Automobile Window Glass - A Design Defect That Should Not Be Overlooked

Most vehicles on the road contain tempered glass in their side, rear and roof window openings. In accidents, this tempered glass shatters and breaks, causing lacerations and other injuries and opening up portals through which occupants can be fully or partially ejected. While the auto industry has long ignored the obvious dangers posed by the use of tempered glass, the tide is now changing and the "glass defect" should no longer be overlooked.

The widespread use of tempered glass for vehicle side windows, rear windows and sunroofs should no longer be considered acceptable design practice. The expanding usage of laminated glass in high-end, luxury vehicles not only is making clear the benefits of laminated glass, but also the ease with which laminated glass could be substituted for tempered glass in passenger cars, pickups and SUVs.

Tempered vs. Laminated Glass

Laminated glass is required in windshields and has been used in the windshields of every car sold in America for decades. Laminated glass is not required in other window locations, and carmakers typically have relied on the use of tempered glass for those window locations.

Laminated glass consists of two pieces of glass bonded together with a plastic interlayer, typically consisting of polyvinyl butyral ("PVB"). In a collision, the glass will fracture but the PVB interlayer holds the fragments together and in place in the window opening. The PVB interlayer serves to hold the glass in place which, in turn, acts to contain occupants by preventing ejections. Even after severe accidents, windshields typically remain in place. Ejections through windshields are largely a thing of the past.

Tempered glass, in contrast, consists of a single layer of heat treated glass. In a collision, when tempered glass breaks, the entire piece of glass shatters and flies about. When this happens, the flying glass can cause lacerations and other injuries and the window opening becomes a potential portal of ejection.

For optimal benefits, laminated glass requires adequate edge support. If the window is fixed, it can simply be directly bonded to the body of the vehicle, similar to how windshields are attached. If the window is movable, it should have a window frame. Most passenger cars already have window framing on doors. For example, the National Highway Traffic Safety Administration ("NHTSA") has noted that 95 percent of Ford vehicles have fully framed windows.ⁱ In many accidents – particularly involving belted occupants – the existing window frames are adequate when used with laminated glass to serve an effective anti-ejection function. In those types of cases, no additional framing or other modifications are needed. In certain other vehicles, the existing window frames can be modified to be effective in retaining the edge of the glass. A window channel known as a t-edge also can be added to further improve the retention at the edge of the movable window.

A Brief Glass History

Beginning in the late 1920s, manufacturers began making windshields out of laminated glass. Eventually laminated glass was used in side and rear windows as well. However, in the late 1950s and early 1960s, the industry shifted to the use of tempered glass in side and rear windows. With the exception of some limited usage of laminated side and rear glass in certain vans, pickups and SUVs in the 1970s through the 1990s – which the industry claims was done for purposes of obtaining a deep window tint – that usage of tempered glass in side and rear window locations, as well as sunroofs, has largely continued to this day. A shift back to the use of laminated glass in these locations is beginning to occur, though it has generally been limited to high-end luxury models.

The Dangers Of Tempered Glass

The dangers of tempered glass have long been known to the auto industry. In real world accidents and in repeated crash testing, tempered glass shatters and flies about on impact. Not only does this open up portals of ejection, but it also exposes occupants to the risk of cuts and lacerations from flying glass. In all types of dynamic crash testing conducted on virtually every vehicle sold in America for the past several decades, tempered side windows, rear windows and sun roofs shatter and break out on impact.

During crash testing required by the Federal Motor Vehicle Safety Standards, tempered glass can vividly be seen literally flying about the vehicle. This occurs in rear impacts, side impacts, frontal impacts and rollovers. The industry often contends that tempered glass breaks into small pieces that are not hazardous, but this claim is not borne out in crash test films – which reveal numerous large pieces with sharp jagged edges. The presence of this shattered glass flying about at head level – including the head level of small children when seated in child seats or booster seats – is unsettling.

Tempered glass is especially dangerous in rollover accidents. Window openings frequently become portals of ejection through which belted as well as unbelted occupants are partially or completely ejected. In a series of NHTSA dolly rollover tests on Nissan pickups, the tempered side windows shattered and belted dummies were repeatedly partially ejected out of the window openings. In real world SUV rollovers, belted occupants frequently receive fatal head injuries when their heads are partially ejected outside the window plane during the roll sequence.

