Study Of Traffic Flow Celluler Automata Models And Their Applications To The Main Road In City Traffic

Cellular automata(CA)are mathematical idealizations of dynamical systems in which space,timea and states are dicrete.It's parallel and simple for computation,so it can simulate variable complex phenomena.Resently,CA have become used for modeling traffic flow.In this paper,firstly we point out the importance and complexity of traffic problems.Then we make a summary of traffic flow theory:from the early car-following model to resently CA model,important models and their theory in diffrent period are presented,especially the CA models.Basing on the traffic flow CA models,we present several new models and study their traffic characters in the following.First,it's a deterministic CA model for single lane.In this model,vehicles have the speed 0 and 2,so it is called(0,2)model.This model is compared with the deterministic FI model for Vmax=2 which is called(0,l,2)model.It founds out that the critical density of(0,2)model is less than that of(0,1,2)model,and the time to get to steady state for(0,2)model is longer,and it jams easily.Second,we introduce a two-lane traffic model which is based on the(0,2)and(0,1,2)models.We mainly study the coupling effect of lanes.In two-lanetraffic ,vehicles can change lanes and overpass.The interactin between lanes is considered as coupling effect.The computer simulation indicate that(Dthecurrent of the system with cupling is greater than that without coupling;0for a certain initial density,the average flow and speed are indepent on the coupling coefficient which is greater than zero;when the initial densities(speeds)of lanes are different,the characters of traffic system will be different.Third,we investigate the improved NS model with open boundary conditions.Based on the NS model,this model considers the relative motion of vehicles when updating the speeds and positions of vehicles.With open boundary conditions,at site i=0(out of system),a vehicle with probability a and with velocity V=Vmax,and at the end of system,vehicles simply move out of the system with probability 3 .The influence of a 3 Vmax and deceleration probability P on the car density average speed and current are investigated.Compared with NS model,the quantities in our model such as density,speed and current are improved greatly.The phase transition from free-flow phase to maximum phase or from jamming phase to free-flow phase is different from that of NS model and some new characters occure.Finally,we propose a main road model in city traffic according to the improved NS model with open boundary conditions,and study some characters about this model with different parameters.Our purpose is to find out the actor which influent the main road's average speed and current,and also the law of city traffic.Then we can give some advise for managing and controlling the main road trffic.Organization and self-organization cooperation in this model is discussed.The effect of roads'length,the number of intercections and their positions is self-organization,and the effect of the deceleration probability,the injection(extinction)rate,the cycle times of traffic lights is organization.We analyse the effect of the parameters above separately.