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.

在业务流中，一旦引发拥塞，到瓶颈下游的吞吐量就会从自由流状态下的最大吞吐量降低。已知在自由流动状态下的最大吞吐量根据同一研究地点的交通状况而变化。如果我们能够根据交通状况正确预测最大吞吐量，则可以通过斜率计量来防止或缓解交通拥堵。在这项研究中，分析了最大吞吐量和匝数比之间的关系。结果表明，随着入口匝数比的变化，每个研究站点的最大吞吐量具有不同的值，并且它们之间存在凸的二次多项式关系。最大通行率对匝道比的弹性受高速公路几何设计和运营因素的影响。这项研究的结果证实，匝道比率控制可以有效地减少容量下降并防止交通拥堵。