Effect of the Right Turning Movement to Road Urban Performance

Abstract

Although right turning movement frequency due to exiting-entering vehicles from or to the social-economic area, particularly located nearby an intersection, could influence travel delay and/or vehicle queuing but it has not been considered when determining both the roadway and intersection capacity and performance. Consequently, they may not describe the actual problems occurred there. Accordingly, this paper investigates it by describing risky situation occurred at two un-signalized intersections which consist of similar traffic and roadway situation. Effect of the right turning frequency to the degree of saturation, delay time and accident risk then was discussed. It was found that the level of side friction were in the low-level categories so that theoretically it does not affect the travel speed and/or degree of saturation. However, the obtained delay time was around 40 s so that it triggers riders to increase their approaching speed to avoid delay which in turn increases accident risk because at the same time the opposite riders insist on crossing the major stream with average critical gap acceptance of 20 m. This strongly indicates that the right turning movement should be considered when determining road performance, urban speed limit, and traffic impact analysis