Trucks and Truck Accidents: Considerations for Litigators

TASA ID: 189


          Big rigs, trucks above 33,000 lbs. gross vehicle weight, also known as "class 8" trucks, are very different from lighter vehicles. They are more complicated and harder to operate, and, of course, much bigger. They can weigh more than 80,000 lbs. and can measure 102" (8'6") wide, 65' long and 14' high, and even bigger with special permits.   Their "performance envelope" - the levels of braking, cornering and accelerating- is smaller than that of light vehicles.  Big rigs require a special operator's license, the "CDL" or commercial driver's license for drivers. 

          The size, capacities and operational characteristics of big rigs have led over the years to a large number of state and federal regulations for heavy trucks. First of all, in most states, trucks above a certain weight are required to obtain "operating authority," essentially a special kind of registration. Most states also require periodic vehicle inspections done by independent mechanics. Some states allow in-house inspectors, but this self-evaluation can lead to problems. These inspections involve brakes, steering gear, suspension, tires, a myriad of mechanical evaluations not normally done on a regular basis with light vehicles. These annual vehicle inspections, or occasionally, the lack thereof, should be investigated whenever the mechanical condition of a truck involved in an accident is suspect. But since big rigs can put on up to 250,000 miles a year, a marginal condition noted on the inspection in January might degrade into a serious problem the following December. It is then always desirable to be able to inspect the vehicle after the accident and not rely on the last inspection.

          The CDL books published by the states spell out the requirements for truck drivers fairly well. It should probably be reviewed whenever driver conduct or performance is suspected in a truck accident. In fact, those unfamiliar with trucking should probably take the time to go through it whenever they have a truck accident case. Many topics in it will be unfamiliar to light vehicle drivers. Included here are such things as additional special licensing requirements for hazmat  (hazardous materials) drivers, special tests for tanker and doubles or triples drivers, and pre-trip inspections and general licensing regulations which don't pertain to other types of motor vehicle operators.

Accident and Injury Causation

          Truck accidents are unique in many aspects. One that may be of special interest to litigators is that, even without causing personal injury, truck accidents can be expensive and involve property damages far above those typically generated by light vehicle accidents. The average "property only" damage claim in 2004 for heavy truck accidents was $66,000.00. This generally didn't even involve totaling the big rig.  Today the rig, i.e., tractor plus trailer, or "straight truck" (no trailer, like a dump truck or other "vocational" truck), will typically cost well in excess of $100,000.00. A truck accident can involve serious property damage, environmental damage, e.g., fuel spills from 150 gallon tanks, or even highway damage when a big rig takes out an overhead sign or tears up guardrails and the median strip. Big rig accidents then may involve complicated damage assessments and larger liabilities than would normally be encountered in light vehicle accidents.

          Personal injury cases involving heavy trucks will likewise probably involve greater harm than those involving similar accidents with light vehicles. Big rigs are bad to hit or to get hit by because of the high weight and also because they lack adequate bumpers and underride protection for both the sides and rear of the truck. The harm potential for big rigs then is designed in and affects occupants both in the truck and in other vehicles. A frequently overlooked aspect of truck accidents is the injuries the big rig operators themselves suffer.  Most of the fatal injuries suffered by heavy truck occupants occur in rollover accidents and are due to flimsy cabs. And, uniquely in the case of motor vehicle accidents, most of these injury mechanisms involve entrapment or positional asphyxiation. There are no federal requirements for the structural integrity of truck cabs which invariably fail on ground contact. The result is that drivers are trapped under the weight of the cab and cannot breathe or cannot escape a fire or other hazard. Note then that recovery possibilities are not necessarily exhausted by workers comp claims when a driver is killed or injured.

          Generally, highway vehicle accident causation admits to three types of considerations: 1. the human element, 2. the vehicles, and 3. the operating environment, this latter topic including roads and road-related topics, e.g., highway signage, as well as weather and factors affecting visibility and conspicuity. All three of these potential factors are different and more complicated for trucks and truckers than they are for other types of vehicles and their operators. We discuss many of them in what follows.

Big Rig Mechanical and Equipment Issues

1. Brakes

          If a truck accident was caused by a mechanical problem, most likely the problem was in the braking system. All heavy trucks use air brakes; high pressure air applies the brakes. The "hiss" you hear at the stop light from the big rig in front of you occurs when the brakes are released, not when they are applied.  Air brake systems are complicated, hard to maintain and less effective than the hydraulic brake systems used on light vehicles. The system includes an engine-mounted air compressor, several tanks, numerous lines and valves, and the actuating units at each wheel. Most importantly, the "S" cam drum brakes, now in almost universal use, have adjustment requirements that are critical for optimal brake operation.

