Abstract
This paper studied driver behavior on freeway entrance ramp terminals using trip data from the SHRP-2 Naturalistic Driving Study (NDS) database from two different US states. The study included a qualitative assessment of driver speed behavior as drivers navigate the ramp and speed change lane (SCL). A trend of continuous vehicle acceleration was evident from the beginning of the ramp controlling curve that continued after merging onto the freeway right lane (FRL). It also was found that a portion of drivers tended to merge onto the FRL on the taper after the SCL had ended; this behavior was dominant on the taper-type SCL. It was shown that the speed and acceleration behavior of drivers differed on the different sites, indicating that it depends on the complete set of geometric characteristics at the site. Linear-mixed models were developed for the speed and acceleration measures and for lead, lag, total accepted merging gaps to account for the repeated measures caused by repeated trips by the same drivers.