For over a decade he has researched bicycle transportation planning and policy in North America and Western European countries. His research seeks to advance the understanding of determinants of bicycling and to identify and share policy lessons on how to achieve a more environmentally sound, economically efficient, and socially equitable urban transport system. Ralph is co-editor of the book City Cycling (MIT Press, 2012) and author or co-author of over 35 peer-reviewed journal articles in journals such as Transportation, Transport Policy, Transport Reviews, American Journal of Preventive Medicine, American Journal of Public Health, and International Planning Studies. Currently Ralph serves as chair of the Committee on Bicycle Transportation for the Transportation Research Board of the National Academies.