Abstract:Transportation agencies rely on scientific information to design and site infrastructure, plan operations, and make policies. However, the ways in which science interfaces with transportation policy are not straightforward: political incentives, usability challenges, implementation failures, and capacity limitations all shape how public organizations use scientific information. To build stronger connections between transportation-relevant science and policy it is necessary to better understand current patterns of scientific information use in practice, particularly as transportation agencies address an expanding purview of policy issues, such as climate change mitigation and intelligent transportation systems. This paper measures science use observed in transportation planning and project documents such as plans, proposals, impact assessments, and other deliverables that agencies are required to produce as part of the policy process. Using state, regional, and county transportation agencies in the state of California as a focal sample, this paper applies automated natural language processing (NLP) tools to analyze documents and identify references to scientific information. Our sample includes 5080 documents from 59 organizations involved in transportation governance in the state of California. We observe that the transportation science-policy interface is a cyclical system in which public agencies act in varying (and simultaneous) capacities as consumers, producers, funders, and brokers of scientific information. For instance, documents produced by state-level entities draw more heavily on academic literature, while regional and county-level agencies rely most heavily on reports produced internally by state agencies and by state-funded research institutes. Understanding where different transportation agencies access scientific information, and how scientific information flows between entities at different levels of government, can help researchers and science-policy boundary organizations increase the uptake of scientific products and design interventions to improve information access and use.