Preston L. Schiller brought a background in sociology and anthropology and work in medical education and public health to issues of air pollution and transportation in the late 1980s, as well as being the author of many research reports and journal articles. He has worked on these at national, state and local levels with several NGOs, including the Sierra Club, as well as serving on numerous government advisory task forces and committees. His career in sustainable transportation began by walking at age one, cycling at age five, and navigating transit solo around Chicago at age 11. Jeffrey R. Kenworthy is a Professor in Sustainable Cities at Curtin University in Perth, Western Australia, additionally holding guest positions at the Frankfurt University of Applied Sciences in Germany and the K2 Swedish Knowledge Centre for Public Transport in Lund. He has almost 40 years of experience in the transport and urban planning field, specializing in international comparisons of cities, and has published extensively on a wide range of urban topics.