=== The TFL Oyster Card: Using it, being tracked by it ===
==== Introduction ====
For those outside London, the Oyster Card is an electronic card that is used for travel around London (mostly on the Tube and buses). In short, the card can be "charged up" with a travel card (that gives unlimited travel for a period of time) or with 'pre-pay' credit. To ride on the Tube, one holds the card against a yellow pad on the ticket barriers. The barrier then reads the card and opens the gate. On exit from the tube system, the user does the same thing, but the barrier deducts the cost of the journey from the credit on the card (if it's pre-pay). For buses, all journeys cost the same, so on simply waves their card over the yellow pad when boarding the bus.
It should be noted that the Oyster computer logs all journeys. For tube journeys this includes start and end stations and times, for buses, the route on which the bus was boarded and the time (and possibly the location of the stop, depending on the bus type).
===== Update, 20th April, 2006 =====
While researching this page, I found very little real, verifiable facts on the Internet (imagine my suprise!). I decided I should do something about this, so sent a letter to the Oyster Central Customer Services asking various questions. For anyone interested in Oyster and it's privacy issues, I'd urge you to read the request and response at
==== General Use ====
For most people, the Oyster Card is a very convenient, safe way to carry a valid ticket for travel in London. If you have a travel card and lose your Oyster, then it can be replaced. Indeed, even pre-pay credit can be recovered (although I've yet to actually hear of that happening). Also, since you keep the Oyster card between days or tickets, the vast majority of people scrounging or touting travel cards at station entrances have disappeared.
Certainly for occasional users, the Oyster Card is a real benefit. Firstly, journeys are discounted over the normal paper ticket price. Secondly, since the journeys you make simply chip away at your pre-pay credit, there's no need to fiddle with change or ticket machines or queue at the ticket window - just wave the card over the reader and get moving. I've personally had an Oyster Card since early January 2004. I've found it to be incredibly handy, and whilst I know the dangers of them (see below), much prefer them to their paper counterparts.
==== Scary Stuff (Tracking and Surveillance) ====
The technology that makes the Oyster Card work is called RFID. Essentially, there's a chip in the card that is activated by radio waves. Once activated, it transmits information to a receiver. In short, when you hold the card over a yellow reader, the reader is sending out radio waves which activate the card. The reader then receives the signal from the card, and then knows the serial number of the Oyster Card, so can open the barriers and let you travel.
In principle, this doesn't sound too bad. So what if 634527382 was there? Of course, if the people operating their illicit reader could look up the Oyster Card details, they they may know it was John Smith, of 32 Hollingdon Road. Even if they don't ever get to look up a card's owner, they will still know if a given card returns to a location. If they have numerous readers in public places, then they'll know how a given card moves around the city.
Taking the 'what if' paranoia out of it for a moment, right now TFL know where every Oyster Card holder goes on a daily basis. It's easy to infer someone's home locality from this information, possibly going so far as to infer work, favourite friends and socialising locations. In short, if you have an Oyster Card, TFL have some idea of your habits and the places you've been in London.
TFL use this data to determine traffic volumes and flows around the transport network. This is useful information when planning where to put tube extensions, or higher capacity. In other words, they absolutely are analysing the patterns of behaviour on Oyster Cards.
Worse than this, TFL hand Oyster travel information to the police (see
==== The Unregistered Oyster Card ====
TFL responded with the 'no registration' Oyster Card. This is half a solution to the problem - there's no need to give TFL any information about yourself. You simply pay the £3 deposit for the card, then charge it up with cash. Seemingly there's no way TFL would ever know who you are (although they'll get your face and iPod with all that camera technology they have).
That's of course apart from any information you may 'leak' to them. For example, if you ever use a bank card to pay for top-up credit, you can bet that gets tied to your Oyster record for ever*.
Incredibly, TFL make you register to replace a broken unregistered card. I just found this out today, when I found my unregistered card had snapped in my pocket (Conspiracy Theory: My old registered one lasted over two years of worse treatment without a hitch). I went to the window, and was told I had to fill out a form. The form states that you have to provide ID when handing in the form. Something like a bank card, recent utility bill, passport etc. There's no good reason for this - apart from to register you by the back door.
In short, if your unregistered card needs replacing, you have to give every last possible bit of information to TFL (including name, address, date of birth, telephone number, Mother's maiden name and an estimate of the credit left on your card). Worse than that, your replacement card is tied the old one - in other words, your replacement card is a registered Oyster Card - it's no longer an unregistered one!
Also, if you decide you've finally had enough of your Oyster Card, you can get a refund for the £3 deposit. The only way to do this is to send it back to TFL. They'll then send you a cheque for £3. Again, that will effectively register all those journeys you made with the card. They may not have known who you were when you travelled, but they know now you're leaving London.
Update: Since March 19th, you can apparently get refunds at a ticket window. However, if the card has ever had anything other than cash deposits, then you have to send away for your refund. Non cash deposits are credit card top-ups, as well as having money transferred from another Oyster card to it (eg. if your card stops working and you get it replaced).
==== Travelling Anonymously with an Oyster Card ====
Short Answer: This is impossible. You can do a few things to make it harder to see where you've been though.
Long Answer: Follow this 'simple' procedure:
- Walk up to a ticket window, buy an Oyster Card with cash (for example, handing over £10 will pay the £3 deposit and give you £7 credit)
- Use your Oyster Card as you like, topping it up as necessary
- After a period of time (defined by your paranoia and wealth), use up as much credit on your card as you can. Visit a ticket window and get a refund for any credit and the £3 deposit.
- Go to step (1) and repeat as necessary
I suppose another way to 'confuse' the recording systems would be to swap old cards around your friends. That way, you'd inherit their old cards, adding different travel habits to the profile. You then pass it on to someone else, and so it goes on. Note though this means your travel history remains in active use, and so if you inherit a card from someone 'dodgy' you may get associated with them. Presumably you have an alibi though, right?
==== My Two Pence ====
My take on this is that the Oyster Card is designed to be a way to track your movements around London. If it were simply to predict traffic volumes, there would never be any need to register people (or surreptitiously tie travel information to a person and their home address).
Here's something fun: Type 'privacy' into the 'Ask Oyster' search box. You'll get no results back!
That said, Oyster is a really useful thing. I'm going to continue to use it, but will be swapping my unregistered cards pretty frequently (and as soon as I can, now I've had to register my otherwise unregistered card!).
* "I read it on the Internet" (and can't find the link). Some more info at