Analysis of Motorcycle Crashes on Interstate 65 in Kentucky: Case Studies of Bowling Green, Elizabethtown, and Louisville

This study conducts geometric and operational variable investigation to analyze motorcycle-related crashes on Interstate 65 (I-65) in Kentucky using three large metropolitan cities as case studies. These are the Cities of Louisville, Bowling Green, and Elizabethtown. Five-year motorcycle crashes (from 2014 to 2018), exported from the Kentucky State Police Collision Database, were used in the analysis. Rarely-explored roadway geometric and operational variables (collected using Google Maps) were used in the motorcycle crash investigation, such as: left shoulder width, lane width, number of lanes, median type, median width, and crash distance to the nearest on/off ramp. The analysis showed that the majority of motorcycle-related crashes (71%) occurred in Louisville. Most crashes occurred on I-65 roadway segments with fewer numbers of lanes (i.e., one to three lanes), narrower lane widths (10 to 12 feet), and wider medians (>14 ft) divided by concrete barriers. Overall, lower motorcycle injury percentage (63%) occurred at distances less than or equal to 1,145 ft (about 0.22 mi) from the on/off ramp, as opposed to distances greater than 1,145 ft (76%). A high motorcycle injury percentage (95%) occurred on wider lanes (>12 ft), as opposed to narrower lanes (10–12 ft), mostly due to speeding. In multiple-vehicle crashes between motorcycle(s) and other vehicle(s), motorcyclists suffered the most severe crash injuries, as opposed to the other involved vehicle drivers. The factors that were determined to significantly affect motorcyclists’ crash injury severity based on the chi-square test of independence were: helmet use, season of the year, weather conditions, lighting conditions, lane width, number of lanes, median width, crash distance to the nearest on/off ramp, and motorcyclist pre-collision action. The Z-test of proportions showed significant motorcycle crash proportion difference between Louisville and Elizabethtown concerning divided concrete barrier median types (65.3% in Louisville versus 22.2% in Elizabethtown). Some safety recommendations included increased helmet use for all motorcyclists, increased educational programs on motorcycle safety for both motorcyclists and vehicle drivers, and the possibility of dedicating a separate travel lane for motorcyclists on those high-crash risk segments on I-65.