The convergence of communication and multi-media platforms has enabled a key capability: mobility tracking via GPS. Business plans of most major cellular phone manufacturers such as Nokia include embedding GPS in all manufactured cell phones within less than 18 months. Thus, a high penetration rate of GPS-equipped travelers on freeways is expected in the near future. This has major implications for the traffic engineering community, which currently monitors traffic using mostly fixed sensors such as cameras and loop detectors, or location specific sensors such as FasTrak or EZ-pass transponders.

Soon, using universally available equipped cell phones, a new category of location-based services will become possible: multi-modal travel time estimation for commuters using bikes, busses, cars, or trains; itinerary advisories for navigation; geolocalization and context aware applications for social networks; cell phone based monitoring applications for epidemiology in developing countries.