Over the past decade or so of ESV/RSV activity it has been a priority to improve occupant protection in frontal impacts and there is evidently a need to continue research towards establishing maximum protection in this mode of impact.

In the ESV program we have seen developments aimed at making larger heavier cars more accommodating to the smaller lightweight cars in collision situations. We have also seen that there are big problems in reducing the aggressiveness of the larger heavier vehicles.

Future developments, particularly for lightweight cars, may therefore have to be based on the assumption that it is not always possible to achieve the ideal of little or no intrusion matched to a restraint system which ideally attenuates the vehicle deceleration.

In these circumstances there appears to be considerable merit in the concept that the occupant be held much more rigidly in the seating position by seat belts considerably stiffer than those currently used.

Recent tests using a typical 30 mph barrier crash pulse show that reduced injury levels and much reduced forward displacement to avoid or reduce the effects of secondary impact, are obtained when adopting this concept.

With a more severe pulse the latter advantages are retained and injury levels, though higher, are still below accepted tolerable levels.

Bearing in mind the fact that a high proportion of frontal impacts are assymetric, producing relatively lower deceleration values but with more intrusion, the overall trade-off would appear to favour the system with reduced forward displacement.