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The Federal Motor Vehicle Safety Standard 571.201 discusses occupant protection with interior impacts of vehicles. Recent rule making by the National Highway Traffic Safety Administration (NHTSA) has identified padding for potential injury reduction in vehicles. Head injury mitigation with padding on vehicular roll bars was evaluated. After market 2 to 2.5 cm thick padding and metal air gap padding reduced the head injury criterion (HIC) and angular acceleration compared to the stock foam roll bar padding. Studies were conducted with free falling Hybrid 50% male head form drops on the fore head and side of the head. Compared to the stock roll bar material, a nearly 90% reduction in HIC was observed at speeds up to 5.4 m/s. A concomitant 83% reduction in angular acceleration was also observed with the metal air gap padding. A 2 to 2.5 cm thick Simpson roll bar padding produced a 70 to 75% reduction in HIC and a 59 to 73% reduction in angular acceleration.

Inverted drop testing of vehicles is a methodology that has long been used by the automotive industry and researchers to test roof integrity. In our laboratory, the inverted drop test methodology was employed on late model production vehicles to simulate the damage incurred by a real world rollover accident. The extent and shape of residual damage matched well with the corresponding accident damage. Modified vehicles were reinforced based upon previously documented techniques. Incorporation of these techniques demonstrated a significant increase in roof strength and corresponding reduction in roof crush with minor weight addition. Finally, a production vehicle and structurally enhanced vehicle were drop tested with instrumented Hybrid-III occupants. This pair of tests confirms that reduction of roof intrusion and increased headroom can significantly enhance occupant protection. It also highlights the need to maintain adequate survival space for the vehicle’s occupants.

The government, automotive industry and scientific community are currently scrutinizing the adequacy of the FMVSS #216 roof crush standard in the United States. As a result of concern about the ability of FMVSS #216 to enforce reasonable protection to occupants in rollovers, The National Highway Traffic Safety Administration (NHTSA) has recently published a Request For Comments in the Federal Register regarding updating this standard1. The inverted drop test methodology is a promising alternative test procedure to evaluate the structural integrity of roofs and is being considered by NHTSA as a possible compliance test. Recent testing on many different vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing at very small drop heights. Drop tests matrices were performed on 9 pairs of vehicles representing the majority of personal transportation vehicle types.