Poster P14 - Analysis of Injuries Sustained During Frontal Collisions at Low and Moderate Speeds

Introduction: In 2021, 32.1% of frontal motor vehicle collisions resulted in injured occupants [1]. Previous studies have indicated that the change in vehicle velocity (∆V) is a significant predictor of occupant injury severity, which is commonly assessed using the Abbreviated Injury Scale (AIS) to classify injuries according to anatomical structure and severity [2]. Research classifying injury severity according to ∆V has primarily targeted specific body regions in low-speed frontal collisions [3]. Furthermore, studies assessing multiple body regions have either not addressed the effects of both low and higher ∆V ranges on injury severity, or have solely investigated higher ∆Vs above 15km/h [4]. With respect to the most recent crash data available, there is a lack of research analyzing adult occupant injury severities resulting from low to moderate ∆V frontal crashes involving multiple body regions. Analyzing low, medium, and high ∆Vs is essential because injuries to specific body regions and their severity can vary based on the vehicle’s ∆V. The purpose of this analysis was to systematically compare the region and severity of occupant injuries at two levels of vehicle ∆V (low: 0-24 km/h and medium: 25-56 km/h) in frontal impacts. This analysis provides injury biomechanists and traffic safety engineers with valuable information to identify typical body regions prone to injury and their corresponding severities within specified ∆V ranges.

Materials and

Methods: Data from the National Highway Traffic Safety Administration Crash Investigation Sampling System (CISS) for 2017 to 2022 were used for this analysis. Frontal collisions were filtered by selecting vehicles with a frontal general area of damage and a principal direction of force of 0°±10°. Vehicles were also restricted to sedans, compact utility vehicles, and large utility vehicles. Collisions were limited to non-rollover vehicle-to-vehicle single impact. Only injuries from belted occupants were considered. Crashes between two levels of ∆V were analyzed (0-24 km/h and 25-56 km/h). These cutoffs were chosen based on ∆V ranges commonly employed in previous low-speed crash tests and as well as in research involving the comparison of severe injury risks [3]. Crashes with documented injury severities between AIS value of 1 (minor injury) and 6 (fatal) were included. Injuries were weighted to account for the unequal selection probabilities in sampled CISS cases. The assessed injured body regions comprised of the head, face, neck, thorax, abdomen, spine, upper extremity, lower extremity, and external (skin).

Results, Conclusions, and Discussions: From a sample of 506 cases, weighted data from 2302 injuries was analyzed. For occupants involved in crashes between a ∆V of 0-24 km/h, 94.1% of the injuries sustained were AIS1, 5.2% were AIS2, and 0.7% had an AIS value of 3 or higher (AIS3+). Figure 1 depicts that AIS1 injuries to the upper extremities (34.9%), lower extremities (16.9%), and spine (12.4%) had the highest occurrence in this range. For occupants involved in crashes between a ∆V of 25-56 km/h, the predominant injuries were AIS1 (88.3%), followed by AIS2 (7.9%), and AIS3+ (3.8%). Figure 2 depicts that AIS1 injuries to lower extremities (26.1%), upper extremities (21.8%), and thorax (17.6%) had the highest occurrence in this range. Head and torso injuries were less prevalent compared to upper and lower extremity injuries, possibly due to the protective effect of airbags, which have decreased the severity of injuries to the head and torso [5]. Common mechanisms leading to upper and lower extremity injuries can include impacts from airbags, impacts against vehicle dashboards, and loading caused by 3-point seatbelts [6], [7]. Severe injury risk (AIS3+) increased with ∆V from 0.7% at low speeds to 3.8% in moderate speed impacts. The low occurrence of AIS3+ injuries could be attributed to the protective function of seatbelts and airbags [3], [4].

This analysis contributes to ongoing research comparing specific injuries resulting from vehicle crashes at various speeds. AIS1 injuries are most common in both low- and moderate-speed frontal impacts; the dominant regions of injury within these ∆V ranges are the lower and upper extremities. Understanding common body regions of injury can aid biomechanists and safety engineers in assessing and creating preventative measures to protect occupants during vehicle crashes within these specific ∆V ranges. Future work should include an analysis of injuries in high ∆V collisions compared with low- and moderate-speed collisions.

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