Abstract:
Outside of limited crash testing experience and more limited real-world crash data, very little is known regarding the probability that an occupants head is ejected out of a vehicle side window, i.e. head slap, in an impact with a traffic barrier. Similarly, a literature review revealed little information regarding occupant ejection specific to traffic barrier crashes. The purpose of this study was to estimate (1) the frequency of occupant ejection and head slap during impacts with traffic barriers and (2) determine characteristics typically associated with these events. Data included 1,367 real-world longitudinal barrier crashes with available vehicle damage, occupant injury, occupant injury source information, and traffic barrier information. The rate of occupant ejection in tow-away level single vehicle, single event barrier crashes was estimated to be 0.25 percent with an upper bound of 0.52 percent. These rates were found to be approximately three times higher than ejection rates for single event, two-vehicle crashes, primarily due to differences in full ejection rates. The results from this study reaffirm that barrier crashes involving ejection result in severe occupant injury and that side ejections dominate. A comparison of barrier ejection and nonejection cases revealed that pickup trucks, older model year vehicles, and unbelted occupants were overrepresented in barrier ejection cases. Although the available data suggests that occupant head slap is rare, barrier height data was not available. Thus, this low rate may be attributed to relatively few barriers with heights exceeding 34.5 inches present in the data. Further study on the incidence of head slap on tall barriers is warranted.
