Rear-facing child safety seat performance in frontal NCAP level crashes

Whitman, Gary R.; Hart, III, Arlie V.; Sicher, Larry; Benda, Brian; D’Aulerio, Louis A.

Affiliations

Abstract

Objective: To study the performance of Rear-Facing Child Safety Seats (RFCSS) when installed in the center- rear occupant position of vehicles involved in New Car Assessment Program (NCAP) severity level frontal crashes, the authors conducted a series of simulated frontal crash tests using a horizontal accelerator.

Method: The authors conducted two series of simulated frontal crash tests using a horizontal accelerator (sled facility) to assess RFCSSs of different designs. The first used a free-standing bench seat, the second used a sled buck constructed from a small domestic SUV. The tests included infant-only (with and without a base) and convertible CSSs, untethered and tethered.

Results and Data Sources: Without a tether, the RFCSSs experienced severe forward translation and forward and downward rotation. This kinematic resulted in the RFCSSs impacting the front-center console, and the infant dummy experiencing very high head accelerations and Head Injury Criteria (HIC) values, indicating a high risk of serious head injury. The use of a tether, with one end attached to the top portion of the CSS’s seat back and the other attached to structure behind the CSS’s occupant position, resulted in a significant reduction of the forward and downward rotation of the RFCSS. This prevented impact with the front seats and center console, and resulted in a significant reduction in peak head acceleration and HIC values.

Discussion and Limitations: RFCSSs are very effective in providing crash protection to young children in frontal crashes. Particularly in Europe and Australia, where RFCSS are often prevented from rotating by various devices, including: tethers, floor supports, rigid attachment, and/or by positioning the RFCSS against the vehicle’s interior. Without these devices, RFCSS can rotate forward and downward significantly during a frontal crash. The amount of rotation depends upon the quality of the RFCSS installation and the geometry of the vehicle interior. The rotation and translation of the RFCSS may result in it impacting the vehicle interior, and/or allow the infant to slide up the RFCSS seat back, increasing the potential for head impact. The Federal Motor Vehicle Safety Standard 213 requires that RFCSSs limit their seat back rotation to 70 degrees from vertical when tested in a 48 kph (30 mph) delta-V simulated frontal crash. Real-world crashes are often more severe. This is why adult restraint systems are assessed in the NCAP frontal crash testing at a delta-V of 56 kph (35 mph). The National Highway Traffic and Safety Administration currently includes CSSs in the rear outboard occupant positions of vehicles tested in the NCAP. However, the public is often advised to install CSSs in the center-rear occupant position where head impact risks are different than at the outboard positions.

This study was limited to frontal crashes. Additional testing in other crash directions is needed to identify the potential benefits of anti-rotation devices in those crash scenarios.

Conclusions/Relevance: The use of anti-rotation devices with RFCSSs significantly increases the crash protection provided infants during frontal crashes.

Links

URL: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv23/23ESV-000010.pdf

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