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The performance advantage of seat belt pretensioners is well documented. But what is the effect for child restraints? We tested four categories of CRS with and without seat belt pretensioners on adult seat belts, using the ECE44.03 dynamic test. We compared outcomes in terms of head excursion, head and chest deceleration and HIC (“Head Injury Criterion”) and used a common type of pyrotechnic pretensioner. For infant restraints, pretensioned conditions lead to a reduction in head excursion and HIC. Two forward facing toddler seats showed lower HIC, and one a large reduction in excursion. Pretensioning led to reductions in HIC for forward facing impact shield boosters and for belt positioning boosters. Three CRS were also tested in a pre-impact braking mode, with and without pretensioner. Here the differences were less pronounced. On the whole, pretensioners did improve the outcome for CRS, in particular for designs which did less well in the “normal” mode.

The performance of child restraint systems (CRS) in precise and constant laboratory testing and their effectiveness in real-life-accidents may differ substantially, mainly due to the variety of interface conditions between motor vehicles and CRS and to misuse of the CRS by the consumer. These differences may grossly impair the safety performance of CRS in a traffic crash. Most accident reports available to crash researchers lack detailed data on crash severity that can be related to injury severity. However, reports usually include full information on injuries of all occupants. The paper proposes a comparison of the injury rate of restrained children and belted adult occupants, the latter “substituting” the unknown data on crash seventy. Given a sufficient number of accident reports, the effectiveness of CRS under real-life-conditions can be assessed, providing a very useful tool, particularly for CRS manufacturers.

This study compares a sample of approximately 900 real-life accidents with dynamic tests using a fully instrumented TNO P 3 dummy, in order to describe the effect of varying degrees of pre-impact braking. Altered test conditions, in particular the forward shift of seat belt anchorage points, are evaluated. It is concluded that pre-impact braking has little effect on horizontal head excursion and chest deceleration. Pre-impact braking does however reduce neck loads, resultant head deceleration and HIC. Reducing the excessive head excursion observed in vehicles with extreme forward anchorages may well require replacing automotive seat belts with a new interface for child restraints.

Based upon the given state of art, general requirements and additional safety criteria for booster cushion systems are established. Applying the safety criteria, the performance and its limitations of a typical booster cushion is investigated by means of an extensive test program. For this purpose a variety of different shoulder point positions is considered. The results obtained from this study lead to design criteria. Systems designed to these criteria should be capable of fulfilling all the requirements established.

The paper describes the positive effect on the convenience of child safety systems by using adult seat belts. It shows how manufacturers of child safety systems in West Germany have gradually switched from supplying specially fitted belt systems to using rear seat adult seat belts. On the basis of accident reports collected over a period of 10 years, the overall performance of an impact shield design, which is using adult seat belts, is investigated and asked, whether additional ease of use or convenience compromises safety. Among other parameters, the head excursion criteria of the specific impact shield system is highlighted. Finally, dynamic sled testing, simulating the effect of additional belt slack and various lower anchor point locations is described.