So, you ask, what are Truck Impact Guards? To borrow from NHTSA terminology, Rear Impact Guards are devices attached to Commercial Motor Vehicles in order to GUARD against deadly underride and intrusion into the occupant survival space of a passenger vehicle when there is a collision or IMPACT [an impinging or striking especially of one body against another, Merriam Webster] at the REAR of a large truck.
Although NHTSA does not yet require them, a Side Impact Guard is, likewise, a device attached to a large truck to GUARD against deadly underride and intrusion into the occupant survival space of a passenger vehicle when there is a collision or IMPACT at the SIDE of a large truck.
Thus, it stands to reason, even though NHTSA apparently has no plans at present to require this life-saving device, a Front Impact Guard is a device attached to a large truck to GUARD against deadly underride and intrusion into the occupant survival space of a passenger vehicle when there is a collision or IMPACT at the FRONT of a large truck.
Truck Impact Guards do not prevent crashes. But, they do compensate for the lack of crash compatibility, which exists due to the geometric mismatch between the “bumpers” of two colliding vehicles that allows one to slide UNDER the other. Effective impact guards ensure that the passenger vehicle’s crashworthiness features — air bags, crumple zones, bumpers, seat belt tensioners — operate as intended to preserve the occupant survival space. This improved crash compatibility can, therefore, serve to make truck crashes more survivable.
These engineer-designed devices can also GUARD Vulnerable Road Users (VRUs) — pedestrians, bicyclists, and motorcyclists — reducing the likelihood of catastrophic injuries during collisions with large trucks.