From July 8, Transport for London (TfL) will begin using Wi-Fi data from mobile devices to analyze the flow of passengers through Underground stations, helping predict delays and congestion.
TfL has been quick to dispel any privacy worries, noting that all data will be depersonalized so you can't be identified, and no logs of your online activity will be collected. The system was developed in-house rather than by third parties, giving TfL full control over its creation.
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At the moment, TfL can track when people tap in and out of Tube stations, but that doesn't give a full picture of how many people are using each line and when. You could make any number of changes on several different lines before leaving a station, even to reach the same destination, and you could spend several minutes waiting for a train, or just checking a map.
How will it work?
When a mobile device has Wi-Fi activated, it's constantly searching for networks to connect to, and sending out a unique identifier to nearby routers. TfL's system will collect these connection requests as you pass through stations (whether you leave the train or not).
In 2016, TfL conducted a four-week trial to test the technology in Zones 1-4, during which it collected anonymous data on 42 million journeys. This revealed results that wouln't have been visible with ticketing alone. For example, people traveling between Waterloo and King's Cross St Pancras took at least 18 different routes, and the two most popular options only accounted for 60% of journeys.
New signs will soon appear in carriages letting travelers know about the new system, and if you want to opt out, you can simply disable Wi-Fi on your device until you're back above ground.