Every truck on the road has a rear under-ride guard to prevent major injuries in rear-end collisions. But there's still the matter of side under-ride events, and they're no less dangerous.

The Insurance Institute for Highway Safety is currently testing under-ride solutions for semi trucks. The IIHS already looked at the rear guards that many of us are familiar with, so now it's turned its attention to side underride guards, which stop perpendicular collisions from turning deadly.

The majority of side cladding you see under a semi truck is built for aerodynamic purposes to help increase fuel efficiency. Those thin panels do next to nothing when a collision occurs. However, companies such as AngelWing and Airflow Deflector Inc beef those panels up to withstand collisions without permitting an underride situation.

A traditional under-ride event is terrifying, as you can see from the watchdog's video. The dummy's head is bent back as the side of the truck intrudes on the passenger area, cutting straight through the windshield and part of the roof. With underride guards in place, it's more of a traditional collision, allowing the dummy to contact the airbags and preventing any cabin intrusion.

There is a clear need for this type of crash-prevention technology. Of the 1,542 people who died in crashes with tractor-trailers in 2015, approximately 20 percent of them involved a side collision. And the numbers have gone up more or less every year since 2011, so the IIHS has started testing side underride guards to see if it can eventually compel more trucking companies to include them.

Right now, federal law mandates the implementation of rear underride guards, but not side underride guards. Certain cities require them on city-owned or contracted trucks, but that's about it. The data IIHS collects might go a long way in changing that.