Analysis of Human Test Subject Kinematic Responses to Low Velocity Rear End Impacts

The head, neck and trunk kinematic responses of four volunteer test subjects, recorded during a series of experimental low velocity motor vehicle collisions, have been measured and analyzed. Using data obtained from multiple high speed film, video and electronic accelerometer measurements of the test subjects, it was found that the actual kinematic responses of the human head, neck and trunk that occur during low velocity rearend collisions are more complex than previously thought. Our findings indicate that the time-honored description of the cervical “whiplash” response is both incomplete and inaccurate. Although the classic “whiplash” neck response to rearend collisions and the widely accepted hyperextension/hyperflexion cervical injury mechanism have been extensively written and speculated about, there have been little human experimental data available, especially for low velocity collisions. Low velocity collisions are defined in this report as motor vehicle collisions in which the impact related change of the rearended vehicle's velocity (AV) is about 12.9 kph (8 mph) or less. Throughout nearly 4 decades of experimental crash testing, low velocity mishaps (as defined above) have been felt to have a minor injury causation potential and have remained a relatively unstudied area. The absence of good experimental data, accurately defining real occupant kinematic response during this common type of traffic accident has spawned a plethora of divergent concepts, ideas and speculation about possible injury mechanisms. In February 1991, a series of vehicle collision tests using fully instrumented volunteer human test subject/drivers and a Hybrid III manikin passenger was conducted, utilizing local testing facilities. This project was undertaken to better define human, dummy and vehicle responses during low velocity collisions.