Driver Mortality in Frontal Crashes: Comparison of Newer and Older Airbag Designs

Abstract

In 1997, the National Highway Traffic Safety Administration amended its requirements for frontal crash performance under Federal Motor Vehicle Safety Standard 208 to temporarily allow 30 mi/h (48 km/h) sled tests with unbelted dummies as an alternative to 30 mi/h head-on rigid-barrier vehicle tests. This change permitted automakers to reduce airbag inflation forces so that they would be less likely to injure occupants who are close to airbags when they first deploy. Most vehicle models were sled-certified starting in model year 1998. Airbag-related deaths have decreased since 1997; however, controversy persists about whether reduced inflation forces might be decreasing protection for some occupants in high-severity frontal crashes. To examine the effects of the regulatory changes, this study computed rate ratios (RR) and 95% confidence intervals (95% CI) for passenger vehicle driver deaths per vehicle registration during 2000–2002 at principal impact points of 12 o'clock for 1998–99 model year vehicles relative to 1997 models. Passenger vehicles included in the study had both driver and passenger front airbags, had the same essential designs during the 1997–1999 model years, and had been sled-certified for drivers throughout model years 1998 and 1999. An adjustment was made for the higher annual mileage of newer vehicles. Findings were that the effect of the regulatory change varied by vehicle type. For cars, sport utility vehicles, and minivans combined, there was an 11 percent decrease in fatality risk in frontal crashes after changing to sled certification (RR = 0.89; 95% CI = 0.82–0.96). Among pickups, however, estimated frontal fatality risk increased 35 percent (RR = 1.35; 95% CI = 1.12–1.62). For a broad range of frontal crashes (11, 12, and 1 o'clock combined), the results indicated a modest net benefit of the regulatory change across all vehicle types and driver characteristics. However, the contrary finding for pickups needs to be researched further.

Keywords:

• Airbags
• Frontal Crash
• Airbag Designs
• Fatalities
• Drivers
• Traffic Accidents

Acknowledgements

The authors would like to thank the following staff members of the Highway Loss Data Institute: Thomas Biggar for providing data on age and gender of insured drivers and Matthew Moore and Drew Knoblauch for compiling a list of vehicles with dual airbags by platform. From the Insurance Institute for Highway Safety, we are grateful to Adrian Lund and David Zuby for helpful comments and Robert Tabor for editorial assistance on the draft manuscript. This work was supported by the Insurance Institute for Highway Safety. An earlier version of this paper was accepted for the annual meeting of the Association for the Advancement of Automotive Medicine, Key Biscayne, FL, October 24–29, 2004.

Notes

¹Frontal defined as 12 o'clock impact point; source of deaths was Fatality Analysis Reporting System.

²Source of vehicle registrations was R.L. Polk and Company. Registrations for age and gender were estimated using insurance data regarding primary drivers for makes, models, and model years of cars in study.

³Vehicle registrations by usual belt use of primary driver were unknown. To calculate RRs by belt use, total registrations for each make, model, and model year were used for both belted and unbelted categories.