  We described the average traffic congestion in several populous cities around
the world from a new concept, namely landscape percolation. The ratio of the
residential area size to road width is a fundamental parameter that controls
the traffic congestion. We have compared the model with data extracted from
several populous cities around the world (directly from Google Earth images)
and demonstrated very consistent results. The criterion for a city landscape
that makes a city is considered as congested or less congested has been
identified. The model also explains remarkably well the consistency of the
measured data with various reports on congestion levels (such as the recognized
Tomtom congestion level or Numbeo traffic index) of some populous cities around
the world. These findings may help in designing new cities or redesigning the
infrastructure of congested cities, for example for deciding what is the
maximum size of the residential area and how width the roads are. This work
also shows the similarity of the problem in conducting composite (electric
current flow), brine transport between icebergs (fluid flow), and traffic
(vehicle flow)
