Phase diagram hints at traffic solution May 28, 1999 Various
types of traffic jams can be explained by modelling traffic flow
as a gas according to group of European physicists. Dirk
Helbing, Ansgar Hennecke and Martin Treiber from the University
of Stuttgart in Germany and Eotvos University in Budapest found
that the equations that explain the kinetics of gases can also
model stop-and-go waves, traffic jams and other traffic patterns
seen on motorways (Phys. Rev. Lett. 82 4360). Transitions
between the different "phases" of the traffic can be triggered
by cars joining the motorway at intersections or other
disturbances such as a change in the number of lanes. Helbing
and co-workers have identified six different traffic phases:
homogeneous congestion, oscillatory congestion, triggered stop-
and-go traffic, moving localised clusters, pinned localised
clusters, and free traffic. One axis of their phase diagram
represents the flow of vehicles already on the motorway, while
the other represents vehicles joining th