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The Underride Slide: Truckers Running without Side Guards Endangering America’s Highways

Posted on March 7, 2019

As of their last tally, the Department of Transportation’s (DOT) Federal Motor Carrier Services Administration (FMCSA) found there was a staggering 2,752,043[i] registered tractor-trailers traversing across America. By themselves, these trucks count for nearly 10% of all the miles driven by American vehicles per year[ii]. With tractor trailer’s presence on the road remaining a ubiquitous portion of virtually every American’s daily commute, the chances for accidents occurring between cars and trailers is at an all-time high.

Accidents involving semi-trucks

Aside from the sheer size difference between an 18-wheeler and a car, a terrifying aspect of a crash between cars and trailers is an industry term known as “side underride”, which occurs when a car travels underneath the trailer portion of a semi, in the space between the front and rear axles. Far from a Fast and Furious stunt, this type of accident can have a shearing effect on the car where the roof is peeled off which can expose the driver’s head and neck to a gruesome guillotine-like action from the body of the trailer. What’s worse, the industry and regulatory bodies such as the DOT have known about this issue for decades. In 1953, the Bureau of Motor Carriers required rear underride guards on most types of commercial big rigs. 45 years later in 1998, the National Highway Traffic Safety Administration (NHTSA) beefed up the requirement to include additional truck types and strength and durability testing for the guards was required[iii]. However, to date, no mandate has been set forth to require side underride guards on semi-trucks.

If you’ve ever noticed a semi driving past with those large metal wings beneath the trailer, you’re seeing a driver that’s doing their part to prevent side underride. These guards can severely limit the impact that a side crash can have on a vehicle and its occupants by deflecting the blow of the impact back into the body of the car, where it was actually engineered to withstand the impact of a collision. In 2015, the Insurance Institute for Highway Safety (IIHS) studied crashes involving underride and found that 301 of the 1,542 passenger vehicle occupants killed in two-vehicle crashes with a tractor-trailer died when their vehicles struck the side of a tractor-trailer[iv]. In comparison, 292 people died after a rear underride collision in the same year yet only rear underride deterrents are mandated.

Causes of Accidents

The FMCSA meticulously compiles data for incidents involving truckers each year. Eye-popping are the statistics showing the number of driver violations in a given year. Between speeding, driving more than the legal 8-hour limit, texting-while-driving, and disobeying traffic signals, some 326,545[v] citations were issued to truck drivers in 2017 alone. Beyond these traffic citations, more than a million violationswere issued for trucks not being equipped with the proper safety equipment including not having running lights (almost half a million violations), malfunctioning brakes, no brake lights, no turn signals, and even not having functioning windshield wipers[vi]. A fully loaded tractor trailer can weigh as much as 40 tons[vii]. With that kind of weight, any type of accident with an ordinary vehicle can be devastating and not having even basic safety equipment puts all other drivers sharing the road at serious risk.

Why don’t all semi-trucks have side guards?

Simply put, most companies don’t employ side guards on their trucks because they are expensive and it’s not yet a requirement of the DOT to have them. Side guard manufacturers are trying to change this and the company Airflow Deflector has invented a guard known as the “Angel Wing” that decreases the likelihood of a side underride event and is also eco-friendly and cost-effective, decreasing the semi’s drag and therefore increasing fuel economy. With these types of viable alternatives, companies that continue to deploy their trucks without side guards are unnecessarily putting other drivers on the road at risk. Because of this, accidents involving semi-trucks without side guards have shown the trucking company acted negligently in some cases. Negligence simply means that a reasonable level of care, in this case for the safety of other drivers, should have been in place but wasn’t.

I’ve been involved in an accident with a semi, now what?

Big trucking companies have big insurance companies covering them in the event of a crash. These companies employ teams of lawyers that will fight tooth and nail to try and remove the liability from the trucking company when an accident occurs. At Farah and Farah, we’ve stood up to these companies and their insurance carriers time and again and won for our clients. If you or a loved one has been injured in an accident involving a semi-truck, put our experience and knowledge to work for you. We have teams of attorneys, investigators, and support staff that do nothing but these types of cases. We know what to look for and how to get you the best possible outcome for your case. Call, click, or come in, we are here to help guide you through the path to recovery.


[i]Federal Motor Carrier Safety Administration https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/safety/data-and-statistics/413361/fmcsa-pocket-guide-2018-final-508-compliant-1.pdf

[ii]Federal Motor Carrier Safety Administration https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/safety/data-and-statistics/413361/fmcsa-pocket-guide-2018-final-508-compliant-1.pdf

[iii]National Highway Traffic Safety Administration https://one.nhtsa.gov/Research/Crashworthiness/Truck%20Underride

[iv]Insurance Institute for Highway Safety https://www.iihs.org/iihs/news/desktopnews/iihs-tests-show-benefits-of-side-underride-guards-for-semitrailers

[v]Federal Motor Carrier Safety Administration https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/safety/data-and-statistics/413361/fmcsa-pocket-guide-2018-final-508-compliant-1.pdf

[vi]Federal Motor Carrier Safety Administration https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/safety/data-and-statistics/413361/fmcsa-pocket-guide-2018-final-508-compliant-1.pdf

[vii]Popular Mechanics https://www.popularmechanics.com/cars/trucks/g116/10-things-you-didnt-know-about-semi-trucks/