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Buses and Motorcoaches: Humps and Bumps

As Originally published by Natioanl Bus Trader, February 2011.

By: Ned Einstein
Tel: 212-766-1121
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I have often written about the impacts of overly-tight schedules as the primary causative factor in incidents - in fact, the underlying cause of perhaps half of them. Because speeding is one of the "cures" to this problem, one of its characteristics is the failure to slow down when the roadway surface is not, as jazz musicians say, "melody." One of the most common scenarios is to cruise over speed bumps and speed humps. Another is to fail to slow over rugged terrain, particularly potholes and the often dysfunctional patches that sloppy road crews create to "repair" them.

The difference between humps and bumps is that speed humps are generally shorter, and thus have smaller radii. So traversing a speed hump, all other things equal, provides a jolt more severe than that encountered, by travelling at the same speed, over a speed bump. This practice is particularly reckless when some of the passengers are elderly or disabled. So too is failing to slow down to avoid racing over potholes and patches, construction zones, or other stretches of the roadway surface that are, to be kind, "sketchy."

The Humpty Dumpty Effect

While traveling too fast over bumpy roads in a vehicle with a pneumatic suspension system can jettison even an able-bodied person into the air, and occasionally break a vertebrae or two, those passengers more fragile or brittle are far more vulnerable to even mildly excessive speeds, particularly in vehicle "conversions" (including schoolbuses) that are constructed as body-on-chassis modifications of either medium-duty truck chasses or, in the case of large schoolbuses, frame-rail, truck type chassis purpose-built for these vehicles, yet almost identical to structures of the same length and width designed for trucks:

  • A schoolbus driver was ill, and his substitute - a mechanic who rarely drove - passed over the speed hump in the school's parking lot, in his full-size schoolbus, at no more than five miles per hour. A wheelchair user with brittle bone disease broke more than 20 bones. Strapped into a wheelchair for the test-drive as the plaintiff's expert, I was not happy at two mph, but after the four mph "run" - which made my teeth hurt, and felt like it was going to carry me and my coccyx bone into surgery - I refused to even take the five mph run. The particular state where this happened had an "immunity cap" for public agencies. So the school district simply handed over its $100,000 limits, and the plaintiff's attorney foolishly tried to sue the bus manufacturer - a poor effort eventually settled for less than the attorney's expert witnesses cost him when we found that the school district had, curiously, installed its own Rube Goldberg wheelchair securement system on top of the one provided by the original bus manufacturer.
  • Another schoolbus drove into a development and cruised over a few of its speed bumps - less severe than speed humps - at no more than 15 mph, since the street configuration was a labyrinth of short, winding roads. But this bus' brittle bone disease passenger broke a dozen or more bones, just the same, and her ensuing lawsuit settled out for a handsome sum.
  • A paratransit vehicle transporting an elderly woman in a manual wheelchair took a "short cut" through a park on the driver's way to his passenger's hospital. Cruising over a speed bump at likely 15 mph, the passenger not secured into her wheelchair (itself not likely secured or secured properly), bounced into air, and came down only to break her vertebrae. When I and the re-constructionist team conducted an exercise over this bump at intervals of five mph each, the vehicle literally "bottomed out" at 20 mph - i.e., the minibus conversion's leaf-spring suspension system did not prevent the underside of the floor from smacking into the upper leaf spring. After his ride on this "run," the stunt-passenger experiencing this ride refused to even participate in the 25 mph test, and limped off the vehicle wincing as he clung to his severely-swollen buttocks. Of course, we videotaped this exercise, and the vehicle was rigged with thermocouples to measure the necessary dynamics. You can probably guess that this lawsuit did not proceed to trial.

Suspension Systems or Not

To some degree, a pneumatic or hybrid suspension system (e.g., Mor-Ryde, EZ-Ride, etc.) will "dampen" the vertical forces from bumps and dips. But they will not eliminate them altogether. In extreme cases - where, for example, a transit driver whose schedule is too tight races over a patch of pot holes and raised "patches" - a passenger can easily be jettisoned upwards from his or her seat, sometimes tossed up a suprising distance. This jettisoning may depend on the location of this passenger's seat (over or near the rear axle seems to be a likely "hot seat"). But it is mostly a consequence of the vehicle's speed over the bump or dip. Keep in mind that pneumatic suspension systems are designed largely to "keep the floor level" - i.e., to counteract the longitudinal and lateral inertial and centrifugal forces that would otherwise minimize the bus' or coach's roll, pitch and yaw (or "directional stabiltiy" in bus terminology). These suspension systems dampen vertical forces far less, since doing so is not their primary purpose. So while air bags may help, they may not help very much when the bumps and dips are significant and the vehicle's speed over them is far in excess of that which is appropriate.

Keeping Humpty on the Wall

Rarely does an entire route traverse a continuous stream of potholes, speed bumps and raised "patches." Instead, these are almost always occasional, or involve small stretches of roadway that has either not been repaired, or has been repaired poorly - or even both when the current year's potholes were not yet patched into the irregular bumps and humps of the preceding year's. Since most drivers - particularly in transit - are familiar with these sections of roadway or their occasional anomalies, passing through them several times a day, it only makes sense to slow down when traversing them. If one is obsessive about maintaining his or her schedule, or under "unofficial" pressure to do so, a far lesser sin is to speed over the smooth portions to make up the time - although I am not remotely recommending this remedy.

An important point to remember is that the inscription on the Statue of Liberty does not state, "Send us your athletes, gymnasts and acrobats yearning to take risks." Instead, and particularly in the ADA era, it would make sense for drivers to operate as though all the passengers are frail - not simply hope that the few who are likely to be will survive the antics of a careless, negligent or reckless driver cruising or racing over roadway irregularities. In other words, even if you do not spot Humpty on your bus, just pretend he is on board, and make sure you do not break him. More importantly, in today's litiguous operating environment - where 60 percent of all motorcoach passengers are elderly - it would be prudent to pretend, if not operate as though, Humpty's entire family is likely on board.

It is not for no reason that, in legal doctrines, disabled or elderly passengers are characterized as "eggshells." This characterization is an expansion of the general legal principle that one "takes the victim as he finds him." In other words, not only is it not simply "too bad" for the poor, already-broken passenger if you break him or her worse, but instead, you are typically considered more liable when you hurt a passenger who is already broken than when you break one who is not. Regardless, break a passenger's bones and you will hear these phrases and principles emerge often in the lawsuit against your driver and company that will almost certain emerge and, on occasion, decimate your business and your livelihood.

Ned Einstein is the President of Transportation Alternatives, a passenger transportation and automotive consortium engaged in consulting and forensic accident investigation and analysis (more than 600 cases). Specializes in elderly, disabled, schoolchildren. Mr. Einstein has been qualified as an Expert Witness in accident analysis, testimony and mediation in vehicle and pedestrian accidents involving transit, paratransit, schoolbus, motorcoach, special education, non-emergency medical transportation, taxi, shuttle, child transport systems and services...

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