Modelling a signal controlled traffic stream using cellular automata

Cellular automata models have formed the theory for the development of several transportation models to simulate various types of elements such as vehicles, pedestrians or even railway traffic. Furthermore, they have been applied to simulate several scenarios from very simple (freeway traffic) to rather complicated ones (lane reduction and signal optimisation). However, the properties of the model when used to simulate a signal controlled traffic stream have not been dealt with in great detail. This paper discusses several issues that arise while using the model for the simulation of traffic at signalised intersections. It also investigates the relationships between the randomisation parameter of the model, the model dynamics and the estimated saturation flow. For the deterministic version of the model, the formulas describing traffic quantities at the intersection are derived and are dependent on the desired speed – a parameter of the model. For the stochastic version, one can adopt several different approaches for the application of the randomisation rule, depending on the simulation needs.