          With a cam brake, the air pressure moves a diaphragm which pushes a rod, which turns a lever that rotates the cam that forces the friction linings into the rotating drum to generate a retarding force. The lever adjustment is critical because the diaphragm and rod can only move so far (about 3"), and if this movement doesn't effectively force the lining into the drum, then the brake unit isn't operating efficiently if it is working at all.  The brake adjustment is done with a 9/16" wrench and a pull bar under the truck in what can sometimes be difficult circumstances. Sometimes it isn't done right or often enough.

          A case in point: Vehicles coming into Oregon from California face a long down hill run as they cross the state line at Siskiyou Summit.  In the past, the Oregon State Patrol has set up check points and pulled trucks over as they entered the state and inspected them. As many as 35% on occasion have been immediately pulled out of service, meaning that they can't be driven further until they are fixed. Most of these out-of-service vehicles had brake problems, and most of these problems were related to brake adjustments. This was probably a good indication of the situation nationwide; if anything, however, hill country truckers probably have better brakes because the drivers realize they need them in mountainous terrain.

          Late model trucks have mandated automatic slack adjusters, which are supposed to prevent out-of-adjustment brakes. (Auto slack adjusters were available as options prior to being required. Most end users did not buy them because of cost and alleged reliability problems.) But older trucks and poorly maintained trucks may still have adjustment problems which can cause accidents. The problems are of two types: low stopping power and brake fade.

          Out of adjustment brakes don't stop the rig as fast as correctly adjusted brakes because the brake units aren't working, or aren't working as hard as they should be to slow the rig down. Big trucks don't stop well anyway; when fully loaded, they take almost twice as long to stop as light vehicles. Any further reduction in stopping power can have serious implication in emergency situations. But the biggest problem associated with poorly adjusted brakes is brake fade. Brake fade, a heat-related problem, can result in a situation where an 80,000 vehicle simply becomes very difficult to stop.

          The driver sets the air pressure, the "application" pressure up to about 100 psi, in the brake chambers via a valve under the brake pedal -for the entire rig- or via a lever on the dash which applies only the trailer brakes. If the brakes aren't adjusted properly, or aren't all adjusted the same way, a situation may develop where the units that are doing the most work overheat and fade out. That is, the linings become slick and don't provide the normal level of friction against the rotating drums. This condition is generally promoted if the driver rides the brakes, that is, uses a continuous low pressure application to slow the vehicles as opposed to stabbing the brakes, i.e., uses short bursts of higher pressure and harder applications. This is especially important in hill country but might even come into play in stop and go freeway driving.

          It should be clear from all of the above that anytime a truck is braking prior to the accident, or may have been or should have been braking prior to the accident, knowledge of the condition of the braking system can become extremely important. The hydraulic brakes on light vehicles basically either work- if the hydraulic system is intact- or they don't. The situation with air brakes is far more complicated. Other problems like air leaks, brake balance and frozen lines and other conditions like load distribution (below) may also merit investigation if braking is involved in an accident. It will, of course, be important to question the driver about the condition of the brakes and how they were applied, e.g., whether he used the foot pedal or the hand valve, prior to the accident.

2. Tires

          Tires are probably the second biggest problem area with respect to accident causation. Tire failure can be caused by manufacturing defects, overloading, under inflation or road hazard. Failure of only one of the 18 tires on a semi can have serious consequences. Failure of a steering axle tire can result in complete loss of vehicle control, especially with older trucks that don't have power steering. If one of the tires on a dual tire drive axle or trailer axle fails, then the other tires will have to do more work, support more weight. This means that adjacent tires on an axle will be more likely to heat up and fail, and a situation involving progressive tire failures on the axle may develop. It probably won't progress too far, however. Most likely, one of the tires will catch fire, or the vehicle will rollover while cornering, both situations which should be evident to the driver. 

          Contrary to a common belief, recaps are not illegal on truck steering axles although they are illegal on bus steering axles. New truck tires are expensive, and recaps are in common use in the industry. The reliability of recaps is sometimes questioned, but the recap industry vigorously defends its practices and technology, and we are unaware of any data that suggests a special problem with recaps. Some investigators have assumed erroneously that any recap tire failure is a cap failure. But in order for it to be a cap failure, there must be no tire cord in the failed section.

