Authors: Yue Liu, Gang-Len Chang, Ruihua Tao, Thomas Hicks, and Eric Tabacek
Journal: Transportation Research Record, In press (presented in Transportation Research Board 86th Annual Meeting, January, 2007)
In this paper the author presents the results of our empirical study on the distribution of dilemma zones for different groups of drivers at signalized intersections. Using a specially designed video-based system, this study has conducted extensive field observations of 1123 drivers’ responses to a yellow phase at six intersections of high accident frequency, including all critical data such as the speed evolution during the yellow phase, the acceleration/deceleration rates, and the approximate reaction time to an encountered yellow phase. Our empirical results have revealed that the dilemma zone is dynamic in nature with its location varying with the driving populations, and the commonly used practice of extending the yellow phase duration recommended may not eliminate all the dilemma zones.Two types of strategies which can effectively eliminate the dynamic dilemma zones are also designed to improve intersection safety.