  Traffic flow is a very prominent example of a driven non-equilibrium system.
A characteristic phenomenon of traffic dynamics is the spontaneous and abrupt
drop of the average velocity on a stretch of road leading to congestion. Such a
traffic breakdown corresponds to a boundary-induced phase transition from free
flow to congested traffic. In this paper, we study the ability of selected
microscopic traffic models to reproduce a traffic breakdown, and we investigate
its spatiotemporal dynamics. For our analysis, we use empirical traffic data
from stationary loop detectors on a German Autobahn showing a spontaneous
breakdown. We then present several methods to assess the results and compare
the models with each other. In addition, we will also discuss some important
modeling aspects and their impact on the resulting spatiotemporal pattern. The
investigation of different downstream boundary conditions, for example, shows
that the physical origin of the traffic breakdown may be artificially induced
by the setup of the boundaries.
