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AUTOMOTIVE SEATS AND SEAT BACKS: By Edward M. Ricci, Esq. FOREWORD For a long time we have all been concerned about the safety of our children riding in car seats. The media has done a good job of educating the public to the dangers of most portable child seats. But what about the seats that come with the car? The ones that adults use. There has been a conspiracy of silence about defects in standard car seats. Flimsy car seats are collapsing in otherwise harmless collision, killing and maiming thousands of people each year. As federal regulators refuse to regulate and auto manufacturers dodge their duty to provide safe products, a tragedy grows in the darkness of ignorance. The victims of poor seat back construction range from Gloria Gray, a 67-year-old grandmother who died after her car was rear-ended and collided with a truck; to former GM engineer Junior Day, who suffers chronic pain and diminished mental capacity after he lost control of his car when his seat collapsed.1 Unfortunately, there is a long history of seat back failures. Government and industry have known of these defects for years. Despite relatively simple and inexpensive design changes, little has been done to ensure occupant safety. Finally, there is a ray of hope for the motoring public. Victims and their families now are insisting that the broken promises of federal safety officials be remedied and auto makers redress their wrongs. They want people to enter their cars and trucks knowing their safety was a paramount importance when the vehicles were designed and built. They want the comfort of knowing their seats are safe. INTRODUCTION Each year 1,200 people die in rear end car accidents, and many thousands more are seriously injured. A large number of these deaths and injuries, probably the great majority, are caused by the partial or total failure of the restraint systems that should be protecting car occupants in rear-end impacts. To most of us, the term "restraint systems" means seat belts and air bags. Most motorists know that properly designed seat belts and air bags are able to provide protection in frontal crashes at speeds in the 30-40 mph range. However, few of us know what kind of restraint protection is being provided in rear-end crashes. We assume it's adequate, when in fact it's dreadfully inadequate. The reason for our false comfort is most car companies and the National Highway Traffic Safety Administration (NHTSA), which talk a great deal about "buckling up for safety" have remained silent about rear-end seat back crash protection. In front-end crashes, the vehicle's forward movement is abruptly stopped. Seat belts keep the occupants from hurdling forward. Air bags do the same thing. The goal is to maintain the occupant in an upright position and to prevent his/her body from striking into hard surfaces, other occupants or from being ejected out of the car. When a car is hit from the rear, the forces are in the opposite direction. The car is abruptly propelled forward, and occupants are thrown backwards. The objective of a seat back is to act as a restraint system in rear-end crashes. Just the way a seat belt holds one in the seat and restricts forward motion, a seat back restricts rearward motion in a rear-end crash. The seat back should maintain the occupant in an upright position and prevent his/her body from striking hard surfaces or other people in the car and prevent the occupant from being ejected out windows or doors. In short, a seat back in a rear-end collision should function just like a seat belt in a front-end condition. If a seat back stays in place, remaining upright while cushioning and containing the occupant's body, it acts just like an effective seat belt or air bag. But if the seat back collapses, the occupant can be ejected, striking his/her head on the rear seat or floor, or collide with another occupant, or traumatically flex the upper spinal column over the top of the seat back. In real world, rear-end crashes, at speeds as low as 12 mph, flimsy seat backs are failing to provide adequate restraint protection. Fully investigated "fender bender" cases dramatically demonstrate that seat back failures in low impact accidents have resulted in inexcusably severe or fatal injuries. Poorly designed, "adjustable" head restraints are adding to the hazard because these head rests can be pushed down flush with the top of the seat back, thus allowing the front seat occupant's head to pivot over the head rest rearward causing severe spinal injury, even quadriplegia. It is not a simple engineering task to design a good automotive seat; it must provide comfort, style and safety, and yet be sufficiently light weight to facilitate vehicle fuel economy and minimize inertial stresses experienced in a crash. Seat designs and materials must be affordable and durable to give acceptable service over the life of the car. In addition to providing for comfort and position adjustments, a seat also must have adequate structure for housing safety and convenience accessories. Tradeoffs are imposed by this complex mix of requirements; however, in seat design we should no longer overlook the requirement for a reasonably safe, collision resistive structure. A brief description of the seat components will allow a better understanding of basic seat requirements and the special seat structure necessary for adequate passenger protection from collision trauma. Structural frame members The seat framework is usually constructed