Floating car data

Floating car data (FCD), also known as floating cellular data, is a method to determine the traffic speed on the road network. It is based on the collection of localisation data, speed, direction of travel and time information from mobile phones in vehicles that are being driven. These data are the essential source for traffic information and for most intelligent transportation systems (ITS). This means that every vehicle with an active mobile phone acts as a sensor for the road network. Based on these data, traffic congestion can be identified, travel times can be calculated, and traffic reports can be rapidly generated. In contrast to traffic cameras, number plate recognition systems, and sensor loops embedded in the roadway, no additional hardware on the road network is necessary.

Different types are possible:

• Floating cellular data = cellular network data-based (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 the GSM localisation is less accurate than GPS based systems, lots of devices have to be tracked and complex algorithms need to be used to extract high-quality data. For example, care must be taken not to misinterpret cellular phones on a high speed railway track that runs parallel to 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 antennas is lower and thus the accuracy increases. FCD based on mobile phones believe to have significant advantages over GPS-based or conventional methods such as cameras or street embedded sensors: No infrastructure or hardware is needed to be built 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 accomplished a breakthrough milestone by demonstrating in Atlanta that such system can emulate very well road sensors data for section speeds.
• Electronic toll collection device data: ETC transponders, which are uniquely identifiable, may be read not only at toll collection points (e.g. toll bridges) but also at many non-toll locations. This is used as a method to collect traffic flow data (which is anonymized) for the San Francisco Bay Area's 5-1-1 service.^[1]
• Global Positioning System-based: A small number of cars (typically cars driving in a fleet, such as courier services and taxi drivers) are equipped with a box that contains a GPS receiver. The data are then communicated with the service provider using the regular on-board radio unit or via cellular network data (more expensive).

It is possible that FCD could be used as a surveillance method, although the companies deploying FCD systems give assurances that all data are anonymized in their systems, or kept sufficiently secure to prevent abuses.

References