The World Academy of Science, Engineering and Technology (WASET) organised the ICTTP 2018: 20th International Conference on Traffic and Transportation Psychology on 22-23 October 2018, in Bali, Indonesia. The Conference aimed to bring together leading academic scientists, researchers and research scholars to exchange and share their experiences and research results on all aspects of Traffic and Transportation Psychology. It also provided a premier interdisciplinary platform for researchers, practitioners and educators to present and discuss the most recent innovations, trends, and concerns as well as practical challenges encountered and solutions adopted in the fields of Traffic and Transportation Psychology. ICTTP 2018 has teamed up with the Special Journal Issue on Traffic and Transportation Psychology.