  A modified version of the Intelligent Driver Model was used to simulate
traffic in the district of Afogados, in the city of Recife, Brazil, with the
objective to verify whether the complexity of the underlying street grid, with
multiple lane streets, crossings, and semaphores, is capable of exhibiting the
effect of critical density: appearance of a maximum in the vehicle flux versus
density curve. Numerical simulations demonstrate that this effect indeed is
observed on individual avenues, while the phase offset among the avenues
results in damping of this effect for the region as a whole.
