How Transport for London, and its media business, uses real time passenger data for ad effectiveness

Transport for London (TfL), the agency responsible for the capital’s Tube, established a privacy-safe system for measuring passenger flow using wifi connections, yielding some surprising results.

Beginning in 2012, Transport for London (TfL) launched a wifi network on its Underground system. The agency responsible for running London’s vast transport network, including the city’s famous Tube, had rolled out connectivity (in stations, not in tunnels)...