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Technical Paper


Roof strength clearly affects the probability of occupant head and neck injury in light vehicle rollovers. Despite this, most manufacturers continue to design and build vehicles with inadequate roof strength. From experimental and biomechanics evidence and rollover crash data, we present the case that weak, antiquated roof designs contribute to severe head and neck injuries. We discuss the deficiencies in modern roof designs, how they cause severe head and neck injuries, and the limitations inherent in the Federal roof crush standard, FMVSS 216. We describe cost-effective examples of materials and technologies that can provide adequate roof strength to protect occupants in most rollovers without imposing significant weight penalties. Finally, we discuss an approach to dynamic roof strength testing that is based on what occurs in an actual, serious injury-producing rollover.
Technical Paper

The Relationship Between Vertical Velocity and Roof Crush in Rollover Crashes

Rollover accidents account for a large number of serious to fatal injuries annually. In the past, these injuries were often the result of unrestrained occupant ejection. Subsequent to mandatory belt use laws, a larger percentage of these injuries occur inside the vehicle, and the head and neck areas sustain a substantial number of these injuries. Rollovers have been characterized as violent events, roof crush as the natural consequence of such violence. Further, head and neck injury have been thus considered unavoidable, even with occupant use of the production restraints. This paper will describe the relationship between the three dimensional extent (severity) of roof crush and the equivalent drop test contact velocity as derived from physical experiments and tests. The drop test contact velocity is directly related to the cumulative change of velocity experienced by a vehicle as a result of roof contact deformation during a rollover accident by validated computer simulations.
Technical Paper

Roof Crush Versus Occupant Injury From 1988 to 1992 NASS

Rollover accidents account for a large number of serious to fatal injuries annually. In the past, these injuries were often the result of unrestrained occupant ejection. Subsequent to mandatory belt use laws, a larger percentage of these injuries occur inside the vehicle, and the head and neck areas sustain a substantial number of these injuries. An analytical effort to understand rollover injuries, using the field accident data of the NASS files and residual headroom as an indicator, was reported by the authors at the 1996 ESV conference in Melbourne, Australia. This paper describes the relationship between roof crush and restrained occupant injury in rollover accidents as derived from the analysis of 1988-1992 NASS files. It extends the residual headroom parameter to the entire population of head, face and neck occupants injured inside the compartment.1
Technical Paper

Human Subject Experiments In Occupant Response To Rollover With Reduced Headroom

This paper describes some human subject experiments in occupant response to rollover with reduced headroom. The results suggest that with a nominal 10 cm of head room, 7.5 to 15 cm of torso excursion in production belts and more than 15 cm of roof intrusion, serious neck injury is likely. Brain damage/head injury is more likely from a combination of roof rail crush and high change of angular roll rate.
Technical Paper

Live Subject Safety Research - Side Impact

For twenty years the dynamic test protocol for automotive safety research has been to use an anthropomorphic dummy in sled and crash test simulations. For the past four years, the author and associates have created and used a computer test protocol to model real world accidents and determine injury reduction from potential design modifications without some of the limitations and cost of the physical hardware and test procedure. The computer test protocol is described and examples of the research results in side and rollover accidents are detailed. Preliminary conclusions about injury reduction countermeasures and continuing research are suggested.
Technical Paper

CRASH 3: Current Status

The computer program, CRASH 3, uses the equations of motion to estimate the changes in velocity of motor vehicles in crashes and their trajectories following a collision. It was developed in the mid-1970's by McHenry at Caispan for use in accident research. There are important limitations on where and how it should be used. CRASH 3 requires a skilled reconstruction of a crash and an interactive execution of the program to provide reasonably accurate results. The paper also discusses the sensitivity of CRASH 3 to various parameters and the potential for improving it. This paper presents the views of its author and not necessarily those of the National Highway Traffic Safety Administration (NHTSA).
Technical Paper

New Technologies and Techniques for NASS Accident investigations

The National Accident Sampling System (NASS) has investigated more than 40, 000 traffic accidents in its six years of operation. This paper discusses some of the new technologies and techniques of accident investigation being adopted in NASS. These include a microcomputer data entry system, the CRASH 3 program for estimating the severity of an impact, a contour gauge for measuring vehicle deformation, and automated scene diagramming techniques. The authors also define some of the unsolved problems in mass accident investigation, and discuss the constraints on solving them.
Technical Paper

Fatality Rates in Toyota Cressidas With Automatic Belts

Automatic belts in Toyota Cressidas have increased belt usage by front-seat occupants of these cars to more than 95 percent. This paper compares the fatal accident experience of these cars with that of the fairly similar Datsun (Nissan) 810/Maxima automobiles (which are equipped with manual belts used by about 20 percent of their occupants). It shows the result of the increased belt usage is a decrease in fatalities among Toyota front-seat occupants. In fatal accidents where no front-seat occupants of the Toyotas or Datsuns are killed, the Toyotas have a higher involvement rate than the Datsuns. Also, on average, the fatally injured front-seat occupants of the Toyotas are 7 years older than those in the Datsuns.
Technical Paper

The Research Safety Vehicle-Present Status and Near-Term Prospects

Mr. Donald Friedman was developing vehicle concepts at GM from 1960 to 1968 and has continued this research since then as president and founder of Minicars, Inc. He has participated in the development of urban electric cars, the DOT/AMF/ESV, passive restraints and structural energy management programs. Mr. Friedman is presently in charge of systems analysis and integration of the Minicars Research Safety Vehicle Program.
Technical Paper

An Inexpensive Automobile Crash Recorder

One of the greatest challenges faced in the design of realistic occupant protection systems is an accurate statistical model of what is really needed. The paucity of data is this realm hinders designers of standards alike. Ideally, a model of crash statistics would correlate, for significant accident modes, injury level (as measured by AMA Abreviated Injury Scale “AIS”) with some adequate measure of crash intensity. Having this information, not only could the required level of safety design be ascertained, but also the justifiable economic expenditure could be estimated. This paper treats the statistical basis for deployment of a data retrival system. It provides a basis for estimates of the amount of data required, the number of vehicles to be instrumented, the crash severity trigger levels, and the economics of recorder installation, for various levels of injury and fatality.
Technical Paper

The Correlative Advantages of Lunar and Terrestrial Vehicle and Power Train Research

Lunar and planetary programs have entered the surface exploration research phase. In this phase, considerable emphasis is needed on high mobility vehicle configurations, reliability and high efficiency, low weight electrochemical energy converters, and electric traction power systems. This research, in many cases, is applicable to solving future mobility problems on earth. Three areas of current lunar and terrestrial research are discussed and analyzed, and the correlative advantages to those working in both fields are highlighted. The three areas are; (1) high mobility vehicle configurations; (2) electrochemical energy converters; and (3) electric traction power systems.