In this paper, a numerical driver behaviour model is presented in terms of how drivers possibly regulate their deceleration in braking tasks. It is based on David N. Lee’s τ-theory, which describes how drivers can perceive values of relative motion like time to collision or headway. This physiological model provides more universal application possibilities than purely empirical models, but its validation within critical traffic situations constitutes great issues. Therefore, a highly dynamic driving simulator providing all the requirements needed is currently under development at the Dresden University of Technology.