Why Every Semi-Truck Has a Mansfield Bar—And Why It Matters

If you’ve ever driven behind a semi-truck, you’ve likely noticed a horizontal bar near the bottom of the trailer, often painted with red and white stripes. This bar, officially known as an underride guard, is a critical safety feature designed to prevent cars from sliding underneath the truck during a collision. While these guards have been mandatory since 1998, their effectiveness has been a topic of debate and ongoing improvement.

In this article, we’ll explore the purpose of underride guards, their history, and why they’re also called Mansfield bars. We’ll also discuss the challenges in making these guards more effective and how they continue to evolve to save lives on the road.

What Are Underride Guards?

The Purpose of Underride Guards

Underride guards are metal bars installed on the rear (and sometimes sides) of semi-truck trailers. Their primary function is to prevent smaller vehicles from sliding underneath the truck during a collision. Without these guards, the high ground clearance of semi-trucks—typically 48 inches—poses a significant risk to passenger vehicles, especially sedans, which can easily wedge beneath the trailer in a crash.

How They Work

In the event of a rear-end collision, the underride guard acts as a barrier, absorbing impact and preventing the car from going under the truck. This reduces the risk of severe injuries or fatalities by ensuring that the car’s crumple zones and airbags can function as intended.

The History of Underride Guards

The Tragic Inspiration: The Mansfield Bar

Underride guards are often referred to as Mansfield bars, named after the tragic death of actress Jayne Mansfield in 1967. Mansfield, a Hollywood star known for her roles in films like The Girl Can’t Help It and Will Success Spoil Rock Hunter?, was killed in a horrific accident when her car collided with the rear of a semi-truck.

The car slid underneath the truck’s trailer, crushing the roof and killing Mansfield and two other adults instantly. Her three children, seated in the back, survived the crash. This tragedy shocked the public and led to calls for improved safety measures, ultimately resulting in the mandatory installation of underride guards on semi-trucks.

Regulatory Milestones

1998: Underride guards became mandatory for all semi-trucks in the United States.
2010s: Studies by the Insurance Institute for Highway Safety (IIHS) revealed that many underride guards were not strong enough to prevent fatalities, especially in partial head-on collisions.
2017: The IIHS recognized five manufacturers for improving the strength and design of their underride guards.

The Challenges of Underride Guard Effectiveness

Early Shortcomings

Despite their lifesaving potential, early underride guards had significant limitations. The IIHS found that many guards failed to withstand collisions at speeds as low as 35 miles per hour, particularly in partial head-on crashes. Between 2011 and 2015, fatalities from rear-end collisions with semi-trucks increased by 39%, highlighting the need for stronger and more effective designs.

Ongoing Improvements

In response to these findings, the National Highway Traffic Safety Administration (NHTSA) has continued to update safety standards for underride guards. Key areas of improvement include:

Increased Strength: Modern guards are designed to withstand higher-impact collisions.
Side Guards: Some advocates are pushing for the addition of side underride guards to protect against angled collisions.
Adaptive Designs: Engineers are exploring innovative designs to account for varying truck sizes and collision angles.

Why Underride Guards Matter

Saving Lives

Underride guards play a crucial role in reducing the severity of collisions between cars and semi-trucks. By preventing cars from sliding underneath trailers, they help protect passengers from catastrophic injuries.

Protecting Vulnerable Road Users

Smaller vehicles, such as sedans and compact cars, are particularly vulnerable in collisions with semi-trucks. Underride guards ensure that these vehicles have a fighting chance in the event of an accident.

A Symbol of Progress

The evolution of underride guards reflects the ongoing commitment to improving road safety. From the tragic accident that inspired their creation to the continuous advancements in their design, these bars are a testament to the power of innovation in saving lives.

Expert Insights: The Future of Underride Guards

We spoke with Dr. Emily Carter, a transportation safety expert, to get her perspective on the future of underride guards.

“Underride guards have come a long way since their introduction, but there’s still room for improvement. The next frontier is side guards, which could significantly reduce fatalities in angled collisions. As vehicles and roads evolve, so too must our safety measures.”

How You Can Stay Safe on the Road

Tips for Drivers

Maintain a Safe Distance: Keep a safe following distance from semi-trucks to reduce the risk of rear-end collisions.
Stay Alert: Pay attention to the road and avoid distractions, especially when driving near large vehicles.
Advocate for Safety: Support initiatives that promote stronger underride guard standards and the implementation of side guards.

A Lifesaving Legacy

Underride guards, or Mansfield bars, are more than just metal bars on the back of semi-trucks—they are a critical safety feature that has saved countless lives since their introduction. While challenges remain, ongoing advancements in design and regulation ensure that these guards continue to protect drivers and passengers on the road.

