  We consider the exclusion process on a ring with time-dependent defective
bonds at which the hoping rate periodically switches between zero and one. This
system models main roads in city traffics, intersecting with perpendicular
streets. We explore basic properties of the system, in particular dependence of
the vehicular flow on the parameters of signalization as well as the system
size and the car density. We investigate various types of the spatial
distribution of the vehicular density, and show existence of a shock profile.
We also measure waiting time behind traffic lights, and examine its
relationship with the traffic flow.
