Abstract
Urban sprawl along arterial road is a common phenomenon in Bangkok. This pattern of urban growth has resulted in uncontrolled access to the arterial road. The most common way to handle the traffic changing to the opposite direction of the road is to provide median openings, which adversely affects road capacity. This study is aimed to investigate the effects of u-turn traffic on road capacity and lane utilization. Video cameras were used to record the traffic data of a median opening on a major arterial in Bangkok.
Regression analysis indicated that at the median opening, capacity of the middle lane is approximately equivalent to 1,680 pcu/h. while the observed capacity is 1,896 pcu/h. It is found that share of traffic in the middle lane remains almost unchanged at above 50 percent throughout the study road section. PCEs for motorcycle, passenger car and truck making u-turn movement are also estimated.
