New London Garden Bridge to Track Visitors Using Their Phone's Wi-Fi

By James O Malley on at

London is currently in the planning stages of building a Garden Bridge over the Thames. The pedestrian bridge, which will be a £60m park over the water, has been championed by Joanna Lumley and will link two already well-connected parts of the river and won't even allow cyclists to use it to avoid either busy Waterloo or Blackfriars bridge.

Now though, it appears that the bridge will also be taking a slightly Orwellian turn too, as the Garden Bridge Trust (GBT), which will be responsible for running the bridge, has published a document (dug up by SE1) explaining plans to track visitors using the Wi-Fi on their mobile phones.

Talking about the plans for "crowd management", the Trust reveals that it plans to use HD CCTV cameras at bridge entry and exit points to count the number of heads – but it will also be counting in a smarter way too:

"The Wi-Fi pedestrian tracking system utilises the anonymous data code emitted by Wi-Fi enabled devices such as mobile phones. This code is then tracked using a number of detector sensors located across the bridge deck and on both podiums. Current research shows that over 95% of people now carry one of these types of devices with WiFi enabled and the system is calibrated to allow for user groups who may not carry a device such as young children. The system can be monitored in real-time by the GBT’s operational staff and will include various trigger alerts to notify staff of increasing peaks in demand or large deviations from the expected levels of arrival and departure based on historic data."

For it to work, all you will need is for the Wi-Fi on your phone to be switched on, then even if you're not connected to a network, Wi-Fi devices will be about sniff out your device and its unique "MAC" address.

Using MAC addresses for tracking people isn't a new idea. A couple of years ago there was a bit of a shitstorm when it emerged that some creepy bins in the City of London had been similar monitoring Wi-Fi devices. The idea there was that by analysing where you go, advertisers could build up a picture of your commute – and thus display adverts relevant to your journey.

In the Garden Bridge's case, the document says that the new technology will be used to ensure the number of visitors on the bridge doesn't exceed the evacuation capacity, which is 2,500 people at any one time. The data will also be used to predict visitor peaks so that they can have the right number of staff on hand to help.

The Garden Bridge is probably far from unique in deploying this technology, but it is one of the rare examples that we know about in the public sphere. Would you be happy to be tracked via Wi-Fi like this? Let us know in the comments.