Getting stuck behind a huge 18-wheeler is no fun. While waiting for an opportunity to pass it, however, Texas motorists may want to look at the extra metal “bumper” hanging down from the trailer’s rear. As CNN reports, that is the rear underride guard that federal law mandates all trailers must have so as to protect the drivers and passengers of passenger vehicles in the event of an accident.

Given that today’s smaller cars place occupants at eye level with a semi’s wheels, the alarming truth is that should the car ram the trailer, the force of the impact may not stop the car. Instead, the car’s forward momentum may cause it to keep going, sliding underneath the trailer before stopping. When this occurs, the car’s hood and windshield often shear off, putting its occupants at grave risk for catastrophic injuries or even a hideous death by decapitation. The purpose of underride guards is to prevent these grisly occurrences.

Rear underride guards

The problem with underride guards is that they may not be sturdy enough to perform their intended function. Congress and regulatory agencies formulated the federal laws mandating these guards in the 1990s. Since then, however, no one has updated their safety standards. Consequently, some of today’s underride guards buckle or even break off when a passenger vehicle strikes them.

Side underride guards

It may surprise motorists to learn that no federal laws exist that require trailers to have side underride guards in addition to a rear guard. Forbes reports that the Insurance Institute for Highway Safety started testing them in 2012, and the results were impressive. In fact, test results revealed that side underride guards reduce the chance of passenger vehicle deaths by up to 90 percent if and when one rams a trailer’s side.

Per the latest statistics available, the IIIHS reports that 1,542 motorists died in a car-truck crash in 2015. Of these deaths, 301 of them were side crashes and 292 of them were rear crashes. Admittedly, the statistics do not include information on whether any of these crashes were underride accidents, but the IIHS estimates that at least 50 percent of them were.

Inexplicably, neither Congress nor the Department of Transportation has seen fit to pass new laws or update the old ones regarding underride guards, despite recommendations from both the IIHS and advocacy groups. This leaves passenger vehicle occupants at very high risk of catastrophic injury or death in the event of a car-truck crash.