Editing Floating car data (section)

==Floating cellular data==
'''Floating cellular data''' is one of the methods to collect floating car data. This method uses [[cellular network]] data ([[CDMA]], [[GSM]], [[UMTS]], [[GPRS]]). No special devices/hardware are necessary: every switched-on mobile phone becomes a traffic probe and is as such an anonymous source of information. The location of the mobile phone is determined using (1) [[triangulation]] or (2) the hand-over data stored by the network operator. As [[GSM localisation]] is less accurate than GPS based systems, many phones must be tracked and complex algorithms used to extract high-quality data. For example, care must be taken not to misinterpret cellular phones on a [[high speed railway]] track near the road as incredibly fast journeys along the road. However, the more congestion, the more cars, the more phones and thus more probes. In metropolitan areas where traffic data are most needed the distance between [[cell site]]s is lower and thus precision increases. Advantages over GPS-based or conventional methods such as cameras or street embedded sensors include: No infrastructure or hardware in cars or along the road. It is much less expensive, offers more coverage of more streets, it is faster to set up (no work zones) and needs less maintenance. In 2007, [[GDOT]] demonstrated in Atlanta that such system can emulate very well road sensors data for section speeds. A 2007 study by [[George Mason University|GMU]] investigated the relationship between vehicle free flow speed and geometric variables on urban street segments using FCD.<ref>Ali, A. T., Flannery, A., & Venigalla, M. M. (2007). Prediction models for free flow speed on urban streets. Transportation Research Board 86th Annual Meeting. Washington D.C. 2007. (No. 07-1954).</ref>