Road departure (RD) crashes are among the most severe crashes that can result in fatal or serious injuries, especially when involving large trucks. Most previous studies neglected to incorporate both roadside and median hazards into large-truck RD crash severity analysis. The objective of this study was to identify the significant factors affecting driver injury severity in single-vehicle RD crashes involving large trucks. A random-parameters ordered probit (RPOP) model was developed using extensive crash data collected on roadways in the state of Kentucky between 2015 and 2019. The RPOP model results showed that the effect of local roadways, the natural logarithm of annual average daily traffic (AADT), the presence of median concrete barriers, cable barrier-involved collisions, and dry surfaces were found to be random across the crash observations. The results also showed that older drivers, ejected drivers, and drivers trapped in their truck were more likely to sustain severe single-vehicle RD crashes. Other variables increasing the probability of driver injury severity have included rural areas, dry road surfaces, higher speed limits, single-unit truck types, principal arterials, overturning-consequences, truck fire occurrence, segments with median concrete barriers, and roadside fixed object strikes. On the other hand, wearing seatbelt, local roads and minor collectors, higher AADT, and hitting median cable barriers were associated with lower injury severities. Potential safety countermeasures from the study findings include installing median cable barriers and flattening steep roadside embankments along those roadway stretches with high history of RD large-truck-related crashes.

道路驶离（RD）撞车是最严重的撞车事故，可能导致致命或严重的伤害，尤其是涉及大型卡车时。以前的大多数研究都忽略了将路边危险和中位危险纳入大型卡车RD碰撞严重性分析中。这项研究的目的是确定在涉及大型卡车的单车RD碰撞中影响驾驶员伤害严重性的重要因素。使用2015年至2019年之间在肯塔基州道路上收集的大量崩溃数据，开发了随机参数有序概率（RPOP）模型。RPOP模型结果显示，局部道路的影响是年平均每日交通量的自然对数（ AADT），存在中层混凝土屏障，与电缆屏障有关的碰撞，在碰撞观察中发现干燥表面是随机的。结果还显示，年长的驾驶员，退路驾驶员和困在卡车中的驾驶员更有可能遭受严重的单车RD撞车事故。增加驾驶员受伤严重性可能性的其他变量包括农村地区，干燥的路面，较高的速度限制，单辆卡车的类型，主要动脉，倾覆后果，卡车起火，具有中间混凝土屏障的路段以及路边固定物体的撞击。另一方面，系好安全带，当地道路和较小的收集者，较高的AADT以及击中中间的电缆障碍物均与较低的伤害严重程度有关。