Modeling Driver Behavior at Freeway-Ramp Merges

Freeway-ramp merging segments are important components of freeway facilities. The composite behavior of acceleration and gap acceptance of the merging traffic as well as the cooperative behavior of the freeway traffic can result in conflicts and trigger congestion. The goal of this research was to develop a ramp-merging model that considered the merging process as perceived by drivers and to investigate the contribution of individual drivers' merging behavior to the breakdown event. Focus group meetings were conducted, and drivers' merging behavior was observed in in-vehicle experiments. The data were used to develop a gap-acceptance model under different merging conditions and a model of driver behavior that predicted vehicle interactions on the freeway with merging vehicles, considering different driver types. A merging turbulence model that evaluated the effect of vehicle interactions on traffic flow also is presented. Study findings can be used to refine existing micro-simulation models, realistically replicate freeway flow breakdown, and provide insight into the triggers of the breakdown of freeway flow.