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Considerable research has been conducted over the past decade on the response of both vehicles and occupants to low speed rear impacts. This research has employed various conditions of target vehicle braking and target occupant awareness. Relatively little effort has been devoted to quantitatively comparing vehicle and occupant responses under different braking and awareness. Given the variety of potential braking and awareness conditions in actual rear impacts, it is desirable to better understand the influence of these reactions on both vehicle and occupant dynamics. Low speed vehicle-to-vehicle rear end collisions were conducted with instrumented vehicles and an instrumented human subject. Six conditions were evaluated: 1) unaware occupant without braking, 2) aware occupant without braking 3) unaware occupant braking “normally”, 4) aware occupant full-braking, 5) unaware occupant with brakes mechanically fully applied, and 6) aware occupant with brakes mechanically fully applied.

Human volunteer kinematic response to low speed rear-end collisions was investigated. Nominal 16 kph (10 mph) car-to-car impacts were conducted, using human volunteers and anthropomorphic dummies. The human volunteers were both male and female, aged 27 to 58 years, with various degrees of cervical and lumbar spinal degeneration (documented by MRI scan) at the time of the tests. Human volunteer response was monitored and analyzed via accelerometers and high speed film. The impacts resulted in no injury to any of the human volunteers, and no objective changes in the condition of their cervical or lumbar spines. The results indicate a minimum injury tolerance to low speed rear-end impacts for males and females with various degrees of spinal degeneration. Kinematic responses of the head, mandible, upper torso and knees are discussed in light of existing theories regarding injury causation and tolerance.