In Part 1 of this series, we examined the problem of crashes involving large trucks (those weighing more than 10,000 pounds) on California’s highways. In this article, we explore the reasons those accidents occur. In Part 3, we will discuss the injuries caused by collisions with large trucks and make some suggestions that might help you avoid becoming the victim of a truck accident.

Primary Causes of Large Truck Accidents

Some crashes involving tractor-trailers and other large trucks are caused by negligent truck drivers. Other large truck accidents are caused by drivers of smaller vehicles. In any collision between a large truck and a car, however, the occupants of the car are more likely to be injured than the truck driver.

Many professional truck drivers are well-trained, careful drivers. They stay alert, they obey traffic laws, and they do not drive more hours per day than federal regulations permit. Other semi drivers (particularly independent operators who are not subject to an employer’s careful supervision) are less responsible.

The Federal Motor Carrier Safety Administration’s Large Truck Crash Causation Study (LTCCS) found that 77% of all crashes in which truck drivers were at fault have one of two causes. The truck driver’s poor decision-making accounts for 42% of crashes while another 35% are caused by the driver’s failure to recognize problems in time to react appropriately.

The study identified a number of bad decisions that result in collisions. Poor decisions made by truck drivers include:

  • Speeding
  • Driving too fast for conditions (such as fog or wet roads)
  • Taking a curve too fast
  • Following another vehicle too closely
  • Misjudging a gap between cars when merging or changing lanes
  • Misjudging the speed of other cars
  • Aggressive driving
  • Making a false assumption about another driver’s behavior
  • Making an illegal maneuver (such as ignoring a “no U-turn” sign)
  • Failing to take correct action (such as failing to apply brakes quickly enough)

Recognition errors (the failure to recognize problems in time to avoid them) include:

  • Inattentive driving (daydreaming, for example)
  • Distracted driving due to something inside the truck cab (such as using a cellphone or setting GPS controls)
  • Distracted driving due to something outside the truck cab (such as looking at an accident scene rather than watching the road ahead)
  • Inadequate surveillance (failing to keep an eye on the movements of other vehicles)

About 8% of accidents that are the responsibility of the trucker are caused by problems with the vehicle, including:

  • Shifting cargo
  • Brake failure
  • Tire failure
  • Suspension failures

A relatively small number of accidents are caused by the trailer on a semi becoming detached from the tractor. Steering, transmission, and engine failures are also relatively rare factors that lead to accidents.

Poor driver performance accounts for 7% of accidents caused by negligent truck drivers. Poor performance differs from poor decision-making in that the driver makes a reasonable decision but fails to execute the decision correctly. For example, a poorly trained or inexperienced driver might overcompensate when losing control of a trailer on a slippery road, causing the tractor-trailer to jackknife.

Environmental factors explain about 4% of large truck accidents. Those include weather conditions such as fog or slippery roads, although careful drivers should usually be able to maintain control of their rigs in bad weather. Other environmental factors include malfunctioning or missing traffic or railroad signals, poor road conditions (such as loose gravel), and debris or other obstructions in the road.

Physical factors leading to “non-performance” (or a temporary failure to drive) make up the last LTCCS category. Those factors are involved in 3% of large truck accidents that truck drivers cause. Falling asleep at the wheel or experiencing a heart attack are examples of non-performance.

Contributing causes of large truck accidents

In addition to the primary causes discussed above, the LTCCS identified several overlapping factors that contribute to poor driver decisions and the failure to recognize problems in time to avoid them. The most significant contributing factors are:

  • Drug use. Prescription drugs, over-the-counter drugs, and illicit drugs can all lead to impaired judgment, drowsiness, or delayed reactions.
  • Inadequate rest, drug use, and other factors discussed below cause fatigue that reduces alertness and contributes to inattentive driving.
  • Whether their problems are legal, financial, or employer-related, upset drivers concentrate on their worries rather than the road.
  • Workplace pressure. Pressure to meet deadlines, to drive while fatigued, to accept more loads than the driver can reasonably handle, and to accept short notice trips may cause drivers to speed or to drive aggressively.
  • Compensation schemes. Drivers who are paid by the hour have no reason to rush their deliveries, while drivers who are paid by the mile have a greater incentive to drive as many miles as they can each day. That motivates them to falsify log books and to drive more hours in a day than the law allows.
  • Inadequate training. Some employers require drivers to undergo meaningful safety training programs, but many drivers (including owner-operators) only need to pass their test for a Commercial Driver’s License before they take big-rigs on the road.
  • Poor screening and supervision. While large companies tend to keep track of their employees’ driving records, other companies do not determine whether their new hires or established drivers have received speeding tickets and other traffic violations.

No matter the cause, any collision with a tractor-trailer or other heavy truck can lead to devastating injuries. We take a look at those in the next article in this series.