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This paper reviews some of the progress that has been made in recent years in the transportation field by behavioral scientists and human factors engineers. The major areas covered are public transportation systems, railroad systems, highway systems, and personal transportation systems. The report suggests what future problems may be encountered in these areas that will need the attention of human factors specialists.

Attention in the United States is centering on investigations of lighter materials, more efficient structures, impact compatibility between cars, as well as between structure and restraints and simulation of collisions using both mechanical and computer techniques. This paper summarizes investigations as well as safety effects.

Locations of key body segments of Hybrid III dummies used in FMVSS 208 compliance tests and NCAP tests were measured and subjected to statistical analysis. Mean clearance dimensions and their standard deviations for selected body segments of driver and passenger occupants with respect to selected vehicle surfaces were determined for several classes of vehicles. These occupant locations were then investigated for correlation with impact responses measured in crash tests and by using a three dimensional human-dummy mathematical model in comparable settings. Based on these data, the importance of some of the clearance dimensions between the dummy and the vehicle surfaces was determined. The study also compares observed Hybrid III dummy positions within selected vehicles with real world occupant positions reported in published literature.

Since 1994, the New Car Assessment Program (NCAP) of the National Highway Traffic Safety Administration (NHTSA) has compiled upper neck loads for the belt and air bag restrained 50th percentile male Hybrid III dummy. Over five years from 1994 to 1998, in frontal crash tests, NCAP collected upper neck data for 118 passenger cars and seventy-eight light trucks and vans. This paper examines these data and attempts to assess the potential for neck injury based on injury criteria included in FMVSS No. 208 (for the optional sled test). The paper examines the extent of serious neck injury in real world crashes as reported in the National Automotive Sampling System (NASS). The results suggest that serious neck injuries do occur at higher speeds for crashes involving occupants restrained by belts in passenger cars.

In vehicle crash accidents, approximately 27% to 30% of passenger car occupant casualties are attributed to side impact accidents. The annual death toll in side impacts for passenger car occupants reached 9,000 in 1975 and 1976 and has been between 7,000 and 8,000 in the 1980's. Since 1977, the National Highway Traffic Safety Administration (NHTSA) and many other groups have conducted a significant amount of research on occupant side impact protection with emphasis on thorax injury reduction. Three important problem areas in the side impact are (1) thorax-to-side interior impact, (2) head impacts with A-pillar/roof rail components and (3) occupant ejection through side doors/windows. While the first problem area has been thoroughly studied, the remaining two areas are seldom discussed and less well understood. Therefore, they are relatively new areas to many people.

Motor vehicle fatalities are expected to continue their long term upward trend for the remainder of the 1980 decade to an annual rate of approximately 50,000 by 1990. The assumptions upon which this projection is based include a greater number of vehicles and drivers, increased travel and a higher rate of economic growth. Although the absolute number of fatalities is expected to increase, private and public safety efforts will result in a continuing decline in fatality risks per unit of travel.

A study was made of the incidence of traffic related injuries, the related disability and impairment, and the resulting economic consequences. Crash data covering the incidence of injuries and their distribution by injury type and severity show that nearly three and a half million persons per year are injured in traffic crashes, with roughly half of them experiencing at least one day of disability. Brain and spinal cord injuries, both believed to have long term consequences, were examined in greater detail. Epidemiological data covering these injuries indicate about 60,000 persons suffer disabling brain injuries and about 4,000 persons suffer disabling spinal cord injuries each year. These are significantly larger incidence values for these two injury types than shown by the crash data. There is little quantatative data on the disability and impairment resulting from traffic crashes, nor is there agreement on how to report such data.

Sixty-three simulated frontal impacts using cadaveric specimens were performed to examine and quantify the performance of various contemporary automotive restraint systems. Test specimens were instrumented with accelerometers and chest bands to characterize their mechanical responses during the impact. The resulting thoracic injury severity was determined using detailed autopsy and was classified using the Abbreviated Injury Scale. The ability of various mechanical parameters and combinations of parameters to assess the observed injury severities was examined and resulted in the observation that belt restraint systems generally had higher injury rates than air bag restraint systems for the same level of mechanical responses. To provide better injury evaluations from observed mechanical parameters without prior knowledge of what restraint system was being used, a dichotomous process was developed.

