Effect of U-Turns and Heavy Vehicles on the Saturation Flow Rates of Left-Turn Lanes at Signalized Intersections

Abdelrahman Abuhijleh, Charitha Dias, Wael Alhajyaseen and Deepti Muley
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Abdelrahman Abuhijleh: Qatar Transportation and Traffic Safety Center, College of Engineering, Qatar University, Doha 2713, Qatar
Charitha Dias: Qatar Transportation and Traffic Safety Center, College of Engineering, Qatar University, Doha 2713, Qatar
Wael Alhajyaseen: Qatar Transportation and Traffic Safety Center, College of Engineering, Qatar University, Doha 2713, Qatar
Deepti Muley: Qatar Transportation and Traffic Safety Center, College of Engineering, Qatar University, Doha 2713, Qatar

Sustainability, 2020, vol. 12, issue 11, 1-14

Abstract: The Saturation Flow Rate (SFR) is a primary measure that can be used when estimating intersection capacity. Further, the efficiency of signal control parameters also depends on the accuracy of assumed SFR values. Driver behavior, type of movement, vehicle type, intersection layout, and other factors may have a significant impact on the saturation flow rate. Thus, it is expected that driving environments that have heterogeneous driver populations with different driving habits and cultures may have different SFRs. In practice, the proposed SFRs based on US standards (Highway Capacity Manual, 2016) have been adopted in the State of Qatar without validation or calibration to consider the local road environment and the characteristics of the driving population. This study aims to empirically analyze the saturation flow rates for exclusive left-turn lanes and shared left- and U-turn lanes at two signalized intersections in Doha city, while considering the effects of heavy vehicles and U-turn maneuvers. Empirical observations revealed that the average base SFR, i.e., when the influences from heavy vehicles and U-turns were excluded, could vary approximately from 1800 vehicles per hour per lane (vphpl) to 2100 vphpl for exclusive left-turning lanes and approximately from 1800 vphpl to 1900 vphpl for shared left- and U-turning lanes. Furthermore, this study proposed different adjustment factors for heavy vehicle and U-turn percentages which can be applied in practice in designing signalized intersections, particularly in the State of Qatar.

Keywords: saturation flow rate; signalized intersections; exclusive left-turning lanes; shared lanes; u-turns (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
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