  This paper focuses on the study of the impact that the class of the vehicle,
leading heavy vehicles in particular, causes on the following vehicle's
behavior, specifically in terms of the bumper-to-bumper distance (gap) between
the following and leading vehicles. This was done by extracting and analyzing
different car-following episodes from the Next Generation Simulation (NGSIM)
dataset for Interstate 80 (I 80) in Emeryville, California, USA. The results of
the statistical analysis are compared to that of the synthesized literature of
research efforts that have been conducted on the topic, then are further
assessed utilizing different behavioral clusters for the Gazis-Herman-Rothery
(GHR) car-following model calibrated from naturalistic driving data. We assess
the similarities and differences in car-following behavior between drivers of
the same vehicle class, validating the results of the statistical analysis and
highlighting possible future implementations for improved modeling in
microscopic simulation.
