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A database derived from information obtained in state police accident reports has been developed to support problem identification and counter-measure development in crash avoidance research. This database is sufficient in size to permit analyses of the relationship between specific vehicle design characteristics and crash involvement. Preliminary analyses of this database suggest that is is comparable with the nation's crash experience.

A review was conducted of injuries associated with ejection through motor vehicle glazing, using the 1988 through 1991 National Accident Sampling System data maintained by the National Highway Traffic Safety Administration. The review indicated that one percent of the occupants in towaway crashes were ejected and that 22 percent of fatalities in towaway crashes were ejected. Fifty-three percent of complete ejections were through the glazing openings in motor vehicles. Current motor vehicle glazing does not contribute significantly to occupant injuries, but the effects of glazing changes on serious injuries will need to be considered.

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.

This report documents the accident data collection, processing and analysis methodology used by the National Highway Traffic Safety Administration (NHTSA) in a major agency agency investigation of the rollover propensity of light duty vehicles. Specifically, these efforts were initiated in response to two petitions for rulemaking requesting the development of a standard for rollover stability. Logistic regression models were used to investigate the ability of a number of stability measures to predict vehicle rollover propensity, while accounting for a number of driver and environmental factors. It is not the intent of this paper to document formal agency policy in the area of any possible rulemaking efforts, and as such, references to these activities are not discussed. The reader can obtain information on this activity through normal agency procedures.

Finite element modelling has been used to study the evolution of strain in a model of the human brain under impulsive acceleration loadings. A cumulative damage measure, based on the calculation of the volume fraction of the brain that has experienced a specific level of stretch, is used as a possible predictor for deformation-related brain injury. The measure is based on the maximum principal strain calculated from an objective strain tensor that is obtained by integration of the rate of deformation gradient with appropriate accounting for large rotations. This measure is used here to evaluate the relative effects of rotational and translational accelerations, in both the sagittal and coronal planes, on the development of strain damage in the brain. A new technique for the computational treatment of the brain-dura interface is suggested and used to alleviate the difficulties in the explicit representation of the cerebrospinal fluid layer existing between the two solid materials.

The National Highway Traffic Safety Administration has initiated research to develop performance specifications for dummy-based accelerometers in the crash test environment, and to provide criteria for defining and establishing equivalent performance among accelerometers from different manufacturers. These research efforts are within the general guidelines on transducer equivalency outlined in the current revision of the Society of Automotive Engineers recommended practice, Instrumentation for Impact Test, SAE 211/2 March 1995. Representative data from vehicle crash and component level tests have been analyzed to determine the acceleration levels and frequency content in a realistic dynamic environment for dummy-based accelerometers.

This paper presents recent results of on-going research to build new maps of driver performance in car-following situations. The novel performance map is comprised of four driving states: low risk, conflict, near crash, and crash imminent - which correspond to advisory warning, crash imminent warning, and crash mitigation countermeasures. The paper addresses two questions dealing with the approach to quantify the boundaries between the driving states: (1) Do the quantified boundaries strongly depend on the dynamic scenario encountered in the driving environment? and (2) Do the quantified boundaries vary between steering and braking driver responses? Specifically, braking and steering driver performances are examined in two car-following scenarios: lead vehicle stopped and lead vehicle moving at lower constant speed.

The rapid development of driver assistance systems, such as lane-departure warning (LDW) and lane-keeping support (LKS), along with widely publicized reports of automated vehicle testing, have created the expectation for an increasing amount of vehicle automation in the near future. As these systems are being phased in, the coexistence of automated vehicles and human-driven vehicles on roadways will be inevitable and necessary. In order to develop automated vehicles that integrate well with those that are operated in traditional ways, an appropriate understanding of human driver behavior in normal traffic situations would be beneficial. Unlike many research studies that have focused on collision-avoidance maneuvering, this paper analyzes the behavior of human drivers in response to cut-in vehicles moving at similar speeds. Both automated and human-driven vehicles are likely to encounter this scenario in daily highway driving.

When a heavy vehicle driver (or in fact a driver of any vehicle) makes a brake application that is too "hard" for conditions - especially when the vehicle is lightly loaded or empty and/or the road is wet or slippery - he is likely to lock some or all of his wheels. Under these conditions, the tractor can jackknife or the trailer can swing out of its lane (if it is a combination-unit vehicle) or the truck can spin out (if it is a single-unit vehicle). Incorporation of an antilock brake system addresses the wheel lock and resultant control loss.

The NHTSA has developed automotive recorders which can measure crash triaxial acceleration/time histories during vehicle collisions. From these acceleration histories (recorded on a magnetic disc), velocity/time histories and velocity change during impact are derived to provide measures of vehicle crash severity. The purpose of developing these recorders is to provide accurate and quantitative relationships of vehicle crash severity with occupant fatalities and serious injuries from real-world accidents. To date, a total of 1200 disc recorders has been produced, approximately 1050 recorders have been installed in fleet vehicles, and 23 accident records have been analyzed. This paper has been prepared to present the progress made in the Disc Recorder Pilot Project as of March 31, 1974. Recorder data from accidents involving vehicles equipped with disc recorders will be discussed and compared with associated reports by accident investigators.

An important new technique in safety engineering for complex systems is the fault tree analysis method. The results of a motor vehicle brake system safety analysis using the fault tree technique are described. The work is directed toward the identification and ranking of brake system failure modes which may be critical as accident causation factors. Safety criticality for each failure mode is defined as the product of probability of occurrence and severity of effect on vehicle control. Failure data for the brake system components are obtained from maintenance and repair records of a large automobile leasing fleet. An effect scale is developed using a method for pooling expert judgements to obtain the relative ranking of various brake faults as to accident causation potential. The fault tree structure is employed to combine probability and effect to obtain the safety criticality value of each fault.