While the use of tempered glass is dangerous in any vehicle, its use in an SUV is especially hazardous given the higher rollover propensity. It is even more hazardous in a rollover prone SUV that has a weak roof and a marginal restraint system. Side window glass in such a vehicle is often the last opportunity to prevent full or partial ejections.

Laminated Glass As A Reasonable Alternative Design

Unlike many automotive crashworthiness cases, in which the alternative design frequently has not been widely used or tested, the alternative design in a window glass (or glazing) case typically is tried, tested and proven. Laminated glass has been used in the windshields of every vehicle manufactured for sale in the U.S. for decades. While laminated glass fractures during accidents, it remains in place, effectively containing occupants and preventing ejections. Occupant ejections through windshields are largely a thing of the past.

NHTSA testing. A wealth of testing from the National Highway Traffic Safety Administration ("NHTSA") is available for use in glazing cases. In the late 1980s, NHTSA conducted a series of dolly rollover tests on eight vehicles containing bilayer glass-plastic glazingⁱⁱ in the side window openings. The test vehicles included the following: a 1984 Honda Accord 4 dr., 1982 Chevrolet Celebrity 4 dr., 1986 Dodge Omni 4 dr., 1982 Mercury Zephyr 4 dr., 1988 Nissan pickup, 1988 Dodge Caravan, 1988 Chevrolet CK-10 pickup and a 1988 Ford Bronco II. The Hybrid III dummies used in the test vehicles were unrestrained in six of the eight vehicles. The glass-plastic glazing remained in place in every test, and the NHTSA researchers concluded that the tests were successful regarding the glazing performance. As the government researchers noted: "The glass-plastic glazing remained in place even with glass fracture and window frame distortion."ⁱⁱⁱ

The results of the NHTSA testing are useful in any glazing case – especially rollovers. In the 1988 Nissan pickup dolly rollover test, the pickup rolled over one and a half times and also experienced severe roof crush as well as direct dummy contact to the window. The bilayer glass-plastic glazing, however, remained in place. The report notes that the glazing was "still able to provide its ejection reduction function."

This test stands in contrast to the series of NHTSA dolly rollover tests conducted on stock Nissan pickups, in which belted dummies were partially ejected through the window openings in four separate dolly rollover tests. The NHTSA Nissan pickup dolly rollover tests are especially useful in proving the benefits of laminated glass in a rollover. The tests provide a direct "apples to apples" comparison in which the only difference between the tests is the window glazing.

Industry testing. Industry testing has also demonstrated the containment benefits of laminated glass. In testing conducted by Ford Motor Company, for example, laminated side glass has been shown to remain in place and prevent partial ejections even after multiple rolls and significant roof crush. Long ago, Ford engineers noted the benefits of laminated glass and the dangers of tempered glass in rollover test reports. These old Ford documents provide a wealth of evidence of the benefits of laminated glass.

Potential savings of lives and injury prevention. According to one recent NHTSA report, up to 1,300 lives per year could be saved by using advanced side glazing.^iv The same report notes that rollover safety in particular would be improved. "Advanced glazing systems may yield significant safety benefits by reducing partial and complete ejections through side windows, particularly in rollover crashes."^v

The benefit of laminated glass in preventing ejection makes it an important part of the vehicle’s overall restraint system. Indeed, the notion that laminated glass can play a significant role in terms of restraining children has been around for decades. In 1985, NHTSA researchers emphasized the restraint role of laminated glass:

Reducing window ejection is a significant child crash restraint means. We have shown that a 6 year old (44 pound) child dummy moving at 20 mph with the head and spine aligned perpendicular to the glazing can be stopped by the DuPont glass-plastic side glazing, with the plastic layer attached as a "safety net" at the window margins with the plastic stretching and holding after the glass breaks.^vi

Historical usage of laminated side and rear window glass. The use of laminated glass in side windows is nothing new. Not only was laminated glass standard in side and rear windows prior to the late 1950s, but the industry continued to use laminated glass in these locations continuing into the 1970s, 1980s and even the early 1990s.

