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Technical Paper

Overstated Safety Belt Use Rates - Evidence, Consequences, And Remedies

The paper at hand deals with issues arising from inflated values of safety belt use. The paper addresses and evaluates data leading to strong evidence that safety belt use rates, as reported in crash records, are inflated irrespective of reasons. Equally strong evidence is found that belt use inflation introduces significant distortions in the estimation of casualty rates, and of the effectiveness of various restraints. The cited effects are evidenced both analytically and by reviewing crash records. No fully satisfactory remedy is yet at hand for controlling the cited distortions. However, a heuristically determined blanket deflation appears to rectify most of the ill effects of belt use inflation. It also appears that blanket remedies for belt use inflation, intended to cure inflated values of restraint effectiveness, may introduce adverse side effects on the cited effectiveness.
Technical Paper

Heart Injuries Among Restrained Occupants in Frontal Crashes

The William Lehman Injury Research Center has conducted multi-disciplinary investigations of one hundred seventy-eight crashes involving adult occupants protected by safety belts and air bags. In all cases, serious injuries were suspected. Nine cases involved serious heart injuries. These cases are not representative of crashes in general. However, when used in conjunction with National Accident Sampling System; Crashworthiness Data System (NASS/CDS) they provide insight into the most severe injuries suffered by restrained occupants in frontal crashes. Heart injuries are rare, but when they occur they are usually life threatening. NASS/CDS shows that heart injuries comprise about 0.2% of the injuries in frontal tow-away crashes. In the NHTSA file of Special Crash Investigations (SCI) of air bag cases, heart injuries are reported in 1% of the occupants over 15 years of age. Twenty-five percent of the fatally injured occupants had heart injuries, and 83% of those with heart injury died.
Technical Paper

Air Bag Field Performance and Injury Patterns

This investigation addresses and evaluates: (a) the frequency of air bag deployments in comparison with belt only protection or no restraint, as a function of calendar year and model year; (b) injury and harm rates as a function of crash severity and restraint use and type; (c) restraint effectiveness in reducing fatalities and injuries as a function of restraint, crash severity, type of impact, and car size; (d) the confounding effects of crash severity; (e) injury patterns by injured body region, injuring contact, and injury severity; and (f) variation of injury patterns as a function of crash severity. It is found that restraints, irrespective of type, appear to be more effective at higher injury severities; the lowest casualty rates, and highest effectiveness values, are associated with the use of an air bag plus safety belt, or safety belt without air bag deployment; the air bag even without the concurrent use of a safety belt appears to offer a certain crash protection.
Technical Paper

Evaluation of Air Bag Field Performance

This investigation encompasses a comprehensive evaluation of air bag field performance, in comparison with the no restraint, or other restraint conditions. The paper at hand addresses: Cars, Exposure, Occupants, Restraints, & Protection provided by the restraints. A companion paper addresses the injury patterns of car occupants. The findings of the investigation are based on two primary sources of national coverage: (i) the field crash experience contained in the records of NHTSA's NASS/CDS 1988-1992; and (ii) the fatal accident experience contained in NHTSA's FARS 1991-1993. The investigation focuses on car drivers. Because of the relatively late and limited introduction of air bags, all other light vehicle populations are either not represented, or represented by a very meager sample in the sources cited above.
Technical Paper

Chest and Abdominal Injuries Suffered by Restraint Occupants

This paper is based on the crash and casualty experience compiled by the National Highway Traffic Safety Administration's (NHTSA) National Accident Sampling System, Crashworthiness Data (NASS/CDS 1988-1992), and by the William Lehman Injury Research Center (University of Miami/Jackson Memorial Hospital/Ryder Trauma Center) crash data files. The NASS/CDS files provide data on injuries to occupants in all types of tow-away crashes. The William Lehman Injury Research Center files provide detailed crash analysis and injury documentation of more than 100 restrained occupants with injuries from frontal crashes. These files provide a basis for recognizing injury patterns among restrained occupants and postulating their causes. The purpose of this paper is to report on an observed pattern of liver and spleen injuries suffered by drivers wearing shoulder belts without the lap belt fastened.
Technical Paper

Safety Performance of Motor Vehicle Seats

Comfort and safety are major considerations in the design of occupant seats in motor vehicles. In rear impacts, the seat is the principal component of the occupant restraint system. However, it also contributes to occupant restraint in frontal. and side impacts, and rollovers. To determine how well automobile seats protect occupants from injuries in rear impacts, crash data from the national accident files in the united states were analyzed. The distributions and causes of injuries in rear impacts were categorized according to injured body region and source of injury. In addition, forty-nine selected accident cases were reviewed, to determined how the seat performed in crashes. Finally, rear impact crash tests of passenger cars were analyzed to determine dummy motion and seat performance. Non-contact injuries were associated with the largest portion of injury harm. The seat and frontal components were the two largest sources of contact injury harm.
Technical Paper

Harm Causation and Ranking in Car Crashes

This paper addresses the crash protection of occupants of the car fleet in transition from the late 1970's to the early 1980's. Three files of the National Highway Traffic Safety Administration are used: the NASS 1979 to 1983, the PARS 1979 to 1983, and the NCSS 1977 to 1979. Fatalities, injured survivors by severity, and all accident involved car occupants are addressed. Risks of crash and injury outcomes are determined and analyzed as a function of risk influencing factors, especially factors that may vary significantly during the time period under consideration. Ejection risks and ejection patterns are addressed explicitly. Harm, an earlier introduced human casualty integrator, and harm distributions are extensively examined and updated with respect to earlier results. Harm and harm pattern changes, whether statistical fluctuations or systematic variations, are analyzed.
Technical Paper

A Search for Priorities in Crash Protection

This paper presents the methodology and results of an analysis of the available information on motor vehicle safety which could be used to provide a basis for establishing priorities for future Government and private sector efforts directed at enhanced crash protection. The work was stimulated by several factors: (1) 5 years have elapsed since the National Highway Traffic Safety Administration (NHTSA) published a plan for motor vehicle safety research and development, (2) motor vehicles have changed substantially over the past several years, (3) the quantity and quality of accident data and vehicle crash performance information have increased dramatically over the past 5 years, and (4) Government policies and the amount of Government and private sector resources available for future efforts are changing.