Empirical Observation of Maximum Throughput Change in Isolated Merging Bottlenecks Depending on On-Ramp Traffic Flow Ratio

초록

In a traffic flow, once congestion is initiated, the throughput to the downstream of the bottleneck tends to decrease from the maximum throughput in the free-flow state. It is known that the maximum throughput in the free-flow state varies according to the traffic conditions for the same study site. If we can correctly forecast the maximum throughput depending on the traffic conditions, traffic congestion can be prevented or mitigated through ramp-metering. In this study, the relationship between the maximum throughput and the on-ramp ratio is analyzed. It turns out that maximum throughput of each study site has different values with the change of on-ramp ratio and there exists a convex quadratic-polynomial relationship between them. The elasticity of the maximum throughput to the on-ramp ratio is influenced by the geometric highway design and operation factors. The results of this study confirm that the on-ramp ratio control can effectively minimize the capacity drop and prevent traffic congestion.

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