Numerous vans, SUVs and pickups were offered with laminated side glass during the 1970s, 1980s and early 1990s. The Ford Econoline van was manufactured with laminated glass in various side window openings between 1975 and 1991. The Bronco was offered with laminated side glass in the late 1970s and early 1980s. General Motors offered laminated side glass in several vans manufactured between 1970 and 1992, including the Chevrolet Cutaway Van, Sportvan and Extended Van and the GMC Vandura. The Chevrolet 2-door Blazer, GMC 2-door Jimmy, GMC large Jimmy and Chevrolet/GMC Suburban were offered with laminated side glass from 1981 to 1991. Certain Chevrolet and GMC pickups were also offered with laminated side glass between 1981 and 1991.

The Jeep Wagoneer in the 1980s contained laminated glass in the sunroof opening. Between 1972 and 1979, the Ford Mark, T-Bird, Torino, Montego, Cougar and Lincoln were offered with laminated glass in the opera and decorative windows. Nissan manufactured the 280ZX with laminated glass in the T-roof opening and the Infiniti Q45 with a laminated rear window.

Recent usage of side and rear laminated window glass. More recently, the Audi A8 and the Mercedes S-Class and CL Series come standard with a full set of laminated glass in all side and rear windows. The Audi A6 in Europe can be purchased with a full set of laminated glass as an option. The Chrysler Cirrus and Dodge Stratus sold in Mexico came standard with laminated side glass starting in 1998, which Chrysler touts as a security feature. The 2003 Lincoln Navigator and Aviator have laminated side glass in the front doors. Ford also is offering laminated glass in certain police cars. The Audi A8 and the Volvo S80, S60, V70 and XC90 offer laminated side glass as an option. The BMW 7-Series and BMW X5 (Europe) offer laminated glass as an option. The Peugot 607 and the Lexus LS 430 also offer laminated side glass as an option. The Toyota Land Cruiser sold in Nepal comes with laminated side windows.

Cost of laminated glass. It is widely accepted that the total cost per vehicle of using laminated glass is well under $100. NHTSA estimated the incremental cost of two movable laminated side windows at $48, including the necessary modifications to the window frame. Potential weight savings would further provide cost benefits. The "price" of safety in a glazing case typically is quite reasonable.

Other Practical Benefits of Laminated Glass

In addition to containing the occupants and preventing full or partial ejections, laminated glass also has additional safety and practical benefits that can be emphasized to the jury, including anti-theft properties. Laminated glass can help thwart car-jackings and ensure that when the vehicle doors are locked, the occupants truly can expect a degree of safety and security from theft. Right now, a tap with a hammer shatters any degree of security that is obtained by rolling up the windows and locking the doors. Laminated glass also offers superior sound-deadening qualities, minimizes sun damage and fading by blocking UV rays and keeps cars cooler by blocking infrared rays, making air conditioning more efficient.

With no serious downside and numerous safety and other practical benefits, laminated glass is both a reasonable and cost effective alternative design. In many accidents – particularly rollovers with full or partial ejections – laminated glass could have made the difference between an injury-free event and an accident with serious, permanent injuries.

What Factors Make A Compelling Glass Case

Ejection out of fixed windows. If the defective glass at issue broke out of a fixed window, the alternative design simply consists of swapping a piece of laminated glass in place of the tempered glass. No additional framing or hardware is necessary. Bonding with urethane – which is now used to bond windshields in place -- would be required to ensure retention, but this is not a major cost.

Minimal occupant compartment intrusion. Lack of occupant compartment intrusion and window frame deformation make it more likely that laminated glass would have remained in the window openings and provided an occupant containment function. While laminated glass and other types of safety glass have been shown to remain in place during rollover events in which the vehicles suffered significant deformation, the lack of deformation makes this all the more likely.

Timeframe of manufacture – 1980s. During the 1970s and 1980s, numerous vehicles, including Ford and General Motors vans, pickups and sport utility vehicles, were offered with laminated glass in side and rear windows. In a glazing case involving a vehicle from this timeframe, the manufacturer will not be able to make the proverbial argument that "no one else was doing it." The extent to which laminated glass was used in these older vehicles dispels any notion that it wasn’t feasible or cost effective.

