Thread by @Psythor

1/ BIG news today for London: TfL is announcing that it is rolling out technology to track passengers using wifi full time from July 8th.

I’ve written about this story for some time, so if you’ll forgive me, a little thread on why this is cool but also… controversial!

2/ So what exactly is happening? TfL will be using the wifi beacons already on the tube to log any devices it picks up. If you have the wifi on your phone switched on, even if you don’t connect to the wifi, it will count you.

3/ This is because it can still detect your phone’s MAC address - nothing to do with Apple computers, it’s like a unique ID number that every phone or wifi device has.

But why would TfL want to collect this data?

4/ …Because the data insights it can learn about the London Underground are incredible - and could massively improve the Tube network in terms of capacity, planning, and letting apps tell us how busy stations/platforms are etc.

5/ A couple of years ago, I obtained under FOI the results some of the results of a month long pilot conducted in December 2016.

It contained awesome diagrams like this, showing what % of people take different route options between Liverpool Street and Victoria.

6/ TfL later published an official report, which had a similarly awesome diagram, showing how people choose to travel between Kings Cross and Waterloo.

Remember: Before, all TfL knew was where your journey started and ended, based on Oyster taps.

7/ The data also gave TfL insights into how people move around individual stations. Here’s a heat-map of Euston station - note how the Southbound Victoria Line is clearly the busiest platform.

8/ This station data also enabled TfL to time how long it takes real passengers in real conditions to traverse through a station. Here’s how long it takes to walk around Victoria station.

9/ Because nothing is pure and wholesome, this data could also be used for advertising - if TfL know where people are standing, or even the commutes people take, advertising can be better targeted or priced differently in different parts of a station.

10/ And yes, there are also privacy concerns. The Tube is the nervous system of London and if you live here you can’t avoid it - do we really want TfL to know everywhere we’ve been travelling?

Luckily, I think TfL have been as responsible as possible. (Cont)

11/ In the new rollout, they repeatedly point out how the stored data is depersonalised so that - in theory - specific data on your journeys cannot be accessed.

In the pilot, they hashed and salted personal data.

I’m told this time around MAC address data will be tokenised.

12/ If you’d like learn more about the rollout, check out this piece I wrote for @WiredUK which has just been published:

wired.co.uk/article/london…

13/ And here’s my original FOI scoop for @GizmodoUK with more cool diagrams and maps:

gizmodo.co.uk/2017/02/heres-…

Here’s a follow-up from TfL’s official report:

gizmodo.co.uk/2017/09/london…

And here’s a big thing on privacy and the trial:

gizmodo.co.uk/2017/09/could-…

14/ Finally this is completely shameless but I am a freelancer, so am available to talk/write about this further if you want to hire me to do so. My DMs are open.

Afternoon plug for my piece on TfL’s wifi tracking rollout for @WiredUK:

https://twitter.com/Psythor/status/1131126872023207938