Comparison of Child Restraint System (CRS) Installation Methods and Misuse During Far-Side Impact Sled Testing 2023-01-0817

Child occupants have not been studied in far-side impacts as thoroughly as frontal or near side crash modes. The objective is to determine whether the installation method of child restraint systems (CRS) affects far-side crash performance. Twenty far-side impact sled tests were conducted with rear-facing (RF) CRS, forward-facing (FF) CRS, high-back boosters, and belt only. Each was installed on second row captain’s chairs from a recent model year minivan. Common CRS installation errors were tested, including using the seat belt in Emergency Locking Mode (ELR) instead of Automatic Locking Mode (ALR), not attaching the top tether, and using both the lower anchors (LA) and seat belt together. Correct installations were also tested as a baseline comparison. Q3s and Hybrid III 6-year-old (6yo) anthropomorphic test devices (ATDs) were used. Lateral displacements of the CRS and head were examined as well as injury metrics in the head, spine, and torso.

For RF CRS, the ELR belt installation resulted in a 91 mm (15%) increase in lateral head displacement compared to ALR belt, along with slight decreases in most other injury metrics. Results were similar between installations with LA only and LA + ALR belt together. For FF CRS, the ELR belt condition showed increased lateral CRS displacement compared to ALR belt: +66 mm (9%) without top tether, +93 mm (12%) with top tether. However, head displacements were similar between conditions (approximately 1% difference). Using the top tether decreased head displacements by 12 to 42 mm (2% to 7%, depending on installation method), which is a priority for children since head injuries due to head contact are the most frequent type of injury. Using the top tether slightly increased head injury criterion (HIC36) and neck loads compared to tests without tether. Booster displacement was less for boosters installed with LA and/or top tether compared to belt only installations, but head displacements were similar (<3% difference) regardless of booster installation method. The presence of side wings did not affect peak head displacement but HIC36 was lower in the booster with large side wings compared to the no-wing booster.