TITLE:
Operational Evaluation of a Compact 120 m Median U-Turn Offset: A Microsimulation Case Study of an Existing Urban Corridor
AUTHORS:
Abdulrahman Badwes
KEYWORDS:
Intersection Design, Median U-Turn, Traffic Delay, Level of Service, Offset Distance Optimization
JOURNAL NAME:
Journal of Transportation Technologies,
Vol.16 No.4,
August
17,
2026
ABSTRACT: As rapidly urbanizing cities face increasing car dependency, traditional intersections often reach saturation, necessitating unconventional geometric interventions. This study evaluates the operational efficiency of an unsignalized Median U-Turn (MUT) configuration, specifically investigating the impact of imbalanced offset distances on a high-volume urban corridor in Riyadh, Saudi Arabia. The research evaluates a compact 120 m crossover representing the lower bound of AASHTO recommendations against a conventional imbalanced configuration featuring offsets of 864 m for the Northbound approach and 1.37 km for the Southbound approach. Utilizing PTV Vissim microscopic simulation under a peak demand of 2,415 veh/hr, the methodology analyzes movement-specific dynamics through a 600 second analysis interval scaled to hourly performance. Findings demonstrate that the unsignalized MUT configuration with an imbalanced 120 m offset provides satisfactory operational performance, achieving a system-wide average delay of only 11.11 seconds per vehicle (LOS A). Critically, despite the high Southbound demand of 1,119 veh/hr, the maximum observed queue of 26.63 m utilized only 22.2% of the available 120 m storage length. These results empirically suggest that extreme distances of 864 m and 1.37 km are operationally redundant for this corridor. Implementing the compact 120 m MUT design reduces the additional travel distance for U-turning vehicles by up to 2.4 km per trip by replacing the existing long crossover configuration. The simulation results demonstrate that the proposed 120 m MUT operates efficiently under the observed traffic demand, providing evidence that a compact offset is operationally feasible while improving land-use efficiency without compromising operational stability.