A research study submitted in partial fulfillment of the requirements for the degree of Master Engineering, School of Civil Engineering

Research Studies Project Report (M. Eng.) - Asian Institute of Technology, 2001

There are many under-standard highways in Thailand. The highway geometric design was not used to design and build those highways. When civilization came into those regions, the existing highways were still used for traveling and transportation. Many problems occurred in particular traffic accidents because of drivers who are not familiar with those highways. The accidents are much more serious when they occurred in mountainous area. This research selected one of the most dangerous highways in Thailand, "Highway No. 323 Thongphaphum District to Sangklaburi District {STA 64+500 to STA 67+000). This highway section can be classed into under-standard and high risk of accident highway because from STA 65+000 to STA 66+500 (1.5 kilometers) is a steep grade downhill with average gradient of 12% (the maximum gradient was more than 20%). At the bottom of this steep grade downhill is a break-elbow-curve locally known as "the Fatal Curve". Many vehicles such as buses, lost control resulted to various severe accidents and those accidents caused many deaths. This research proposed solutions to improve the existing highway to be the conceptual standard highway by using highway geometric design techniques and road safety audit approach. Project cost is also developed to show feasibility of the recommended improvement of this highway section