- Seat spacing, as noted earlier, is a particularly tricky variable. With lapbelted passengers (and even large three-point belted passengers), increasing the envelope of restraint would eliminate the otherwise “fulcrum effect” noted for all but the tallest passengers. However, in addition to reducing seating capacity by increasing the envelope of restraint, those unbelted passengers thrown from their seats in frontal and oblique collisions, as well as from “stop-shorts,” would travel further, and smack into the seatbacks in front of them at higher rates of acceleration. This phenomenon would be compounded if the seatback in front were reclined, while it would be lessened if the seatback in front were compartmentalized (and further, if also not reclined).
- However, if the seatbacks were compartmentalized, striking even reclined seatbacks would involve greater impact forces if the envelope of restraint were increased. But again, the only way to completely limit these impacts with lapbelts would be to space the seats much further apart – and dramatically further apart if the seatbacks recline – resulting in a reduction in seating capacity that would completely alter the pricing dynamics of motorcoach travel, if not drive the industry out of business altogether.
- Regardless of the type of belts installed (lap belts versus three-point belts), they comprise a serious risk, and enormous liability, when the vehicle requires evacuation – particularly if the passengers are disoriented by the vehicle catching fire or suddenly submerged, and compounded further if the fire, explosion or submersion startles them awake from a deep sleep or even a nap. Particularly with lapbelts, the buckles are sometimes located at the passenger’s navel, like those in airplanes, and generally easier and more intuitive to release than those “red buttons” otherwise placed at the hip position (as in automobiles and taxicabs). These differences, or the awkwardness of finding and pressing the often “sticky-from-repeated-use” red buttons on the hip side, can translate into panic in a catastrophic motorcoach incident where the chaos continues to unfold, much less escalate, after the initial collision – as a fire or submersion would create. Keep in mind, after the most several collisions, the vehicle is not always in an upright position. When it has rolled or tipped over, even without burning or submerging, this disorientation would make it far more difficult for a belted passenger to locate and depress the seatbelt release latch or button. This would be particularly true with three elementary school-age children seat-belted onto a 39- or even 42-inch wide seat bench [some newer school bus configurations include 3+2 seating, with more seat space for each passenger], where in the chaos of an accident, these younger children might experience great difficulty locating and/or pushing their respective release buttons. But even as motorcoach passengers – 30% of whom are schoolchildren taking “field” or “activity” trips – younger passengers could experience difficulty pushing the red hip-positioned release buttons, particularly if they are not replaced after extended usage (as one often finds in such belts installed in taxicabs, where the release buttons may be broken, sticky or otherwise compromised).
- Remembering that most catastrophic motorcoach accidents involve (a) charter services (where shift inversion and other factors translate into fatigued drivers often falling asleep to trigger the incident), (b) poorly- or illegally-operated mom-and-pop companies or owner/operators, and (c) older vehicles, the likelihood of maintaining or replacing “sticky” seatbelt release buttons is dramatically less than it would be for a responsible operator deploying newer vehicles, and whose drivers would far more likely examine these devices as part of their pre- and post-trip inspections, notwithstanding the unreasonable amount of time this would take, and it’s understandable deterrence to performing such a procedure even among the finest operators who monitor their drivers’ performance.
