01126600

Component

The increased use of left-forbidden management at signalized intersections has significantly resulted in U-turn movements in urban roadways. To reduce the safety concerns due to such U-turn measures, signal systems specifically for U-turn control are installed and operated at many median openings and intersections. However, some uncertainties exist in the characteristics of U-turn movements in terms of headway distributions and capacity of U-turn lane. This paper presents a study of U-turn discharge headway and capacity of the U-turn opening lane using the data that were collected with exclusive lane and protected phasing at six median openings and intersections in the City of Kunming, a big city in southwest area of China. The results indicate that the U-turn discharge headways grouped by queuing vehicle position follow the logarithmic normal distribution, and the saturation headways can be measured from the eighth queuing vehicle. In addition, turning radius and gender have insignificantly impact on the U-turn saturation headway. The discharge headway and capacity of U-turn lane are compared with through and left-turn lane. Finally, control delay are calculated by the methods by Design Regulations for At-grade Intersections on Urban Street (DRI), Highway Capacity Manual (HCM, 2000 version) and the U-turn software developed by the authors. The U-turn software produces more accurate control delay estimates compared to the results from DRI and HCM, using the real-world observed data.

01120148

09-2550

English

17p

2009

Transportation Research Board 88th Annual Meeting

DVD

Figures; Photos; References (9) ; Tables (8)

Headways; Highway capacity; Highway design; Operations; Signalized intersections; Traffic flow; Traffic queuing; Turning radius; U turns

Highway Capacity Manual

Kunming (China)

Highways; Operations and Traffic Management; I73: Traffic Control

Transportation Research Board Annual Meeting 2009 Paper #09-2550

TRIS, TRB

Jan 30 2009 6:54PM