SUV cases. It is easier to make a persuasive case for laminated glass when the accident vehicle is an SUV that the manufacturer knows will roll more readily and more often than a passenger car. Partial ejections of both belted and unbelted SUV occupants were all but assured by the decision of the major manufacturers to use tempered side and rear window glass in virtually every SUV on the road.^vii

Timeframe of manufacture – late model vehicle. The newer the accident vehicle, the more difficult it is for the manufacturer defend a glazing case on the technical merits. The number of vehicles utilizing laminated glass in side and rear window openings has grown steadily in recent years. These vehicles tend to be high-end, luxury models whose safety is all but assumed. The use of laminated glass by such manufacturers as Lincoln, Mercedes, Volvo, Audi and Lexus makes it more difficult for carmakers to rely upon some of the arguments traditionally used in glazing cases – such as the argument that laminated glass causes more lacerations. Few jurors are likely to conclude that manufacturers like Mercedes and Volvo are using unsafe glass in their high end models.

Belted occupants. When a belted occupant becomes partially ejected through a window opening and sustains injuries, the glazing claim is especially strong. The NHTSA testing as well as other testing conducted by manufacturers like Ford demonstrates how laminated glass easily can prevent partial ejections of belted occupants. In serving as a barrier that contains the occupant, laminated glass performs much the same role as an inflatable side curtain that deploys during a rollover.

Belted occupants, moreover, have a reasonable expectation that they should not become partially ejected. If the seatbelt is incapable of preventing such partial ejections, why shouldn’t the manufacturer utilize other means of containment, such as laminated glass?

Injury Causation

Glazing cases often are set apart from the typical crashworthiness case, in which injury causation is a key battleground. If an occupant is partially or fully ejected and sustains injuries while outside the vehicle, injury causation can be fairly straightforward as far as a glazing claim. Occupants who remain within the vehicle typically do not sustain traumatic amputations, degloving injuries and the types of serious head injuries (such as massive skull fractures) sustained by occupants who are partially or fully ejected through window openings.

NHTSA’s testing demonstrates how laminated glass continues to contain occupants during rather severe rollover events in which vehicles suffer roof deformation as well as dummy contact to the window. In one of the NHTSA tests, the bilayer side glass remained in place in a modified 1988 Dodge Caravan that was flung onto its side off of an elevated dolly and slid to a stop. In the NHTSA dolly rollover on the Nissan with a bilayer side window, the window remained in place despite roof deformation and dummy contact to the window. Old Ford tests show similar results in terms of containing occupants.

The Practical Appeal Of Glazing Cases

There are aspects of glazing cases that potentially are appealing to potential jurors.

First, there is a common-sense notion that occupants should not be exposed to large jagged pieces of flying glass during routine collisions. In focus group work conducted by the author, mock jurors have reacted negatively to the flying glass seen in crash test films. People see little reason why the glass should shatter and fly about as a matter of design in so many different accident scenarios.

Second, laminated glass is a "low tech" fix which has been used successfully for many decades. While it might be difficult to convince a jury that an early 1990s SUV should have had inflatable side curtains designed to deploy in rollovers, it is a much easier "sell" to argue that it should have contained laminated side windows – which used to be standard equipment.

Discovery Battlegrounds – Ford, Volvo and Lincoln Glazing Documents

Ford purchased Volvo Cars in March of 1999 and currently operates Volvo as a Ford brand or division. Despite that fact, Ford has been reluctant to produce documents in product lawsuits reflecting Volvo’s use of laminated glass. Today, Ford offers laminated side glass in the Volvo S80, S60, V70 and XC90 as well as in the Lincoln Navigator, Lincoln Aviator, Lincoln Town Car and its police interceptors. At the time that this article was prepared, motions to compel were either pending or were being prepared in several Ford glazing cases. These motions seek to compel Ford to produce its more recently generated glazing design and testing documents, including Volvo documents.

Any claim by Ford that Volvo documents are somehow "off limits" would lack merit. Throughout Ford’s web site and annual reports, Volvo is treated no differently than Lincoln, Mercury, or any other Ford brand. Throughout its web site and its annual reports, Ford repeatedly describes Volvo simply as one of its many "brands."^viiiThe documents generated by Volvo and the other manufacturers using laminated side and rear glass likely will demonstrate the benefits of laminated glass in potential occupant retention and minimization of ejection.

