The effects of vehicle air bags on the severity of off-road, fixed-object crashes as indicated by the effect that the air bag has on severity indexes (SI's) for fixed objects were studied. In an earlier study, preliminary indications based on data from one state were that the presence of the air bag might reduce SI's for various fixed objects by 35 to 75 percent. This study extends that work by adding data from two other states and from additional crash years. Severe-injury SI's were developed for different roadside objects for two samples of late-model vehicles, one with air bags and one without. The states chosen for use in this effort were those in which injury could be linked to a specific object struck.
The data were also chosen to reflect a newer vehicle fleet (i.e., vehicle year 1989 or later) and more recent crashes (i.e., those occurring between 1990 and 1994). Although there were some inconsistences within classes of objects and between states, analyses indicated that the air bag appears to be related to a decrease in proportion of serious or fatal driver injuries of 10 to 30 percent for point objects such as trees and utility poles, 40 to 50 percent for guardrails, and 10 to 20 percent for other barriers. For many of the objects tested, the results were not statistically significant, probably because of the sample sizes available.
Forrest M. Council, Yusuf M. Mohamedshah, and J. Richard Stewart. Effects of Air Bags on Severity Indices for Roadside Objects, Transportation Research Record 1581, TRB, National Research Council, Washington D.C., 1997