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The value of on scene in-depth accident research studies has been recognized internationally and many countries worldwide have such teams. Since such detailed information is essential for improving the safety of cars, a strong collaboration with automakers developed. This resulted in Germany in a joint project between FAT (Forschungsvereinigung Automobiltechnik -Automotive Industry Research Association) and BASt (Bundesanstalt für Straßenwesen -Federal Road Research Institute). The project started on July 1999 and is called “GIDAS” (German In-Depth Investigation Accident Study). The paper is describing the methodology of this project with statistically orientated procedure of data sampling on the one hand and will give an overview of procedures for the determination of impact speed on the basis of an on scene investigation on the other hand.

Crash information, e.g. driving and impact speed, have to be determined from traces on the scene, as well as from examination of deformation patterns in order to assess the impact condition and the movement trajectories of the impacted body of bicyclists and pedestrians after car collision. Experts use the following information to calculate speed: Information on final position of vehicles, deformation pattern on vehicles, traces found on the road, such as braking and sliding marks, throw distances of pedestrians and cyclists and injury pattern, all these issues are given possibilities for reconstruction of the movement of the human body. While in car to car crashes the speed calculation is based on the momentum analysis and on energy balance hypothesis of classical physics, the calculation for pedestrian and bicycle accidents have to be based on traces only. The paper describes the possibilities of the use of throw distance as a reconstruction method.

In Europe there is less experience with air bag deployments in accidents than the US-scene. Within the continuing in-depth investigations at the Medical University Hannover 41 accidents with air bag deployments could be documented. A detailed description of selected accidents is given in the study. The injuries of the occupants are described and the injury mechanisms caused by the air bag deployment are discussed. In the study the distribution of injury severities are compared for accidents with seat belt system only correlating to those with air bag additionally. The air bag fitted cases demonstrate that the protective effect was essentually based on using the seat belt. Especially for less load level some injuries occured which can called as airbag specific injuries. These are some haematoma in the thorax and face region als well as burn injuries, but a higher risk for distorsions of the cervical spine AIS 1 could be seen.

The objective of this study was to analyze the injury risk of the windscreen pane and to consider means for an injury reduction by an optimized structure and angle of the windscreen pane and give demands for the vehicle construction. Accident documentations from in-depth investigations by the Accident Research Unit of the Medical University Hannover (ARU Hannover) by order of German Federal Road Authority (Bundesanstalt für Straβenwesen) were analyzed for this purpose. For that 71 belt-protected front-seat passengers and 192 pedestrians and cyclists resepectively who suffered injuries by impact to the windscreen pane in frontal collisions were investigated. An impact to the windscreen in the region of the frame appears to have especially serious consequences. 5.9% of the belt-protected front occupants and 22.8% of pedestrians or cyclists respectively suffered serious injuries (AIS 3+).

City vehicles are, as a rule, small and light vehicles, built without a distinct fronthood. Within the framework of the study, the influences of the length of the vehicle fronthood on the injury severity of pedestrians' head is investigated from the Accident Research Unit Hannover1. It must be assumed that vehicles with shorter fronthood lengths are mostly vehicles of the lower weight class and, with mostly long fronthoods ranks among curb weights above 1,000 kilos. The body height and the collision speed determine the throwing up distance and the occurance of head impacts. With short fronthood skull fractures occur more frequently. The above study reveals that with a short fronthood length an increase in head impact frequency to the windscreen occur. The injury severity is mainly influenced by the collision speed. With short fronthood lengths, an earlier occurance of serious injuries is already established in collision speeds of up to 30 km/h.

382 passenger cars concerning isolated lateral collisions are analysed in this study. The basis are representative traffic accidents investigated in a statistical spot-check plan directly at the site of the accident by a team of scientists of the Accident Research Unit of the Medical University Hannover. The mechanisms and impact situations responsible for the resulting injuries to the various body regions by side collisions are shown. The different deformation patterns are analysed by a special matrix measurement system. With this system deformation characteristics are established. The injury causation is explained, and the importance of intrusion analysed. It was analysed that the head, thorax as well as the upper and lower extremeties are the most frequently traumatised body regions in lateral collisions. The most frequent impact is under 35 to 45 degrees from a frontal direction to the compartment located in the region of the A-pillar.

In the study 140 belt-protected car drivers with foot fractures, distortions and luxations were analysed and the injury mechanisms in the car interior which are responsible for the occurance of foot fractures were defined. Accident documentations carried out from 1985 to 1990 by the traffic accident research of Hannover are the basis of these investigations. It was established that foot fractures for car drivers are, to an amount of 1.3%, quite rare. In view of the fact, however, that foot fractures result in a rather high rate of injury consequences in treatment it is shown that the demand for modifications of the vehicle interior is justified. The study demonstrates that two characteristic mechanisms must be regarded seperately: This is on the one hand in direct succession the force mechanism which always results from footroom deformations.

For this study 614 accidents of two-wheel users were investigated by a scientific research team within the framework of local accident documentations. The accident and injury situations are described, and cognitions from accident simulation tests are additionally evaluated with dummies. Throwing distances of two-wheelers and riders reveal the characteristics of the movement kinematic, in relation to impact speeds. Head impact points are described in detail and sustained injuries are recorded, divided into type and severity (AIS). Furthermore, differences of traumatizing between children and adult cyclists are discussed.

Within the framework of local accident investigations, the injuries of 608 belt wearing front-seat passengers were documented and discussed for various collision types. The special feature of this survey is the detailed description of injuries, in correlation with the injury-causing interior car parts. References are also made to the injury situation of rear-seat passengers.