- Similarly, any type of seatbelt could cause significant problems in any type of rollover. One might reasonably argue that, in a multiple rollover, most passengers would still be better off being abused by his or her belts than rebounding within the passenger compartment, much less ejected. But in a more typical, simple 90-degree tip-over, the passengers on the non-ground side would be suspended in mid-air by their belts, usually with the belts pressing against their soft tissue and internal organs while gravity is otherwise pulling them downward. While never studied to my knowledge, three-point belts might actually worsen the damages, since many suspended passengers would now be at least partly-suspended by their necks. Further, a passenger’s successful effort to release the seatbelt button could worsen his or her plight: That passenger might still be hung in the now-distorted network of belts even when the release button has been successfully engaged. Or if not still hung in the belts, he or she would drop six to eight feet to the new “floor,” on top of passengers already lying on top of the often-broken windows by virtue of their having been seated (and worse, seatbelted) on the side onto which the vehicle has tipped. So getting out of one’s seatbelt at the “ceiling side” would not merely drop those passengers onto others on the “floor” side (as they would have done instantly if unbelted), but would now do so only after their bodies were first abused by the seatbelts – assuming they got out of them at all, which is a speculative assumption, particularly in a vehicle on fire and filling up with smoke, or under water. It is noteworthy that the incident about which this series of installments was derived, tipped onto its side adjacent to a creek: Had it rolled over another two quarter-rolls, it would likely have landed in the creek itself, and possibly upside down (i.e., with only one more quarter-roll) – thereby suspending every seatbelted passenger in the air had that vehicle been outfitted with such technology, and its passengers using it.
- Belt width and material strength affect the degree of trauma to the passenger: The wider the belts, the more surface area over which the impact forces will be distributed, and the less damage to most body parts as a result. However, the thicker and stronger the belts, the higher the cost and weight, and the more difficult to release an injured passenger from by using a typical “belt cutter.”
- Similarly, the flexing and stretching characteristics of belt materials differ greatly, affecting the degree to which they inhibit their occupants’ movement. However, these belts are stretched, to some degree, every time the vehicle brakes or even decelerates significantly. As a consequence, their strength and composition is marginalized tens of thousands of times, or more, depending on the replacement intervals — over the course of a belt’s existence. So after tens or hundreds of thousands of braking or deceleration events, the materials tend to stretch. Even with the best intentions of replacing them when they are compromised to a certain point, there are no criteria or devices available for determining at what intervals this replacement should occur. This determination is further camouflaged by dirt, inconsequential fraying, and other aspects of a seatbelt’s normal wear-and-tear which tend to disguise the belt’s containment capabilities as much as they may compromise it.
- Needless to say, the buckles are also compromised over time – not only from the constant tugs on them, but also from the myriad of latching and unlatching episodes every time a passenger buckles or unbuckles his or her seatbelt. Ideally, drivers should test the latching and release capabilities of every seatbelt during the pre- and post-trip inspections. But realistically, how many drivers really do this? Worse, most drivers involved in catastrophic motorcoach accidents are providing charter service – service often provided by small, poorly-managed Mom-and-Pop fleets or single owner/operators’ usually old motorcoaches, and often committing dozens of regulatory violations, and in some cases, deploying vehicles ordered “out of service” by Federal or State enforcement officers. While there are certainly plenty of stellar small operators for which safety is a top priority, those lying at the opposing end of the spectrum, and whose vehicles and drivers appear to be involved in the majority of catastrophic accidents, are unlikely to even perform pre-trip inspection check-outs at all, much less buckle, unbuckle, test and tug each and every seatbelt. Yet even if they did, imagine how much extra time would be needed to conduct these FMCSA-required inspections twice a day, on 47 or 55 seats?! It would be naïve to not factor in the costs of this extra time over decades’ of trip-making, just as it would be naïve to assume that even a significant fraction of drivers would ever perform such efforts.
- As a small but noteworthy footnote to this extra inspection time, the time needed to perform these seatbelt inspections at the beginning and end of every trip would cut into the 15-hours of time drivers are allowed to spend on a shift, driving or otherwise. It would be naïve to think that non-compliant operators would not cheat either by not performing such inspections or shoe-horning them into the eight-hour off-duty period required between drivers’ shifts, further compounding the risks of driver fatigue. If, in contrast, operators were compliant in checking out this equipment while not violating hours-of-service requirements in the process, the distance their drivers could travel in a single shift would be decreased noticeably, and the “service area” from which they could draw passengers would shrink geometrically, since, mathematically, area equals pi R squared (see article titled “Pi R Squared” in August, 2003 issue of National Bus Trader).
