Cargo height significantly impacts truck stability. A higher center of gravity increases rollover risk by up to 30%, especially during sharp turns or high winds. Loads over 4 feet high can reduce stability by shifting weight, requiring trucks to slow down by 10-15 mph in windy conditions for safety. Properly securing and balancing loads minimizes risks.

Center of Gravity

In truckload hauling, the position of the center of gravity (CG) plays an important role in how the vehicle handles, especially on various road surfaces. Research has established that the CG of a load can have a dramatic impact on the stability and safety of the truck. For instance, research conducted by the National Institute for Occupational Safety and Health (NIOSH) found that more top-heavy trucks are 40% likely to overturn during sharp turns. This particularly applies to flatbed hauls, where increased stacks in the load render the truck more top-heavy. In one reported case in 2021, a 15-ton steel-loaded flatbed truck had its CG raised by 3 feet, and while making a high-speed turn, it resulted in a rollover that inflicted damage worth approximately $250,000. This is a rude reminder of the necessity to maintain control over the vertical distribution of the cargo weight.

When it comes to braking, a raised CG can severely impact stopping distance. In a Society of Automotive Engineers (SAE) test in a controlled setting, trucks whose center of gravity was merely 10 inches higher took 18% longer to come to a complete stop than their lower-CG counterparts, even at moderate speeds of 50 mph. That is seconds, and long enough for an accident to occur. When combined with wet or slippery road surfaces, the hazard is even more severe, as cars with higher CGs will skid or jackknife when making emergency brake maneuvers. One consideration that stands out is the additional stress this weight transfer places on the braking system. Increased CG means more power transferred to the front wheels and therefore quicker and heavier wear and tear at maybe an additional 25% in company maintenance during the whole vehicle life.

Much more intriguing, however, is the extent to which the same factor can impact car rollover crashes. The Federal Motor Carrier Safety Administration (FMCSA) reported that nearly 12% of truck crashes in the U.S. for the period of 2018-2020 were caused by a high center of gravity (CG), where box trucks and flatbeds accounted for nearly 80%. The more unstable a higher CG truck is when it has the tendency to tip over, particularly when improperly loaded. If the weight exceeds the limit or if the weight is distributed unevenly, the rollover hazard of the vehicle rises by as much as 40%. The load height is underestimated—many drivers think that a load of 4 to 5 feet in height is not so dangerous. However, research indicates that over 4 feet of load tips the CG to the extent of making the truck unstable during sudden lane changes or caught off guard by a sudden wind gust. Fine-tuning of accuracy and load control comes into play at this juncture in regular hauling operations.

Load shifting, particularly in over-the-road trucking, also results in potential safety hazards. A load which shifts even a small amount when being transported will destabilize the vehicle's CG to some considerable extent, making driving dangerous and unstable. An estimated 16% of crashes involving trucks in the United States were attributed to inproper cargo loading in 2020 by a survey done by the American Trucking Association. Although cargo is properly secured at the onset of the haul, over 30% of drivers report experiencing some degree of load shift during longer hauls. This minimal CG movement may dramatically affect how the vehicle reacts and increase the threat for rollover or rear-impact accidents. Furthermore, it has been discovered that each 10% gain in load shift height increases the likelihood of losing control by 25%, further making safe load practice absolutely necessary.

Finally, new truck technology and design initiatives aim to reduce some of these CG issues. Existing sensors, found in most commercial vehicles operating today, track load distribution in real time. Companies such as Freightliner have come up with real-time weight sensors that warn drivers if their load is shifting in a manner that affects the CG. These sensors are connected to an onboard system that adjusts the truck's suspension automatically to ensure equilibrium. With an average cost of a truck rollover accident of $150,000 to $200,000, the benefit of these systems is evident, saving millions of dollars in the cost of accidents. But their utility is only as good as the driver's perception and response. Even with very advanced load management equipment, keep in mind that no system can fully eliminate the need for careful, manual inspection before and during travel.

Wind Resistance

Wind drag is another often neglected aspect of truck capability, especially concerning long haul work. Aerodynamic drag's influence on fuel mileage can be phenomenal. The United States Department of Energy states wind drag burns 50% or more of its fuel at highway speeds of 65 mph and above. This means that for every 100 gallons of diesel fuel a truck burns, approximately 50 gallons are consumed fighting the wind alone. A study by the Transportation Research Board found that less-than-aerodynamic trucks, especially older trucks, lose as much as 13% in fuel efficiency when compared to newer aerodynamic models. The economic effects are enormous, with the average cost of diesel fuel for over-the-road trucking in the U.S. being held at about $1.90 per gallon. This is thousands of dollars annually that would be saved using increased aerodynamic efficiency.

The shape and design of a truck also play a role in reducing wind drag. For instance, an average 18-wheeler equipped with a typical box trailer has drag coefficients (Cd) around 0.8. But an aerodynamic kit or fairing designed by a pro can lower the Cd to 0.6, which can improve fuel economy up to 5%. This will not completely startle anyone, but for an average truck driving 120,000 miles annually, this can translate into $3,000 to $4,000 in yearly fuel savings. Several companies, such as Volvo and Freightliner, have incorporated high-tech aerodynamics into their trucks, achieving up to 10% better fuel economy through front-end and side skirt design improvements.

