At the Venice Biennale this week, visitors to the contemporary art and design exhibition can see graphic displays of how residents and tourists are moving about Italy's capital city, Rome. A project called Real Time Rome uses data gathered from cell phones and other wireless technologies to create a map that illustrates where people are -- whether they're stuck in traffic, congregating at a tourist destination or passing through a thinly populated neighborhood.

Real Time Rome is the brainchild of engineer and urban planner Carlo Ratti, who is director of the Senseable City Laboratory at Massachusetts Institute of Technology (MIT). The lab is focused on studying the impact of new technologies on cities.

For the Real Time Rome project, Ratti's team set out to map the movement of people according to their mobile phone usage. (He has done similar projects in other cities, including Graz, Austria.) The project analyzes cell phone activity logs, using aggregate data collected by communication service providers. The project's principal sponsor, Telecom Italia, collects data through two methods: by measuring "Erlang," which describes the amount of telecom traffic in a particular area; and by recording the interpolated signal strength of mobile phones engaged in calls in a particular area of Rome. Real Time Rome also ties in data from GPS devices mounted on buses and taxis.

Back at MIT in Cambridge, Mass., the Senseable City Lab receives the aggregate phone and GPS data and runs proprietary software to analyze it. By crunching the data, the team can discern the difference between a mobile phone signal from a caller who is stuck in traffic, and one that is sitting in the pocket of a pedestrian wandering down the street, for example. Wireless communication activities are then overlaid on city maps to illustrate the patterns of pedestrians, public transportation and vehicular traffic.

Click to see: GIS

For the Venice Biennale installation, the Senseable City Lab sends the images to Venice for viewing -- roughly five minutes after the data is collected. Seven large acrylic screens display data sets such as traffic congestion around Rome; movements of the city's buses and taxis; and how pedestrians move about the city.

Data is made anonymous and aggregated from the beginning, so there are no implications for individual privacy, Ratti says. "There is no way to link any information we use to individuals," he says.