Shortage of Commercial Vehicle Parking and Truck-Related Interstate Ramp Crashes in Tennessee

Abstract

Interstate ramps are the location of more crashes per mile than any other segment of interstate, yet commercial vehicle (CMV) drivers are often left with the last option of parking along these segments for off-duty rest to meet federal hours-of-service regulations. Past literature has evaluated the shortage of CMV parking facilities and examined characteristics of freeway ramp crashes. However, relatively little research has studied the influence of CMV parking deficiency on crash frequency involving parked CMVs along the ramps. This study examined 179 police-reported illegally parked CMV-involved crashes on 1,221 rural and urban ramps in the State of Tennessee, United States. Three Bayesian binary logit models using varying prior distributions were used to analyze the odds of a CMV crash occurring based on CMV parking shortage and ramp attributes. The results illustrated the higher frequency crashes (N = 4 or 5) occurred on entrance ramps of shorter length and often were adjacent to public parking facilities. Approximately one-third of the collisions on interchange ramps had a parking facility utilization rate of 90% or higher, and 23 ramps (15.8%) were adjacent to parking facilities that were at or over-capacity. Several ramp characteristics were significantly associated with an increase in the occurrence of an illegally parked CMV-involved crash and include the presence of a parking facility on exit, ramps with illegally parked CMVs, diamond-shaped ramp configurations, larger ramp shoulder widths, and exit ramps. This study illustrates the impact of the CMV parking shortage on the safety of ramps and highlights the need for more parking facilities.