As U.S. DOT and its state partners continue to make significant investments in transportation infrastructure, accurately assessing and forecasting the nation’s transportation needs has become more critical than ever. Decision-makers face complex questions: How much funding is necessary to maintain and improve roads, bridges, and transit systems? Where should investments be prioritized to achieve the greatest economic and safety benefits?

To support these vital questions, U.S. DOT continues to develop and refine advanced modeling tools that estimate the infrastructure requirements of the future. The U.S. DOT Volpe Center has provided data modeling expertise to U.S. DOT for decades, and performs economic, data, and policy analyses to support this important work. These efforts are central to ensuring federal investments are effective and aligned with national priorities.

At the core of this work are two interrelated projects: the Highway Economic Requirements System (HERS) and the Transit Economic Requirements Model (TERM). These models provide detailed forecasts of transportation infrastructure needs based on a range of economic, technical, and policy considerations. Their data and insights feed into U.S. DOT’s biennial Status of the Nation’s Highways, Bridges, and Transit: Conditions and Performance Report (C&P Report), a critical document that informs Congress and guides transportation policy and budgeting.

A U.S. DOT Volpe Center team applies state-of-the-art tools and methodologies to develop, maintain, and improve these models. They support data collection efforts, refine model parameters, and interpret the results within the context of federal funding statutes and future policy discussions. The U.S. DOT Volpe Center team’s work ensures the models remain robust, accurate, and relevant to current infrastructure challenges.

HERS, which has been in use since 1992, forecasts highway investment needs by combining detailed data on roadway segments with empirically validated engineering relationships and cost estimates. The model examines how different levels of investment influence outcomes such as congestion, pavement conditions, and roadway user costs.

Most recently, U.S. DOT Volpe Center experts supported the 26th edition of the C&P Report. The report, currently under review by U.S. DOT leadership before submission to Congress, demonstrates how targeted investment can improve road conditions and reduce congestion nationwide.

Similarly, TERM models transit asset conditions by assigning and forecasting “state of good repair” condition ratings on a scale from 1 to 5—where assets above 2.5 are considered in good repair. It captures aging, usage patterns, weather impacts, and maintenance practices to predict future deterioration and identify optimal timing for replacements or upgrades. Recently, the U.S DOT Volpe Center team supported the migration of TERM from an MS Access platform into an SQL/Python environment to enhance its flexibility and scalability. The model’s results contributed to the draft 26th edition of the C&P Report, with plans to use the model for future editions and more frequent reports of investment needs.

These modeling projects support U.S. DOT’s primary goal of strengthening infrastructure to enhance safety, efficiency, and economic growth. They align with the Secretary’s emphasis on applying economic principles to investment decision-making, ensuring federal funds are allocated in a cost-effective manner. The models help quantify infrastructure needs, prioritize investments, and evaluate the potential impacts of different funding scenarios—ultimately guiding policy decisions that sustain and advance America’s transportation network.

One significant finding from recent analyses highlights a $140.2 billion backlog in transit asset rehabilitation needs as of 2022—about 10 percent of transit assets by value—underscoring the scale of investment required to maintain system safety and reliability. For highways, increased spending levels correlate with improvements in pavement quality and reductions in congestion, demonstrating the tangible benefits of strategic investment.

Through complex economic, data-driven modeling, U.S. DOT is better equipped than ever to plan for future infrastructure needs. Supported by the U.S. DOT Volpe Center’s multidisciplinary expertise, these tools provide essential insights for policymakers striving to build a safer, more efficient, and resilient transportation system that meets the demands of a growing nation. This commitment to rigorous planning and analysis underscores the Department’s dedication to investing wisely in America’s transportation future.

About the U.S. DOT Volpe Center

Since 1970, the U.S. DOT Volpe Center has advanced transportation innovation for the public good, providing multimodal applied research, collaborating with federal, state, and industry partners, and multidisciplinary technical leadership and expertise to solve complex transportation challenges. Learn more at www.volpe.dot.gov.