  A kind of fluid dynamic description for the collective movement of
pedestrians is developed on the basis of a Boltzmann-like gaskinetic model. The
differences between these pedestrian specific equations and those for ordinary
fluids are worked out, for example concerning the mechanism of relaxation to
equilibrium, the role of ``pressure'', the special influence of internal
friction and the origin of ``temperature''. Some interesting results are
derived that can be compared to real situations, for example the development of
walking lanes and of pedestrian jams, the propagation of waves, and the
behavior on a dance floor. Possible applications of the model to town- and
traffic-planning are outlined.
