Occupant Compartment Research Articles

Firearms and Fatalities-Reply

In Reply. —Dr Blackman suggests that the public health paradigm may not be appropriate for motor vehicle crashes and may not be applicable to firearm injuries. We think the public health paradigm is useful for organizing information and identifying prevention strategies along logical and consistent lines. This epidemiologic triad helps us view deaths and injuries as resulting from interactions of the host, vehicle/ agent, and environment. Deaths and injuries can be reduced by changing the relationship of these factors, and the reduced speed limits and improved emergency medical responses that Blackman mentions are good examples of how changes in the environment affect motor vehicle crash injuries. Changes in vehicular design, including air bags, seat belts, and crashworthy occupant compartments, and constructive changes in human behavior by reduced drunk driving have further contributed to the reduction in motor vehicle crash deaths and form the second and third parts of the triad.

Firearms and fatalities

<h3>In Reply.</h3> —Dr Blackman suggests that the public health paradigm may not be appropriate for motor vehicle crashes and may not be applicable to firearm injuries. We think the public health paradigm is useful for organizing information and identifying prevention strategies along logical and consistent lines. This epidemiologic triad helps us view deaths and injuries as resulting from interactions of the host, vehicle/ agent, and environment. Deaths and injuries can be reduced by changing the relationship of these factors, and the reduced speed limits and improved emergency medical responses that Blackman mentions are good examples of how changes in the environment affect motor vehicle crash injuries. Changes in vehicular design, including air bags, seat belts, and crashworthy occupant compartments, and constructive changes in human behavior by reduced drunk driving have further contributed to the reduction in motor vehicle crash deaths and form the second and third parts of the triad.

A study of injury-producing crashes on median divided highways in southwestern Ontario

The University of Western Ontario Accident Research Team investigates every fatal crash, and approximately one out of every 50 personal-injury crash, within a defined geographic area of three counties. Over a seven-year period, the team investigated 107 collisions (62 fatal and 45 personal injury) that occurred on median-divided highways. These crashes were representative of over 2,300 collisions on the highways involving 81 fatalities and injury to over 3,200 vehicle occupants. Vehicle loss of directional control prior to any impact occurred in 55 of the 62 fatal cases and in 36 of the 45 personal-injury cases. In 36 fatal cases and 17 personal-injury cases loss of control was initiated after a vehicle travelled from the roadway onto the gravel shoulder. Rollover collisions were the most frequent collision type investigated and comprised 25 fatal and 25 personal-injury cases. Unrestrained occupants made up 24 of the 29 rollover fatalities with 96% of these unrestrained occupants being ejected from the vehicle. Collision with an oncoming vehicle after median-crossover occurred in 26 fatal cases. These crashes were usually frontal or side impacts characterized by extensive vehicle damage and massive intrusion into the occupant compartment. Severe head injury (AIS 5 or greater) predominated as the cause of death in all collision types.

Fatal injuries to restrained passenger car occupants in Canada: Crash modes and kinematics of injury

Passenger car collisions with other vehicles and with fixed objects were studied from a representative sample of fatal and injury-producing collisions collected according to a prescribed sampling plan. This paper describes our analysis of accidents involving restrained passenger car occupants who are fatally injured in collisions. Lateral collisions were found to be predominant, and both lateral and frontal collisions were associated with marked intrusion into the occupant compartment, causing direct, severe injuries to the head and chest of these occupants. Multiple severe injuries to more than one body region were common, and 90% of these victims died within one hour of the collision. The seat belt generally offered no protection to these fatally injured occupants. Reducing the incidence of fatal injury to properly restrained passenger car occupants will necessitate diminishing these very severe intrusion forces, especially from heavy trucks and fixed vertical hazards. For vehicle design modifications to be effective, it appears likely that roadway and roadside design and management must be included in the safety equation. Excessive speeds, inadequate traffic control, and unforgiving roadside hazards are playing a major role in the incidence of fatal injuries documented in this study.

