The a case study of Sukhumvit area, Bangkok, Thailand Chu, Cong Minh creator Sano, Kazushi Chairperson Yordphol Tanaboriboon Chairperson Park, Dong Joo Examination Committee Government of Japan Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 2002 continuing eng 65 leaves Traffic congestion is one of major problems in big cities. The way to relieve traffic congestion includes expanding the capacity, improving transit service, amending traffic control, etc. This research proposes a solution to reduce traffic congestion in urban road network, especially in Sukhumvit area - Bangkok - Thailand. One model has been modified to estimate an OD matrix from traffic counts. The model based on the information of link use probabilities from link travel time by using multi-path assignment. The model uses the link traffic volume to estimate the OD matrix consistent with the link volume available. Thus, one program based on this model has been developed and applied to achieve OD demand with the traffic data in Sukhumvit road network. The traffic simulation model TRAF- NETSIM is used to simulate the traffic condition in Sukhumvit area. The improvement of traffic condition is discussed by changing traffic policies. Three approaches are introduced in this research: changing one-way roads to twoway roads, constructing two new roads and changing one-way roads to two-way roads accompany with constructing one new road. The research indicated that after conducting third approach, average travel time would be reduced (10.15 %), average speed would be increased (11.55%) and it is the best one in comparison among three approaches. A research study submitted in partial fulfillment of the requirement for the degree of Master of Engineering, School of Civil Engineering Special Studies Project Report (M.Eng.) - Asian Institute of Technology, 2002 Traffic congestion Simulation methods Thailand Bangkok Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B08050 http://203.159.5.9/ait-thesis/detail.php?q=B08050 021115 20260818112900.0