3. Other Components and Systems

          Because trucks can be 8 ½' wide and traffic lanes are generally no more than 12' wide,  there  is  a much greater chance of a lane violation with a big rig than with a light vehicle, which is typically no more than 7 ' wide and is frequently even narrower. This smaller margin of error makes steering and front end alignment even more important for trucks than it is for smaller vehicles. Whether a truck runs straight or not is determined mostly by front end alignment, chiefly the caster adjustment, tire pressures and tire loading (weight distribution), and maybe even tire type or tread pattern. Unfortunately, much of the information about the relevant components can be lost if the truck hits something and the front end is damaged. But any case involving a lane violation and a big rig probably mandates a check of the service records and drivers' reports for indications of directional control problems.

          The importance of powertrain problems in truck accident causation is frequently overlooked. Heavy trucks have very low power-to-weight ratios compared to light vehicles. The biggest engines now available produce about 600 horsepower. The average for the installed fleet is probably less than 400 horsepower. Four hundred horsepower in an 80,000 lb. vehicle is the same as 20 horsepower in a 4,000 vehicle like a pickup truck. This means that at best, trucks cannot get up to speed or get out of the way quickly. An engine running poorly or a transmission that is difficult to shift may aggravate problems that are inherent to the vehicle and promote accidents whose causes are difficult to identify and may be missed.

          Hills and freeway on-ramps are the most likely places for powertrain problems to show up.  A big rig going up a hill may only be able to hold 40 mph on the grade while light vehicle traffic is doing 60 mph. This 20 mph speed difference can pose a problem for traffic approaching from the rear because it is extremely difficult to determine the relative velocity of an object dead ahead of you. But this speed difference is probably manageable.  But if the truck can only pull 20 mph on the grade because the engine is in bad shape, the resulting 40 mph speed difference might well be a contributing factor in a rear end accident. Similarly, if a truck driver pulling up a freeway on-ramp misses a gear shift, say because the clutch is bad, he may then have to stop the vehicle completely while on the ramp and start out again in first gear. This can result in extremely low speeds relative to following traffic when the big rig enters onto the freeway.  (Most heavy trucks have manual transmissions. The few exceptions are generally vocational trucks like cement mixers and dump trucks.)

          Failures of frame rails, suspension components and alike can also cause accidents. A broken spring can and probably will cause a fully loaded truck to rollover unless the vehicle is stopped in time. The problem with these items in accident reconstruction is that it can be difficult to determine whether the failure was the cause or the result of the accident

4. Visibility and Conspicuity

          Many big rigs have a blind spot on the right side where smaller vehicles cannot be seen by the truck driver. The rarer short nose cab-over models also have a blind spot in front of the truck which can extend out several feet, depending on the height of the pedestrian or obstacle in front of the rig.  The right side blind spot extends out in front of the right fender and goes back to the right side door. A special right side mirror or a cutout in the right side door is required to eliminate the blind spot. The door cutout in the "daylight door "can easily be covered by items carried in the cab, however.  Moreover, in the past, both the daylight door and the mirror were optional equipment; trucks came without them unless they were specially ordered. In some cases they may have been delete options -removable for credit.  In our view, both situations mark design defects in the affected vehicles.

          Since 1999 all trailers have been required to have reflective tape- "conspicuity tape"- on the sides. But straight trucks, one piece trucks without separable trailers, don't have to have it. Some of these straight trucks can be long van trucks that pose the same problem as combination rigs unfortunately. The problem is one of figure-ground recognition. A large flat surface under the right optical conditions can appear to be background and may not be detected by approaching traffic. Thus, any vehicle that lacks conspicuity tape or has the tape obscured by dirt can then represent a hazard to traffic approaching from the side.

Drivers and Operational Considerations

          There seems to be a constant shortage of truck drivers, so there always tends to be a number of bad or dangerous truck drivers on the road because the good ones are in short supply. The bad driver problem is probably greater with "gypos" -small operators- and part-time truckers than it is with the big fleets, who tend to monitor their drivers more carefully. But any driver can be suffering from the effects of fatigue or drug or alcohol use. Fatigue may well be the single biggest reason for driver-caused truck accidents. Current regulations allow up to 14 continuous hours of driving, a rule that is probably pushing it, and is sometimes violated. Drivers are supposed to record their operating hours and down time in a log book, but the accuracy of these self-reports has often been called into question.

