  Traffic flow data collected by an induction loop detector on the highway
close to Koeln-Nord are investigated with respect to their dynamics including
the stochastic content. In particular we present a new method, with which the
flow dynamics can be extracted directly from the measured data. As a result a
Langevin equation for the traffic flow is obtained. From the deterministic part
of the flow dynamics, stable fixed points are extracted and set into relation
with common features of the fundamental diagram.