of tubular steel. Historically, the function of this structural backbone has been limited to providing shape for the cushions, support for its own weight and that of the occupant. Re-design and strengthening of the seat framework in conjunction with its anchorages can provide the force resistance necessary for occupant restraint in moderate to severe front, side and rear-end collisions. Non-structural seat material Cushions, springs and upholstery provide the necessary means of load distribution between occupant and seat frame; they also provide contour and geometry necessary for occupant comfort. Seat adjustment mechanisms These mechanisms should be strengthened to withstand collision forces as well as rigors of everyday usage. Physical differences among drivers necessitate a multiplicity of seat adjustments to assure that a given seat provides the multiple functions of driver positioning for correct reach and view, as well as for adequate comfort. Head restraint height adjustment is a common feature of current production seats. Unfortunately, many recent seat designs provide no head support protection from even minor rear-end collisions when the head restraint is in its most commonly used, down position. Seat anchorages Most vehicle designs depend on seat attachments at the floor or at the sill and tunnel to transmit forces between the vehicle and the seat. This anchorage is generally interposed between the seat adjustment mechanism and the vehicle floor pan or lower structure. Under static conditions, the seat anchorage transmits compression, tension and sheer forces from the seat to the floor or side structure. In the event of collision or handling accelerations, the resulting forces are transmitted in reverse direction from floor to seat. The seat anchorage structures and attachments require a design of adequate strength to accommodate seat and occupant inertial forces. Besides the usual floor, sill and tunnel anchorages, other potential anchorage locations for strength in seat systems include side and roof attachment. TYPES OF SEAT BACK FAILURES Seat backs can fail under various circumstances, however, the ultimate cause of these failures is the rearward loading of the seat by the occupant's body mass. Some seats fail due to the relative acceleration of this mass during a collision, whereas others fail under the weight of the occupant while a vehicle is stationary or travelling at a constant velocity. The two most common types of failure are the failure of the seat back support system to maintain an upright position and the deformation of the seat back frame itself. Less common are failures that have been attributed to deformation of the mounting system that holds the seat to the vehicle floor or to a collapse of the vehicle floor pan. Another problem is the detachment of non-integral head restraints during an accident. HAZARDS CREATED BY SEAT BACK FAILURES When an automobile front seat fails in a rear-end collision causing the seat back to move suddenly rearward, three serious hazardous conditions can arise: 1. Loss of control, thus exposing occupants to otherwise avoidable multiple crashes; 2. Ejection rearward out of the failed seats, possibly through rear or side windows or doors; 3. Interior impacts, by being hurled into the rigid interior structures of the vehicle or, even worse, into other occupants who then also may be injured; 4. Blockage of exits, when the collapsed seat/seat back structures hinder egress for crash victims from the vehicle's doors - a horrendous defect when the fuel system has ruptured and the car is on fire. INJURIES CAUSED BY SEAT BACK FAILURES Catastrophic results of seat back failure are brain damage, paraplegia, quadriplegia and death. Non-catastrophic injuries include many forms of painful and disabling upper spinal column and head trauma. GOVERNMENT, INDUSTRY FAIL TO TAKE SAFETY INITIATIVE The importance of seat rigidity in rearward crashes has been known for many years. Studies published by the Society of Automotive Engineers show significant industry awareness of the problem as early as the 1960's.2 In 1968 after conducting an extensive test program of rear-end collisions, Severy concluded that "rigid seat backs assure more effective support of the occupant during rear-end collisions, providing the seat back support is high enough to also resist rearward movement of the head.3 Conversely, "a seat that yields appreciably rearward... places the motorist in a semi-reclined posture that may serve to attenuate some of the injury-producing forces, but at the same time adversely displaces the motorist to higher elevations relative to the seat back, thereby reducing the measure of support that may be derived." In another 1968 paper, Martinez noted "... the seat back as part of the restraint system should be designed with the following objectives: 1. It should be strong enough not to fail under heavy torso loads resulting from a rear-impact of some design speed (30 mph?). 