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This study aims at determining, with the maximum precision, the performance of the 3 point safety belt in different accident configurations, and more particularly in frontal collisions. For this purpose, two matched samples were taken from a file of 3000 accidents, analysed by a multidisciplinary study group. These samples of 100 front seat occupants wearing seat belts, and 100 not wearing seat belts were made up in such a manner that, for every belted occupant, corresponds an occupant not wearing a belt, the one and the other being in equivalent circumstances, using the following factors: Make and type of the vehicle Seat occupied Age (as far as possible) Direction of impact Violence of the impact (same class of ▵V and mean γ) Possible intrusion of passenger compartment Possible overload caused by a rear seat occupant Using this method of comparison, one can appreciate the effectiveness of the 3 point belt and explain the variations of effectiveness that appear in normal case studies.

One studies the conditions in which occurred side impacts having led to death of 369 car occupants. This sample is representative of the population of fatal collisions having occurred on French roads, in 1980. 28 % of killed were victims of collisions against another private car, 34 % struck a fixed obstacle, 21 % undergone a collision against a truck. The other types of collisions account for 17%. The performances to be reached in order to spare an important number of victims are of a high level. This is measured in function of the distribution of impact violences and occupants' ages.

With drivers wearing 3-point seat belts, the head-steering-wheel impact occurs in most serious accidents, so inducing mainly face injuries. In a first part, the authors analyze the injuries observed in a sample of 1180 belted drivers involved in frontal collisions, making a distinction, mainly for facial impacts, between injuries related to the properly so-called face and those to the skull and brain and the different possible lesional correlations. In the second part are presented the results of work carried out in order to define a human face model adaptable to any type of Hybrid II or Hybrid III dummies' heads. The use of this model allows one to elaborate a new protection criterion for the face, destination of which should be to complete the head and skull protection criterion, such as the HIC (or another equivalent criterion which could possibly replace it).

Safety of children as car occupants raises a specific problem: it is necessary to take into account two factors which are particular to them: their very fast growth and their behavior, which corresponds to a need for movement. An analysis of statistical and accidentological data, points to the fact that whereas traffic accidents account for 25 % of adult deaths, they account for nearly 50 % of deaths for children (all kinds of road-users). Measures were adopted in France; such as the obligation for children of less than 10-years-old to travel on rear seats of cars and the definition of an homologation procedure for children restraint devices, with the aim of limiting the consequences of these accidents. The most common restraint devices look like little individual seats and are designed to protect young children (less than 3-years-old). Recently, new restraint devices, called “cushions”, were developed.

In 1344 car-to-car side collisions, the risk of serious or fatal injury to the occupants of struck vehicles seem to increase proportionally to the difference in mass ratios in favor of the striking vehicle. However, in-depth analysis of 63 collisions during which the impact occurred on the side panel of the passenger compartment reveals that the difference in mass ratios is not the principal determinant of injury severity. The frequency and severity of injuries correlates better with the amount of intrusion of the side panel, a type of intrusion which occurs almost systematically, and even at low impact speed, when the bumper and structure in front of the side rail of the striking car override the rocker panel of the struck car.

So far, analysis of real-world crashes has not made it possible to evaluate the occupant change of velocity in side impact. This change of velocity is the most pertinent of the lateral-collision violence parameters when occupants are exposed to intrusion by car bodies. The present paper describes a method for calculating this parameter, and includes a description of the data that must be collected concerning real-world crashes in order to enable its application. The validity of this method is demonstrated by its application to a series of experimental collisions. The results are highly correlated to the values resulting from the integration of the accelerations found for the pelvis and thorax. The method is then applied to 60 real-world car-to-car side collisions from the accident survey.

