tapped in and out as you would normally) LU may actually charge "Same station fare" and the rules are pretty esoteric.
[Edited to add: Stupid web site doesn't have working fragment markers, click "Same Station Exits" near the top... ]
In practice, as it explains elsewhere on the site, these charges are mostly to discourage attempted fare evasion, and if you're a regular user who just does this once in a while it'll delete the journeys after it decides this isn't suspicious after all, otherwise you need to talk to a human if you really didn't travel anywhere.
The 'same station exits' section of that page is fascinating. The great thing is that most people will never need to worry about this, so they discourage fare evasion without inconveniencing honest passengers.
I wonder: if there were better enforcement of fares in San Francisco, would public transport be better? Right now, I almost never use public transport in SF because ~100% of my journeys would take 2x to 3x as long as they do by car. This is very sad for me, having previously lived in two cities with excellent public transport (London and Beijing).
When you leave without going through the turnstile your card is locked and you can't re-enter via the turnstiles. That's what the sticker is for: it tells the station agent that you should be able to re-enter via the emergency exit.
Will that result in a charge or other problem?
(On the London Underground, it would result in a charge, as the system is designed to assume you exited somewhere but somehow managed to leave without tapping out.)