2. If the seat back does fail, it should do so in a manner involving a considerable expenditure of energy-crumpling or tearing of metal, or hydraulic damping, as this will limit the energy still to be dissipated by the occupant being protected."4 In 1972 Melvin and McElhaney, stated that "... rearward deflection of the seat back can eject the unrestrained occupant out of the seat with possible serious impact to the rear window area of the vehicle...."5 Non-catastrophic injury to the head and neck has also been documented in the engineering and scientific literature. These injuries are exacerbated by poor seat back construction including poorly designed head rests.6 For years National Highway Traffic Safety Administration has lacked the courage to stand up to pressure from the auto industry by failing to enact meaningful motor vehicle safety standards for seat back and head rest performance in rear-end collisions. The government has been privy to rear-end 30 mph moving barrier crash tests for two decades and in virtually every instance the films accompanying the crash test reports document complete failure of the seat backs with the dummies flying into the rear seat or being ejected out of the vehicles. Nevertheless, Washington has chosen to turn a blind eye towards this safety problem. In 1971 NHTSA promulgated FMVSS 207 which calls for a totally inadequate static loading test for seats and seat backs. The test simply requires that an empty seat be attached to a pulley at the upper portion of the seat back and a static load applied twenty times the empty seat weight with minimal deflection. For example, an empty seat that weighs 10 lbs is only required to withstand a static load of 200 pounds before collapsing. As cars have become lighter to meet fuel economy requirements so have car seats with the corresponding reduction in the minimal level of protection provided by a standard which was already grossly inadequate. FMVSS 202, also adopted in 1971, similarly sets static loading limits for head rests. While seat belts and shoulder harnesses are required to meet dynamic crash tests conditions where the vehicle is run into a concrete wall at 30 mph, no such companion requirement for the seat back exists for rear-end collisions. Documented cases dramatically illustrate how a seat back can collapse in a real world, rear-end crash at speeds as low as 12 mph and still meet the performance requirements of FMVSS 207. In 1974, NHTSA published proposed rule making to strengthen these standards by combining head restraint and seat performance requirements into a single rule, and then imposing dynamic crash test requirements on the overall "rear impact restraint system" that would incorporate these components. These requirements would have been similar to those in FMVSS 301, which sets test criteria to determine fuel system integrity in rear-end crashes. Faced with the auto industry's opposition, NHTSA halted all action on the proposal. In April 1979, it terminated the 1974 rule making and replaced it with a regulatory plan for overall "significant upgrading" of occupant protection in all directions, including rear, side, front and rollover, and including "new comprehensive standards... developed in terms of injury levels that occur" in dynamic crashes in all four modes.7 In addition, in a November 1980 letter to the manufacturers, NHTSA's administrator at the time noted, "A number of seat track and seat back failures" in NHTSA's new car assessment program crash series," and urged that the companies "review their designs to insure that seats do not fail catastrophically in crashes...." The 1979 regulatory plan, which would have upgraded seat "restraint" performance in "crash exposures representative of the real world" was abandoned by the incoming Reagan administration. Nor did NHTSA follow up to determine manufacture responsiveness to the November 1980 letter. Meanwhile it had been well established by researchers that production-model seats and seat backs were failing to provide adequate restraint against injuries in rear impacts, and that alternative designs to provide such restraint were available. The rear-end barrier crash test series run by the Insurance Institute for Highway Safety in the mid-1970s threw a further spotlight on the problem when, in every one of six impacts in the 30 mph range, seat backs failed in the struck cars.8 If this overwhelming evidence was not sufficient, further evidence has been provided in case after case brought against manufacturers on behalf of people injured because their seats or seat backs failed in rear impacts. In 1989 NHTSA again acknowledged the obvious: that the rear-impact injury problem, which results from weak seat/seat back/head restraint standards, deserves attention. NHTSA promised the motoring public in 1989, that it would take "prompt" action toward a remedy. Like the heads and spinal columns of people needlessly injured by rear-impact seat failures, that promise has been inexcusably broken. The record shows that in 1989, NHTSA received two petitions9 containing detailed descriptions of seat and seat back failure modes in rear-end impacts and offering guidelines for more stringent crash performance requirements for those components in both moderate and higher-force rear crashes. The petitions requested rule making to require adequate rear-impact crashworthiness. The petitioners also asked for dynamic testing of seats and seat backs, which is not now required. NHTSA officially granted the petitions within a few months of receiving them. Under NHTSA rules, when a petition is granted, a rule making proceeding must be "promptly commenced in accordance with applicable NHTSA and statutory procedures."10 The law states that if NHTSA grants a petition it "shall promptly commence the proceeding requested in the petition."11 Thus NHTSA committed itself in 1989 to moving quickly to initiate rule making that could lead to adequate standards for seat and seat back "restraint" performance in rear impacts. What has happened at NHTSA to provide adequate protection