Meeting The Defenses In A Glazing Case

Seatbelts. The seatbelt defense can be a hurdle if your occupant is unbelted – particularly if it is clear that the use of a seatbelt would have prevented the injuries. Many states have statutes that prohibit the introduction of evidence of nonuse of a seatbelt to show Plaintiff fault or for other purposes. However, the evidence often comes in for other purposes, such as to negate causation or to demonstrate the vehicle was crashworthy. If seatbelt evidence comes in – or it is obvious the plaintiff was not belted – the following might assist in meeting the defense.

First, it is clearly foreseeable that occupants might not buckle up. If your client’s accident occurred in the 1980s, moreover, the manufacturers’ own submissions to NHTSA reveal that belt usage was low during that timeframe. By some accounts, as many as ninety percent of rear seat occupants did not buckle up in the mid to late 1980s. Even today, belt usage is not 100% and the manufacturer knows some occupants will not buckle up.

Second, seatbelt-based defenses can be rebutted by pointing to other incidents involving the accident vehicle in which belted occupants were partially ejected and injured. Belted occupants frequently are partially ejected in rollovers due to a combination of poor seatbelt design and roof crush. NHTSA’s dolly rollover tests on Nissan pickups demonstrate how belted occupants get partially ejected out of window openings when the tempered glass breaks. Seatbelts also become unlatched during rollovers and other accidents and allow the occupant to experience excursion sufficient in many instances to lead to a partial ejection. Seatbelts cannot prevent all partial ejections. Only the use of laminated side glass can ensure an injury free event in many accident scenarios.

Safety/Lacerations. Some manufacturers claim that tempered glass is safer than laminated glass in that it causes fewer lacerations. The research does not bear this claim out. No major manufacturer, moreover, has produced anything of substance in discovery that would support this claim.

When NHTSA studied the effectiveness of glass-plastic windshield glazing in rental fleets, it concluded that the injury reduction of glass-plastic windshields was "substantially less than predicted." Notably, the report concluded that conventional windshields -- comprised of High Penetration Resistant ("HPR") glass since about 1966 -- had already brought about "a major reduction in the frequency and severity of head and facial injuries . . ." The windshield injuries that still remained were "primarily those in the minor severity category."^ix

If a manufacturer makes this claim, it should be challenged to identify current research (i.e., conducted on HPR laminated glass) concluding that laminated side windows are less safe than tempered side windows.

Overall, the use of laminated glass would lead to a significant reduction in both fatal and serious injuries (MAIS Levels 4, 5 and fatal) with an increase in minor injuries (MAIS Levels 0 and 1). NHTSA’s researchers concluded that "the fatality prevention benefit of advanced glazing would likely greatly outweigh any such disbenefits [such as additional lacerations]."^x In the serious glazing cases, the occupant would be much better off with Level 1 injuries than with serious injuries like amputations, degloving injuries and catastrophic head injuries.

In any event, it cannot be credibly argued that laminated glass is less safe than tempered glass -- particularly given the types of vehicles in which it is now offered standard or as an option. It would be difficult for a manufacturer to convince a jury that Mercedes, Volvo, BMW, Audi, Lexus and Peugeot are equipping their vehicles with defective or dangerous glazing.

Industry Custom. Manufacturers love to portray themselves as being with the "pack" as far as the use of tempered glass. This defense can be rebutted by pointing to the numerous vehicles during the 1970s through the early 1990s that contained laminated side and rear window glass as well as to the growing list of vehicles using laminated glass in locations other than the windshield today.

NHTSA’s Rulemaking Termination. In August 2001, NHTSA terminated its rulemaking on alternative glazing materials.^xi In so doing, NHTSA noted that advanced side glazing appears to increase the risk of neck injury. NHTSA was reluctant to require use of advanced side glazing materials that may increase injury risk to the neck. However, it is questionable whether there actually is a real neck injury risk. While neck loads were measured to be higher, the testing was done using a Hybrid III dummy. There is a lack of data that relates neck loads measured to actual injury risk to humans.

NHTSA indicated it will continue to explore the feasibility of ejection mitigation through such safety devices as side airbag curtains and that it would pursue development of more comprehensive, performance-based test procedures. It is significant to note that a performance based test would allow a manufacturer to choose any technology that achieves the necessary performance. Advanced glazing could be a potential solution to a performance based rule. It also is important to note that the continued development of side curtain airbags and the rush to make them deploy in rollovers indicates the extent to which the auto industry is concerned about partial ejections during rollovers.