TfL will start tracking tube passengers through WiFi – here’s what that means
Understanding movement on the Underground could help ease congestion
We all know the unpleasant feeling of squeezing on to a crowded Tube train – but similarly, we also know just how expensive new tunnels, stations and trains can be.
So the obvious question to ask is: Is there anything else that Transport for London (TfL) can do to squeeze any extra capacity out of the London Underground?
It turns out, there might be.
This week TfL announced that from 8 July it will be switching on a WiFi tracking system that will use the existing wifi beacons installed in 260 stations to keep a log of passengers who pass through by using their mobile phone’s unique identifying number – known as a “MAC” address, whether or not you are connected to TfL’s WiFi network. (Don’t be fooled – MAC addresses are nothing to do with Apple – every phone has one).
Why would it want to do this? At the moment, all TfL knows about us is the stations that we tap into and tap out of. With the WiFi data, TfL can learn a whole lot more.
For example, a month long trial of the technology in late 2016 revealed that it was possible to use WiFi data to detect which routes passengers chose to take between two points.
For example, of the 18 different routes people took between Kings Cross and Waterloo, wifi data tells us that 32% take the Victoria line to Oxford Circus, and then change to the Bakerloo, and 26.7% change at Green Park instead and switch to the Jubilee instead.
The data also revealed that 0.1% of people taking that route are clearly masochists – choosing to travel via the Circle Line to Liverpool Street, then taking the Central one stop to Bank, then going on the Northern Line to London Bridge, before finally taking the Jubilee to Waterloo.
It also works inside of stations too, and can capture data on how many people are changing trains without touching in or out, which could reveal something closer to the true number of people having to endure Oxford Circus at 8:30am.
The potential benefits of such technology are enormous: Wifi data could help TfL understand how we actually move around the Tube network, and it could help inform planning when lines go wrong, so TfL can better predict which alternative routes are about to be hit by a tonne of extra passengers.
It could even lead to apps like CityMapper being able to direct us to a less crowded alternative route.
With great innovation, however, comes potential controversy over privacy implications, as after all, this new system will be logging the travel habits of millions of Londoners. But TfL, for its part, has been incredibly proactive in insisting that it is taking data collection seriously – and has taken a belt and braces approach to security.
‘We do not collect any other data generated by devices, including web browsing data and data from website cookies. We also do not store unencrypted MAC addresses and have no means of decrypting them once they are encrypted,’ says TfL’s chief data officer Lauren Sager Weinstein.
TfL’s approach appears to be following best practice – it has been signed off by the Information Commissioner’s Office and the organisation’s own cybersecurity team. TfL also says that collected data will be stored for two years, before being destroyed, and that staff are given data protection training every year.
But even given the extensive precautions, there is still some uncertainty over whether it could be conceivably possible (however unlikely) to reverse-engineer identifying information using what security experts call a ‘rainbow table’, or by looking at behavioural patterns in the data.
What is clear though is that if you’re really paranoid and want to opt out there is always one option: Simply switch of the wifi on your phone, and the tracking system won’t work. But if you do leave it on – you could be helping improve the Tube for passengers in the future.
James O’Malley tweets as @Psythor.