  A large number of models for pedestrian dynamics have been developed over the
years. However, so far not much attention has been paid to their quantitative
validation. Usually the focus is on the reproduction of empirically observed
collective phenomena, as lane formation in counterflow. This can give an
indication for the realism of the model, but practical applications, e.g. in
safety analysis, require quantitative predictions. We discuss the current
experimental situation, especially for the fundamental diagram which is the
most important quantity needed for calibration. In addition we consider the
implications for the modelling based on cellular automata. As specific example
the floor field model is introduced. Apart from the properties of its
fundamental diagram we discuss the implications of an egress experiment for the
relevance of conflicts and friction effects.
