Gap-Acceptance Behavior of Motorcyclists at Roundabout Approaches in Khon Kaen University

Abstract

Modern roundabouts are effective intersection control measures, especially for homogeneous lane-based traffic. However, Thailand’s roundabout operates with heterogeneous traffic environments. Sharing the road with larger vehicles, smaller motorcycles are not forced by roundabout geometry and exhibit non-lane-based movements, which increases the conflict risk at roundabouts. Consequently, it is essential to comprehend the gap-acceptance behavior of these non-lane-based vehicles. Therefore, the objectives of this study are to identify the critical gap and factors affecting gap-acceptance behavior of motorcyclists. This study examined rider behavior at fourteen roundabout approaches at four roundabouts at Khon Kaen University. Unmanned aerial vehicles (UAVs) were used to video the movement of traffic. 813 data on gap acceptance were extracted. Raff's method was used to calculate the critical gap. A binary-logistic regression analysis was used to determine the variables influencing the motorcyclist's gap acceptance. According to the study's findings, the critical gap value was 2.63 seconds. Factors influencing the increase in gap-acceptance include larger gap sizes, the driver who chooses to enter the roundabout on the far side of the splitter islands and chooses to keep left in the circulating roadways, bigger island, and wider radius of deflections. While the factors influencing the decrease in gap acceptance are the presence of the pillion passengers and in the case of the rear car in the gap being a car. This research could contribute to the design and development of safer roundabouts that operate in non-lane-based traffic environments.