As we look to the future, the story of underride guards serves as a reminder of the importance of innovation, regulation, and public advocacy in making our roads safer for everyone.

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Despite not being enjoyable, the 2026 Toyota Corrola Cross hybrid is funny

by George Mensah 2025-10-29

Generative AI has moved from specialist interest to part of daily life — transforming all from entertainment to the workplace. From AI-generated art, deepfakes, and intelligent chatbots capable of talking like humans, AI is now part of modern life. Yet with technology racing ahead, so do fears it will spin out of control.

Now, a new generation of scientists, business leaders, and celebrities are calling for a slowdown on the next frontier: AI superintelligence — a form of artificial intelligence that potentially could surpass human intellectual ability in almost every dimension.

The Pushback: A Global Call to Slow Down AI Development

A collection of public personalities — such as Virgin Group creator Richard Branson, Apple co-founder Steve Wozniak, Prince Harry and Meghan Markle, actor Joseph Gordon-Levitt, and musician will.i.am — signed a new open letter called the “Statement on Superintelligence.”

The warning asks developers and businesses racing towards state-of-the-art AI systems, including OpenAI and Elon Musk’s xAI, to delay the magnitude of massive AI projects until there is a “broad scientific consensus that it will be done safely and controllably” and a “strong public buy-in” to support it.

Notably among them are two of the leading AI researchers, who are also cofounders of modern machine learning. The movement is thus quite heavily weighted.

“We must ensure that AI is serving humanity, and not vice versa,” the letter demands, threatening dire consequences in the event of runaway progress.

What Is AI Superintelligence — and Why Does It Worry Experts?

In order to understand the alarm, defining what AI superintelligence really is, is essential. Superintelligent AI, according to IBM, is a system which not only matches but far exceeds human intelligence — capable of reasoning, learning, and solving problems for itself in every respect, free of human control.

Contrary to current AI systems such as ChatGPT or Gemini, whose boundaries and data sets are defined, superintelligent AI would be continuously learning and evolving, rewriting its own code to increase efficiency and capability. Such recursive enhancement could make it almost impossible to contain.

“A true superintelligence would no longer need human oversight,” said Stuart Russell, an AI researcher at UC Berkeley. “At that point, its goals might diverge from ours — and we’d have no way to stop it.”

The Risks: From Job Losses to Existential Threats

The possible dangers of AI superintelligence go much beyond job automation or misinformation. The threat is mentioned by experts as the possibility of AI systems executing on their own in pursuit of ends that are in conflict with human values or safety.

Some of the highest threats:

Massive Job Displacement – AI already revolutionizes industries, but an entirely automated self-enhancing system could eliminate entire professions, ranging from programmers to creative professionals.

Loss of Human Control – The moment an AI begins to be smarter than the people who create it, it might be beyond control.

Weaponization and Surveillance – AI might be utilized by governments or corporations for total surveillance or robot war.

Existential Risk – In the worst-case scenario, a rogue AI with goals of its own would view humankind as an obstacle — one which scientists describe as a “digital doomsday.”.

Even if these ideas sound like science fiction, specialists argue that rejection of them would be naively dangerous. History has shown that humanity always underestimated the capabilities of its own inventions — from nuclear energy to biotechnology.

Increasing Public Alarm and Demand for Regulation

Public sentiment is shifting rapidly. A 2025 Pew Research Center survey found that 67% of Americans now support greater government regulation of AI, up from 42% two years earlier. The European Union has already legislatively signed the AI Act into law, establishing the globe’s first extensive regulatory framework for artificial intelligence, while U.S. lawmakers are determining how to follow.

Tech giants, however, are still racing ahead. OpenAI, xAI, Google DeepMind, and Anthropic are investing billions in “next-generation” AI models that could approach or surpass human-level reasoning.

“We’re in an AI arms race, and everyone wants to be first — but that could also mean being first to make a catastrophic mistake,” warned Richard Branson in a recent statement.

Is It Already Too Late to Stop?

Until now, actual AI superintelligence is still theoretical, although most experts foresee that it might arise in the next two decades if trends continue. The question is not whether or when it will happen, but whether human civilization will be prepared — morally, technically, and legally — when it does.

“The clock is ticking,” declared Yoshua Bengio. “We still have time to make this technology safe. But not much.”

The Bottom Line: Humanity at a Crossroads

The debate over AI superintelligence is no longer confined to labs or tech circles — it has become a global conversation about the future of humanity itself. As generative AI becomes ubiquitous, the next phase could redefine civilization in ways we’re only beginning to imagine.

