What Can Be Done to Protect People from Going Under Tractor-Trailers During a Crash?

Michael GrossmanFebruary 15, 2017 4 minutes

Many people suffer from anxiety when driving in close proximity to tractor-trailers and while they may not realize it, there's a good reason for this fear. The space under an 18-wheeler's trailer actually has a dangerous, even lethal, legacy. This problem is illustrated by a recent crash in Houston between a motorcycle and an 18-wheeler, which hopefully will add weight to the ongoing argument in favor of safety improvements that should be made to freight trucks.

Houston, TX: January 30, 2017

According to authorities, the crash occurred in the early evening on Monday, January 30. A motorcycle rider traveling east near the 8300 block of Fallbrook Drive collided with a Volvo tractor-trailer on its way out of the nearby FoxConn Assembly parking lot. Investigators suggest the driver of the 18-wheeler, Alan King, stopped partway out of the lot, yielding to westbound traffic while fully blocking the eastbound lane. Because of this sudden obstacle, the motorcyclist did not have any way to steer clear on his Harley Davidson bike.

Reports note that the rider heavily applied his brakes, but was unable to stop before colliding with back of the truck and the front of the trailer. He was taken by Life Flight to Memorial Hermann Hospital, but died of his injuries shortly after arriving. His name was not released by the police.

Photos from the scene suggest that the motorcycle actually went under the trailer, into the empty space between it and the road.

Traffic Collisions and Trailer Underrun

Most people on the road don't stop to consider it, but the area underneath a freight trailer is extremely dangerous. Many collisions between passenger vehicles and 18-wheelers involve a "sideswipe" scenario like the one described above, and given the usual height of the trailer, standard cars have an unfortunate tendency to get wedged under its clearance.

Most of a passenger vehicle's safety features are rendered useless in such crashes, because they are designed to mitigate lateral collisions at a height comparable to the car's. If the car's speed is sufficient at the time of the collision, it is possible for the side of the trailer to shear off the top of the vehicle and fatally injure its occupants. Studies suggest that these "side underride" crashes claim about 200 lives per year.

Rear-ending an 18-wheeler had similarly lethal consequences for many years, until a high-profile collision took the life of noted film starlet Jayne Mansfield in 1967. Having rear-ended a freight trailer with no safety countermeasures attached, Mansfield suffered head trauma and passed away. Given the high degree of public attention--Mansfield was very popular with moviegoers--the National Highway Traffic and Safety Administration (NHTSA) strongly encouraged the shipping industry to make badly-needed safety upgrades to the undercarriages of their vehicles:

  • In the rear, a Rear Underrun Protection System (RUPS) was designed to prevent further collisions. Also called a "Mansfield Bar," the system is a rigid construction of welded bars that hangs below the rear bumper, providing a measure of protection against a vehicle being driven under the trailer by its forward momentum. Without recognizing it as a safety feature, the device might be mistaken for an additional step to climb into the trailer.
Rear Underrun Protection System (RUPS)
Highlighted in blue: Rear Underrun Protection System (RUPS)

A similar system, both in design and intent, can be applied to the front of a truck as well. Called the Front Underrun Protection System (FUPS), it receives less attention because the truck's cab doesn't have the same high clearance as the trailer. Despite the relatively simple design and construction of the feature, many trucking companies have dragged their feet about adding it to their fleets. We'll talk more about that in a moment.

  • The sides of a tractor-trailer have their own significant pitfalls. The space between the front and rear axles of the trailer has sufficient clearance to be very dangerous for other vehicles and pedestrians. Side crashes are also statistically more likely than front- or rear-end collisions. Families of people injured or killed by collisions with a trailer's undercarriage have clamored for safety measures to be added to protect motorists and pedestrians, and some firms have responded by developing side undercarriage guards, more formally called Side Underrun Protection Systems (SUPS). Long sheets of plastic or fiberglass are secured over a framework between the trailer's axles, preventing access to the space that otherwise could prove especially hazardous to pedestrians, bicyclists, or motorcyclists, which are characterized in some reports as Vulnerable Road Users (VRUs). The panels are also beneficial for the aerodynamic qualities of an 18-wheeler, as they reduce drag experienced by the truck when it travels over 60 mph. Studies have suggested a fuel-cost reduction of roughly 5% in long-haul trucks with the guards installed.
  • undercarriage side panels
    One of a few forms the undercarriage side panels might take.

    Most countries industrialized countries outside of North America require side safety features on commercial trucks and trailers. Some areas in the United States have tentatively begun to add these improvements to their trucks (they can be retrofitted to older trucks as well as attached to new fleet vehicles), but major logistics firms are resistant to making the changes.

    Why Are Trucking Firms Pushing Back?

    While these safety improvements are generally encouraged by consumer advocates and government groups, they are still fairly expensive on a per-truck basis. Because it is still viewed as an expense rather than an investment, and because so far no legislation has been enacted to make these improvements mandatory, most firms have not yet pulled the trigger on retrofitting their fleets or buying new trucks with protected undercarriages. Research has suggested they would see a return on their investment within two years due to the panels' improvements to their trucks' fuel economy, but until regulation requires it, their trucks' undercarriages remain an additional crash hazard.

    In fairness, trucking firms are businesses, and standard business practice is not to pay money one doesn't have to. With that said, the cumulative cost of settling injury and wrongful death suits might overshadow the expense of increasing truck safety. If humanity isn't enough and the government remains reluctant to issue any edicts, maybe actuarial data will sway their decisions. The sooner we can get them on board with these safety improvements, the better.