The Transportation Research Board (TRB), part of the National Academies of Sciences, Engineering, and Medicine, promotes innovation and progress in transportation through research. In an objective and interdisciplinary setting, TRB facilitates the sharing of information on transportation practice and policy by researchers and practitioners; stimulates research and offers research management services that promote technical excellence; provide expert advice on transportation policy and programs; and disseminates research results broadly and encouraged their implementation. The National Academies are private, nonprofit institutions that provide expert advice on some of the most pressing challenges facing the nation and the world. TRB is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. TRB was established in 1920 as the National Advisory Board on Highway Research to provide a mechanism for the exchange of information and research results about highway technology.