Guidelines for Offsetting Opposing Left-Turn Lanes on Divided Roadways

Offsetting opposing left-turn lanes at intersections has been found to improve the driving performance of older drivers. Previously recommended guidelines for offsetting opposing left-turn lanes were based on observations of left-turning vehicles for only one offset condition. The guidelines developed in the present research are based on left-turning vehicle positioning and maneuver-time data collected at intersections with left-turn lane offsets of from –4.3 to 1.8 m (–14 to 6 ft). A 1.2-m (4-ft) offset was found to provide unrestricted sight distances in most situations.