Effects of Short Exit Lane on Gap-Acceptance and Merging Behavior of Drivers Turning Right at Unconventional T-Junctions

Abstract

The right turn from minor road at a three-legged or T-junction with stop control is a critical movement as it needs to yield to four other movements on the major road. This study aims to investigate and compare the effects of short exit lane and merging behavior of vehicles turning right at unconventional T-junction with conventional T-junction. Field studies were conducted at three types of T-junctions to study the gap acceptance of vehicles turning right and the merging behavior of vehicles turning right with vehicles on the major road using pneumatic road tubes and video camera. The results indicated that the critical gap and follow-up times for T-junctions with exit lanes decreases by 16% and 10%, respectively. Additionally, the average speed of vehicles turning right with a short exit lane is approximately 30 km/h. Findings also show that 22.1% of vehicles on the major road reduce their speed more than 5 km/h when interacting with right-turning vehicles at T-junction with a short right-turn exit lane. Conversely, up to 55.4% of vehicles reduce their speed by 5 km/h or more when interacting with vehicles turning right at T-junction with a short through exit lane. These findings proved that the presence of a short right-turn exit lane at T-junction can reduce the conflict between right-turn movement from the minor road with through movement of the major road. Therefore, outcomes from this study are important as they can contribute to improving the design approach of unsignalized intersections.