The SISAME methodology is a system for extracting one-dimensional lumped parameter vehicle crash models from non-oblique crash test data, and for simulation of such models. Model extraction is based on constrained least squares optimization of an overdetermined system of target equations for the model parameters. The SISAME computer program performs extraction and simulation with a number of features that allow user control of the computations and outputs. Additional computer programs perform data assessment/correction and filtering. Experience has shown that the SISAME methodology can efficiently produce predictively useful models that accurately capture the motions of the actual crash event. The essential formulation of SISAME and some sample applications are presented in this paper.

Head injuries are considered a significant safety problem for vehicle occupants involved in vehicle crashes. Although medical literature on the subject is extensive, the emphasis is mainly on the clinical and studies frequently involve data samples that are not representative to the vehicle occupant population. Also, research efforts on head injury have focused on the head rotational acceleration mechanism. The effect of head contact on brain injuries has not been adequately acknowledged and there has been disagreement regarding skull fracture and its relationship to brain injury. The human head, being an extremely complex structure, has many independent injury modes which cannot be described satisfactorily by a single brain injury mechanism. Many individual pathophysiological disturbances to the skull and its contents together comprise head injuries.

In the New Car Assessment Program (NCAP), beginning with the model year 1994 vehicles, the National Highway Traffic Safety Administration (NHTSA) developed and adopted a simplified nonnumeric format for presenting the comparative frontal crashworthiness safety information to consumers. This paper presents the basis for the development of this “star rating” system. The injury probability functions which are used for the star rating system are also applied to the results of the recent NCAP real-world correlation studies and a review of these studies is given. The safety performance for restrained occupants as measured in NCAP is dependent on several parameters which include: the design of the restraint system, the maintenance of the integrity of the occupant space, and the energy management performance of the front structure.

Since model year 1983, one hundred and seventy five light trucks, vans, and sport utility vehicles (LTVs) have been included in the New Car Assessment Program (NCAP) frontal crash tests. In this frontal test, vehicles are crashed at 35 mph such that the entire front impacts against a rigid, fixed barrier. Instrumented anthropometric dummies are placed in the driver and right front passenger seats. Accelerometers are placed on the vehicle to record the response of the structure during the crash. A number of recent papers have examined the compatibility of LTVs and cars in vehicle-to-vehicle collisions. The studies in these papers, generally, consider three factors for vehicle-to-vehicle compatibility: (1) mass, (2) stiffness, and (3) geometry. On June 5, 1998, Transport Canada and the National Highway Traffic Safety Administration held a forum entitled “Transport-NHTSA International Dialogue on Vehicle Compatibility,” in Windsor, Canada.

This report is a condensed version of the December 1993 New Car Assessment Program (NCAP) report to Congress and provides: an historical review and future goals for NCAP. the results of an 18-month study to assess consumer and media needs in understanding and promoting the use of NCAP data. This included consumer focus groups and media studies. These studies indicated that consumers and the media desire comparative safety information on vehicles, a simplified NCAP format to better understand and utilize the crash test results, and would like to see NCAP expanded to include other crash modes. studies of real-world crashes versus NCAP crash tests. These studies conclude that NCAP test conditions approximate real-world crash conditions covering a major segment of the frontal crash safety problem and that there is a significant correlation between NCAP results and real-world fatality risks for restrained drivers.

When the Hybrid III 10-year old (HIII-10C) anthropomorphic test device (ATD) was adopted into Code of Federal Regulations (CFR) 49 Part 572 as the best available tool for evaluating large belt-positioning booster seats in Federal Motor Vehicle Safety Standard (FMVSS) No. 213, NHTSA stated that research activities would continue to improve the performance of the HIII-10C to address biofidelity concerns. A significant part of this effort has been NHTSA’s in-house development of the Large Omnidirectional Child (LODC) ATD. This prototype ATD is comprised of (1) a head with pediatric mass properties, (2) a neck that produces head lag with Z-axis rotation at the atlanto-occipital joint, (3) a flexible thoracic spine, (4) multi-point thoracic deflection measurement capability, (5) skeletal anthropometry representative of a seated child, and (6) an abdomen that can directly measure belt loading.

