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 movements. They turn with probability γ, 0⩽γ⩽1. The model is presented in two variants depending on the direction of the flow on the different streets. We numerically find that the mean velocity of traffic continuously decreases with increasing concentration of cars. For a given concentration the mean velocity is minimum for γ=0.5 in both variants of the model. Exact expressions for γ=0,0.5,1 are found for an infinite city and a global picture emerges in terms of asymptotic order, local jam and fluctuations.