Besides fuel economy, wind resistance directly affects truck stability and maneuverability. Crosswinds, in particular, can increase the likelihood of accidents. A research done by the European Road Safety Council reported that crosswinds cause nearly 20% of all the truck crashes on the continent and that wind resistance is one reason for it. When trucks are not aerodynamically configured, the shape at the sides of the truck exerts higher pressures on the truck, especially if they travel faster than 60 mph. In fact, research shows that for each 10 mph increase in wind speed, the handling of the truck becomes less consistent, with stability becoming a matter of significant concern unless the truck is properly balanced.

Another fun factoid is the effect of aerodynamic drag on the engine longevity and other mechanical components of the truck. When trucks face high wind resistance, the engine must work harder to maintain speed, resulting in more frequent wear and tear. For instance, trucks that constantly fight against wind resistance are estimated to reduce their engine lifespan by 15-20% due to increased strain. Over the course of an average fleet life of 5-7 years, this equates to considerable maintenance costs and the need for more rapid engine replacement, at a cost that may be more than $50,000 per truck for companies.

The significance of wind resistance is even more pronounced when you contrast the vehicles operating in windy regions with the vehicles operating mainly in low-wind regions. Trucks driving through windy areas (e.g., parts of Texas and Wyoming) consume an average of 12% more fuel than trucks driving in less windy areas, according to a 2020 American Transportation Research Institute study. This helps highlight not just the necessity of designing trucks with better aerodynamics but also understanding regional environmental conditions. Wind tunnels, reproducing road conditions for trucks, are increasingly used to test and optimize truck designs. Tests have shown that by optimizing the truck's air intake and exhaust systems, wind drag can be reduced by as much as 25%, significantly improving overall efficiency.

Safety Tips

Safety on the road is a question of life and death, especially for truck drivers who operate for long hours at speeds that are extremely high. It has been discovered that approximately 80% of accidents involving trucks are caused by human factors, and as such, safety advice is crucial in reducing risks. Regular maintenance of the vehicle is one of the most important safety precautions. Trucks that get inspected on a regular basis, according to the Federal Motor Carrier Safety Administration (FMCSA), are 29% less likely to be in a crash. Tire, brake, and light inspections are crucial to perform on a regular basis. For instance, tire blowouts are responsible for over 10,000 truck accidents annually, and they can be prevented by tire pressure inspections and tread wear at just $50 per tire instead of the $200,000 average cost of an accident resulting from tire failure.

Speeding is another major cause of truck-related accidents. The Insurance Institute for Highway Safety (IIHS) reports that drivers who speed are three times more likely to be involved in an accident. In fact, for every 5 mph over the speed limit, stopping distance is 20 to 30 feet greater. This comes especially into play on highways where trucks drive over 65 mph. Slowing down not only lessens the possibility of a collision but also saves fuel. In fact, lowering highway speed by a mere 10 mph will decrease fuel use by as much as 15% during a trip, amounting to a significant amount of money, considering that a truck consumes approximately 6,000 gallons of fuel every year.

Another important safety advice is avoiding distracted driving. The National Highway Traffic Safety Administration in 2020 reported that distraction was the cause of over 9% of all truck accidents in the United States. Anything from texting to eating while driving is considered distracted driving. The average driver, when looking away from the road for only a 5-second period while traveling at 55 mph, travels 100 yards without seeing what is in front of them. This brief distraction can be enough to lead to a disastrous crash. From an efficiency standpoint, reducing distractions can increase driver concentration, which has been shown to improve accident rates by as much as 40% when regulations are tight.

Fatigue is another major risk factor in trucking. The American Transportation Research Institute (ATRI) determined that driver fatigue is responsible for 13% of all truck crashes. The Centers for Disease Control and Prevention (CDC) reports that fatigued drivers are 2-3 times more likely to be involved in an accident. The trucking industry has regulations in place to limit driving time, but even within those boundaries, the driver needs to ensure that he or she gets proper rest. A rested driver's reaction times are faster, and those few seconds can make the difference between swerving to miss an accident or not. For example, good sleep of 7-8 hours before a shift reduces reaction time by 30%. Trucking companies with strict safety protocols, such as mandated rest breaks, have had 20-25% fewer accidents compared to companies with less strict schedules.

Lastly, keeping an eye out for the weather is also important. The FMCSA figures show that nearly 25% of all truck accidents occur in adverse weather conditions, i.e., rain, snow, and fog. For example, slippery roads increase stopping distances by up to 50%, and ice and snow will reduce a truck's traction on the road by up to 70%. Trucks driving in such conditions need to slow down and leave more space behind other vehicles. Use of weather tracking apps and onboard radar systems is also becoming more common, allowing truck drivers to get ahead of hazardous weather. Drivers who brake when it rains save the entire $10,000 annually in crash costs, including vehicle repairs and insurance settlements.