As the sophistication and effectiveness of safety devices have increased over the years, safety engineers have begun to look beyond the crash itself. While work has continued on traditional devices such as airbags and seatbelts, increasingly engineers are investigating ways to prevent or reduce the severity of collisions before they occur. However, whether the work had been on traditional devices or novel concepts, almost always, the concentration has been upon single impacts. Multiple impacts are accident sequences in which a vehicle sustains two or more collisions in the course of a single occurrence. Current data indicates that nearly half of all seriously injured occupants were in multiple impacts. Past study of multiple impacts has been limited with multiple impacts traditionally being eliminated or excluded in automotive safety studies. This work seeks to expand the understanding of this complex issue and provide the groundwork for development of multiple impact specific safety systems.
The problem of multiple impacts is addressed by examining the basic multiple impact type; a multiple frontal impact. A multiple frontal impact is one wherein the two most severe impacts sustained by the vehicle are to the front plane. The problem is approached from the standpoint of safety systems design with the intent of characterizing the conditions and dynamics of multiple frontal impacts and providing the basic outlines for a multiple frontal impact protection system.
Multiple frontal impacts were analyzed using the three themes of prevention, prediction and protection. Each theme addressed a specific aspect of multiple frontal impacts. Prevention examined the possibility of preventing the occurrence or reducing the severity of multiple frontal impacts. Prediction examined the possibility of using current or proposed vehicle sensor systems to predict the occurrence of multiple frontal impacts. Protection examined the opportunities for current and proposed safety devices to protect an occupant in a multiple frontal impact.
Multiple frontal impacts were examined through a combined approach which utilized currently available data, individual case analysis and computer based simulation. The combined approach allowed for the weaknesses of each data source to be supported by the strengths of the other. Together, the variety of sources provided the basis for analysis of multiple frontal impacts from sources not traditionally designed for it.
This study identified the relationship between lane / roadway departure and the occurrence of multiple frontal impacts. The link between the obliqueness of an initial impact and the occurrence of multiple frontal impacts was also identified. The capability of utilizing vehicle impact speed and predicted collision severity as a predictor of multiple frontal impacts was presented. The increase in extremity injuries in primary - secondary type multiple frontal impacts and the increase in head injuries in secondary - primary type multiple frontal impacts was also identified. These findings were combined with the knowledge of current safety systems to present the basis for design of a multiple frontal impact safety system which addresses all three aspects of the problem; prevention, prediction and protection.
|Advisor:||Digges, Kennerly H., Eskandarian, Azim|
|Commitee:||Hamdar, Samer H., Hollowell, William T., Silva, Pedro F.|
|School:||The George Washington University|
|Department:||Civil and Environmental Engineering|
|School Location:||United States -- District of Columbia|
|Source:||DAI-B 73/07(E), Dissertation Abstracts International|
|Keywords:||Accident investigation, Accident reconstruction, Frontal impacts, Multiple impacts, Nass, Transportation safety|
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