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This paper describes a National Automotive Sampling System (NASS) case in which a parked 1958 Chevrolet Bel Air was rear-ended by a 1991 Dodge Grand Caravan whose unbelted driver sustained fatal chest injuries despite the presence of an airbag. This particular case was chosen because different reviewers of the information from the crash investigation have proposed conflicting conclusions about the role of the airbag in the fatal injuries. The NASS investigators and others concluded that the driver bottomed out the airbag resulting in fatal chest injuries. Insurance Institute for Highway Safety researchers concluded that the driver either was out of position due to late firing of the airbag or was slumped over the wheel due to a high blood alcohol concentration; in either case they attributed the fatal injuries to airbag inflation forces. Thus, in one scenario the airbag had insufficient power, and in the others it had too much power.

Excessive movement of steering columns in crashes can significantly degrade the performance of restraints, especially airbags. Although steering column movement does not appear to be a major problem in full-width rigid barrier crashes, it can be an issue in other frontal crash types. Results from 106 frontal offset crash tests at 64 km/h (40 mi/h) were used to characterize different patterns of steering column intrusion for different vehicle types. Large movements of the steering column often were associated with the dummy’s head striking the steering wheel through the airbag. Some of the tested models were redesigned over the course of this testing, and comparisons with older designs showed that improving the structural integrity of the occupant compartment could lead to less longitudinal movement of the steering column, but this was not necessarily the case for vertical column movements for some models in the data set.

Despite extensive media coverage to the contrary, mismatches among cars, utility vehicles, and pickups in crashes is not a big problem from a societal perspective. On the other hand, if you are riding in a small car that is about to be hit by a big utility vehicle, then the problem looms large. Crash compatibility has attracted a lot of attention lately because utility vehicles have become so popular. The concern is that their designs pose a threat to people riding in smaller cars. But the fact is, two-vehicle collisions between cars (including passenger vans) and utility vehicles or pickups account for only about 15 percent of all car occupant deaths. As a result, countermeasures that focus on making utility vehicles and pickups more crash compatible, however appropriate, can have only small effects on crash injuries and fatalities. On the other hand, improvements in crashworthiness not only reduce crash incompatibilities but also protect across a wider spectrum of crashes.

Since the 1973 model year minimum levels of new car bumper performance have been specified by federal standards. Beginning with the 1974 model year, the safety bumper standard required that bumpers protect safety related equipment in 5 mph front-and rear-into-barrier tests. This standard was superceded in the 1979 model year by the no-damage standard which restricted dollar damage in the same tests. For 1983 and later models the barrier test speed requirements of the no-damage standard were reduced to 2.5 mph. There is convincing evidence from crash tests and insurance data from real world crashes that the federal 5 mph bumper standards substantially reduced much of the unnecessary damage that was occurring in low speed crashes because the performance of pre-standard bumpers was so poor. There is a real danger that this progress will be eroded, however, due to the weakening of the no-damage standard.

Laws requiring seat belt use have had some limited success in reducing occupant fatalities. However, fatality reductions have been considerably less than expected from the reported increases in belt use rates because belt use by those in crashes has not increased to the same extent. Occupants most likely to be in serious crashes are least likely to increase their use of belts in response to laws. In addition, many involuntary belt users comply with belt use laws by wearing their belts incorrectly, in ways that greatly reduce their effectiveness, and many in front seats who wear belts in response to laws are susceptible to being impacted in crashes by unbelted rear seat occupants. The incomplete success of belt use laws does not reduce their importance as a countermeasure, but does reinforce the importance of providing automatic (“passive”) protection to vehicle occupants as an alternative or supplementary countermeasure.

Data on deaths of car occupants during the calendar year 1975 were obtained from the National Highway Traffic Safety Administration's Fatal Accident Reporting System, and national vehicle registration counts were obtained from R. L. Polk National Profile as of July 1, 1975. Occupant deaths per 10,000 registered cars in the 1971 through 1974 model years were examined by vehicle size. Occupant death rates generally increase as car size decreases. The relationship between smaller cars and increased deaths is especially pronounced in frontal crashes, and in car into other vehicle crashes. Because of this, increased occupant crash protection in frontal crashes-such as provided by air bags and passive seat belts-could substantially reduce much of the disadvantage presently faced by occupants of small cars.

A major difficulty in performing cost-benefit analyses of bumper designs is the fact that much of the damage from low-speed crashes is never reported either to public agencies or insurers. Much of this unreported crash damage remains unrepaired, at least for some time after the crash, and thus surveys of unrepaired crash damage can provide one source of data for some of the unreported crash damage. During the summer of 1974, surveys of unrepaired crash damage were conducted in seven metropolitan areas. The results of these surveys are presented. It is concluded that the present state of knowledge on the frequency and amount of unreported crash damage is too limited to enable this essential component to be adequately incorporated into cost-benefit analysis of bumper designs.

The concepts of “cost-benefit” and “cost-effectiveness” are increasingly cropping up in debate over present and future motor vehicle standards. Often they are introduced to attack, or justify, a particular standard. Just as often, they are misunderstood and misused. Since a motor vehicle safety performance standard has no costs per se, it cannot be evaluated either in cost-benefit or cost-effectiveness terms. It is the particular design alternatives available to manufacturers to achieve the objectives of a standard that have societal costs. The various design alternatives can be evaluated. Cost-effective designs should be chosen to minimize societal costs, and until there is evidence that cost-effective designs have been chosen, cost-benefit studies are premature.