A few months ago, in “The Danger Deterrent” (National Bus Trader, April, 2016), I explored the unsettling dangers associated with vehicles with long wheelbases making left turns. In that article, I mentioned having served as an expert witness in at least two-dozen left-turn-related lawsuits. Yet I have never been involved in a case involving a right turn. Superficially, one could only wonder why, since the “rock-and-rolling” necessary to view around otherwise blind spots in order to turn right is far greater than that needed to turn left. Plus, most of the victims of left-turning accidents are visible directly through the windshield, often for several seconds before being struck by the nose of a bus or coach.
No reader should deduce from these comments that he or she need not be concerned about right turns, as a safety matter. They have their challenges. The most fascinating of them is that, other than turns into wide, multi-lane arterial streets or sweeping boulevards, right-turning vehicles with long wheelbases must necessarily spend a few seconds in at least one oncoming lane of the roadway into which they turn. I call this potentially shared space “the dance floor.” But with all this potential sharing of space, why are there so few collisions with right turns compared to the considerable number of left-turn collisions — turns that superficially appear far easier to make?
Physics and Directional Stability
Almost every common motorist has, at one time of another, driven up or down a freeway ramp too fast, and experienced the sudden difficulty of keeping his or her car on the road while balancing this feat with the effort to avoid a rollover. Usually, and fortunately, one feels this sensation from the suspension system before one set of tires actually leaves the pavement. But turning too quickly on a curve, and sensing the start of a possible rollover, is a scary moment. And it is a sensation grounded in science (more specifically, the existence and nature of centrifugal force).
In a nutshell, the sharper the arc of a turn, the lower the speed at which the vehicle’s outside tires will begin to leave the pavement, and the lower the speed at which the vehicle will actually roll over. There are plenty of sub-factors involved here: The vehicle’s center of gravity, tire conditions, type of suspension system and rolling resistance on the roadway surface, to name only a few of the most important ones. But the general principle remains true. And the degree to which wheelbase length factors into this dynamic is even more complex. Just the same, this reality helps explain why the first rule about turning, in any vehicle with a large mass and a long wheelbase, is to do it slowly — if not first come to a complete stop altogether. But the second rule is to not do it too sharply. This second rule may lessen the time that the bus or coach remains on the “dance floor.” But it also increases the risk of it being tossed off the dance floor. This is because, once again, the defining constraint is the arc of the turn. If one wishes to turn faster, that arc must be wider. If the arc of the turn is sharper, one must turn more slowly.
One must also keep in mind that the rear tires of a vehicle with a long wheelbase do not follow the path of the front tires in most proper left turns — and much less so in a typically-tighter right turn. But because the turn should not begin until the rear drive axle aligns with the extended near-side curb line, such a vehicle’s nose usually take a dance-step or two into the oncoming lane, often by necessity. The wider the arc of the turn, the more space this dance step takes up in one or more oncoming lanes. And the more time the vehicle spends in this or these oncoming lane(s), the more dangerous the turn becomes. The driver of a large commercial vehicle with a long wheelbase simply cannot have it both ways:
- If the vehicle creeps around the turn like a disabled snail, then the driver can minimize the space his or her vehicle occupies of an oncoming lane or two.
- At the same time, slowing to a crawl to minimize this space extends the time that the vehicle must spend in this or these perpendicular, oncoming lane(s).
I do not recall right turns described in such terms in any operating manuals I have ever reviewed. Many or most bus, coach and heavy-duty truck drivers learn about these principles either, if through driving experience, or (if lucky) from behind-the-wheel training — even it such phenomena and procedures are not found in their classroom training or written training materials. Clearly, most commercial drivers do not experience a rollover or two to get the point. With increasing experience, most drivers naturally become better at striking a balance between turning speed and turning sharpness (with respect to the arc of the turn allowed by the configuration of the roadway). Yet reflecting the trade-off noted above, this balance lies between two constraints:
- Even apart from the dance floor, a commercial driver cannot realistically creep around a corner, in a traffic stream, like a snail. At least not if one wants to avoid a few nasty honks from behind, some risk of being rear-ended, or worse, the sizeable risk of colliding with an oncoming vehicle on the dance floor the bus or coach just turned into.
