Improved Methods for Checking Forces Based Models of Pedestrian Dynamics

The force based models of pedestrian dynamics like the social force model or the centrifugal force model can demonstrate and sometimes explain many features of the collective behaviour of pedestrian crowds as self organization effects based on fairly simple microscopic rules. However, experiments that have been done either gave only collective data like averages of flux and density, or treated only very simple situations like two person interactions. The progress of digital cameras and of image processing during recent years now allows the measurement of pedestrian movements on a ``microscopic'' scale with low costs. Comparing forces derived from measured trajectories with calculated ones for the same situation allows a microscopic analysis of models and shows what parameters are important in special situations. Applying these methods to bottleneck experiments shows the importance of removing the effects of head movement and of stepping from the trajectories before calculating forces.