          A basic problem with American truckers is that unlike say, European truckers, they tend to get paid by the mile. This fact, in addition to the occasional delivery deadline, means that some drivers will be driving too fast or too long for safe operation. A careful review of the driver's log with some mathematical analysis -time and distance analysis- may reveal some discrepancies in the log and suggest reasons that a driver could be at fault in an accident. It is also worth checking occasionally whether or not what looks like a reasonable run, say 400 miles in ten hours, could have actually been done at the time indicated or if weather, road conditions, traffic or some other problem would have actually prevented it.  Two other telltales on the driver found in trucks are the "Tachograph," used by some fleets, which records vehicle speed over time, and the "ECM" or engine control module. ECMs vary as to what they record and for how long, and are basically about the engine and not the driver. Occasionally they will yield important information, such as the engine speed at the time of an accident if they are recovered and read quickly enough. (If you know the engine speed, transmission gear selection, final drive ratio and tire rolling diameter, you can compute the vehicle's speed. Always ask a driver what gear he was in at the time of an accident anyway).  It should also be noted here that today some fleets use GPS systems to keep track of their rigs, so the home office may have real time information about what their drivers are doing, and presumably, some record of it.

          Heavy trucks are sometimes found where they shouldn't be due to faulty pre-trip planning and route evaluation. Modern roads make routing problems far less common than in the past, but we still find trucks getting stuck under underpasses or causing pavement failures on substandard roads. Tight turns, narrow roads and other highway conditions may produce difficulties and accidents with big rigs which could and should have been avoided. It is sometimes useful, then, to consider the question of whether or not the truck should have been there at all, or if another route was possible and advisable.

          We have previously discussed two aspects of the big rigs' performance envelope that differ from those of light vehicles: acceleration and braking. The final performance parameter, cornering ability, or more generally, stability with respect to lateral forces, is just as important although it is frequently overlooked. When a vehicle is changing its direction of travel, as in rounding a curve or turning a corner, the tires must generate lateral forces to cause this change in direction. These lateral forces tend to upset the vehicle and roll it over. There is a ratio, the so- called "static stability factor," T/2H,  where "T" is essentially the width of the vehicle and "H" the height of the center of gravity that determines the vehicle's resistance to rollover as a result of these lateral forces. The higher the ratio, the more stable the vehicle. For sports cars the ratio can be as high as 1.3.  For most passenger vehicles the ratio is about 1.2. For big rigs the ratio starts at about 0.6, gets lower as the rig is loaded, and can perhaps approach a dynamic value of about 0.15 if the load can move.

          This means that big rigs will roll over under circumstances that would barely cause notice in a light vehicle. Very gradual curves taken at slightly too high a speed or a highway maneuver that would not be problematic in a lighter vehicle will cause the big rig to roll over. Drivers are more or less aware of this, but knowing that it can happen isn't of much use unless you know how to prevent it.  Speed is thought to be the predominate cause of rollovers, but this probably isn't true. While going around a curve too fast will definitely roll the rig, many other driver mistakes and highway conditions will also. The minimum speed required to roll a big rig is probably around 5 mph. In contrast, the lowest speed ever recorded for a passenger vehicle rollover was about 25 mph for a Jeep CJ5, and even the pickup-based, rollover- prone SUVs probably won't go over below 30 or 35 mph.

          Most truck rollovers probably occur when the rig inadvertently leaves the road and the driver tries to return to the paved surface from a soft or undercut shoulder.  Then, the wheel catches the pavement edge and trips the vehicle, or the driver turns the wheels too far and is steering too hard when he hits the pavement. This can happen with any vehicle and is a common cause of SUV accidents, but it  is far more likely to happen and much easier to do in heavy trucks because they require lower upsetting influences -as a percentage of vehicle weight- due to their lower static stability factors. Still another way to roll a big rig involves "outtracking." The front and rear tires of a tractor- trailer rig do not follow the same path while the vehicle is rounding a curve. At certain speeds, the trailer tires follow a wider path than the steering axle tires on the tractor. This means, for example, that while the front tires may be running well inside a curb or other obstruction, the rear tires may run into it, causing the rig to roll over.

          Several other handling problems unique to big rigs merit special mention here  All are related to braking problems which are controlled or eliminated with modern anti-lock braking systems (ABS) but are still prevalent in most of the heavies on the road today. Tractor- trailer rigs can jackknife when the tractor brakes are locked. A similar phenomenon, which, to the uneducated eye, may look the same but isn't, is trailer swing. If the trailer wheels are locked while the tractor wheels are unlocked, the trailer can swing out into adjacent lanes, much to the irritation of traffic in those lanes. Finally, if the tractor is bobtailed - no trailer- the drive axle brakes at the rear of the tractor can very easily lock up, throwing the tractor out of control and into a spin. While rear wheel lockup is possible with any vehicle without ABS, it is far more likely to occur in a bobtailed semi because the brakes are designed for high weight on the drive axles. When it isn't there, the brakes lock up very easily.

