Time is discretized into time steps. This discretization in both space and time results in a cellular automaton. One can think of a cell as being a few car lengths long and the maximum velocity as being the speed limit on the road. The time step is then the time taken for a car at the speed limit to travel around 10 car lengths. However, the model can also be thought as just a way to understand or to model features of traffic jams by showing how interactions between nearby cars cause the cars to slow down. In each time step, the procedure is as follows.