Scenario-based operational evaluation of Median U-Turn intersections across traffic demand levels.

Abstract

This paper presents a microscopic simulation modeling of 30 signalized intersections in Riyadh, using detailed datasets on direction traffic volume, lane configurations, and current signal control structure. Six distinct Median U-Turn scenarios were developed, categorized by longitudinal offset from the intersection center ranging from 120-300 meters. These configurations were closely evaluated against the conventional signalized intersection for operational viability. Simulations were executed within PTV VISSIM for both the baseline signalized control and the six MUT alternatives, resulting in more than 3,000 simulation runs to ensure statistical soundness in extracting travel time, delay, and queue length metrics. The final results indicate that the MUT design outperforms the conventional signalized intersection at total entering volumes (TEV) of 4,000 vehicles per hour (vph) or less. Within this range, the results identify optimal offsets of 150m for moderate volumes, 180-210m for high directional splits, and 250-300m for high-intensity demands (>1,200 vph). While MUT designs excel below 4,000 vph, the conventional four-leg signalized intersections consistently emerge as the superior design once this total volume threshold is exceeded.