The London subway operator “Transport for London” (TfL) uses the WLAN signals from the passengers' smartphones to create motion profiles of these. The aim is to better analyze the use of the metro network and thereby be able to give passengers better information on utilization and optimal routes.
Wi-Fi tracking will begin on July 8 of this year and will be in close consultation with the UK Privacy Commissioner and the law. Accordingly, all data are pseudonymized, so that no inference to individual persons is possible. Also any search by the use of the WLAN will not be recorded. The pseudonymized motion profiles are to be stored for two years. TfL would like to draw on the WLAN data from a total of 260 stations in the metro network of the city.
MAC address as a unique identifier
The detection of a smartphone is based on the transmitted MAC address, which is transmitted to routers when searching for available networks. A connection to the network of the TfL is therefore not a prerequisite to be detected by the system. If you do not want to be recorded, you can only evade data collection by deactivating the WLAN or by using the flight mode.
So far, the company only uses information from its own ticketing system to analyze how it drives on its own network. While this may show where passengers enter and exit the subway network, they do not gather any information about how they move within the stations. By using WLAN, the movements within the network can be monitored in near future in real time.
First field trial in 2016
The launch of Wi-Fi tracking in July was preceded by a four-week field trial at 54 stations in 2016. It collected 509 million records from 5.6 million smartphones, representing approximately 42 million journeys on the metro network. Among other things, it was clear that passengers choose very different routes and 40 percent of them, for example, not the two most visited routes between King's Cross St. Pancras and Waterloo chose.
Data should be made accessible via API
The movement data should also be made available to developers and scientists via a free API so that they can integrate the accessible information into apps such as route planners or use it for research.