P. Liu, F. Hu, JJ. Lu
This study analyzed the operational effects of a widely used access management treatment: using U-turns at downstream signalized intersections as an alternative to direct left-turns. Data were collected on eight selected roadway segments in the Tampa Bay area in Florida. A total of more than 300 hours of traffic data were collected. Regression models were developed based on the collected field data to quantitatively evaluate the operational impacts of U-turns and left-turns. Delay models provided a tool to help address public concerns related to the operational impacts of U-turns and would be particularly helpful in identifying the circumstances in which vehicles making right turns followed by U-turns (RTUT) will have less delay and travel time than those making direct left-turns (DLT). Additionally, a ratio model was developed to estimate how many drivers would like to make a RTUT instead of a DLT under specific traffic volume levels and roadway geometric conditions. The findings of this study are helpful in providing local and state transportation agencies with recommendations for the design and selection of median treatments on six to eight lanes urban or suburban arterials.
Keywords: U-turn; left-turn; signalized intersection; delay