Head and Neck Loading Trends in IIHS Side Impact Testing

Low- to moderate speed side impacts occur with some frequency in the real world. Prior research into occupant responses in low- to moderate speed side impacts are sparse and have largely focused on evaluating responses of volunteers in low severity collisions or using Hybrid III Anthropomorphic Test Devices (ATDs) for comparison with volunteers and/or in moderate severity impacts. The objective of this study was to examine trends in head and neck loading during side impact testing in new vehicle models over the prior two decades. Data from 371 simulated side impact crash tests (model years 2002 to 2020) conducted as a part of the Insurance Institute for Highway Safety (IIHS) Vehicle Side Impact Crashworthiness Evaluation Protocol were obtained. This evaluation involved a stationary test vehicle struck on the driver side by a crash cart fitted with an IIHS deformable barrier element at an impact velocity of approximately 50 kph resulting in a change of velocity of approximately 24 kph (23.8 ± 3.7 kph) of the test vehicle. Instrumented 5th percentile female SID-IIs dummies were positioned in the driver seat and the left rear seat. Head injury criterion (HIC 15), maximum lateral bending (Mx) and compression (I-S force) were calculated for all tests to evaluate head and neck loading, respectively. Qualitative and quantitative comparisons were also made for the 22 paired optional side airbag tests. Trends in the test dummy responses were compared across model years and vehicle classes (passenger light trucks and vans versus cars). There appeared to be a decrease in biomechanical loading with model year for the head and neck metrics (HIC 15, lateral bending, and compression). There were also differences observed between driver and passenger metrics. It is noteworthy that all data points were well below published injury assessment reference values for all model years and vehicle types.