- At the same time, a driver cannot sweep across multiple oncoming lanes to create the arc needed to whip around a tight turn without risking a rollover — or at least losing some control of the vehicle..
These constraints necessarily force the driver of a long vehicle to strike some balance. As I have seen precious little written training material about it, I can only conclude, again, that bus, coach and heavy-duty truck drivers learn to strike this balance largely through experience. Frankly, more training would seem helpful, and should be welcomed.
Frankly, I think that turning safely is one of the most difficult things a commercial driver must learn. So the typical six weeks of training many bus and coach drivers receive is hardly excessive. This particular maneuver (i.e., turning) is rendered all the more complex by the fact that not only do the arcs of turns vary considerably, but so too do speed limits. And while most vehicles would roll over while turning right at the speed limit, they often approach the turn at or near the speed limit — even though the industry standard is to slow down considerably, if not come to a complete stop before turning, even with a green traffic signal in the vehicle’s favor. This failure to slow down or stop is far more common to left turns — which largely explains why these turns appear to cause so many more collisions. Regardless, mastering the nuances of turning is all the more important when one recognizes that a vehicle does not usually have the entire dance floor to itself.
Sharing the Dance Floor
One basic highway-engineering tool used to control the dance floor (or the intersection) is the “limit line.” On roadways on which commercial vehicles operate, the limit lines behind each spoke of an intersection are often placed far enough behind the intersection so as to allow the nose of a turning bus, coach or large truck to rotate through the intersection-edge of the oncoming lane without striking an oncoming vehicle. Yet this tool only comes into play when vehicles are stopped at this line — as they should when the intersection is controlled by a traffic signal or stop sign. (Rules for stopping at crosswalks actually vary from State to State; in some States, for example, one is only required to do so if a vehicle is parked close to the intersection.)
Further, another factor that “crowds the dance floor” is the improper placement of limit lines, on the perpendicular street, too close to the intersection. This placement literally invites a stopped vehicle to intrude onto, and often wait on, the dancefloor. Further still, many motorists stop forward of these limit lines — sometimes even “inching up.” The inability to read a fellow-driver’s or motorist’s mind can be a problem. So if a bus or coach ends up colliding with another vehicle or pedestrian on the dance floor, the victim’s attorney may fail to file against the city or county engineering department, or department of public works, responsible for improperly positioning this limit line. Or he or she may fail to file against a State department of transportation, if the limit line were improperly placed on a state highway. If so, your attorney can often push much of the blame onto this “Third party” — even if it is not being sued.
In contrast, when vehicles in an oncoming lane are not brought to a stop by one of these devices, signs or markings, the dance floor is wide open. During the turn, a bus or coach driver must not merely “rock-and-roll” to make sure there is no pedestrian to be run over or no oncoming vehicle to smash into. And its driver must not merely align the rear axle with the extended near-side curb line before turning (to avoid turning even further into an oncoming lane, or even rolling over a corner with the rear tires). A commercial driver’s “rock-and-roll” must allow him or her to also peer a reasonable distance down the oncoming lane of the perpendicular roadway. For he or she must make sure that his or her vehicle has both enough room and enough time to not share the same spot on the dance floor with an oncoming vehicle. This sharing is commonly referred to as a collision.
Further, the higher the speed limit on the intersecting roadway, the further down this oncoming lane (or lanes) a commercial driver must look and see — and the faster he or she must get the bus or coach off the dancefloor.
Finally, at a signalized intersection, the “red phase” of the traffic cycle typically overlaps by three or four seconds, providing a “window” of safety for this dance maneuver – even if the bus, coach or truck driver turns during the “stale” end of a green light. However, vehicles cruising through the amber light and/or racing through a red one reduce this safety margin significantly. Further, all intersections are obviously not signalized. So in these instances, the dance floor can become crowded more easily. For this reason, turning before coming to a complete stop is necessarily and unpredictably risky.
