GVWR in the Fast Food Nation: Passenger Weight Exceeding Suspension System Capabilties

Incidents where seated passengers get thrown down the stepwell and through a closed door seem to be rare – although I have been involved as a forensic expert in several lawsuits where such incidents have occurred. But passengers being propelled forward from their seats, and standees slipping and falling when the vehicle accelerates, decelerates, brakes, turns and merges are common staples of bus and motorcoach incidents and the lawsuits that inevitably follow them.

The Balancing Act

When a floor surface moves, forces are exerted on those objects resting upon it. When this surface moves longitudinally, these forces are referred to as inertial. When it moves laterally, they are referred to as centrifugal (although the term centripetal is sometimes employed, and has a similar meaning). Finally, when it moves obliquely, both inertial and centrifugal forces are applied.

The vehicle feature designed to counteract these forces, and to protect passengers and freight from their dysfunctional consequences, is the suspension system. This system includes air bags (most monocoque buses and coaches), leaf springs (most body-on-chassis vehicles and cutaway vans) or coils (most vans and van conversions), as well as tires, wheels, shock absorbers, trailing arms and other structural and mechanical elements.

The amount of weight that a vehicle’s suspension system can support is measured by several indicators. ‘Gross vehicle weight rating’ (or GVWR) denotes the weight of the vehicle loaded to the full capacity – including standees (encompassed by the vehicle’s ‘crush capacity’) plus the driver, a full tank of fuel and all fluids – that the entire suspension system can safely support. Other terms used for this measurement are ‘laden’ weight and ‘wet’ weight. In contrast, the vehicle’s ‘unladen’ weight reflects only the vehicle – although this term is sometimes employed (sloppily) to include fuel and fluids, which can weigh as much as several passengers, depending on the size of the vehicle and its fuel tank.

Finally, each axle must individually support a certain amount of weight. This weight is referred to as the ‘gross axle weight rating’ (or GAWR). Because the distribution of passengers with respect to each axle is rarely perfect, the sum of GAWRs generally exceeds the GVWR and, as such, provides a margin of error. However, many vehicles’ GAWRs contain no margin of error. And even those which do generally incorporate this margin of error only into the rear axle. Particularly on transit buses containing standees, passengers tend to move or shift forward (bunching up closer to or forward of the front axle) as the bus decelerates, brakes and/or merges while approaching and pulling into the stop. Particularly because they contain only a single door in the front, motorcoaches deployed in commuter/express service can experience this phenomenon even more severely than most transit buses.

Fast Food Nation

Except for the driver, fuel and fluids, the difference between a vehicle’s GVWR and its unladen weight is represented by the passengers. For purposes of calculating these weights, the estimate of 150 pounds per passenger has traditionally been employed. In Today’s Fast Food Nation,1 whom are we kidding?! In the boxing world, someone weighing 150 lbs. is not even a middleweight (this moniker is reserved for a boxer weighing between 154 and 160 pounds).

In a product defects case in which I was recently engaged, I conducted an axle- and vehicle-loading exercise employing 28 randomly-selected employees at one of the plaintiff’s facilities. Weighing each one individually on a bathroom scale, I found their average weight to be 171 pounds. Depending on their distribution on the vehicle, they overloaded the front axle by as much as two thousand pounds!

Because of the tri-segmented, seesaw nature of a plane resting on two axles, the formula for calculating the distribution of the floor’s load on each axle is quirky and complex, and involves apportioning and totaling all or part of the loads lying (a) forward of the front axle, (b) between the axles, and (c) behind the rear axle … to each of the axles, depending on where these loads lie with respect to them. In the axle-loading exercise cited above, the weight borne by the front axle was actually greater when only 24 passengers were on board compared to the 28 who could be accommodated when the bus was fully loaded to its seating capacity. When I shifted all 28 passengers to a position forward of the rear axle – a scenario simulating the typical positioning of a bus full of passengers immediately prior to a pull-in – I found the weight on the front axle to be even greater.

Thankfully, the operator deploying this bus prohibited standees as a policy matter. Regardless, these scenarios helped to explain the vehicle’s serious handling problems: The bus swam all over the road, experiencing undulations in pitch, roll and yaw. On ice, the rear end of a stopped bus began to swing around immediately upon acceleration. Even on extended straight-aways, drivers had to steer constantly. In truth, these dysfunctions occurred when the vehicles were practically empty. But these problems were exaggerated when they were fully or near-fully loaded.