- Variations in passenger size and characteristics are also considerable. While some three-point belts systems have variable positions for the shoulder harness, there are no variables for the lap-belt segments other than slack. And other than a few lapbelts with retractors (common to school buses and, increasingly the wheelchair securement belts on paratransit vehicles), lap belt slack is adjusted manually, rather than automatically by retractors. Regardless, individuals at the spectrum’s extremes are the most vulnerable. For example, thin and frail individuals may occasionally submarine beneath the belts, obese passengers are the most likely to remove them, while double-amputees can override lap belts. But even so, as noted, the internal organs and bones of younger children, elderly and disabled passengers and a few others, respectively, are far more vulnerable to lap belts, while other types of passengers (e.g., those with broken arms or women in advanced stages of pregnancy) are more vulnerable when a shoulder harness is added to the mix. Commonly, when lapbelts are engaged, and not properly affixed over the hip bones, the lower abdomen may compress the viscera against the passenger’s lumbar spine, injuring the digestive tract. Further, impact forces exerted against one’s abdomen are distributed in all directions, sometimes tearing apart internal organs in the process.
- Even bus length is a variable. The longer the vehicle, the great the “columnization” or longitudinal collapse – which may appear counterintuitive, since impact forces tend to dissipate as one moves further away from the zone of intrusion or point of impact. Yet columnization is an exception to this general principal, and as a result, passengers seatbelted in the rear of a 40- or 45-foot-long motorcoach may suffer more trauma than those seated in the middle.
- Floor structures also matter considerably. Particularly with body-on-chassis vehicles (including motorcoach “conversions”), the floors may buckle as the bodies tend to shift forward on the chassis following a severe frontal or oblique impact. This buckling further accelerates the movement of passengers against the seat backs in front, just as it increases the body’s loads on the lap belts or three-point belts, increasing the risk of injury to internal organs. And floor structures tend to deteriorate over time, especially in damp climates, making this problem even worse for older buses or coaches – which include most of the vehicles involved in catastrophic motorcoach accidents.
- Also, some approaches to seat belt anchorage, even among otherwise top-quality buses and coaches, is deplorable: Instead of anchoring the belt connections to structural frame members, holes are merely drilled through the floor (often made of nothing but 5/8” plywood, despite many States requiring ¼-inch steel plates) and attached by wing nuts simply tightened against oversized washers on lengthy bolts. In severe frontal impact or oblique collisions, or even high-impact rear-end collisions (when “delta V” is great, in common engineering terminology), the moorings simply break and rip through the floor, often resulting in a coach full of foot, ankle, leg and knee injuries as the hardware above the floor deforms around the passengers’ feet and legs. Depending on the configuration of the bus or coach’s under-floor frame member configuration, it is often difficult and expensive to attach the anchorages only to frame members, and doing so often adds far more weight to the vehicle than just drilling through the floor and attaching the seats with wing nuts and washers tightened around bolts.
- Collision orientation is also a dramatic variable. Each type of seat and seatbelt system acts differently depending on the collision orientation. Two illustrative examples are the fact that compartmentalized school bus seats offer no protection from side-impact collisions (whereas even lapbelts on these seats prevent them from flying sideways out of their seats or occasionally through the windows), and the fact that no type of seatbelt offers any protection from rear-end collisions. Partly because many studies and/or accident statistics have revealed that rear-end collisions are the most common collision scenario (even though they are, of course, generally far-less-severe than rarer front-end collisions), NHTSA did not endorse three-point seatbelts on large school buses in its study published in 2004. (Another reason was, of course, that all school bus seats are compartmentalized.) As noted, oblique collision orientations make shoulderbelts extremely risk-laden, particularly as the passengers rotate since, upon impact, the vehicle often spins around, initially at a very high rate of speed.
- Another similarly-complex trade-off involves the frequency of each collision orientation. For example, seatbelts are most valuable in rollovers, where ejection is more likely to occur than in any other collision orientation. Yet rollovers are rare. In contrast, as noted above, many data suggest that the most frequent collision orientation is a rear-ender, where seatbelts are virtually worthless. In other words, those collision orientations in which seat belts provide the most benefits occur least often, while those collision orientations where seat belts provide the least value occur most often.
