This proceedings consists of 91 peer-reviewed papers presented at the fourth international conference on traffic and transportation studies,held at Dalian of China from August 2 to 4,2004.The papers discuss transportation planning and modeling,information systems,infrastructure and advanced applications.Three tracks of sessions were scheduled for the paper presentations based on the following topics in transportation:transport policy,environment and sustainability,transport planning and operational optimization,traffic flow models with applications,traffic demand management,mass transit systems,physical distribution and logistics,transportation issues in developing countries.