Rules of the Road
“Rules of the Road” is a common catchphrase or cliché sloppily employed to cover a range of procedures whose authors was usually too lazy or inept to properly define them in sufficient-enough detail. One often thinks of rules of the road as largely involving courtesies, like making eye-contact with fellow-drivers or -motorists, and perhaps “waving on” an oncoming or turning motorist. Sometimes, such rules are embodied in traffic codes, such as a principle like “Pedestrians have the right of way.” Or at an intersection, the vehicle to the right should be allowed to proceed first. I have always found this latter “rule” somewhat confusing — especially when a vehicle is poised at all four (or occasionally more) positions in front of the intersection. Then there is the rule, commonly embraced in traffic codes, that through-traffic should be allowed to proceed before turning traffic, unless directed otherwise by a traffic signal or today’s rare live “traffic cop.” This last rule actually makes good sense. Drivers should look far down the road from which they are turning in order to observe oncoming vehicles. If they fail to do so, a vehicle approaching from much closer than it may seem (an easy error to make at night when gauging distance solely from oncoming headlights) and/or traveling faster than it may seem. But when a bus or coach driver misjudges this, and the oncoming vehicle is unable to stop before crashing into it, the larger vehicle that “turned prematurely” is usually the loser in a courtroom.
There are at least some rudimentary rules that make sense in many common driving situations. One example is the need to not turn in front of an oncoming vehicle until one is certain it is too far away to reach your big, long one. But these broad, simplistic “rules of the road” are usually not enough. Sharing the dance floor with an oncoming vehicle traveling toward an intersection from a perpendicular street is no simple matter.
Respect and Responsibility
In many previous National Bus Trader articles about “Safety and Liability,” I have opined that operating a full-size bus or motorcoach is, in many ways, as difficult as flying an aircraft. In stating this, it is fair to acknowledge that almost any idiot, with minimal training, can be taught to lift off in an aircraft. The challenge is landing it (as opposing to crash-landing it). And operating a bus or motorcoach is more difficult than piloting a plane in many other ways. One example is that pilots have little responsibility for passenger management and, particularly since 9-1-1, cockpit doors are even closed to passengers (at least in theory). So not only should there be no threats and no acts of violence, there should be no distractions. And, of course, air traffic controllers ensure that aircraft do not fly in anything remotely resembling traffic — other than perhaps the heavily-controlled, relatively slow movements they make on the ground — a far cry from anything like even light street traffic.
As far as turning, I will admit that this seems more difficult for an airplane, particularly given the speeds at which they travel, and the balance they must maintain in order to not quickly fall into a dive. At the same time, the arc of a plane’s turn is exponentially wider than that of a ground vehicle turning on a roadway. Plus, if the pilot is capable, an aircraft can roll over multiple times with precious little risk (assuming this is done with the plane still in the air) — although this is obviously not a terribly good idea for a commercial passenger aircraft.
In her popular recording “gone platinum” long ago, Aretha Frankly belted, “R-E-S-P-E-C-T. Tell you what it means to me.” What it means to me is, that to earn and deserve my respect, a commercial driver must accept and embrace the responsibility of mastering the challenging skills noted above. If not, the most important rule-of-the-road should be to stay off it.
The formula for the force of two colliding objects sloppily approximates the inverse of the square of their respective masses. So a 2000-lb. automobile colliding with a 40,000-lb. bus or coach absorbs not 20-times the impact that the bus does, but closer to 400 times that impact. When the loser in this match is made of skin and bones rather than steel, glass and rubber, and weighing only a fraction of the mass of even the smaller of the two vehicles employed in this comparison, these dynamics are greatly exaggerated. So the operators of such vehicles must be more than both skilled and careful. They must be very skilled and very careful. And they must be very knowledgeable and very awake and alert.
If a driver fails to master these skills, and/or fails to exhibit the degree of concern warranted — notwithstanding a third party compromising his or her ability to properly exercise these skills — he or she is going to lose my respect quickly. Far more importantly, he or she is likely to lose the respect of some jury. And along with it, the insurance carrier of that driver’s employer is likely going to have to open its wallet, and open it wide. While two steel vehicles colliding may often result in a mere fender bender, such vehicles do more than bend a fender when they strike a pedestrian. When a 53,000-lb. motorcoach does this, the affair rarely has a happy ending. This dance does not end like the pleia of a ballet, or even with the gracious “dip” at the end of a ballroom foxtrot. It ends more like a crucifixion. Unfortunately, this crucifixion follows the incident into the courtroom when the inevitable lawsuit emerges.