Search Results

Frontal crashes (11-1 o'clock) were reviewed from the National Accident Severity Study file (NASS) for years 1980-87. Adult drivers and front right passengers, with lower extremity injuries of the pelvis, thigh, knee, leg or ankle/foot were reviewed. Analysis of age differences, injury contacts, and effectiveness of the 3-point restraint system were studied. Unrestrained drivers have a higher frequency of knee injuries than passengers, fewer leg injuries than passengers and both have the same frequency of ankle/foot injuries. Older unbelted drivers have more injuries to the pelvis, leg, and ankle/foot region than do young drivers. Passengers have more leg injuries. The instrument panel is the major contact for most of the lower extremity injuries. Lap/shoulder belts significantly reduce lower extremity injury frequency.

The factors that influence airbag-induced upper-extremity injuries sustained by drivers were investigated in this study. Seven unembalmed human cadavers were used in nineteen direct-forearm-interaction static deployments. A single horizontal-tear-seam airbag module and two different inflators were used. Spacing between the instrumented forearm and the airbag module was varied from 10 cm to direct contact in some tests. Forearm-bone instrumentation included triaxial accelerometry, crack detection gages, and film targets. Internal airbag pressure was also measured. The observed injuries were largely transverse, oblique, and wedge fractures of the ulna or radius, or both, similar to those reported in field investigations. Tears of the elbow joint capsule were also found, both with and without fracture of the forearm.

Standing reach envelopes are important tools for the design of industrial and vehicle environments. Previous work in this area has focussed on manikin-based (where a few manikins are used to simulate individuals reaching within the region of interest) and population-based (where data are gathered on many individuals reaching in a constrained environment) approaches. Each of these methods has merits and shortfalls. The current work bridges the manikin- and population-based approaches to assessing reach by creating population models using kinematic simulation techniques driven by anthropometric data. The approach takes into account body dimensions, balance, and postural cost to create continuous models that can be used to assess designs with respect to both maximal and submaximal reaches. Cost is quantified as the degree to which the torso is involved in the reach, since the inclination of the torso is a good measure of lower-back load and may be related to subjective reach difficulty.

The ease of getting into and out of passenger cars and light trucks is a critical component of customer acceptance and product differentiation. In commercial vehicles, the health and safety of drivers is affected by the design of the steps and handholds they use to get into and out of the cab. Ingress/egress assessment appears to represent a substantial application opportunity for digital human models. The complexity of the design space and the range of possible biomechanical and subjective measures of interest mean that developing useful empirical models is difficult, requiring large-scale subject testing with physical mockups. Yet, ingress and egress motions are complex and strongly affected by the geometric constraints and driver attributes, posing substantial challenges in creating meaningful simulations using figure models.

Recent crash data was used to evaluate the safety performance of drivers who transport children. The age difference between drivers and children was found to be an important predictor of crash-related driving behavior and choices. Also, certain driver behaviors and choices when transporting children were identified as creating elevated risk. This study provides information that parents might use to reduce risk when their children are riding with other drivers. The results may also be of interest to professionals concerned with graduated licensing and the establishment and enforcement of laws relating to child endangerment such as drinking and driving with child passengers.

The National Highway Traffic Safety Administration and the University of Michigan Transportation Institute are investigating truck design countermeasures to provide safety benefits during collisions with light vehicles. The goal is to identify approaches that would best balance costs and benefits. This paper outlines the first phase of this study, an analysis of two-vehicle, truck/light vehicle crashes from 1996 through 1998 using several crash data bases to obtain a current description and determine the scope of the aggressivity problem. Truck fronts account for 60% of light vehicle fatalities in collisions with trucks. Collision with the front of a truck carries the highest probability of fatal (K) or incapacitating (A) injury. Truck sides account for about the same number of K and A-injuries combined as truck fronts, though injury probability is substantially lower than in crashes involving the front of a truck.

Effective application of human figure models to truck interior design requires accurate data on the postures and positions of truck drivers. Errors in positioning of figure models propagate to errors in reach, visibility, and other analyses. This paper describes methods used in a recent study to measure in-vehicle driving postures in Class 6, 7, and 8 trucks. A three-dimensional coordinate measurement machine was used to measure body landmark locations after a driver completed a short road course. The data were used to validate posture-prediction models developed in a previous laboratory study. Vehicle calibration, driver selection, and testing methods are reviewed.

