  Traffic safety at intersections is studied quantitatively using methods from
Statistical Mechanics on the basis of simple microscopic traffic flow models.
In order to determine a relationship between traffic flow and the number of
crashes, the modelling focus is on the building block of any road network,
namely the crossing of two streams. In this paper, it is shown that the number
of crossing conflicts is proportional to the product of the two traffic flows
from which a simple model is developed. This model substantiates known
empirical findings. Since real crash data are obtained by an involved process
from such building blocks, there is a difference between the theoretical and
empirical results. This process is modelled here as well and narrows the gap
between theory and observation.
