  We simulate the dynamical behavior of M elevators serving N floors of a
building in which a Poisson distribution of persons call elevators. Our
simulation reproduces the jamming effect typically seen in large buildings when
a large number of persons decide to leave the building simultaneously. The
collective behavior of the elevators involves characteristics similar to those
observed in systems of coupled oscillators. In addition, there is an apparently
rule-free critical population density above which elevators start to arrive
synchronously at the ground floor.
