Merging preparation behavior of drivers: How they choose and approach their merge positions at a congested weaving area

Vehicle merging is a tactical process. In the existing merging models, drivers need to select a target gap and adjust their speed to reach a comfortable merge position to execute lane changing. However, such sequential premerging preparation process has not yet been well-captured on the basis of the field trajectory data. In this study, the authors will focus on analyzing the lane-changing behavior as drivers choose and approach their merge positions at congested merging areas. This study is based on noise-filtered computer-based trajectory data. The authors classify the observed merging vehicles in a congested weaving section into original-gap-targeting (OGT) and forward-gaptargeting (FGT) vehicles. The analysis of the merge-position selection indicates different selection behavior between OGTand FGT merging vehicles. The length of target gap, the speed, and the route plan of vehicles surrounding the merging vehicles have an influence on their merge-position selection. To investigate merge tactics of merging vehicles, their speed synchronization and acceleration behaviors when approaching their merge positions were analyzed. The results illustrate that the acceleration and deceleration behaviors of the FGT merging vehicles in the approaching process should be split into two distinct stages: acceleration to overtake the rejected gap and deceleration to execute speed synchronization. The findings from this study shed light on the complex lane-changing process at merging areas.