Exterion Media has started tracking tube journeys and browsing activity of millions of O2 customers
The London underground carries 1.3 billion passengers every year, with Waterloo being the busiest stationReuters

Exterion Media has started tracking the Tube journeys and browsing activity of millions of O2 customers. The data will be used by the out-of-home media owner to guide marketing companies on where best to display their advertisements on London's Underground route, which carries 1.3 billion passengers every year, with Waterloo being the busiest station.

The company, which was responsible for covering London's Routemaster buses with giant Adidas adverts, will also use information that the telecom operator already has on its customers. Data such as wealth, age, gender and hobbies of O2 customers will be used to target advertisements most relevant to them.

The tracking, which started on 11 February, is expected to give the location where people with certain spending habits or shared interests are likely to be at any given point of time. For instance, for a ladies fashion advert, the tool will provide information on the whereabouts of affluent young women at any given hour.

Mike Ridley, head of data at Exterion said, "We can add other details like an 'affluence level', based on how people use their phones – if the smartphone has recently been on holiday, for example, or based on where the owner goes to work."

While the data will be anonymous, Exterion Media will track the apps and the web pages customers are logging on to. The information will then be aggregated and sold to both big brands and advertising companies.

The New York-headquartered company has started the process only within London's Zone One and will track an estimated one million journeys a day made by O2 customers. However, it said it plans to extend this tracking research to other transport networks.

This is not the first time advertisers have used GPS data to track when and where their target customers will be. While this has been used for some years, Ridley said that this was the first instance where real-time mapping of people's behaviour on the Underground was being done. "The level of insight to be gained from analysing behavioural data just does not exist. Until now [this hasn't] been applied to dynamic environments like the London Underground," Ridley added.

Robert Franks, who heads the digital commerce business at Telefónica, O2's parent company, said this process by Exterion will ensure the right advertising content will reach "the right people, in the right location and at the right time" according to The Telegraph.