Should airbags be deactivated for wheelchair-seated drivers?

Objective: Field data have shown significant benefit from driver airbag for occupant protection in frontal crashes. However, vehicle modifiers almost always permanently deactivate airbags for wheelchair-seated drivers. The objective of this study was to conduct sled tests and computational simulations to answer whether driver airbags should be deactivated for drivers seated in wheelchairs.

Validation of a parametric finite element human femur model.

Objective: Finite element (FE) models with geometry and material properties that are parametric with subject descriptors, such as age and body shape/size, are being developed to incorporate population variability into crash simulations. However, the validation methods currently being used with these parametric models do not assess whether model predictions are reasonable in the space over which the model is intended to be used. This study presents a parametric model of the femur and applies a unique validation paradigm to this parametric femur model that characterizes whether model predictions reproduce experimentally observed trends.

Response and Tolerance of Female and/or Elderly PMHS to Lateral Impact.

Eight whole fresh-frozen cadavers (6 female, 2 male) that were elderly and/or female were laterally impacted using UMTRI's dual-sled side-impact test facility. Cadavers were not excluded on the basis of old age or bone diseases that affect tolerance. A thinly padded, multi-segment impactor was used that independently measured force histories applied to the shoulder, thorax, abdomen, greater trochanter, iliac wing, and femur of each PMHS.

PMHS impact response in 3 m/s and 8 m/s nearside impacts with abdomen offset.

Lateral impact tests were performed using seven male post-mortem human subjects (PMHS) to characterize the force-deflection response of contacted body regions, including the lower abdomen. All tests were performed using a dual-sled, side-impact test facility. A segmented impactor was mounted on a sled that was pneumatically accelerated into a second, initially stationary sled on which a subject was seated facing perpendicular to the direction of impact.

Biomechanical considerations for assessing interactions of children and small occupants with inflatable seat belts.

NHTSA estimates that more than half of the lives saved (168,524) in car crashes between 1960 and 2002 were due to the use of seat belts. Nevertheless, while seat belts are vital to occupant crash protection, safety researchers continue efforts to further enhance the capability of seat belts in reducing injury and fatality risk in automotive crashes. Examples of seat belt design concepts that have been investigated by researchers include inflatable, 4-point, and reverse geometry seat belts.

Safety, usability, and independence for wheelchair-seated drivers and front-row passengers of private vehicles: a qualitative research study.

A survey and observational study was conducted with 29 people who remain seated in their wheelchair when driving (21) or riding as a front-row passenger (8) in their personal vehicle. Each subject was observed and surveyed in their own personal vehicle that has been modified for use by occupants seated in wheelchairs. Our survey obtained responses on issues related to occupant restraint (seat belt) system usage, wheelchair securement device usage, and perception of personal safety while riding in a vehicle.

Descriptions of motor vehicle collisions by participants in emergency department-based studies: are they accurate?

Introduction: We examined the accuracy of research participant characterizations of motor vehicle collisions (MVC).

Methods: We conducted an emergency department-based prospective study of adults presenting for care after experiencing an MVC. Study participants completed a structured clinical interview that assessed the number of lanes of the road where the collision took place, vehicle type, road condition, speed limit, seat belt use, airbag deployment, vehicle damage, time of collision, and use of ambulance transportation.

RESNA's position on wheelchairs used as seats in motor vehicles.

This position paper is based on the premise that those who ride seated in wheelchairs are entitled to equivalent occupant safety when they are traveling in motor vehicles. The document summarizes research and best practice for safety and selection of crashworthy wheelchairs with the requisite features required by the WC19 safety standard when it is necessary for individuals to use a wheelchair as a seat in a motor vehicle. Recommendations are based on data from accident and injury databases, prior research and a synopsis of the design, testing, performance and labeling requirements of ANSI and ISO voluntary industry standards for wheelchair transportation safety.

Biomechanical assessment of a rear-seat inflatable seatbelt in frontal impacts.

This study evaluated the biomechanical performance of a rear-seat inflatable seatbelt system and compared it to that of a 3-point seatbelt system, which has a long history of good real-world performance. Frontal-impact sled tests were conducted with Hybrid III anthropomorphic test devices (ATDs) and with post mortem human subjects (PMHS) using both restraint systems and a generic rear-seat configuration. Results from these tests demonstrated: a) reduction in forward head excursion with the inflatable seatbelt system when compared to that of a 3-point seatbelt and; b) a reduction in ATD and PMHS peak chest deflections and the number of PMHS rib fractures with the inflatable seatbelt system and c) a reduction in PMHS cervical-spine injuries, due to the interaction of the chin with the inflated shoulder belt.

Effect of frozen storage on dynamic tensile properties of human placenta.

