From 8 July, TfL have been tracking passenger movements using the Underground’s Wi-Fi system and mobile phones, to gain data on how the transport network is being used. It has been reported that the system will track a mobile phone and provide the relevant data, even if the phone is not connected to the Wi-Fi network. Can you confirm whether that is correct?
When a mobile device is near one of Transport for London’s (TfL’s) station Wi-Fi access points, and has Wi-Fi enabled, the device will send a probing request to connect. These requests contain the media access control (MAC) address of the device, which TfL depersonalises using industry-standard methods. If the device is signed up to use TfL’s Wi-Fi services, TfL uses this depersonalised information to understand how customers as a whole travel on the transport network. TfL does not identify any individuals from the data collected. If a device has not signed up to use the free Wi-Fi provided on the London Underground network, the system identifies the device as an ‘un-authenticated device’ and TfL will not process the information from the device for travel pattern analysis. Customers can opt-out of Wi-Fi data collection by turning off Wi-Fi on their device, turning the device off, or putting the device in airplane mode while at stations. TfL has published detailed information on its website about its Wi-Fi data collection and how customers can opt-out.