to motorist in rear-end impacts? Essentially, nothing. In October 1989, NHTSA published a catch all "request for comments" in which it offered no regulatory proposals but instead invited submissions on a wide range of topics related to seat performance, frontal restraint system performance, side impacts and other crash modes. Predictably, responses were largely from manufacturers, the vast majority of them opposed a strengthened standard for seats and seat backs and opposed dynamic crash testing of components. Not all responses were negative. Mercedes-Benz supported a dynamic test requirement and noted the importance of protecting "the front occupants during rear impacts through maintaining a mostly vertical seat back position."12 Transport Canada, on behalf of the Canadian government, provided NHTSA with a study of rear impact seat back collapses and resulting injuries. It concluded: "for a number of years it has been observed that the existing [U.S.] seat back strength requirement does not prevent seat back collapse. Seat back failure during a crash cannot only result in injury to rear occupants but provides an avenue of ejection even when the occupant is using the [belt] restraint system. It has also been observed that during CMVSS 301 rear impact test, virtually all bucket seats and split bench seat backs fail."13 CMVSS 301 is identical to NHTSA's FMVSS 301, which requires rear-end crash testing for fuel system integrity . General Motors opposed any strengthening of the standard. "Implementation of proposals to stiffen vehicle seats to the extent proposed would significantly increase costs and mass," it said in a letter to NHTSA dated December 4, 1989.14 Yet a General Motors engineer testified during a seat back collapse-injury trial in June 1991 that "there are problems associated with a seat back/head rest that is designed to yield under rear impact."15 He agreed that when seat and seat backs collapse, "a potential hazard can exist from the high compressive loads imposed on the vertical spine as the occupant's head is being forced into the rear seat cushion after he has slid up the front seat back/head rest." Faced with the weight of such evidence, which simply confirms what has been repeatedly shown in research and litigation for years, and faced with its own 1989 commitment to take "prompt" regulatory action, what possible excuses can NHTSA, now offer for further delays in initiating rule making leading to rapid implementation of effective standards governing seat and seat back restraint performance in rear-end crashes? WHAT THE AUTO INDUSTRY AND NHTSA CAN DO Dynamic crash test standards already apply to restraint performance in frontal impacts, windshield performance in frontal impacts, fuel system integrity and rear impacts in many other crash modes. It is inexcusable that rear-crash performance of seats, seat backs and head restraints should be exempted from such standards. The automotive industry and the government's mandate is clear. At a minimum the following should be adopted: 1. 30 mph fixed barrier rear impacts and longitudinal and angled configuration should be required, and parameters should be set to minimize seat track separation, seat back collapse, maximum rearward seat back deflection and other seat "restraint" failures in these and other foreseeable rear impacts; 2. Integration of head restraints of seat backs should be required thus eliminating "adjustable" head restraints which can be hazardous when adjusted downward. For example, an adjustable head restraint placed in the "low" position by a short person will present a severe hazard to a subsequent, unsuspecting taller person whose head and upper spinal column can flex over the head restraint in a rear impact; 3. Anchoring of seat belts on seat structures should be promoted in order to assure that belts remain snugly around their occupants throughout the crash, thereby providing the greatest possible protection against occupant movement out of the belt or seat. In part because of the weak designs of their seats, most manufacturers have chosen to anchor lap belt segments to the car floor. As a consequence when a seat deforms away from the belt and anchorage, the occupant no longer is restrained by the belt, whether in a rear or frontal impact; 4. Defect investigation and recall of vehicles whose seats and seat backs are found to be needlessly failing in real-world, rear-end crashes. CONCLUSION The lack of federal safety regulations has kept unsafe seat and seat backs on the market. As a result, the vast majority of cars driven by Americans today fail to provide a level of protection that the American consumer is entitled to. Current Federal Regulatory policy encourages manufacturers to continue to provide weak, defective seat back systems. As a result of the inaction of both the federal government and most of the automotive industry, the consumer is being asked to drive in vehicles with inadequate, hazardous seats and seat backs. Because of the government's passive attitude toward safety related problems of seats and seat backs, automobile occupants are being injured or killed and consequently the only recourse is the tort system. By litigants pursuing rightful claims for safer seat and seat backs they will continue to bring pressure on callous and indifferent manufacturers and, hopefully, NHTSA to honor their responsibilities to provide restraint systems that are safe and to replace those that are not. ENDNOTES |
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