Belted driver fatalities in frontal crashes in 2017-2023 CISS

The study analyzed lap-shoulder belted driver fatalities in frontal crashes over 7 years (2017-2023) and evaluated the usefulness of NHTSA's 90 km/h oblique OMDB (offset moving deformable barrier) crash test to bring about meaningful reductions in fatalities.

NHTSA online database of CISS (Crash Investigation Sampling System) crashes was searched for driver fatalities in frontal crashes (0 deg PDOF) with delta V ≥ 48 km/h (30 mph). Each case was downloaded and summarized for: 1) vehicle make, model and year and crash damage, 2) the road type, weather and lighting conditions, 3) the pre-crash maneuvers and type of frontal damage, 4) driver demographics, alcohol-drug use and number of occupants in the vehicle, 5) restraint performance, steering system damage and intrusion and 6) the injury severity, body region, type and source.

There were 16 driver fatalities with known lap-shoulder belt use in 2017-2023 CISS. The seatbelt wearing rate was 30.8%. The vehicles were 12.2 ± 7.3 years old with 68.8% ≥10 years old. The delta V was 72.2 ± 15.6 km/h (44.8 ± 9.7 mph) with 101.4 ± 30.5 cm of maximum frontal crush. Most (68.8%) of the crashes occurred on 2-lane roads. The crashes clustered into: 1) near-center impacts with a tree or pole (31.3%), 2) small overlap impacts with another vehicle (31.3%), 3) full width frontal impacts (25%) and 4) oblique or offset impacts with frame engagement (12.5%). The drivers were 61.5 ± 15.5 years old. Many were obese (61.5%). Most (68.8%) were alone in the vehicle. Four used alcohol (25%), two were also positive for drug use. Most drivers (57.1%) had severe chest injuries MAIS 4-6 with multiple rib fractures, some with heart and aorta lacerations. The most common injury source (61.5%) was the shoulder belt and steering wheel. In many cases (62.5%), the steering wheel was deformed and/or the column was displaced. The upper body kinetic energy was 8,698 ± 4,178 J in the fatal crashes.

The drivers were typically alone, obese and older. Most vehicles were older; they typically moved left (75%) into an oncoming vehicle or off road hitting a tree or pole. The combination of collision severity and driver BMI pulled webbing from the load-limiting retractor (when equipped), compressed the airbag and deformed the steering wheel resulting in severe chest injuries (85.7%). The restraints allowed too much excursion into the steering system to protect the drivers. NHTSA's 90 km/h oblique OMDB test involves 4,516 ± 535 J of upper body energy and 57.6 ± 6.8 cm crush. It is not severe enough to bring about meaningful changes in vehicle structures or restraints. A 113 km/h OMDB impact has upper body energy consistent with the fatal crashes, but further testing is needed to determine if a higher speed OMDB test is useful. A 72 km/h (45 mph) sled test with the 95^th or 82 km/h (51 mph) with the 50^th dummy would be useful because it has upper body kinetic energy to bring about meaningful design changes to reduce driver fatalities.