For a while now, enforcement authorities have been able to track movements of people with the help of their cellphones. Now, researchers at the Massachussets Institute of Technology have electronically mapped a whole city with the help of just the cellphone usage data, which, in future, could help authorities in responding to issues like traffic congestion and disasters in a city.

Using anonymous cellphone data, the researchers created electronic maps of Graz, the second-largest city in Austria.

"The real-time city is now real: a system that is able to continuously sense its condition and can quickly react to its criticalities," says Carlo Ratti, architect and engineer and head of the project at the SENSEable City Laboratory, MIT.

A cellphone network operating in the city of Graz sent anonymous information about the density of cellphone calls made and the origin and destination of calls.

Combined with this, the team used the data of voluntary participants who agreed to get their mobiles 'pinged' by the team, to map a whole city in all its vibrancy. Ratti and his team used anonymous and voluntary data to offer traffic planners a new way to track congested areas in Graz.

The computer-generated images showing the physical landscape of Graz and colourful representations in red, green and yellow showing as to how much the phones were being used during the time of the research are currently in display at the M-City Exhibition at Kunsthaus Graz.

Experts believe that the research could be put to use in times of large-scale emergencies as it is possible to simultaneously 'ping' the cellphones of thousands of users - thereby establishing their precise location in space at a given moment in time.

Despite the apparent advantages invlolved in the use of the technology, Ratti believes that the availability of such dynamic information will raise new questions - how should location information be managed and by whom?