In simple terms, the passenger-weight figures employed to calculate GVWR do not remotely affect the reality of Today’s passengers – at least American passengers. The fact that a full third of the U.S. population is classified as overweight fails to reflect the percentage of bus passengers who are overweight: Because most bus and motorcoach passengers are relatively poor, and modern America’s huddled masses are generally fatter than “the Swells” (largely for dietary reasons, but also because they have less time to exercise), it is likely that close to or more than half of all bus and motorcoach passengers are overweight.

Tuna and Altoona

These passenger considerations suggest that actual laden weights are considerably greater than the 38,000 lbs. which most full-size transit buses’ and school buses’ suspension systems are designed to accommodate. Of course, most motorcoaches contain dual rear axles – providing significantly greater GVWRs, and rendering these dynamics moot at least insofar as axle weight limits are related to roadway wear-and-tear. Further, transit and motorcoach front axles are generally heavier-duty than those typical of body-on-chassis vehicles and, as a consequence, more likely to accommodate uneven distributions of the loads. Just the same, smaller and lighter over-the-road coaches are increasingly being deployed in both transit and motorcoach duty cycles, as the economics of the industry and the U.S. regulatory environment increasingly dictate.

Considerations of “directional stability” measured qualitatively by the Altoona Testing Facilities largely reflect a concern for rollover propensity. In contrast, the sandbags positioned on board during these tests are dramatically more stable than passengers. As a consequence, the impacts of directional stability on the passengers’ abilities to remain seated or secured (i.e., standing while holding onto stanchions or grab handles) is not measured at all. Further, the Altoona Testing Facility does not quantify any characteristics of directional stability, for which standards are elusive (to the degree they even exist). Finally, because few of them are purchased with Federal funds (MCI is the primary exception), most motorcoaches do not undergo Altoona testing.

These observations are not meant as a criticism of the Altoona program, which provides valuable (one might argue invaluable) information and insight to manufacturers who might otherwise not even conduct many (much less all) of the same tests. The Federal Transit Administration’s subsidizing of 80 percent of the testing costs provides a significant incentive to subject one’s vehicles to this testing, as does the fact that a bus or motorcoach may not be purchased with Federal funds without undergoing it. Just the same, test results are not used to pass or fail the vehicle. Instead, these results are used simply (a) to classify the buses with respect to durability (in terms of mileage and/or years) and (b) to qualitatively identify some salient safety features (most importantly, brake, steering and suspension system performance).

This information is presumably employed by the manufacturers to improve their products. Of course, the fact that Altoona testing is a requirement associated with the purchase of vehicles with Federal funds, and the fact that the classifications yielded are exploited for marketing and pricing purposes, do nothing to guarantee that the information will be used by the manufacturers at all. In one product defects case in which I am involved, the manufacturer produced several models of dramatically different lengths and wheelbases (much less vividly different components), classified all of them as “commercial vehicles,” subjected only one model to Altoona testing, and marketed and sold the entire product line as “Altoona-tested.” Particularly with respect to brake, suspension and steering system performance, this approach is akin to a farmer vaccinating his pigs and then advertising his cows as fully inoculated. So while the Altoona Testing Facility’s results may be seaworthy, the use of its results can be mighty fishy.

Slicing Up the Pie

A guy walks into a pizza parlor and orders a large pie. As the pie comes out of the oven, the clerk asks him whether he would like it cut into six or eight pieces. “Oh,” replies the customer, “cut it into six. I can’t eat eight.”

When incidents resulting in deaths or injuries occur, the attorneys and their experts involved often become embroiled in complex and costly blame-placing debates, arguing the assignment of errors and omissions to sundry drivers, policy-makers, mechanics, manufacturers (i.e., in terms of product defects), passengers (referred to in civil litigation as ‘contributory negligence’), third parties – and in even more complex cases, folding in dealerships, distributors, leasing companies, employment agencies and even doctors and lawyers. Understandably, multiple parties translate into greater complexity, higher costs, longer resolution times and, in some cases, more inequity (some of it from concessions to frustration). The paperwork and cardboard boxes generated can knell the death of a large tree.

