Transporting children with additional needs is challenging because of the range of physical and cognitive impairments, anthropometry, occupant safety, regulations and usability. Not only does the child restraint system (CRS) need to protect the child in a crash but the carer must also be able to assist the child in and out of the seat. In Australia CRS, except those for children with additional needs, must meet AS/NZS 1754. Unlike, European and USA standards, AS/NZS 1754 has a dynamic side impact test. The objective of the paper is to report on the results of dynamic impact tests conducted on a range of CRS for children with additional needs and identify opportunities for improving the crash performance. A secondary objective was to assess the strength requirements of the top tether anchorage point.

Nine CRS models designed for children with additional needs were tested in front and side dynamic impact tests at the NSW Roads and Maritime Services Crashlab. The tests were conducted according to AS/NZS 1754 specifications. The CRS models were not subjected to full certification or compliance tests. A rebound sled was used and the CRS models were tested with a 36 kg, P10 series Anthropomorphic Test Device (ATD). The frontal impact sled pulse was Δv = 49 km/h with acceleration 24-34 g and side impact was Δv = 32 km/h with acceleration 14-20 g. Head and chest resultant acceleration were measured as well as seatbelt and tether forces. CRS models performed relatively well in frontal impacts:​ peak resultant head accelerations were less than 150 g. In side impacts the average peak headform acceleration across all models was 272 g and the average peak chest acceleration was 178 g, largely because of the lack of ATD restraint and side wings. Those impacts were severe and if they occurred in a real crash would lead to significant head, brain and chest injury. In one test the estimated upper anchorage reached over 10 kN, which is greater than the anchorage strength requirement. There were some breakages or failures of seat and belt components in the tests. Alternative systems to a tether strap for mounting the seat were found to be successful. CRS for children with additional needs performed well in frontal impacts, which reflects the certification of these models to either USA or European standards. The ATD head invariably struck the door panel in the side impact test. The results identified that the CRS models can accommodate and function in frontal tests with the 36 kg crash test dummy, or child, but their performance for heavier occupants is unknown. Further testing with heavier ATDs and a variety of seated postures would be informative. Suitably biofidelic ATDs and child specific injury assessment reference values are study limitations. Dynamic testing of the CRS models was informative in terms of both policy and practice. Improving impact performance and occupant safety is a demanding proposition when the operational context of these systems is considered.