A Comparison of the Performance of Dedicated Child Restraint Attachment Systems (ISOFIX)

Problems with the current methods of attaching child restraints to the vehicle structure have led to the development of new attachment systems. These proposals have been coordinated by the International Standards Organisation (ISO) with the intention of generating an international standard system for the attachment of child restraints - ISOFIX. These proposals attempt to balance the requirements for good dynamic performance in impacts with the requirements for ease of use, low misuse and the cost and complexity of the child restraint and of incorporating the system into the vehicle design. This research programme was designed to compare the dynamic performance of a range of systems and how they would be used by parents. Prototype child restraints designed to four different schemes being proposed for ISOFIX were produced based on a single design of child seat shell. These were subject to frontal, side and rear impacts. Various degrees of slack were introduced into the systems to determine the sensitivity to misuse. In addition, a small user trial was undertaken to determine the user reaction to the different systems and likely misuse modes. Both the dynamic tests and the user trials included a conventional child restraint using the same child seat shell for comparison. The results demonstrated that all systems could perform well, particularly in the frontal impact tests, provided that any adjustment in the attachment system was pulled tight. However, some systems were particularly sensitive to slack. Overall, those systems with rigid attachments performed best, particularly in side impacts. These were favoured also by the user group.