Meanwhile, Floating Car Data (FCD) is a widely available and affordable data source for
traffic surveillance. The German Aerospace Center, Institute of Transportation Systems
(DLR-TS) receives FCD from taxi-fleets ranging from 300 to 4000 vehicles from various
German and European cities since the year 2002.
To extract common traffic variables like travel times or travel speeds and generate traffic
information out of it, the raw GPS data of the vehicles are matched to a digital road network.
However, compared to data from inductive loops, where each vehicle passing a loop
generates data and the whole traffic flow is covered, the FCD represent only singular
measurements. Thus, they are very noisy (especially when passing signalized intersections)
and typically need to be aggregated to yield useful information. This means, a single
delivered value is not very reliable and does not necessarily represent the state of the traffic
flow on the according street segment. Data from some vehicles have to be aggregated and
smoothed for some time interval and/or space to obtain reliable traffic information