Whether the Statement on Superintelligence does indeed result in change is yet to be known. But this much is definite: the world has finally realized that the latest technology human beings have ever come up with has the potential to be the most deadly — unless we can learn how to control it before it controls us.

Cars

Why Did Caterpillar Stop Making Truck Engines? The Full Story Explained

by George Mensah 2025-10-27

For half a century, Caterpillar Inc. has been a heavyweight of heavy machinery and industry globally. Renowned for producing some of the world’s hardest-nosed loaders, bulldozers, and tractors, the Illinois company has built a reputation for toughness and reliability. But behind earthmovers and mining equipment, Caterpillar had another profitable business — truck engines that powered some of America’s most iconic long-distance rigs on highways from sea to shining sea.

Engines like the Cat 3406E and C15 became legends of the trucking aspect, being famous for pure torque, longevity, and going a million miles with TLC. But despite popularity, Caterpillar finally closed down its on-highway truck engine manufacturing — something that took many by surprise within the industry.

So, what drove one of the biggest brands in diesel power to walk away from the trucking market it assisted in generating?

Caterpillar’s Truck Engine Heritage Traces Back to 1939

Eight decades of producing truck engines for Caterpillar started in 1939, when the company entered its first foray into this marketplace with the Caterpillar D468, a six-cylinder diesel engine that produced 90 horsepower at 1,800 RPM — humble by today’s standards, but revolutionary at the time.

This initial introduction began the long-term legacy of Caterpillar in the trucking industry. Over the years, the company released a number of other important engines, including the D312, 3408, and the wildly popular 3406E. The latter, introduced in the 1990s, was a driver and fleet operator favorite due to its power, fuel efficiency, and smooth performance.

But with the dawning of the 21st century, the landscape of diesel engines was about to change overnight — and Caterpillar found itself at a crossroads.

The Emissions Challenge That Changed Everything

By the early 2000s, governments around the world — and especially the U.S. — began implementing stricter emissions regulations to reduce emissions of NOx and particulate matter. For engine manufacturers, this meant massive investments in cleaner-burning technology in a bid to meet the 2007 and 2010 EPA standards.

Caterpillar initially responded to the challenge with its Advanced Combustion Emission Reduction Technology (ACERT) technology. This cutting-edge technology utilized a mix of precise fuel injection, advanced air management, and electronic controls to minimize emissions without compromising power.

But even with its greatness, ACERT engines began causing headaches in the real world. Truck operators reported reliability issues, maintenance nightmares, and higher operating costs, all of which smudged Caterpillar’s then-tarnished image in the trucking industry. There were even customers who sued for performance issues, further damaging the brand’s reputation with its top highway customers.

Meanwhile, competitors like Cummins, Detroit Diesel, and PACCAR were adapting faster and better to the new emission regulations. Their engines met emission regulations with fewer problems of reliability — leaving Caterpillar in a more and more vulnerable position.

Too Costly to Compete

Meeting the rapidly evolving emission standards would cost more than technical expertise — it would cost millions of dollars. Caterpillar would have needed to spend a lot on research, redesigning, and testing to keep its engines in compliance and competitive.

For a company whose business is in the construction, mining, and industrial segments, the revenues no longer justified the investment for its trucking operations. Rather than continue investing in a shrinking, regulation-based business, Caterpillar decided to strategically phase out on-highway truck engine production in 2010.

Though Caterpillar’s off-highway engines — those that drove heavy equipment, generators, and marine equipment — were still strong, driving big rigs was no longer in its plans.

The Legacy Lives On

Even though Caterpillar is no longer making on-highway truck engines, its reputation can’t be shaken. Engines like the 3406E and C15 remain legends for their strength and longevity, typically commanding high prices on the used market. Many owner-operators still rebuild and maintain these engines to this day, holding them as symbols of a generation when power and simplicity ruled the road.

In the last couple of years, Caterpillar has exerted enormous efforts in shifting its focus toward sustainable energy solutions like hybrid systems, electrically propelled machinery, and next-generation diesel technologies optimized for reduced emissions in mining and construction purposes.

Although the golden age of Caterpillar truck engines is in the past, the company’s engineering skills and genius continue to shape industries across the globe — ensuring that legends also evolve with the times.

Final Thoughts

Caterpillar’s decision to stop making truck engines wasn’t a decision based on rules alone — it was one based on survival on a strategic level. Compliance expenses, changing market dynamics, and the emergence of cleaner technology all played a role.

Today, with the trucking sector moving toward electrification and alternative fuels, Caterpillar’s pullback appears a visionary move that allowed it to focus on its core strength: building the world’s toughest machines.

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