People Rarely Leave 6-Mile Circle

The Planning Commissioners Journal looks at a handful of studies using cellphone GPS data, and discusses the merits (detailed travel information) and the drawbacks (personal privacy issues) of the technique.

"In Rome, they combined that information with GPS data from city public transportation to capture an ever-changing picture of the city's activity, from traffic jams to nightlife hotspots. The information, [MIT professor Carlo] Ratti says, 'could be useful to traffic planners, emergency planners and others.'"