GAO Examines Potential Variables for New Highway Funding Formulas
The U.S. Government Accountability Office (GAO) released a report in May 2025 titled "Highway Funding: Information on Variables for Potential New Formula Grant Programs" (GAO-25-107097), which responds to a Congressional request to identify variables that could be used to design new federal highway formula grant programs. The study arrives as Congress considers future surface transportation authorizations, building on the over $300 billion already distributed under the Infrastructure Investment and Jobs Act (IIJA) for fiscal years 2022 through 2026.
The GAO conducted interviews and surveys with 31 entities, including Tribes, state departments of transportation, metropolitan planning organizations (MPOs), and stakeholders with transportation policy expertise. Of the 96 total variables suggested through this process, 27 received broad support from at least three-quarters of respondents. These variables predominantly relate to four potential program types: infrastructure condition, freight movement and economic vitality, highway safety, and system reliability. Examples of widely supported variables include total lane miles, vehicle miles traveled, bridge conditions, truck travel reliability, and injury and fatality rates per population or per vehicle miles traveled.
While survey participants showed support for these specific variables, they expressed more hesitation toward creating entirely new highway formula programs. Many state DOTs preferred providing greater flexibility in the use of existing funds rather than navigating new eligibility requirements and administrative hurdles. Concerns were also raised about potential negative incentives—such as rewarding jurisdictions with deteriorating infrastructure—or fluctuations in funding caused by changing variables like population or traffic patterns.
GAO also evaluated whether existing federal datasets could support these proposed variables. Encouragingly, 22 of the 27 supported variables already have measurable federal data sources, primarily maintained by the Department of Transportation (DOT) through its Highway Statistics Series and Transportation Performance Management program. For the remaining five, data limitations stem from privacy concerns or lack of a statutory mandate for collection. Notably, FHWA plans to expand data collection for some variables, such as bridge deck area and seismic vulnerability, beginning in 2026.
However, federal agencies reported data gaps for several variables that received less support. For instance, neither DOT nor EPA currently aggregate certain air quality data at the state level, and no agency collects standardized national data on sidewalk mileage or project delivery delays. Still, GAO found that creative use of rolling averages or baseline funding guarantees could help mitigate volatility and equity concerns in any future formula design.
This report contributes meaningfully to ongoing discussions about how the federal government should structure and modernize transportation funding in ways that align with national goals—such as safety, economic competitiveness, and system resilience—while balancing local control and predictable project planning. Credit for the report goes to Elizabeth Repko, Director of Physical Infrastructure at GAO, and her team.
Disclaimer:
This blog post is for informational purposes only and is not guaranteed to be accurate. It does not constitute legal advice. For the official report, visit GAO-25-107097.
