  It was recently found that the Social Force Model of pedestrian dynamics in a
macroscopic limit for 1d movement does not reproduce the empirically found
inflection point of the speed-density relation. It could be shown that,
however, a simple and intuitively comprehensible extension of the Social Force
Model shows the inflection point. Motivated by this observation in this
contribution the relation of the Social Force Model with the Kladek formula for
the speed-density relation of urban motorized traffic is discussed. Furthermore
the models are compared to results data from experiments on vehicular, cycling,
and pedestrian dynamics.
