CELLULAR-AUTOMATON BLOCK MODEL OF TRAFFIC IN A CITY

We present a cellular automaton model of traffic in a city where cars sit between crossings so that they never block the transversal movemen ts. They turn with probability gamma, 0 less than or equal to gamma le ss than or equal to 1. The model is presented in two variants dependin g on the direction of the flow on the different streets. We numericall y find that the mean velocity of traffic continuously decreases with i ncreasing concentration of cars. For a given concentration the mean ve locity is minimum for gamma=0.5 in both variants of the model. Exact e xpressions for gamma=0, 0.5, 1 are found for an infinite city and a gl obal picture emerges in terms of asymptotic order: local jam and fluct uations.