Investigating Head-On Crash Severity Involving Commercial Motor Vehicles in Kentucky

This study examines various features affecting the severity associated with commercial motor vehicle (CMV, i.e., large truck and bus) head-on collisions on Kentucky highways. Recent five-year (2015–2019) crash data and variables rarely explored before (e.g., presence of centerline rumble strips, type of passing zone, and terrain type) were collected and prepared using Google Maps. A total of 378 CMV-related head-on collisions were analyzed. The generalized ordered probit (GOP) model was employed to identify the significant factors affecting the severity level resulting from CMV head-on collisions. The model allows the coefficients to vary across the injury severity categories for reliable parameter estimations. From the preliminary investigation, rolling terrains had the highest share of severe CMV head-on crashes (62% and 71% for multilane and two-lane roadways, respectively). The presence of centerline rumble strips could reduce severe crash outcomes along multilane and two-lane facilities. The GOP model identified various significant predictors of minor and severe injuries from CMV head-on crashes. Occupants wearing seatbelt were 39.3% less likely to sustain severe head-on crash injuries. From the roadway characteristics, presence of median cable and concrete barriers could significantly reduce the probability of severe head-on crash injuries, with median cables being more effective. With regard to the driver characteristics, drug impairment and speeding increased the risk of sustaining fatal/serious injuries by 39.5% and 26.4%, respectively. Necessary safety recommendations are proposed to reduce the severity of CMV head-on-related collisions. One example is installing median cable barriers along roadway stretches with a history of head-on CMV-related crashes.

State of the Art: Centerline Rumble Strips Usage in the United States

Centerline Rumble Strips (CLRS) are used to avoid cross-over roadway departures, making rural highways safer. The objectives of this study were to obtain nationwide, updated information about states’ policies and guidelines for utilization of CLRS and to provide a list of gaps in research along with good practices. Results indicate that 36 states reported the use of CLRS. The total CLRS approximate mileage is 11,333 miles. The predominant CLRS pattern is: milled, length 16”, width 7”, depth 0.5”, spacing 12”, continuous. This survey reported that 17 states have written policies or guidelines. A list of good practices used by the states is presented.

Evaluation of Football Shaped Rumble Strips Versus Rectangular Rumble Strips

Shoulder and centerline rumble strips have become predominantly used safety measures along American highways in almost all states and in Canadian provinces. Milled shoulder rumble strips are cut indentations along the shoulder of a highway to warn drivers with an audible and tactile alert if they start drifting off the road. Centerline rumble strips are similar, but are placed between lanes, usually on undivided two-way, two-lane highways, to warn drivers who may start drifting into oncoming traffic. Researchers at Kansas State University (KSU) have conducted research on a new football-shaped highway rumble strip designed by an independent firm in Kansas. Test strips were installed along a Kansas highway, and the KSU research team conducted several tests to evaluate the new football shaped rumble strip versus the rectangular rumble strip. The comparison consisted of water and debris collection, interior sound and vibration production, and the opinions of bicyclists.Based on the literature review, the limited tests performed, and the surveys conducted, it can be concluded that no significant difference was found between the two types of rumble strips.