Transport for London harnesses Wi-Fi to measure movement
Given the near-100% penetration rate of smartphones in the UK, as in so many other markets, there is great potential value at a macro level of the tracking information they generate. From July, Transport for London (TfL), the body that runs London’s public transport, will begin collecting such data from mobile devices to analyse the flow of passengers through the capital’s Underground stations. Specifically, TfL will rely on Wi-Fi signals to generate a big picture of crowd movement.
When a mobile device connects using Wi-Fi, it’s constantly searching for networks to connect to, and sends out a unique identifier to nearby access points. TfL’s system will collect these connection requests as travellers pass through stations.
TfL stresses that collected data will be depersonalized, meaning it cannot be tracked to a specific person or device, and no browsing or historical data will be collected. Realising that privacy will be a concern, TfL says it has worked with the Information Commissioner’s Office to address privacy and transparency issues.
TfL already uses ticketing data to understand the journeys people make, but this new data will give a higher level of accuracy, as it will show which routes people take within a given station, as well as the stations they travel between. New signs will soon appear in carriages letting people know about the new system, and travellers who want to opt out can simply disable Wi-Fi until they’re back above ground.
In 2016, TfL conducted a four-week trial to test the technology, during which it collected anonymous data on 42 million journeys. Analysis of the data was an eye-opener, providing detail well beyond that offered by ticket purchases. For example, people travelling between King’s Cross St Pancras and Waterloo took at least 18 different routes, and the two most popular options only accounted for 60% of journeys.
TfL promises that there will be big commercial benefits from collecting this data, providing better and more-efficient service by learning the behaviour of passengers. The data can also be used to maximize advertising revenue by revealing which sites in stations get the heaviest foot traffic. TfL, which is under heavy budgetary restraints, could rent such sites at a premium. It might also license the technology to other transport services around the globe, as it has done with its ticketing system in Sydney and New York.
Given the volume of traffic, creating and maintaining this system will be no small task. The amount of data generated by a full roll-out of Wi-Fi tracking across the London Underground network will be staggering. For example, during the four-week 2016 trial, which took place on a small part of the network, more than 509 million depersonalized pieces of data were collected from 5.6 million mobile devices.
TfL may face a few speed bumps. The tracking system piggybacks on existing Wi-Fi infrastructure that provides customers of some telecom providers with free Wi-Fi access in stations. The quality of the service is variable, and it can take long enough to establish a connection that the train is already pulling out of the station before a web page can load. And, unlike other city metro systems, such as Barcelona and Hong Kong, there is no cellular coverage underground.
There’s a risk that the public will associate free Wi-Fi access and travel tracking. Problems with one system may tarnish the reputation of the other.
There’s plenty of evidence that people are willing to share data if it gives them free access to a good service — Google is a great example. But Google is also a good example of getting Wi-Fi tracking wrong. Eight years ago, the company was criticized for using its Street View vehicles to collect Wi-Fi details from homes; and its recent Sidewalk Labs urban regeneration project in Toronto has come under fire for the amount of personal data it would collect using sensors around the site.
A spotlight on Wi-Fi might prompt calls for TfL to provide a better Wi-Fi service, or even modernize the whole communications system for users of the London Underground. One of the last refuges from always-on communications could disappear.
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