Thoughts on privacy and Oyster cards

This ship has long since sailed, but yesterday I found another reason to be a bit sad that TfL has phased out cash as a payment mechanism.

I logged into my Oyster account for the first time today, and I was struck by how much location data they have. You can reconstruct a large chunk of my diary from that data – for any Tube station or bus stop outside the core, there’s only really one person I would be visiting, and now you know when and for how long I was with them.

Intellectually, I knew this was happening – if I’m using the same card each time, I’d almost be more surprised if they weren’t recording the fine-grained data. But it’s sobering to see it all laid out, in complete and unerring detail.

I’ve never had to worry about stalkers or people coming after me, but I’d be pretty unnerved if I was.

Cash lets you travel anonymously, but you can’t use it on buses, and paper tickets on the Tube are more expensive. So if you’re somebody who doesn’t want your location tracked – or doesn’t have a card you can use – public transport in London is a bit harder for you to use.

A couple of examples sprang to mind:

There are probably others, and while your Tube data along might not give away your secrets, it could prompt awkward questions.

(This post originally appeared on Twitter.)