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Technical Paper

Crashworthiness Safety Features in Rollover Crashes

Rollover crashes continue to be a serious and growing vehicle safety problem. Rollovers account for about 9% of passenger car crashes, and 26% of light truck crashes. Belt use in rollover crashes is about 51%, compared with 62% in planar crashes. Overall, 26.4% of the serious and fatal injuries to occupants exposed to crashes are in rollovers. Among this injured population 74.4% are unbelted. In light trucks, rollovers account for 47.4% of the serious or fatal injuries. Unbelted occupants suffer about 87% of the serious injuries and fatalities in light truck rollovers. The use of safety belts offers a dramatic reduction in injury rates for rollover crashes. For belted occupants of pickup trucks and utility vehicles in rollover crashes, the injury rates are about the same as for belted occupants of passenger cars in planar crashes. Improvementsts in safety belts offer large opportunities in safety.
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

Relationships Between Crash Casualties and Crash Attributes

This work addresses and evaluates the likelihood of human casualty in highway crashes, projected on the basis of field crash data that may become available electronically by sensors at crash time, and/or observed at the crash scene by emergency attendants. Termed collectively as a “crash signature”, such data are treated as predictors and are selected from: crash severity, general area of damage, direction of force, occurrence of rollover, intrusion, vehicle crush and its specific horizontal location, collision partner, vehicle class and size, occupant age, gender, restraint use and type, seating position, and other. Crash signatures are converted into responses such as: (a) the likelihood of the most severe outcome, fatality or survived injury, by severity AIS per occupant; and (b) the same per vehicle. Cars are the vehicles selected for this investigation.
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

Injuries Sustained by Air Bag Protected Drivers

The William Lehman Injury Research Center has conducted multi-disciplinary investigations of fifty crashes involving drivers protected by air bags. In all cases, serious injuries were suspected. Nine cases involved fatal injuries. These cases are not representative of crashes in general. However, when used in conjunction with NASS/CDS they provide insight into the most severe injuries in crashes of vehicles equipped with air bags. A comparison with data from the National Accident Sampling System; Crashworthiness Data System (NASS/CDS) shows that head injury and abdominal injury make up a larger fraction in the Lehman data than in NASS/CDS. Examination of fatal cases indicates that head injuries are frequently caused by intruding structure or by unfavorable occupant kinematics among the unrestrained population.
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

Airbag Protected Crash Victims - The Challenge of Identifying Occult Injuries

A multidisciplinary, automobile crash investigation team at the Jackson Memorial Hospital/Ryder Trauma Center in Miami, Florida, is conducting a detailed medical and engineering study. The focus is restrained (seatbelts and/or air bag) occupants involved in frontal crashes, who have also been severely injured. More than 60 crashes have been included in the study to date. Analysis of the initial data indicates that restraint systems are working to reduce many of the head and chest injuries which unrestrained occupants suffer. However, internal injuries among air bag-protected occupants may be unrecognized in the field providing new challenges in triage and injury diagnosis. In other cases, survival in extremely high severity crashes presents trauma management challenges due to the extent and complexity of the multiple injuries which result. The paper provides case examples to illustrate types of chest and abdominal injuries associated with air bag cases.
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

Discerning the State of Crashworthiness in the Accident Experience

This paper addresses the risks of occupant casualties in highway accidents. Such risks are determined from U.S. accident experience in the past 10 years. Risks are analyzed as a function of vehicle type, car market class, make, nameplate, and model year for crashes of various impact types and various severities. Both absolute risks, per unit exposure, and relative risks are addressed. The influence of many exposure variables is examined and necessary adjustments, to a common set of exposure conditions, are made. The control variables for this purpose are: calendar year and car age; occupant's seating position, restraint status, and age; time and place of travel; and various roadway characteristics. Adjusted risks are reviewed versus major characteristics of cars as implied by make, nameplate, and model year. Occupant ejections and rollovers receive special attention due to their risk sensitivity to car class
Technical Paper

Problems in Crash Avoidance and in Crash Avoidance Research

This paper presents the methodology and results of an analysis of the available information on motor vehicle accident occurrence which could be used to provide a basis for establishing priorities for future Government and private sector work directed at enhanced crash avoidance or mitigation. The work was stimulated by several factors: (1) the absence of a recent and updated framework for problem evaluation; (2) motor vehicles have changed substantially in the past several years; (3) the quantity and quality of accident data and vehicle accident avoidance performance information have increased very substantially over the past 5 years; and (4) Government policies and the amount of Government and private sector resources available for future work have changed. This study takes the Agency's automated files on accident experience as the baseline information on motor vehicle involvement in accidents of all types.
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.