A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1991

Intersection capacity is based on saturation flow rate. In reality, the saturation flow rate changes considerably on such road and traffic conditions s uch as the geometry of intersections number of right-turn vehicles, number of left-turn vehicles, number of heavy vehicles in the traffic stream and etc . Therefore, in principle the saturation flow rate should be determined base on the actual measurement at the concerned intersections. In this study , the saturation flow rates of straight- ahead and unopposed right-turning movements were surveyed. The ef feet of trucks was also evaluated. Saturation flow rates and PCEs determined by different methods were then compared. New approach for PCEs and saturation flow rates were developed and tested. Theoretically, the PCEs depend on the truck's position in the queue, but for practical work, the difference can be ignored. Right turn movement is equivalent to straight-ahead movement for passenger cars. The average headways of straight- ahead movement obtained for Phahonyothin - Pradiphat, Ratcahwithi - Rama VI and Rangsit are 1.91 , 1.86 and 2.16 respectively . PCE for trucks of right turning is larger than that of straight- ahead movement . PCEs of straight- ahead movement and right turn movement obtained in this study for Rangsit intersection were 1.53 and 1.68 respectively .