Dynamic mechanical properties of placenta tissue are needed to develop computational models of pregnant occupants for use in designing restraint systems that protect the fetus and mother. Tests were performed on 21 samples obtained from five human placentas at a rate of 1200 %/s using a set of custom designed thermoelectrically cooled clamps. Approximately half of the samples from all five subjects were tested within 48 h of delivery.

BioTab--a new method for analyzing and documenting injury causation in motor-vehicle crashes.

Objective: To describe a new method for analyzing and documenting the causes of injuries in motor vehicle crashes that has been implemented since 2005 in cases investigated by the Crash Injury Research Engineering Network (CIREN).

Methods: The new method, called BioTab, documents injury causation using evidence from in-depth crash investigations. BioTab focuses on developing injury causation scenarios (ICSs) that document all factors considered essential for an injury to have occurred as well as factors that contributed to the likelihood and/or severity of an injury.

Factors associated with abdominal injury in frontal, farside, and nearside crashes.

The NASS-CDS (1998-2008) and CIREN datasets were analyzed to identify factors contributing to abdominal injury in crash environments where belt use and airbag deployment are common. In frontal impacts, the percentage of occupants sustaining abdominal injury is three times higher for unbelted compared to belted front-row adult occupants (p<0.0001) at both AIS2+ and AIS3+ injury levels.

Applying basic principles of child passenger safety to improving transportation safety for children who travel while seated in wheelchairs.

Occupant restraint systems are designed based on knowledge of crash dynamics and the application of proven occupant-protection principles. For ambulatory children or children who use wheelchairs but can transfer out of their wheelchair when traveling in motor vehicles, there is a range of child safety seats that comply with federal safety standards and that therefore offer high levels of crash protection. For children who remain seated in wheelchairs for travel, the use of wheelchairs and wheelchair tiedown and occupant restraint systems (WTORS) that comply with voluntary industry standards significantly enhances safety.

A stochastic visco-hyperelastic model of human placenta tissue for finite element crash simulations.

Placental abruption is the most common cause of fetal deaths in motor-vehicle crashes, but studies on the mechanical properties of human placenta are rare. This study presents a new method of developing a stochastic visco-hyperelastic material model of human placenta tissue using a combination of uniaxial tensile testing, specimen-specific finite element (FE) modeling, and stochastic optimization techniques. In our previous study, uniaxial tensile tests of 21 placenta specimens have been performed using a strain rate of 12/s.

Predicting the effects of muscle activation on knee, thigh, and hip injuries in frontal crashes using a finite-element model with muscle forces from subject testing and musculoskeletal modeling.

In a previous study, the authors reported on the development of a finite-element model of the midsize male pelvis and lower extremities with lower-extremity musculature that was validated using PMHS knee-impact response data. Knee-impact simulations with this model were performed using forces from four muscles in the lower extremities associated with two-foot bracing reported in the literature to provide preliminary estimates of the effects of lower-extremity muscle activation on knee-thigh-hip injury potential in frontal impacts. The current study addresses a major limitation of these preliminary simulations by using the AnyBody three-dimensional musculoskeletal model to estimate muscle forces produced in 35 muscles in each lower extremity during emergency one-foot braking.

State of the science workshop on wheelchair transportation safety.

The Rehabilitation Engineering Research Center on Wheelchair Transportation Safety held a state-of-the-science workshop on wheelchair transportation. The workshop had three purposes: reviewing and documenting the status of wheelchair transportation safety, identifying deficiencies, and formulating, discussing, and prioritizing recommendations for future action. The final goal was to disseminate the workshop outcomes for utilization in formatting future research priorities.

Using in-depth investigations to identify transportation safety issues for wheelchair-seated occupants of motor vehicles.

In-depth investigations of motor-vehicle crashes involve detailed inspection, measurement, and photodocumentation of vehicle exterior and interior damage, evidence of belt-restraint use, and evidence of occupant contacts with the vehicle interior. Results of in-depth investigations thereby provide the most objective way to identify current and emerging injury problems and issues in occupant safety and crash protection, and provide important feedback on the real-world performance of the latest restraint-system and vehicle crashworthiness technologies. To provide an objective understanding of real-world transportation safety issues for wheelchair-seated travelers, the University of Michigan Transportation Research Institute (UMTRI) has been conducting and assembling data from in-depth investigations of motor-vehicle crashes and non-crash adverse moving-vehicle incidents, such as emergency vehicle braking, turning, and swerving, in which there was at least one vehicle occupant sitting in a wheelchair.

WC19: a wheelchair transportation safety standard--experience to date and future directions.

ANSI/RESNA WC19 (i.e., WC19) is a voluntary standard that specifies design and performance requirements for wheelchairs that are suitable for use as seats in motor vehicles.