CAUSES AND COSTS OF INJURIES IN MULTIPLE TRAUMA PATIENTS REQUIRING EXTRICATION FROM MOTOR VEHICLE CRASHES

Prospective and contemporaneous medical and economic cost studies of 144 victims of motor vehicle crashes admitted to a regional level I trauma center with multiple injuries (ISS > or = 16) revealed 122 non-ejected patients, of whom 102 required extrication (EXTRIC) from the vehicle for physical or medical reasons and 20 who did not (N group). There were no differences in age (EXTRIC, 34 +/- 17 years; N, 41 +/- 24 years), type of crash (Frontal: 57% EXTRIC, 60% N; Lateral: 32% EXTRIC, 35% N) restraint use (35% EXTRIC, 35% N), or mortality (29% EXTRIC, 30% N). However, the estimated maximum speed before the crash was higher in EXTRIC patients (50 +/- 16 mph vs. 46 +/- 18 mph N, p < 0.04), as was the change in velocity (delta V) on impact (EXTRIC 30 +/- 15 mph; N, 24 +/- 8 mph, p < 0.01). Brain injuries (51% EXTRIC vs. 35% N) and lower extremity injuries were more numerous in EXTRIC patients (59% vs. 20% N, p < 0.003) and the number of splenic, lower extremity, and pelvic injuries associated with shock was greater in EXTRIC patients, p < 0.02; as were postinjury complications. As a result, operating room costs from orthopedic and plastic surgery increased professional charges in the EXTRIC group versus the N group ($20,000, EXTRIC; $17,000, N) and critical care costs ($13,000, EXTRIC; $4,000, N) with total costs of $72,000 and $77,000, respectively. The lower extremity injuries in EXTRIC patients were primarily a result of body part contacts with intrusions (CIs) of the car occupant compartment structures [73% with vs. 24% without (p < 0.0001)]. In lateral MVCs, brain injuries were also more commonly associated with CIs of the side window frame or A pillar (72% CI vs. 25% no CI; p < 0.035); but as a whole in MVCs in which extrication was necessary, lower extremity injuries from instrument panel or toepan CIs appeared more frequent than those resulting from contacts only (p < 0.0001). In EXTRIC patients, 69% of those in shock had CI injuries, and 80% of the deaths in the EXTRIC group were associated with CI injury. These data suggest that measures designed to prevent CIs by strengthening car passenger compartment structures may reduce the incidence of severe brain and lower extremity injuries and may reduce the need for extrication after MVCs.

SAFETY BELT RESTRAINTS AND COMPARTMENT INTRUSIONS IN FRONTAL AND LATERAL MOTOR VEHICLE CRASHES: MECHANISMS OF INJURIES, COMPLICATIONS, AND ACUTE CARE COSTS

A 3-year prospective study examined 76 frontal (F) and 45 lateral (L) motor vehicle crash (MVC) patients with regard to seatbelt restraint use and occupant compartment contact and intrusion injuries. These 121 MVC victims with multiple injuries (39 belted [B] and 82 non-belted [NB]), admitted to a level I trauma center, were studied by accident reconstruction and medical data analysis. They had a MVC mean impact velocity (delta V) of 30 +/- 11 mph and an injury Severity Score of 29 +/- 12. Proper restraint use reduced brain injury in F MVCs (30% FB vs. 47% FNB) but had no effect in L MVCs (63% LB vs. 30% FB [p < 0.06]). Belt use did not protect against lung, liver, spleen, pelvis, or lower extremity (LE) injury. These appeared to be more a function of crash direction, with LE injuries higher in F crashes (p < 0.04) and pelvis injuries (p < 0.001) higher in L crashes. In FB crashes, however, properly used safety restraints were the primary cause of bowel or colon injuries (p < 0.006). Belts did not prevent thoracic or abdominal solid organ injuries in L crashes. Contact-intrusions (CI) of the car occupant compartment in F crashes were the main cause of brain (A-pillar), lung and liver (steering wheel and instrument panel), and LE (toepan) injuries; but in L crashes, side-door CI caused lung, aorta, liver, and pelvic injuries. In contrast, contact-only (CO) injuries of the steering assembly were mainly responsible for injuries to the lung, heart, and liver in F crashes, and side-door CO for lung, liver, and spleen injuries in L crashes. Deaths and complications after injury were higher among F MVC occupants, or when delta V was > or = 30 mph. Hospital and professional costs reflect the complex care needed for victims of multiple injuries: FB, $99,000; FNB, $95,000; LB, $75,000; LNB, $79,000; total, $10.7 million. Present vehicle safety standards are not adequate, and structural design changes are needed to improve restraints and protect occupants from intrusion-related injuries.

Head and neck dynamics in an automobile rollover

The purpose of the study was to investigate the effect of roof deformation and head clearance on the dynamic forces transmitted to the head and neck of a restrained occupant in an automobile rollover. A modified version of the Total Articulated Body three-dimensional model was used. The occupant was modeled using fifteen segments connected by fourteen joints. These segments represented the lower torso, center torso, upper torso, neck, head, right upper leg, right lower leg, right foot, left upper leg, left lower leg, left foot, right upper arm, right lower arm, left upper arm, and left lower arm. The automobile was modeled as primary and secondary vehicle segments. The primary vehicle was modeled by 16 contact planes representing the seat cushion, seat back, floor-board, toe-board, left header, windshield, lower dash, mid-dash, instrument panel, left door, right door, fire-wall, footwell, upper dash, header, and latch. The secondary vehicle simulated the intrusion of the roof into the occupant compartment. A lap belt and a shoulder harness were used to hold the occupant in the driver seat. The components of the vehicle and the ground were represented by planes with specified contacts with body segments. Occupant motions indicated various dynamic contacts with the vehicle interior. Higher forces were generally associated with increased accelerations between the occupant's segments (e.g., head) and the vehicle planes (e.g., roof). Increased roof crush increased the forces transmitted to the head-neck region of the occupant. Increased head clearance for a given roof deformation decreased the forces transmitted to the occupant's head and neck. Without roof crush minimal forces were produced. These simulations indicate that for a restrained non-ejected occupant, there is a critical combination of roof crush and head clearance for a given roll velocity that limits the dynamic forces transmitted to the occupant's head and neck. Beyond this threshold an increase in transmitted forces may lead to injury.

