Traffic behavior near an off ramp in the cellular automaton traffic model.

In this paper, we investigate the off-ramp system on the highway using the cellular automaton traffic model. Both the system without an exit lane (case 1) and that with an exit lane (case 2) are considered. The phase diagram and its variation with L(D) (the length of exit lane in case 2 and the length of a special lane-changing section in case 1) is studied. Two phase regions are found in case 1 and a new phase, i.e., the maximum flux phase, is reported in case 2. The density (velocity) distribution near the off ramp and the influence of L(D) on the traffic flow are also discussed in both cases.