TRAFFIC JAM AND SHOCK FORMATION IN STOCHASTIC TRAFFIC-FLOW MODEL OF A 2-LANE ROADWAY

We present a stochastic cellular automaton (CA) model to simulate the traffic jam induced by a car accident in the traffic flow of a two-lane roadway. The CA model is an extended version of the one-dimensional asymmetric exclusion model to take into account the stochastic exchange of cars between the first and second lanes. We study the traffic how of the system when the translation invariance is broken by the insertion of a blockage which is induced by a car accident on the first lane. Using the computer simulation, it is found that the dynamical jamming transions occur successively from the phase 1, through the phase 2, to the phase 3 with increasing the density of cars. The phase 1 is characterized by the property such that no cars exist in the first lane and the cars on the second lane move with the maximal velocity. The phase 2 is characterized by the shock formation (a discontinuity of density) and the maximal current. In the phase 3, the discontinuity disappears and the traffic flow is not affected by the car accident.