          Big rigs, especially tractor trailers, need ABS far more than light vehicles do, yet they have been slower to get it. There were electronic systems available in the early 1970's which were essentially mandated by the Federal Government with the (FMVSS) "121" law. But complaints about these earlier systems led to rescinding this regulation so that big trucks had decades of poorly controlled braking systems until the development of modern electronic ABS systems in the 1990's. This is essentially the industry's story anyway. But the fact is that some imported medium trucks had non-electronic brake pressure modulating systems - load-sensing mechanisms - throughout this period that could have been and should have been adopted for class 8 trucks.

Cargoes and Loads

          Any load that can move is a problem, and all loads can move. Basically, the load - here the weight associated with the cargo- should at a minimum be secure within the inertial parameters of the vehicle's operating envelope as the vehicle is shaken, jarred or bumped during the course of travel.  This means that the load should not move under the influence of  forward accelerations on the order of 0.1g -0.2g's  (1g = weight of the vehicle), lateral forces of about 0.6 g's and braking forces of about the same order. But this is during and after the travel interval; it is not a static standard. Cargo shakes loose; it doesn't break lose, for the most part. Cargo that can move is problematic, not just because it can fall off onto the roadway or onto other vehicles, but because it tends to produce control problems for the affected vehicles. In particular, it tends, in the case of lateral movement, to cause them to roll over. Load shift means weight shift, and weight shift in a moving vehicle isn't good.

          One problem here is that even if most loads can be adequately secured, some cannot. Some loads have to move: concrete in a mixer truck. Some loads may want to move: cattle in a cow hauler. And some loads have to be allowed to move: liquids in a tanker. Cement trucks can become dangerous if "the mud gets high," that is, if the concrete starts sticking to the rotating drum. Livestock rigs are probably thought to be more dangerous than they actually are, if, in fact, the animals are penned up and can't move much

          Tankers are the biggest problem here. When a tanker is being filled, it is frequently necessary to allow some room for the expansion of the contents as they heat up. Before the load warms up, however, there is an unfilled space in the tank which allows the contents to move. This is particularly important when the vehicle is cornering. Sloshing liquids can be very detrimental to vehicle stability. While most tankers have internal baffling that inhibits back and forth motion of the contents, they generally lack the type of baffling that limits side-to-side motion, and side-to-side motion can cause rollovers. This problem is greatly aggravated by partially-filled tankers, say tankers that left full but have now dumped some portion of their original load. The worst case involves a tanker that is about two-thirds full, something which the industry knows but which individual operators may not be aware of.

          The load has to be secure, and it has to be located correctly on the truck.  If the weight is too far back, you can get a situation where a big tail is wagging a small dog. If the weight is too far forward, the trailer brakes can get touchy and trailer swing, as described above, is promoted in emergency situations. Composite loads and loads with elements that can move relative to one another -like steel or finished lumber-can be particularly hard to secure. In general, when a moving load has caused a problem, it is necessary to ask not only why the load came loose, but what other means could have been used to more adequately secure it. Sometimes, different equipment, including a different kind of truck or trailer, would have been advisable.

          Regardless of why a load moved or came off a truck, the driver will get blamed for it. Blaming the driver for everything that goes wrong is a tradition in trucking. Whether or not the driver is really at fault is another question. At any rate, professional drivers always do it right in recollection, after the fact, even if they weren't quite sure what they were supposed to do at the time of the accident. Many CDL books suggest something like this: "Cargo security should be inspected within 25 miles after beginning a trip" and then "... as often as necessary during a trip to keep the load secure...." It's a good bet that the driver will say he checked the load at the 25 mile point although he might have lacked knowledge of this regulation at the time of the accident.  Even when drivers know the rules, the rules can be hard to follow. Checking a load, for example, might require pulling off a freeway or finding some place to stop on a state route, neither of which is necessarily very convenient in a big rig. But the problem of loose loads can go well beyond the driver. The technical issue concerning responsibility for a failure in cargo security can be complicated and may require careful analysis; it might be the driver, the trailer deck surface, a lumper (cargo handler), a shipper or the supplier of the retention equipment.


          Heavy truck accidents can be challenging. They require special knowledge and careful investigation to evaluate liability issues.

This article discusses issues of general interest and does not give any specific legal, medical, or business advice pertaining to any specific circumstances.  Before acting upon any of its information, you should obtain appropriate advice from a lawyer or other qualified professional.

This article may not be duplicated, altered, distributed, saved, incorporated into another document or website, or otherwise modified without the permission of the author, who will be contacted by TASA.

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