From:
https://www.thetimes.co.uk/article/transport-for-london-may-track-commuters-via-phones-to-reduce-overcrowding-b0ss982j7?shareToken=d3406a5e9a7b95fb4dd49507b8be3 071

Commuters could be tracked using their mobile phones under plans to tackle
overcrowding and increase revenue from advertising.

Transport for London (TfL) followed 5.6 million phones over four weeks
before Christmas via wifi in stations and is assessing how to develop the
monitoring system. The trial identified pinch-points in stations,
overcrowding on platforms and favoured routes around the network.

Controversially, the system could be used to sell advertising, with
companies charged more to buy space on platforms where travellers spend the
longest time.

Anonymised phone data is seen as a far more accurate way to track journeys
than entry and exit logs at barriers.

An evaluation of the trial, published today, shows that passengers used 18
routes to go between King’s Cross/St Pancras and Waterloo, the busiest
stations on the network, with 40 per cent of people who were tracked
failing to take the two fastest routes. The data showed that even within
stations a third of passengers did not use the quickest routes between
platforms and could be wasting up to two minutes.

Transport for London is assessing how best to employ the system in the
future and admitted yesterday that it could be used to track passenger
movements in “real time�.

It said it was talking to the Information Commissioner’s Office about its
plans and passengers could opt out by switching their wifi off. It said
that the phone data was “de-personalised�, with nothing to identify
individuals.

The system works by using 1,070 wifi access points on the Tube network.
They pick up on a code that identifies each phone, the media access control
(MAC) address, and track them from point to point.

Each MAC address was “irreversibly� encrypted, TfL said. Prior to
encryption, a random code is added to each to ensure that the phone cannot
be identified even if the encryption could be reversed. No browsing data
was collected, meaning that emails and the internet habits of passengers
could not be shared with third parties.

Privacy campaigners expressed concern over the technology. Renate Samson,
chief executive of Big Brother Watch, said: “Analysing movements of people
via their device may provide unique analytical benefits but is still a
process of tracking and monitoring as they go about their daily business.
It is critical that the public are completely clear on what is being done,
when, how and why, and how they can opt out.�

TfL, which handles up to 4.8 million journeys a day, spent £100,000 testing
the technology in 54 stations.

Val Shawcross, deputy mayor for transport, said: “The analysis of secure,
de-personalised wifi data could enable us to map the journey patterns of
millions of passengers and understand in much greater detail how people
move around our transport network. It will provide real benefits, helping
TfL tackle overcrowding, provide more information for passengers about
their best route and help prioritise investment.