One hundred cars equipped with a GPS-enabled Nokia N95, and driven by students from the University of California, travelled a 10 mile stretch of road near San Francisco to show how real-time traffic information can be collected from a GPS feed, while preserving the privacy of the devices’ owners.
During the experiment, special software on the mobile devices periodically sent anonymous speed and location readings from the Nokia N95 to servers.The feeds were then combined to create a real-time picture of traffic speeds and projected travel times.
The experiment was carried out to test the traffic data collection and aggregation system, while studying the trade-offs between data accuracy, personal privacy, and data collection costs. The software aggregating the GPS feeds immediately disassociates the data from an individual device and combines it with the general stream of traffic data. To protect privacy, all data is anonymous and aggregated, and protected by encryption.
‘Mobile device users control the service. If an individual does not want their device to transmit position data they turn off the feed from their GPS,’ said Quinn Jacobson, research leader at Nokia Research Center, Palo Alto.
‘Nokia is excited at the potential for this system to revolutionise travel planning, carrying on from the Nokia Maps navigation service available today on certain Nokia devices,’ continued Jacobson. ‘Integration of traffic information with functions such as calendar and online timetables may one day mean the mobile device can act as personal travel planner.’
‘There are mobile device-based systems out there that can collect data in a variety of ways, such as measuring signal strength from towers and triangulating position, but to our knowledge, this is the first demonstration of this scale using GPS-enabled mobile devices to provide traffic related data such as travel times, and with a deliberate focus on factors like bandwidth costs and personal privacy issues,’ said Thomas West, director, UC Berkeley’s California Center for Innovative Transportation.
The researchers believe that fewer than five per cent of drivers need to contribute location data for the system to be effective on any particular highway.
For state transportation agencies such as The California Department of Transport (Caltrans), tapping into the vast network of mobile phones on the road could one day remove the need to invest in expensive infrastructure to obtain traffic information as well as greatly expanding the coverage of such services.
The project brought together research teams from the Nokia Research Center (NRC) in Palo Alto and from UC Berkeley, interacting through UC Berkeley’s California Center for Innovative Transportation (CCIT). The teams are developing the algorithms, software and architecture of this GPS-based traffic monitoring system.
The project is supported by a $186,000 grant from Caltrans. Additional support comes from the National Science Foundation, Nokia, Tekes, Rutgers University’s WINLAB, the University of California Transportation Center and the Volvo Center of Excellence for Future Urban Transport at UC Berkeley’s Institute of Transportation Studies.