The data presented in this paper were yielded by tests performed on unembalmed human cadavers fitted with three-point seat belts and subjected to frontal collisions. The purpose is to define one or more functions predictive of thoracic injuries to cadavers whose rib “resistance” is known (i.e. BCF parameter (1)*). These functions predict the number of rib fractures and the thoracic AIS in terms of : anthropometrical data on the cadavers, data representative of the thoracic resistance of the cadavers and physical parameters arising from the deceleration pulses measured on the cadaver vertebrae during the occurrence of impact. By integrating the BCF data which characterize the ribs of the population exposed to the risk of thoracic injury, it is possible satisfactorily to define the tolerance of living road users, in terms of their age. Provided that maximum admissible injury level, and the age for which this limit is required are set, a tolerance criterion can then be defined.

A large number of experiments involving cadavers - including real-world-accident reconstructions - have been performed for the purpose of enhancing the state of knowledge concerning tolerance levels and protection criteria relevant to side-impact conditions. However, the scatter of the findings, as well as the considerable differences in injury severity levels (differences that cannot be accounted for by age differences alone) have limited the conclusions that it was possible to draw from these investigations in terms of criteria, mainly concerning thoracic protection. The major cause of scatter is the considerable differences in skeleton quality between subjects. Analysis of the rib characterization test findings made it possible to define a thoracic resistance index enabling the establishment of a classification of subjects. This index, which was validated with our sample, allowed us to evaluate the pertinence of the various side-impact protection criteria considered.

Accidentological studies show, firstly, what kind of injuries are sustained by seat-belt wearers in frontal collisions, to abdomen, lumbar spine and lower members and, second, how to determine their frequencies and severities. Corresponding data are presented. Then, a synthesis is made in which the results of extensive cadaver testing more than 300 human subjects-are examined with particular emphasis on the abdominal injuries, and on the association of injuries, such as lumbar spine injuries. Causation is particularly looked at. This experimental survey is completed by the results of specialized testing in abdominal tolerance when submarining occurs. These two surveys enable the development of protection. Finally, former attempts for defining an abdominal protection criterion are reviewed and a final definition for such a criterion is presented and justified.

Since July 1, 1973, the wearing of seat belts by front seat occupants is compulsory in France. This requirement is respected by 60 to 90% of motorists, depending on the type of road. If seat belts were not worn, a 55% increase in fatalities for front seat occupants would be observed. On the other hand, if seat belts were worn by occupants in all seats 100% of the time, fatalities would be reduced by another 30%. Improvements of the seat belt over the past ten years have had a significant influence in the following areas: - Incentives for wearing the belts - Limitation of belt stretch and spool-out - Reduction of the number of submarining cases. In this paper, emphasis is put on the levels of performance which no other sytem has been able to attain, or even equal, and which result in practically guaranteeing protection against the risk of ejection, especially in a side impact or rollover.

In France, as in other countries, accident research studies show that the greatest proportion of restrained occupants sustaining severe injuries and fatalities are involved in frontal impact (70% and 50% respectively). In severe frontal impacts with restraint occupants and where intrusion is not preponderant, the oldest occupants very often sustain severe thoracic injuries due to the seat belt. In the seventies, a few cars were equipped in France with load limiters and it was thereby possible to observe a relationship between the force applied and the occupant's age with regard to this thoracic risk. The reduction of intrusion for the most violent frontal impacts, through optimization of car deformation, usually translates into an increase in restraint forces and hence thoracic risks with a conventional retractor seat belt for a given impact violence.

This paper deals with frontal crash simulations with 3 point seat-belts, in which the conventional anthropomorphic test dummy has been replaced by a fresh unembalmed cadaver. Numerous test conditions have been used. Here are the complete results on the thorax for 31 cadavers in dynamic tests and 7 others in static tests. Specific interest in the thorax comes from the examination of injuries which has shown that, for a normal test, severe injuries are seldom located elsewhere than in the thorax. Methodology, which is the first described, states in particular how the cadavers are prepared with reconstitution of blood pressure and lung inflation and how skeleton strength is characterized. Among the results shown are those for the thorax autopsies, the corresponding seat belt restraint forces, some measurements with dummies used simultaneously and some data on recorded thorax deflections.