This proceedings, ""Traffic and Transportation Studies"", consists of papers presented at the First International Conference on Transportation and Traffic Studies, ICTTS '98, held at the Northern Jiaotong University in Beijing, China, from July 27-29, 1998. The technical areas covered in the papers include transportation planning, traffic operations and optimization, railway transportation management, highway management systems, and transportation policies. The papers are arranged based on these four themes in transportation: Transportation Policy and Management, Transportation Planning and Optimization, Transport Design and Appraisal, and Applications of New Technologies.