Browsing by Author "Ambelu, Worku"
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Item Factors Affecting Saturation Flow at Signalized Intersections in Addis Ababa(Addis Ababa University, 2011-01) Ambelu, Worku; GlYohannes, Emmanuel (PhD)This study was conducted to identify factors affecting saturation flow at signalized intersections in Addis Ababa. Secondary data collected using headway method, synchronous method and asynchronous method were used for the analysis. The data consisted of headways, number and type of vehicles, number of lanes in an approach, approach grade, green time length of a signal, lane width, number of pedestrians crossing vehicle flows, and percentage of large buses that made vehicle flows in a lane (as derivative information). Lane wise saturation flows were determined using headway ratio method, synchronous regression method and asynchronous reg ression method. Passenger car equivalents for each class of vehicles were also estimated. The saturation flow estimated from the th ree methods was regressed on the independent variables. Based on the coefficient of determination, synchronous regression method was found to have better explanatory power. Slope of an approach and number of pedestrians crossing vehicle flows were found to be significant factors affecting saturation flow of veh icles at signalized intersections when the synchronous method was applied to estimate saturation flows. Therefore, attention should be paid to approach grade while designing new road intersections and modifying existing ones and pedestrians should be given sufficient awareness so that they do not disrupt traffic flow during green phase of traffic signal.