I am proud to be among the research leaders in the U.S. who have contributed to the 33% drop in pediatric fatalities since 2004 to children under age 10. Some of this improvement may stem from one of my earliest research projects that suggested children should use booster seats until they are 4’10”[1], which has been included as a threshold in many state laws since then. In addition, the paper based on my dissertation research to estimate infant head injury tolerance and impact response[2] is one of my most cited works (n=122). Much of my recent research related to child passenger safety has concentrated on improving child restraint and vehicle compatibility, developing tools and procedures to allow more realistic testing of child restraint products, and analyzing crash data to identify how resources can be directed to make additional improvements. To disseminate our findings, I have presented our research results at national conferences and at state-level trainings for child passenger safety technicians on 21 occasions. Our website, cpsbestpractice.org, also shares the results of recent research by providing rationale for best practice recommendations for child passenger safety.
[1]Klinich KD, Pritz HB, Beebe MS, Welty KA (1994) Survey of Older Children in Automotive Restraints and Booster Seats. Technical Paper 94222. SAE Transactions: Journal of Passenger Cars-Mechanical Systems, Vol. 103.
[2] Klinich KD, Hulbert GM, Schneider LW (2002) Estimating infant head injury criteria and impact response using crash reconstruction and finite element modeling. Technical Paper 2002-22-0009. Stapp Car Crash Journal: 46:165-194
Several studies used measurement of the vehicle fleet, development of procedures and tools, and testing with volunteers to improve child restraint and vehicle compatibility. A series of research projects identified vehicle features related to the usability of the LATCH (lower anchors and tethers for children) system used to secure child restraints in vehicles. This work is the basis for IIHS vehicle vehicle ratings on LATCH usability and a NHTSA proposed rulemaking on the topic.
Other projects in this area have led to the development of fit envelopes to increase compatibility between child restraints and vehicles. Adapting a model used by the International Standards Organization, if a child restraint system fits in an envelope, and the envelope fits in a vehicle, the child restraint and vehicle should be compatible. The project analyzed the shape of a range of recent child restraint models and documented their installed position in ten late model vehicles. Size envelopes representing the installed position of small, medium, and large rear-facing and forward-facing child restraints have been developed and are now available for vehicle and child restraint manufacturers' use. Another vehicle/child restraint compatibility project used volunteer testing to evaluate new seatbelt designs that could reduce the chance for injurious seatbelt entanglement by occupants while still allowing safe installation of child restraints.
I led analysis of national datasets and child passenger safety (CPS) laws in each state to develop a rating system for CPS laws, identify how laws effect child restraint use, and improve understanding of factors contributing to pediatric injury in crashes. Laws whose language aligns more closely with best practice recommendations lead to higher rates of children using the recommended type of restraint. The injury analysis indicated that children under age 10 have a 30 to 55% reduction in injury risk if they are using optimal rather than suboptimal restraints.
The 2014 upgrade to FMVSS No. 213 includes seating procedures and injury criteria for use in evaluating belt-positioning booster seats that were developed at UMTRI. The new procedures seat the ATD in a manner closer to that selected by child volunteers of similar sizes; the belt tension is also now set to a more realistic level. These changes will allow booster seat designs to be assessed in a more realistic condition that is closer to how they are used in vehicles. Other research projects have continued to develop improved procedures for evaluating child restraints. One study developed procedures for appropriately testing rear-facing restraints with higher weight limits, which have been included in a proposed upgrade to federal test procedures for child restraint testing. To improve assessment of belt-positioning booster performance, our team designed a surrogate seatbelt retractor fixture and procedures to allow more realistic testing, and we have proposed candidate measures that better differentiate the performance of booster models.
Another study identified how different types of misuse affect child restraint performance. This work supported the best practices recommendation to keep children rear-facing as long as possible, because installations errors degrade performance of forward-facing child restraints substantially more than rear-facing child restraints. The study also reinforced the benefits of tether use, because it mitigates the effects of other child restraint installation errors.
FMVSS No. 213 primarily focuses on dynamic testing requirements and labeling specifications. Fit of children within child restraints is generally limited to accommodating 12MO, 3YO, and 6YO ATDs; manufacturers also check child restraint dimensions against key anthropometry measures collected in the 1970s. To provide another tool for assessing fit of different sized children within a particular child restraint, data collected on the size, shape, and posture of child occupants have been incorporated into digital pediatric anthropometry models that can be used to design child restraint system features (humanshape.org).
This study used computer models to study how unconventional seating positions and orientations in vehicles with automated driving system (ADS) may affect occupant response metrics for harness-restrained children and vehicle belt-restrained children. We first conducted a literature review to frame a simulation plan, including selections of surrogate ADS-equipped vehicles, potential seating arrangements, impact scenarios, ATD models, and child restraint system (CRS) models that are relevant to the selected ATD occupant models. Due to the lack the impact tests with child ATD and CRS in farside, oblique, and rear impacts, we conducted 16 sled tests with CRS harness-restrained ATDs and vehicle belt-restrained ATDs seated in conventional and unconventional vehicle seat orientations in frontal, farside, oblique, and rear impact conditions, and use the sled tests to validate a set of computational models. A total of 550 MADYMO simulations was then conducted with CRABI 12MO in rear-facing CRS, H33YO ATD in both rear-facing and forward-facing CRS, H36YO in a backless booster and H310YO with and without a booster across a range of conventional and unconventional seating locations and orientations under five impact directions and various CRS installation methods. We did not find major safety concerns in harness-restrained ATDs based on the nature of ATD contacts, although some injury measures are over injury assessment reference values. CRS may rotate laterally in farside and oblique impacts, which could result in higher HIC and chest acceleration due to inertia loading to the CRS, and there is a risk that the larger lateral rotation of the CRS my lead to a contact between CRS and vehicle interior. The major safety concern for vehicle belt-restraint ATDs is that they have the potential to contact the seat next to them or the instrument panel behind them in a farside or oblique impact. Unconventional seating does not necessarily create additional safety concerns beyond what we know with the conventional seating. However, due to the orientation of the unconventional seats, they may involve in higher percentage of oblique and rear-oblique impacts than the conventional seats, which should be considered in future design process. This is the first study using different child ATDs and CRSs to investigate child occupant responses in a wide range of impact directions and seating orientations. Results from the sled tests and simulations provide a better understanding of child occupant responses in those crash conditions, but also identified several limitations of using frontal ATDs in other crash directions.