Transport for London, the operator of the London Underground, has announced today that it will start tracking commuters’ phones on its Wi-Fi network by default starting July 8th. The phones’ MAC addresses will be tracked by the Wi-Fi access points across 260 of London’s metro stations. TfL will be able to use this data to see the routes commuters take as they move from one place to another.


TfL currently uses data from its ticketing system to get a sense of how journeys are made across the tube network. The data is true for people entering and exiting the stations but it can’t show the flow of movement through a station. That’s where the Wi-Fi data comes in as it will provide an almost real-time understanding of the flow of people through stations.

It says that this “secure, privacy-protected data” will provide benefits such as better alerts about delays and congestion within stations. It also promises that individual customer data is never going to be shared and commuters will not be personally identified from the data collected.

That’s because it’s using MAC addresses to track the phones. That’s what phones automatically send to Wi-Fi access points anyway when they’re trying to connect. So the only way that commuters have to not get tracked is to keep the Wi-Fi disabled on their phone.

TfL does say that it will anonymize the data by tokenizing the MAC addresses. They will be replaced with an identified that can’t be traced back to a smartphone or the person who owns it. No browsing or historical data will be collected from the devices.

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