- The “point of intrusion” affects a number of factors that anoint any form of seatbelt with both benefits and problems. For example, a vehicle’s stiffness affects the degree to which another vehicle can penetrate it, and factors like bumper misalignment or the “illusion of structure” below the floor level of buses without luggage compartments (e.g., many school buses) permits automobiles to submarine beneath the side of the bus – preventing injury to the bus passengers while often beheading the automobile passengers under-riding the bus. In contrast, in accidents like Fox River Grove (1995), students seated in the section of the school bus sitting on the railroad tracks were able to jump out of their seats and dash to other parts of the bus before the oncoming freight train barreled into the “zone of intrusion,” separating the bus’ body from its chassis by several meters. Young students observing this phenomenon likely would have been far less successful performing this maneuver had they needed to first unfasten their seatbelts.
- There are also problems with seatbelt maintenance, repair, vandalism and even abuse (most typically by schoolchildren using the buckles as weapons). The absence of retractors (less of a problem in newer models) also leaves loose belts lying on the floor, comprising trip hazards, and greatly compounding the risks involved in vehicle evacuation (including evacuation drills).
- As an institutional matter, the installation of seatbelts may not only increase liability at the operating level, but may do so as a product liability matter – depending, of course, on the incident scene scenario. Ironically, the perverted and, frankly, idiotic claims about market forces promoted by certain plaintiffs’ attorneys in a number of recent lawsuits used the absence of seatbelts as a liability ruse – one incident of which led to the publication of this entire series of installments. (These specious claims will be covered later in this series.)
- Carryover effects are also a consideration – although they do not affect the liability of a bus or coach manufacturer. In contrast, the tendency to not use a seatbelt on a bus or coach (particularly on a school bus whose seats are relatively safe from the most common of severe collision orientation – frontal impact collisions – because of their compartmentalization) may “carry over” to that same passenger not using his or her seatbelt in an automobile or lightweight van or minibus, whose seats (other than with small school buses) are not compartmentalized, and where the use of seatbelts is of critical importance because of the typically similar mass of the vehicle compared to those fellow vehicles and other objects with which it might collide.
Given such a range and diversity of trade-offs, it is absolutely impossible to claim that even three-point seatbelts are clearly beneficial to even large buses or coaches. The trade-offs are not only enormous, but involve an almost dizzying degree of complexity. When only lap belts are involved, or when the separate shoulder belt sections of certain types of three-point belt configurations are not employed, the use of lap belts on large vehicles are profoundly dangerous, particularly as rollovers and their ejections are so rare while the enormous mass of a full-size bus or coach largely swats away most objects in which it might come in contact in a non-rollover collision.
Finally, the more the vehicle costs as a result of installing seatbelt technology – including reinforced, heavier seats and significantly stronger anchorages (since the loadings on the seats themselves will be four or five times as great in those instances when the passengers use them), as well as the increased operating costs for carrying around all this extra weight for 20 or more years, and/or the reduced seating capacity needed to offset it (or the costs of beefing up the rear suspension system) – the fewer buses and coaches will be affordable and available. Because travel by bus or coach is exponentially safer than travel by any other mode (other than aircraft or passenger rail, both traveling in exclusive corridors or on exclusive guideways), the reduction in the number of buses or coaches available will effectively doom other would-be bus/coach passengers to travel in or on other far-less-safe modes. This last point may be the most important of any considerations associated with the installation of seatbelts on full-size buses or motorcoaches – and accounts for the fact that only six States have mandated seatbelts on school buses, including Florida, New York and New Jersey, which have mandated only extremely dangerous lap belts.
Other than the few digressions into three-point belts included above (because they so closely related to the same points about lapbelts), the pros and cons of three-point seatbelts will be treated in Installment #6 of this series, to follow next month.