Optimizing Traffic Flow on Highway with Three Consecutive On-ramps

In this paper, we study traffic flow on a highway with three consecutive on-ramps by using the Nagel-Schreckenberg model, which is a generalization of our previous work concerning with highway with two ramps. We still focus on how to improve the system capacity by assigning traffic demand to the three ramps. It is shown that when all ramps are in free flow and the main road upstream of the ramps is in congestion, assigning a highest proportion of the demand to the upstream on-ramp, and lowest proportion of the demand to the downstream on-ramp could improve the overall flow. This is explained through studying the spatiotemporal patterns and analytical investigations. The conclusion could be generalized to highway with more on-ramps, i.e., the more downstream an on-ramp is, the lower the traffic demand should be assigned.