This book is a collection of original peer-reviewed papers presented at the 2025 3rd International Conference on SmartRail, Traffic and Transportation Engineering, which is organized by Fujian University of Technology and Beijing Jiaotong University, and held on October 31-November 2, 2025, in Pingtan Island, China. It delves into key areas of transportation engineering, including Intelligent Transportation, Cooperative Control, Intelligent Rail Transit, Transportation Organization, Advanced Rail Vehicle-Track-Bridge Systems, AI and Big Data Applications in Transportation, Optimization and Control in Intelligent Networks as well as Green and Sustainable Transportation Systems. The book provides valuable insights into the latest advancements and trends in transportation engineering and technology, with a particular emphasis on smart and sustainable transportation. As a comprehensive resource, it serves as an essential reference for professionals, researchers, and students working in the field of transportation engineering and related disciplines.