| dc.description.abstract | Many state agencies consider exclusive truck facilities to be an alternative to
handle the safety and operational issues due to the increasing truck volumes. No such
facilities exist, and there are no standard tools or procedures for measuring safety
performance of an exclusive truck facility. This thesis aims at identifying factors that
affect truck crashes, whose results could be used for better designing exclusive truck
facilities. To accomplish the objectives of this thesis, five years’ roadway and crash data
for Texas was collected to develop a comprehensive crash database. Negative binomial
regression models were used to establish a relationship between truck crashes and various
environmental, geometric and traffic variables. Separate models were developed for
truck-related (involving at least one truck and another vehicle), truck-only (two trucks or
more) and single-truck crashes. The results suggested that the percentage of trucks in
Average Annual Daily Traffic (AADT), classification of the roadway (Rural/Urban),
posted speed limit, surface condition, alignment and shoulder width are associated with
truck crashes. It was observed that truck-related and truck-only crashes decreased as the
percentage of trucks increased on freeway facilities. Based on conclusions derived from
the literature review and statistical analyses, straight segments with wider shoulders and
uniform grades are recommended for exclusive truck facilities. It is also recommended to
provide ramps, horizontal and vertical curvature and signing based on truck size, driver
eye height, braking ability and maneuverability. These models were developed using
mixed-flow traffic data to understand the association of various factors with truck
crashes. These models should not be used directly to estimate or predict truck crashes.
Further analysis with more detailed data under different flow conditions might help in
quantifying the safety performance of exclusive truck facilities. | en |
