  The modelling of traffic flow using methods and models from physics has a
long history. In recent years especially cellular automata models have allowed
for large-scale simulations of large traffic networks faster than real time. On
the other hand, these systems are interesting for physicists since they allow
to observe genuine nonequilibrium effects. Here the current status of cellular
automata models for traffic flow is reviewed with special emphasis on
nonequilibrium effects (e.g. phase transitions) induced by on- and off-ramps.
