Evaluating operational efficiency of split merge, diverge, and weaving solutions for reducing freeway bottleneck congestion

The speeds of traffic and freeway throughputs at the merge, diverge, and weaving areas are reduced significantly due to vehicle lane changes and increased traffic volumes. This study proposes a solution, referred to as split design (i.e. split merge, diverge, and weaving). The key concept is to make geometric changes to the existing ramp designs to create two merge or diverge points, such that potential conflicts of the mainline and ramp traffic can be distributed apart spatially. This potentially decreases unnecessary interactions between the mainline and ramp vehicles. This study also uses microscopic traffic simulation to assess operational efficiency of the proposed alternative geometric design; and to develop managerial insights for state DOTs to better design, enhance, and manage their freeway systems in the future. We find that, overall, the split design can potentially increase throughput by 6% to 9% and reduce delay by 35% to 80% across different scenarios.