Modeling Driver Behavior and Safety on Freeway Merging Areas

Abstract

Access to freeways is provided through interchanges to maintain the design concept of uninterrupted traffic flow. Therefore, provision of an appropriate entrance ramp and acceleration lane geometry that allows the entering vehicle to accelerate to a speed closer to the through lane speed is important for comfortable and safe merging maneuvers. In this paper, speed and traffic data were collected from 23 merging sites on Highway 417 located within the City of Ottawa, Canada, to study the traffic behavior at freeway merge areas. Analysis of traffic behavior showed that merging speed depends on both ramp and speed-change lane (SCL) geometrics. Lower merging speed was shown to be associated with higher collisions on the acceleration lanes. Right lane traffic volume and merging speed of entering vehicles were shown to significantly affect right lane speed along the acceleration lane. In addition, several statistically significant models were developed for the prediction of 85th percentile passenger car right lane speed, merging speed, merging distance, and acceleration on the SCL. A safety performance model was also developed to relate the total number of collisions on the acceleration SCL to the features of the merge area including the merging speed.