Transport for London (TfL), the capital's transport authority, has been accused of selling data about passengers using the Wi-Fi service it provides on the London Underground - but TfL has denied selling the data for more than £300m.
TfL had originally said that it was tracking passenger's devices in order to study the movement of crowds through the underground system for planning purposes. However, Sky News reported that the organisation is also planning to sell this information to third parties and hopes to raise £322m by doing so.
This raises important questions about the dividing line between use of personal data for research and commercial activities, and also about achieving consent from those being tracked. The only way that passengers can avoid being followed through the Tube network by TfL's beacons is to switch the Wi-Fi off on their phone.
Documents obtained by Sky News under a FoI request show potential financial benefits to uppermost in TfL's considerations. In one document a section called Advertising Partnerships states: "Enabling TfL to achieve £322m revenue generation over the next eight years by being able to quantify asset value based on the number of eyeballs/impressions and dynamically trade advertising space."
TfL originally ran a pilot study of Wi-Fi tracking in the underground train system in December 2016, it stated aim "to better understand how people navigate the London Underground network, allowing TfL to improve the experience for customers".
No mention was made at the time or since about any commercial use of the data harvested. While TfL says that the data will be anonymised and aggregated, true anonymisation is very hard to achieve in the age of big data where datasets can be combined with information from other sources to re-identify subjects with relative ease.
Cofounder of PersonalData.IO Paul-Olivier Dehaye told Sky News: "TfL don't seem to understand what 'anonymised' means in data protection terms. While the pilot was running, the data was merely pseudonymisation, while retaining the technical capacity of easily combining this data with external datasets."
Renate Samson, chief executive of Big Brother Watch, said: "it is critical that the public are completely clear on what is being done, when, how and why, and how they can opt out."
While the TfL scheme was reportedly okayed by the ICO, incoming data protection legislation, including the EU GDPR, is likely to require that citizens have the right to opt out of such schemes. In addition, consent to one activity, such as studying the movement of people, will not mean consent is also granted to have personal data sold on for commercial purposes.
TfL is apparently unconcerned about such dividing lines, however.
"The excitement on this project has been how to create a project that will have great customer benefit and how do we explain to our customers what we're doing and why. We have been very transparent about all the documents and our thinking on this," Lauren Sager Weinsten, chief data officer at TfL, said, refusing to rule out the resale of aggregated passenger data to third parties.
A TfL spokesperson told V3:
"We have no intention of selling any personal data. The data would simply allow us to get a better understanding of where people travel through stations so that any advertising / retail units are placed where there are higher footfall flows.
"We are already in discussions with key stakeholders, including the Information Commissioner's Office, privacy campaigners and consumer groups about how this data collection could be undertaken on a permanent basis, possibly across the full Tube network.
"I can't stress enough how open and transparent we have tried to be with this pilot."
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