Injury patterns for occupants of small trucks

A limited number of studies have been completed on the factors contributing to accident-related injuries sustained by occupants of pickup trucks. The increasing number and changing pattern of use of light trucks necessitates the need to critically review this vehicle type with respect to contributing accident factors and associated injuries. This paper investigates the injury mechanisms of occupants of pickup trucks and the surfaces that the occupants contact in roadway accidents. Selection of cases from the Canadian vehicle database was based on the location of the vehicles' most severe impact deformation. The overall occupant injury severity was examined with respect to impact location, impact speed, and magnitude of occupant compartment intrusion. The results of the investigation illustrate the benefits of seat belt restraint use. In addition, identification of frequent injury contact surfaces establishes a reference for improved vehicle design initiatives and standards.

Injuries to unrestrained occupants in small car-small car and large car-large car head-on collisions

Estimates were made of the effects of observed differences in the crash responses of small and large cars on the likelihood of injury to unrestrained occupants in small car-small car and large car-large car head-on collisions using a simple spring-mass model. Two measures of the likelihood of injury were computed: the relative velocity of an unrestrained occupant and car at the instant the occupant strikes the interior, and the approximate closing speed at which occupant compartment intrusion would be expected to begin. Model estimates of the intrusion thresholds for large ear-large car and small car-small car head-on crashes were comparable. However, unrestrained occupants were predicted to strike the interiors of their cars at a lower relative velocity in a head-on crash involving two large cars than in a similar crash involving two small cars. Head-on crashes involving a large and small car were also modelled for purposes of comparison. The estimated intrusion thresholds for small cars in such crashes were considerably lower than in small car-small car crashes. Also, calculations indicated that in a small car-large car head-on crash, an unrestrained small car occupant strikes the interior of his car with a higher relative velocity than an unrestrained large car occupant, and this velocity is higher than if his car struck another small car. However, the difference in the relative velocities with which unrestrained small and large car occupants impact the interiors of their cars in small car-large car collisions was found to diminish with increasing closing speed. These results suggest that the frontal structures of small cars should be longer and less stiff than on current models and the occupant compartment should be stiffer. Such designs would help to reduce injuries to restrained and unrestrained small car occupants in collisions with both small and large cars.

In depth study of seriously injured seat belt wearers : Traffic Accident Research Unit, Department of Motor Transport, New South Wales, Australia, Report No 1/77, June 1977, 134 pp.

In depth studies of vehicles and injuries were made following hospitalization of 142 persons who wore seat belts during crashes in or about the city of Sydney. Most of the studied crashes involved car to car collisions. Main hazards were found to be narrow unyielding parts of car interiors which could be reached by heads, chest, pelvises or limbs of seat belt wearers. Seat belts were often adjusted loosely, in a few cases they broke and in some cases they transmitted forces to chest or abdomen which resulted in severe to serious injuries. Several of these cases involved unrestrained rear seat occupants pushing seat backs on to front seat belt wearers to substantially increase the forces in the seat belts. Reduction of injuries would be expected from redesigning occupant compartments to reduce the presentation of narrow unyielding surfaces or edges to occupants. Application of thick, stiff padding is needed on surfaces within reach of occupants, and more distant or yielding window glass might be beneficial. Some occupants would be helped by more strongly attached seats, others by more reliably attached engine bonnets. Further study of the effects of recent measures dealing with seat belt adjustment and strength is recommended. (A) this report is the project report on impact 2, the title of the study.

A national program for fire safety in transportation

The rule making process in all U.S.A. government agencies as well as the Department of Transportation is more and more coming into question by the Congress and the public with regard to its efficacy. Safety, environment, energy, ecology, effectiveness and economy are all major concerns of the public today. Yet, the question of how one might generate rules that provide for maximizing or minimizing each of these major concerns with regard to the flammability of materials in the occupant compartment of vehicles has not been explored in a methodical manner. Secretary Coleman has requested administrators of the various modal agencies under his direction to develop procedures and methodologies whereby these concerns can be addressed before the fact rather than reacting to public outcries and Congressional admonition. It is the intent of this paper to lay out a basic program highlighting key ideas with the minimal amount of demonstration in order to set into motion considered thinking on the subject of new methodology development in rule making.