The effects of child safety seats have been well documented in the medical literature. Scattered throughout the medical literature are individual case reports of cervical injury to children restrained in child restraint systems. A review of the literature is provided identifying previous documented cases. The authors also provide new case details of children with cervical spine injury without head contact. An overview of the growth of the infant and specific details in the cervical spine that may contribute to significant cervical injury without head impact is presented.

Crash injury reduction via lap-shoulder belt use has been well documented. As any interior car component, lap-shoulder belts may be related to injury in certain crashes. Relatively unknown is the fact that cervical fractures or fracture-dislocations to restrained front seat occupants where, in the crash, no head contact was evidenced by both medical records and car inspection. An extensive review of the available world's literature on car crash injuries revealed more than 100 such cases. A review of the NASS 80-88 was also conducted, revealing more examples. Cases from the author's own files are also detailed.

A person's ability to perform a task is often limited by their ability to maintain balance. This is particularly true in lateral work performed in seated environments. For a truck driver operating the shift lever of a manual transmission, excessive shift forces can necessitate pulling on the steering wheel with the other hand to maintain balance, creating a potentially unsafe condition. An analysis of posture and balance in truck shifter operation was conducted using balance limits to define the acceptable range of shifter locations. The results are dependent on initial driver position, reach postures, and shoulder strength. The effects of shifter force direction and magnitude were explored to demonstrate the application of the analysis method. This methodology can readily be applied to other problems involving hand-force exertions in seated environments.

The road damage caused by heavy trucks is accentuated by the dynamic loads excited by roughness in the road. Simulation models of trucks are used to predict dynamic wheel loads, but special models are required for tandem suspensions. Parameter values to characterize tandem suspension systems can be measured quasi-statically on a suspension measurement facility, but it is not known how well they fit dynamic models. The dynamic behavior of leaf-spring and air-spring tandem suspensions were measured on a hydraulic road simulator using remote parameter characterization techniques. The road simulator tests were duplicated with computer simulations of these suspensions based on quasi-static parameter measurements to compare dynamic load performance. In the case of the walking-beam suspension, simulated performance on the road was compared to experimental test data to evaluate the ability of the walking-beam model to predict dynamic load.

Tilt-table testing is one means of quantifying the static roll stability of highway vehicles. By this technique, a test vehicle is subjected to a physical situation analogous to that experienced in a steady state turn. Although the analogy is not perfect, the simplicity and fidelity of the method make it an attractive means for estimating static rollover threshold. The NHTSA has suggested the tilt-table method as one means of regulating the roll stability properties of light trucks and utility vehicles. One consideration in evaluating the suitability of any test method for regulatory use is repeatability, both within and among testing facilities. As a first step toward evaluating the repeatability of the tilt-table method, an experimental study examining the sensitivity of tilt-table test results to variables associated with methodology and facility was conducted by UMTRI for the Motor Vehicle Manufacturers Association. This paper reports some of the findings of that study.

Late model passenger cars and light trucks incorporate occupant protection systems with airbags and knee restraints. Knee restraints have been designed principally to meet the unbelted portions of FMVSS 208 that require femur load limits of 10-kN to be met in barrier crashes up to 30 mph, +/- 30 degrees utilizing the 50% male Anthropomorphic Test Device (ATD). In addition, knee restraints provide additional lower-torso restraint for belt-restrained occupants in higher-severity crashes. An analysis of frontal crashes in the University of Michigan Crash Injury Research and Engineering Network (UM CIREN) database was performed to determine the influence of vehicle, crash and occupant parameters on knee, thigh, and hip injuries. The data sample consists of drivers and right front passengers involved in frontal crashes who sustained significant injuries (Abbreviated Injury Scale [AIS] ≥ 3 or two or more AIS ≥ 2) to any body region.

Although driver-side airbag systems provide protection against serious head and chest injuries in frontal impacts, injuries produced by the airbag itself have also been reported. Most of these injuries are relatively minor, and consist primarily of skin abrasions and burns. Previous investigations have addressed the mechanisms of airbag-induced skin abrasion. In the current research, laboratory studies related to the potential for thermal burns due to high-temperature airbag exhaust gas were conducted. A laboratory apparatus was constructed to produce a 10-mm-diameter jet of hot air that was directed onto the leg skin of human volunteers in time-controlled pulses. Skin burns were produced in 70 of 183 exposures conducted using air temperatures ranging from 350 to 550°C, air velocities from 50 to 90 m/s, and exposure durations from 50 to 300 ms.

