Validation and Verification of CA-Based Pedestrian Dynamics Models.

Verification and validation (V&V) of pedestrian dynamics models have become a subject of extensive discussions over the last few years. While some requirements and tests are proper for all models, simultaneously each type of model requires also its own set of specific tests. In models based on Cellular Automata (CA) discretization of space and time is the main source of possible errors. This paper addresses some issues, that should be carefully investigated in order to obtain a final, reliable model. The negative effects of discretization are discussed, as well as, the problem of maintaining pedestrian speed in different grid configurations i.e. movement isotropy. In parallel we show that wall penetration can occur in CA models and that input geometry has to be validated. The issue of automatic detection of collective effects in CA-based models is mentioned. Finally, the necessity of fundamental diagram application in validation is broadly discussed. The aim of this paper is to bring the CA-based pedestrian dynamics models into current general discussion about V&V and to indicate specific issues of CA- based models.