To help prevent the dangers of fatal underride accidents, the NHTSA requires that all truck trailers with a gross vehicle weight rating (GVWR) of 10,000 pounds or more manufactured on (or after) January 26, 1998 have truck rear impact guards that meet DOT (Department of Transportation) specifications. The GVWR is the total weight of the truck when loaded, including passengers, cargo, and the vehicle itself. Federal regulations allow cargo trucks to weigh up to 80,000 pounds (40 tons). As yet, no similar requirement exists for truck side impact guards.
The DOT requires that these truck rear impact guards meet specific strength testing and energy absorption requirements. Despite these requirements, recent government data indicates that:
1. The total number of fatalities from car rear-end collisions with trucks has not decreased;
2. The number of fatal crashes per 1,000 crashes has not decreased; and
3. The percentage of fatal rear-end car impact collisions has not decreased relative to other fatal car-truck collisions.
(In other words, the existing truck rear impact guards don’t seem to do much good in preventing fatal underride accidents.) So the IIHS (Insurance Institute for Highway Safety) has petitioned the government for stronger safety standards to address the issue. (This makes some sense since it is the insurance industry that ultimately ends up paying for many of the costs associated with devastating, fatal underride accidents.) But the petition focuses on rear guards without focusing on the equal need for truck side impact guards.
A crash test study by the IIHS involving crash test dummies produced ugly results. The study tested several types of DOT-approved truck rear impact guards and some guards meeting higher Canadian standards. The IIHS study found that in impacts as slow as 35 mph (generally much slower than actual highway impacts), rear guards came loose and otherwise gave way, providing no protection to the crash cars or their long-suffering dummies.
So the IIHS has asked for much stiffer standards for truck rear impact guards to help prevent fatal underride accidents. After the studies, some question seems to linger regarding the effectiveness of any such guards for cars and their passengers at real highway impact speeds. It seems that any impact guard strong enough to stand up to the force of the impact will pose its own dangers to smaller vehicles and their occupants. And stiffer truck rear guard standards still do not address the dangers of side impact underride accidents. Truck side impact guards have yet to receive the attention focused on the rear guards. Yet side impact underride accidents are just as fatal as the rear underride impacts.
The fact remains that in any accident impact between a truck and a smaller, lighter-weight passenger vehicle, the contest remains drastically uneven. Trucks have mass, momentum and force on their side. Mass increases with velocity. A car just can’t win.