The objective of this analysis is to evaluate the effectiveness of restraints in preventing injury-producing contacts of specific body regions, such as the head or chest, with specific interior components. In order to make comparisons by restraint use, an injury rate is calculated as the number of injury-producing contacts per hundred involved occupants. Data, including the Occupant Injury Classification (OIC), are from the 1988-92 National Accident Sampling System (NASS) Crashworthiness Data System (CDS). The analysis presented is limited to passenger vehicle drivers in towaway, frontal impacts. Injury-producing contact rates are compared for four restraint configurations: unrestrained, three-point belted, driver airbag alone, and driver airbag plus three-point belt. For each restraint configuration, contact rates are compared by three categories of injury severity, AIS 1, AIS 2, and AIS 3-6, body region injured, and contact area producing the injury.

An appropriately contoured lumbar support is widely regarded as an essential component of a comfortable auto seat. A frequently stated objective for a lumbar support is to maintain the sitter's lumbar spine in a slightly extended, or lordotic, posture. Although sitters have been observed to sit with substantial lordosis in some short-duration testing, long-term postural interaction with a lumbar support has not been documented quantitatively in the automotive environment. A laboratory study was conducted to investigate driver posture with three seatback contours. Subjects† from four anthropometric groups operated an interactive laboratory driving simulator for one-hour trials. Posture data were collected by means of a sonic digitizing system. The data identify driver-selected postures over time for three lumbar support contours. An increase of 25 mm in the lumbar support prominence from a flat contour did not substantially change lumbar spine posture.

This paper summarizes how modem computer simulation methods have been used to develop a “fleet” of heavy truck simulation programs called TruckSim Kinematical and dynamical modeling assumptions appropriate for simulating the general three-dimensional behavior of heavy trucks are described to the extent needed to construct such a model in a multibody program such as the AUTOS1M symbolic code generator Alternative kinematical assumptions were tested and compared to determine their influence on the simulation efficiency and accuracy As part of the validation, simulation results for the new programs were compared with results obtained with an older program that was developed by hand

This paper describes an ongoing effort to develop computer-simulated instrumentation for the UMTRI Driver Interface Research Simulator. The speedometer, tachometer, engine and fuel gauges, along with warning lights are back projected onto a screen in front of the driver. The image is generated by a Macintosh running LabVIEW. Simulated instrumentation (instead of a production cluster) was provided so that new display designs can be rapidly generated and tested. This paper addresses the requirements for prototyping software, the advantages and disadvantages of the packages available, and the UMTRI implementation of the software, and its incorporation into the driving simulator.

This study examined perceptual adaptation to nonplanar (spherical convex and aspheric) rearview mirrors. Subjects made magnitude estimates of the distance to a car seen in a rearview mirror. Three different mirrors were used: plane, aspheric (with a large spherical section having a radius of 1400 mm), and simple convex (with a radius of 1000 mm). Previous research relevant to perceptual adaptation to nonplanar mirrors was reviewed. It was argued that, in spite of some cases of explicit interest in the process of learning to use nonplanar mirrors, previous research has not adequately addressed the possibility of perceptual adaptation. The present experiment involved three phases: (1) a pretest phase in which subjects made distance judgments but received no feedback, (2) a training phase in which they made judgments and did receive feedback, and (3) a posttest phase with the same procedure as the pretest phase.

In a review of 540 crashes in which the steering-wheel airbag deployed, 38% of the drivers sustained some level of upper extremity injury. The majority of these were AIS-1 injuries including abrasions, contusions and small lacerations. In 18 crashes the drivers sustained AIS-2 or-3 level upper extremity injuries, including fractures of the radius and/or ulna, or of the metacarpal bones, all related to airbag deployments. It was determined that six drivers sustained the fracture(s) directly from the deploying airbag or the airbag module cover. The remaining 12 drivers had fractures from the extremity being flung into interior vehicle structures, usually the instrument panel. Most drivers were taller than 170 cm and, of the 18 drivers, 10 were males.