Transport for London is now tracking the movement of passengers on the Underground using data from smartphones.

For the past week, TfL has been using WiFi connection requests from mobile phones to monitor where people are, and how they move around the Tube.

This means anyone with WiFi switched on on their phone will be monitored when they enter more than 260 stations with internet access.

TfL already tracks journeys through its ticketing system – but the phone data will now show exactly where customers are within stations.

The transport network says information on passenger movement will help it ease congestion on the Tube by giving commuters faster updates on delays. 

The data is always depersonalised – meaning the identity of individual users cannot be tracked, it says.

But civil liberties campaign Big Brother Watch said it was worried that passengers would not know how to opt out.

A spokesperson for the group said: “We should all be concerned when our phones are tracked and movements monitored without our consent.

“The public should be fully informed about what data will be taken from their phones, when and why, and reminded of their ability to prevent this tracking by turning off their WiFi.”

But TfL’s chief data officer Lauren Sager Weinstein said the data would provide “enormous” new insights, which would help to improve services.

She said: “By better understanding overall patterns and flows, we can provide better information to our customers and help us plan and operate our transport network more effectively for all."

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