By law every Australian child <7 years travelling in a motor vehicle must use an age-appropriate child restraint. However, the benefit of using an age appropriate restraint is severely compromised if the restraint is used incorrectly. Children who incorrectly use restraints are at a 3 fold risk of injury in a crash¹. In 2008 we conducted a population-referenced observation study and estimated that 53% of children in NSW were incorrectly restrained. There is a need to repeat this observation study to allow more current population estimates.

Our previous research indicated variations in error rates with different restraint designs² but the specific design features associated with the lowest propensity for incorrect use remains unknown. Furthermore, our recent research³ suggests ergonomic features impacting a child in a restraint are likely to be essential to maintaining correct use through a journey, but this has not been studied. The most important ergonomic features for correct use therefore remain unknown.

The aim of this study is (i) to determine restraint features associated with the lowest propensity for errors and (ii) to obtain up-to-date population estimates of errors in restraint use. We will achieve these aims through an observational analysis of children in cars to examine how restraint design features influence usage errors in a population representative sample.