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).

This paper focuses on the overall structure of the Crash Injury Research and Engineering Network (CIREN), how data are collected, and what makes it unique. It discusses how it can be used to expand and enhance the information in other databases. CIREN is a collaborative effort to conduct research on crashes and injuries at nine Level 1 Trauma Centers which are linked by a computer network. Researchers can review data and share expertise, which will lead to a better understanding of crash injury mechanisms and the design of safer vehicles. CIREN data are being used in outreach and education programs on motor vehicle safety. CIREN outreach and education has already been credited with lifesaving information dissemination.

This paper presents the details of the model for the physical steering system used on the National Advanced Driving Simulator. The system is basically a hardware-in-the-loop (steering feedback motor and controls) steering system coupled with the core vehicle dynamics of the simulator. The system's torque control uses cascaded position and velocity feedback and is controlled to provide steering feedback with variable stiffness and dynamic properties. The reference model, which calculates the desired value of the torque, is made of power steering torque, damping function torque, torque from tires, locking limit torque, and driver input torque. The model also provides a unique steering dead-band function that is important for on-center feel. A Simulink model of the hardware/software is presented and analysis of the simulator steering system is provided.

Based on a long recognized need, the National Highway Traffic Safety Administration (NHTSA) has begun to reexamine the potential for international harmonization of side impact requirements. To this end, NHTSA, as directed by the U.S. Congress, has recently submitted a report to the Congress on the agency plans for achieving harmonization of the U.S. and European side impact regulations. The first phase of this plan involves crash testing vehicles compliant to FMVSS 214 to the European Union side impact directive 96/27/EC. This paper presents the results to date of this research. The level of safety performance of the vehicles based on the injury measures of the European and U.S. side impact regulations is assessed.

Parallel and coordinated accident studies were conducted in the United States and in the Federal Republic of Germany to determine the extent, the level, and the comparability of neck injuries in automotive accidents as reported in the National Crash Severity Study (NCSS), and the Association of German Automobile Insurers (HUK-Verband) files. To determine the comparability of the two data sets, three primary evaluation criteria were used: 1) the distribution of overall injuries by AIS level by various occupant parameters, 2) the risk of occupant AIS injury vs. delta V, and 3) the distribution of neck injuries by AIS for restrained vs unrestrained occupants. Frequencies and severities of neck injuries in car accidents were compared in parallel layouts between the two data sets in frontal, side and rear impact modes. In further breakdown the frontal impact file was separated into driver/passenger and male/female categories.

A major focus of the National Highway Traffic Safety Administration's (NHTSA) vehicle compatibility and aggressivity research program is the development of a laboratory test procedure to evaluate compatibility. This paper is written to explain the associated goals, issues, and design considerations and to review the preliminary results from this ongoing research program. One of NHTSA's activities supporting the development of a test procedure involves investigating the use of an mobile deformable barrier (MDB) into vehicle test to evaluate both the self-protection (crashworthiness) and the partner-protection (compatibility) of the subject vehicle. For this development, the MDB is intended to represent the median or expected crash partner. This representiveness includes such vehicle characteristics as weight, size, and frontal stiffness. This paper presents distributions of vehicle measurements based on 1996 fleet registration data.

The National Highway Traffic Safety Administration (NHTSA) has developed its Light Vehicle Antilock Brake Systems (ABS) Research Program in an effort to determine the cause (s) of the apparent increase in fatal single-vehicle run-off-road crashes as vehicles undergo a transition from conventional brakes to ABS. As part of this program, NHTSA conducted research examining driver crash avoidance behavior and the effects of ABS on drivers' ability to avoid a collision in a crash-imminent situation. The study described here was conducted on a test track under dry and wet pavement conditions to examine the effects of ABS versus conventional brakes, ABS brake pedal feedback level, and ABS instruction on driver behavior and crash avoidance performance. This study found that drivers do tend to brake and steer in realistic crash avoidance situations and that excessive steering can occur.

The National Highway Traffic Safety Administration (NHTSA) has developed its Light Vehicle Antilock Brake Systems (ABS) Research Program in an effort to determine the cause (s) of the apparent increase in fatal single-vehicle run-off-road crashes as vehicles undergo a transition from conventional brakes to ABS. As part of this program, NHTSA conducted research examining driver crash avoidance behavior and the effects of ABS on drivers’ ability to avoid a collision in a crash-imminent situation. The study described here was conducted on the Iowa Driving Simulator and examined the effects of ABS versus conventional brakes, speed limit, ABS instruction, and time-to-intersection (TTI) on driver behavior and crash avoidance performance. This study found that average, alert drivers do tend to brake and steer in realistic crash avoidance situations and that excessive steering can occur. However, this behavior did not result in a significant number of road departures.

A comprehensive review of casualty-reducing effectiveness estimates of child safety seats in actual use, obtained by statistical analyses of highway accident data. Recent analyses of large samples of New York and Maryland accidents show statistically significant injury reductions for child safety seats; so does a new analysis of the National Highway Traffic Safety Administration's accident files. Results from Washington State, Tennessee, New Jersey, and Idaho are also reviewed, as are Nationwide restraint usage and fatality trends. The findings are critically examined for possible data biases. It is concluded that child safety seats definitely reduce deaths and injuries in highway crashes, but that their effectiveness cannot be accurately estimated at this time because of inconsistencies and possible biases in the various studies.