Because both Federal and state courts employ some variation of ‘comparative negligence,’ juries are often charged with the task of “splitting the pie” (arrogant plaintiffs’ attorneys call it “carving the turkey”) – effectively assigning percentages of the total damage award to the various parties liable. As a psychological matter, this dynamic tends to facilitate the jury’s finding of negligence altogether, as the apportionment of damages among multiple parties may soften its impacts on any one of them. But it also tends to increase the magnitude of the damage award.

While civil proceedings in all states employ some form of comparative negligence, the formulas for assigning it differ widely. In some states, the pie can simply be sliced. In others, if the plaintiff is assigned even one percent of the liability, the other parties walk away without paying any damages. In still others, the plaintiff must be assigned 51 percent of the liability in order for the other parties to be dismissed.

Juries can be extremely sophisticated in their understanding and application of these principles, especially when a judge explains them properly. In a recent case where I helped defend a school bus contractor in a crossing case, the jury assigned precisely 51 percent of the blame to the schoolchild who stepped out into moving traffic before his schoolbus was even in sight. For whatever reason (my suspicion is that they actually understood their instructions and realized there was no monetary penalty associated with the determination), they also assigned 28 percent of the blame to the co-defendant operating contractor. However, because of this state’s formula for apportioning negligence and damages, this assessment was academic, and that defendant (my client) skipped out of court scot-free – apart from, of course, the tens of thousands of dollars it spent on attorneys’ fees, expert witnesses (including a waiting room full of medical experts) and court costs.

Fasting or Starving

The implications of both the automotive and litigation dynamics identified above – in terms of both safety and liability – are troubling for the public transportation industry: As passengers grow heavier and heavier, we will either have to install larger, more expensive axles and other suspension system elements, or limit seating and crush capacity. Given the economic problems increasingly being faced by all U.S. bus and motorcoach sectors, both these choices are imminent, and both are unwelcome. But the U.S. litigation environment may render increases in automotive investment and/or decreases in capacity less costly than continuing to employ traditional GVWR assumptions and calculations. As a famous muffler shop used to advertise, “You can pay us now, or you can pay us later.” ‘Later’ always seemed to mean ‘more.’

For those unfamiliar with the Americans with Disabilities Act, charging passengers (compared to freight) according to their weight is not practical, and may not even be legal. Many or most individuals in our society would probably find such an approach ethically offensive or morally repugnant. Several years ago, an ADA-related class action lawsuit resulted in the ruling that obese individuals who cannot squeeze into coach-class airline seats not only must be provided with two seats (obviously adjacent) but, further, need not pay a penny more for the pair than they would otherwise be charged for either. ADA regulations applying to airline travel are currently being revisited by a web of new rulemaking (Notice of Proposed Rulemaking, November 4, 2004, Federal Register, beginning on p. 64364). Somehow, I do not expect it to thin or thin out the passengers.

Flab and Flubber

Adding a bathroom scale to the stepwell may seem Orwellian – if it doesn’t trigger allusions to Peter Sellers, Jerry Lewis or Mr. Bean. But some form of this approach may not be so farfetched: If motorcoaches are increasingly fined for being overweight, their more anorexic passengers may resent the increase in fares needed to cover the vigorish. For those readers too young to have viewed Disney’s famous Fred McMurray film (or its recent remake), I would like to point out that we are far away from affordable anti-gravity technology – at least within planet’s Earth’s gravitational field.

Like many of the public transportation industry’s troubles, the same socio-economic forces responsible for shrinking the passengers’ wallets are also responsible for thickening their buttocks. Something must eventually give. I just hope that what gives is not safety. If it does, one can be certain that increased liability will fill the void.

The average American consumes 62 pounds of high fructose corn syrup a year. Starving the passengers is not a realistic option. Instead, as socio-economic and political forces continue to gut the public transportation industry, we will have to face these realities at the vehicle design, specification, policy-making and operating levels. If we fail to do so, personal injury attorneys will feast on our flesh. It will not be pretty.

1Fast Food Nation: The Dark Side of the All-American Meal. Eric Schlosser, Houghton Mifflin Company, 2002.


Publications: National Bus Trader.