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Sound localization of a backup alarm is important in situations when vehicles are reversing. Previous work has demonstrated the effects of ambient noise level and the spectral content of the backup alarm on localization. In the current study, we investigate the effects of backup alarm mounting location on localization performance. To address this question, we asked blindfolded listeners to localize backup alarms installed in positions that provided either direct (e.g., installed on the outer rear aspect of the vehicle) or indirect (e.g., installed within the inner frame rails of the vehicle) sound propagation paths to the listener. Additionally, we explored the effects of ambient noise level and the direction of origin of the alarm (behind, in front of, or to the left or right of the listener), and the interactions among all three factors (alarm location, ambient noise, and alarm direction relative to the listener).

Although most of the research on vehicular rear impacts has focused on the neck, there is increasing current concern about the lumbar spine. Spinal bending superimposed with sudden spinal compression has been suggested as a mechanism of creating acute herniations on the rare occasion in which low back pain associated with an intervertebral disc herniation was reported. During automotive rear-impacts, the vehicle accelerations are directed anteriorly, and the seat backs deflect posteriorly. In vehicle seats equipped with floor-mounted seatbelt restraints, the pelvis is restrained by the seatback and seatbelt, while the torso ramps upward and rearward on the seatback during the rearward motion, producing tension in the lumbar spine. However, in an all-belts-to-seat arrangement, the lumbar spines may experience overall compressive and bending loads.

A method of computing dynamic roof crush in rollover accidents has been proposed (Bidez, et al., 2005; Cochran et al., 2005). The method used data obtained from accelerometers mounted to the roof rails of sport utility vehicles, along with other measurements, to compute the instantaneous deformation of the roof rails during dolly rollover crash tests. We examined the feasibility and practicality of this methodology in three ways. First, the theoretical derivation was examined. Errors appeared to have been made in deriving and/or interpreting the equations used to compute instantaneous roof crush. Next, a three-dimensional dynamic rollover simulation program was run to produce ideal acceleration data (Yamaguchi et al., 2006, 2005). Using these data, the equations in original, uncorrected form predicted dynamic roof deformations when none existed. When the equations were corrected, the simulation data yielded proper roof positions and no roof deformations.

Vehicle aspect ratio has been reported as a significant factor influencing the likelihood of fatality or severe injury/fatality during single-vehicle rollover crashes. To investigate this, dynamic simulations of friction-induced rollover accidents were performed using different roof heights, but otherwise identical vehicle parameters and initial conditions. Higher aspect ratios tended to cause the leading side roof to impact first, with significant impact force. The roof impact forces during the first roll of higher-roofed vehicles were primarily laterally directed with respect to the vehicle. Impact locations during subsequent rolls were less predictable. Lower aspect ratios produced higher impact forces on the trailing side roof that were more vertically oriented with respect to the vehicle. The vertically oriented forces potentially create greater risk for severe neck or head injuries.

The mechanics of on-road, friction-induced rollovers were studied with the aid of a three-dimensional computer code specifically derived for this purpose. Motions of the wheels, vehicle body, occupant torso, and head were computed. Kane's method was utilized to develop the dynamic equations of motion in closed form. On-road rollover kinematics were compared to a dolly-type rollover at lesser initial speed, but generating a similar roll rotation rate. The simulated on-road rollover created a roof impact on the leading (driver's) side, while the dolly rollover simulation created a trailing-side roof impact. No head-to-roof contacts were predicted in either simulation. The first roof contact during the dolly-type roll generated greater neck loads in lateral bending than the on-road rollover. This work is considered to be the first step in developing a combined vehicle and occupant computational model for studying injury potential during rollovers.

Lateral head motions, torso motions, lateral neck bending angles, and electromyographic (EMG) activity patterns of five human volunteer passengers are compared to lateral motions of a Hybrid III ATD during right-left and left-right fishhook steering maneuvers leading to vehicular tip-up. While the ATD maintained relatively fixed lateral neck angles, live subjects leaned their heads slightly inward and actively utilized their neck musculature to stiffen their necks against the lateral inertial loads. Except for differences in neck lateral bending, the Hybrid III ATD reasonably reflects occupant kinematics during the pre-trip phase of on-road rollovers.