Development of a Comprehensive Roadmap for Traffic Congestion Reduction

Abstract: Congestion has become a critical issue across the United States, disrupting transportation networks and impacting society in multiple ways. Its effects extend beyond traffic delays, adversely affecting public health, quality of life, and the environment. Between 2000 and 2019, national travel delays surged from 5.1 billion to 8.7 billion hours, while fuel consumption due to congestion rose from 2.4 billion to 3.5 billion gallons. During the same period, greenhouse gas emissions increased from 25 million to 36 million tons, and the economic cost of congestion more than doubled, climbing from $77 billion to $190 billion. Congestion in freight movement alone accounted for an increase in costs from $7 billion to $20 billion.

Although these figures temporarily declined in 2020 due to COVID-19 lockdowns, recent data show a resurgence in post-pandemic congestion. The severity of congestion varies by roadway type, geographic region, and time of day, with cities and metropolitan areas experiencing the greatest impacts. While many studies have addressed congestion, a comprehensive, integrated roadmap to mitigate it, leveraging emerging technologies and multifaceted approaches, has yet to be developed.

This study, sponsored by the National Institute for Congestion Reduction, aims to fill that gap by creating a strategic roadmap for congestion reduction. The roadmap highlights key and emerging mitigation strategies from prior research, offering a practical guide for practitioners, researchers, students, and policymakers involved in addressing this issue. It also serves as a decision-making tool for evaluating congestion-reduction strategies, infrastructure investments, policy improvements, and sustainable transportation.

To develop this roadmap, the research team conducted an extensive literature review and interviewed experts in the field. Through this process, successful case studies and lessons learned were identified to inform the roadmap’s structure. A total of 14 distinct congestion mitigation strategies were analyzed, with their effectiveness varying by metropolitan area size and expected implementation timeline. The full benefits of advanced and emerging technologies are projected to be realized over the long term. A rating system was applied to identify the most effective strategies based on area size and timeline, enabling targeted and efficient congestion reduction efforts.

The findings from this project provide a significant contribution to addressing the nation's congestion crisis by offering a clear, evidence-based framework for action. The roadmap integrates existing research and successful case studies, while also serving as a forward-looking guide for implementing advanced technologies. This ensures that stakeholders can make informed, impactful decisions to achieve both short- and long-term congestion relief. Given the far-reaching implications for urban mobility, environmental sustainability, and economic productivity, the project’s outcomes present a valuable opportunity for broad dissemination. Additionally, the roadmap has the potential to inspire collaboration, foster innovation, and help shape future transportation policies.