Recently there has been a greater awareness of the increased risk of certain injuries associated with air bag deployment, especially the risks to small occupants, often women. These injuries include serious eye and upper extremity injuries and even fatalities. This study investigates the interaction of a deploying air bag with cadaveric upper extremities in a typical driving posture; testing concentrates on female occupants. The goals of this investigation are to determine the risk of upper extremity injury caused by primary contact with a deploying air bag and to elucidate the mechanisms of these upper extremity injuries. Five air bags were used that are representative of a wide range of air bag ‘aggressivities’ in the current automobile fleet. This air bag ‘aggressivity’ was quantified using the response of a dummy forearm under air bag deployment.

As Intelligent Transportation Systems (ITS) become more prevalent, the need to archive data from field tests becomes more critical. These data can guide the design of future systems, provide an information conduit among the many developers of ITS, enable comparisons across locations and time, and support development of theoretical models of driver behavior. The National Highway Traffic Safety Administration (NHTSA) is interested in such an archive. While a design for an ITS data archive has not yet been developed, NHTSA has supported the enhancement of the Test Planning, Analysis, and Evaluation System (Test PAES), originally developed by Calspan SRL Corporation for the U. S. Air Force Armstrong Laboratory, for possible use in such an archive. On a single screen, Test PAES enables engineering unit data, audio, and video, as well as a vehicle animation, to be time synchronized, displayed simultaneously, and operated with a single control.

This paper describes the results of a 2 year study into the field accident performances of two basic designs of energy-absorbing steering assemblies. The two basic designs are the axial-collapse type of steering column used in conjunction with a shear capsule and the self-aligning energy-absorbing steering wheel mounted on a nonstroking column. The study identifies major injury causation factors for these two types of steering assemblies. The analysis was performed on 161 accident cases selected for unrestrained drivers in frontal accidents in two vehicle types.

The National Highway Traffic Safety Administration (NHTSA) upgraded the side impact protection requirement in Federal Motor Vehicle Safety Standard (FMVSS) No. 214 and added dynamic requirements to reduce the likelihood of thoracic injuries in side crashes. As part of the agency's research in developing the requirements of the standard, NHTSA developed a mathematical model for simulation of side impacts. This paper investigates the overall safety performance, based on Thoracic Trauma Index (TTI) as the criteria for passenger cars in real world side crashes, with the aid of the simulation model. A Thoracic Trauma Index Factor (TTIF) is utilized to compare relative safety performance of passenger cars under various conditions of impact. The concept of relating energy dissipation in various side structure and padding countermeasures is used to develop a family of curves that are representative of a design platform.

In crashes between heavy trucks and light vehicles, most of the fatalities are the occupants of the light vehicle. A reduction in heavy truck stopping distance should lead to a reduction in the number of crashes, the severity of crashes, and consequently the numbers of fatalities and injuries. This study made use of the National Advanced Driving Simulator (NADS). NADS is a full immersion driving simulator used to study driver behavior as well as driver-vehicle reactions and responses. The vehicle dynamics model of the existing heavy truck on NADS had been modified with the creation of two additional brake models. The first was a modified S-cam (larger drums and shoes) and the second was an air-actuated disc brake system. A sample of 108 CDL-licensed drivers was split evenly among the simulations using each of the three braking systems. The drivers were presented with four different emergency stopping situations.

This paper describes computer crash simulations performed by the National Highway Traffic Safety Administration (NHTSA) under the current research and testing activities on large school bus safety restraints. The simulations of a frontal rigid barrier test and comparative dynamic sled testing for compartmentalization, lap belt, and lap/shoulder belt restraint strategies are presented. School bus transportation is one of the safest forms of transportation in the United States. School age children transported in school buses are safer than children transported in motor vehicles of any other type. Large school buses provide protection because of their size and weight. Further, they must meet minimum Federal motor vehicle safety standards (FMVSSs) mandating compartmentalized seating, improved emergency exits, stronger roof structures and fuel systems, and better bus body joint strength.