Submarining Protection for 50th-Percentile Male Anthropomorphic Test Devices in the Rear Seat during Frontal Crash Sled Tests

While historically the rear seat has been considered safer than the front seat, recent studies have suggested that adult occupants have a higher relative risk of injury and death in the rear seat compared to the front seat. Advancements in safety technologies in the front seat have outpaced those in the rear seat, where they vary greatly between vehicle makes and models. Of particular concern is occupant submarining, for which the lap belt slips off of the pelvis and directly loads the abdomen. In this study, frontal crash sled tests with seven vehicle bucks were conducted to assess submarining protection for two rear-seated 50th-percentile male anthropomorphic test devices (ATDs), the Hybrid III-50M and THOR-50M. Tests involved either a ΔV of 56 kph or 32 kph. Submarining incidence and severity for the Hybrid III and THOR were assessed using post-test photographs, high-speed videos, and seat belt loads. Abdominal pressure (using the ABdominal Injury and SUbmarining Prediction [ABISUP] prototype abdomen) and anterior superior iliac spine (ASIS) forces and moments were also used in the submarining assessment for the THOR. Twenty-four tests were conducted including three repeated tests. The Hybrid III did not submarine in any test, but the THOR submarined in 16 of 24 tests (in 5 of 7 vehicles). Submarining occurred in 3 out of 4 vehicles having conventional restraints and 2 out of 3 vehicles having advanced restraints. The results indicate that the Hybrid III-50M and THOR-50M have different submarining responses. Additionally, advanced restraints alone will not mitigate submarining, but other factors in seat, restraint, and vehicle design also contribute to submarining protection in the rear seat.