Traffic Bottlenecks: Identification and Solutions

Hale, David; Jagannathan, Ramanujan; Xyntarakis, Michalis; Su, Peng; Jiang, Ximiao; Ma, Jiaqi; Hu, Jia; Krause, Cory · 2016 · ROSA P / United States. Federal Highway Administration. Office of Operations Research and Development

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Summary

This report addresses the critical problem of recurring traffic congestion in the United States, identifying bottlenecks as the primary cause of mobility delays, environmental harm, and economic loss. Motivated by the inadequacy of traditional peak-hour analyses and the high cost of infrastructure expansion, the study aims to develop practical, data-driven methods for prioritizing bottlenecks and implementing low-cost, operations-focused mitigation strategies. The research seeks to update outdated congestion management approaches by introducing new identification tools and a comprehensive playbook of mitigation techniques that require minimal infrastructure investment. The methodology involved the development of a data-driven Congestion and Bottleneck Identification (CBI) software tool featuring new performance measures, including the Bottleneck Intensity Index (BII) and Annual Reliability Matrix (ARM), to precisely quantify and rank bottlenecks. To evaluate mitigation strategies, the researchers conducted extensive traffic simulations and benefit-cost (B/C) analyses. The study focused on five low-cost operational strategies: dynamic lane grouping (DLG), dynamic merge control (DMC), modest extension of auxiliary lanes, hard shoulder running (HSR), and reducing lane widths to add new lanes. Additionally, the report introduces three innovative strategies: dynamic HSR, dynamic reversible left-turn (DRLT) lanes, and contraflow left-turn (CLT) pockets. These were assessed through case studies, sensitivity analyses, and preliminary design guidance for signing, signalization, and striping. The findings demonstrate that the identified low-cost strategies produce favorable benefit-cost ratios with only minor modifications to existing infrastructure. The CBI tool successfully provided robust, quantitative rankings of bottlenecks, overcoming the limitations of judgment-based assessments. Simulation results indicated that underrated strategies, such as DMC and DLG, offered significant operational benefits comparable to or exceeding those of extensively researched methods like ramp metering. Specifically, the study found that dynamic lane use and reversible lane configurations could significantly reduce vehicle delay and improve throughput at signalized interchanges and freeway merges. The benefit-cost analyses confirmed that these operations-focused solutions yield substantial monetary savings through reduced travel time and emissions, validating their economic viability. The significance of this work lies in its provision of a practical, evidence-based framework for transportation practitioners to prioritize and mitigate bottlenecks without excessive capital expenditure. By introducing a new playbook of 70 mitigation strategies and validating specific low-cost operations solutions, the report offers immediate, actionable guidance for improving traffic flow. The development of the CBI tool and new performance measures enhances the scientific rigor of bottleneck identification, allowing for more accurate investment decisions. Ultimately, the study shifts the focus from expensive infrastructure expansion to efficient, data-driven operational management, offering a sustainable path to reducing congestion and its associated societal costs.

Key finding

Low-cost bottleneck mitigation strategies such as dynamic lane use, hard shoulder running, and lane width reduction produced favorable benefit-cost ratios with only minor modifications to existing infrastructure.

Methodology

modeling

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• traffic density
• perceptual countermeasures
• speed management
• work zones