Dc. Viano et Mf. Gargan, HEADREST POSITION DURING NORMAL DRIVING - IMPLICATION TO NECK INJURY RISK IN REAR CRASHES, Accident analysis and prevention, 28(6), 1996, pp. 665-674
The gap and relative height of headrest behind drivers were determined
for 1915 vehicles approaching an intersection on a two lane road. Veh
icle type and headrest adjustment were also evaluated using film of no
rmal driving taken by the Insurance Institute for Highway Safety. Only
10% of drivers had headrests in the most favorable position to preven
t neck extension during a rearend crash. 73% of cars had adjustable he
adrests, but only a quarter were placed in the up position. 83% of the
adjustable headrests could have been raised to better protect the dri
ver. Hyge sled tests were run to determine biomechanical responses for
the various conditions observed in normal driving. This included thre
e headrest heights and three gaps behind the head. Neck extension from
the Hybrid III dummy was normalized to the response for a high, close
headrest, and injury risk was assumed to be proportional to neck exte
nsion. The current driving situation has a relative injury risk of 3.4
in rearend crashes, compared to 1.0 for the favorable condition. If a
ll adjustable headrests were placed in the up position, the relative r
isk would be lowered to 2.4, a 28.3% reduction in whiplash injury risk
. Public education and vehicle design should address the importance of
proper headrest placement for driving safety. Copyright (C) 1996 Else
vier Science Ltd.