How do Underrides Happen?

An underride accident occurs when a passenger vehicle collides with the rear end or side of a truck, trailer, or other large commercial vehicle that is not equipped with effective an underride guard or bumper. Without an underride rail or guard, the vehicle under rides the truck’s rear or side frame by traveling beneath the taller chassis of the larger vehicle. The impact between the truck’s rear end or side rail frame of a truck, whether in the rear or on the side, is equally devastating to the occupants of the car or vehicle. The roof supports or roof pillars of the vehicle can not withstand the collision energy, and collapse. The truck’s frame or rail then slices the top of the roof and roof pillars off the vehicle resulting in severe head and upperbody trauma and death to the occupants.

NHTSA estimates:

  • 11,500 rear impact crashes into trucks, trailers and semitrailers each year
  • 400 fatalities to occupants of the passenger motor vehicles
  • 5,000 injuries to occupants of the passenger motor vehicles
  • Only 27 percent of the fatalities and 18 percent of the injuries occurred when a passenger motor vehicle impacted the rear of a single unit truck, even though single unit trucks represent 72 percent of the heavy vehicles registered in the U.S.
  • Trailers and semitrailers represent 28 percent of the heavy vehicles registered in the U.S., but account for 73 percent of the rear impact fatalities and 82 percent of the rear impact injuries.

Potential Benefits of Rear Impact Guards or Side Impact Rails

NHTSA estimates that rear impact guards would be between 11 percent and 17 percent effective in preventing fatalities and injuries due to passenger motor vehicles underriding heavy vehicles. But not all fatalities in rear impact crashes into heavy vehicles are due to underride. Many rear impact crash fatalities and injuries will occur despite the rear impact guard. While NHTSA has established the energy absorption characteristics for the rear impact guards themselves, it is possible that the rear impact guard itself could worsen the crash severity in some instances.

NHTSA’s overall estimate is that rear impact guards on trailers and semitrailers would save 4 to 15 lives per year. In addition, 29 non-minor and 145 minor injuries would be prevented.

If the same effectiveness rates were applied to single unit trucks and buses, it would appear that 1 to 6 lives might be saved and 6 to 32 injuries might be prevented by the installation of rear impact guards on both single unit trucks and buses. School buses are a subset of this group. As a result, the potential safety benefits of rear impact guards on school buses are even smaller.

School Buses and Rear Impact Guards

During the course of its research and analyses to develop and promulgate FMVSSs Nos. 223 and 224, NHTSA reviewed and analyzed considerable real-world data on the rear impact guards on heavy motor vehicles. Of particular concern were any effects such devices would have on the operation of the vehicles.

The major operational consideration was whether the rear impact guard would cause the bottom of the guard to scrape or “hang” on the ground when the vehicle mounts a steep incline. This type of situation could occur when approaching or departing a raised railroad grade crossing, a steep driveway entrance, or any number of situations in a hilly or mountainous area.

In comments received to the Notice of Proposed Rulemaking for FMVSSs Nos. 223 and 224, numerous commenters cited operational concerns to single unit vehicles if rear impact guards were required, and noted that statistically very limited benefit would begained from putting such devices on single unit vehicles. One of the commenters cited school buses as an example of how a rear impact guard would severely impact the vehicle’s “angle of departure.” [The “angle of departure” is the acute angle formed by the ground and a line connecting the point where the rear tires meet the ground with the bottom of the guard. The lower the bottom of the rear impact guard, the smaller the departure angle and the greater the chance the vehicle will scrape or “hang” on the ground when the vehicle mounts a steep incline.]

NHTSA’s Rationale for Excluding Single Unit Trucks and Buses

In issuing the Final Rule establishing FMVSSs No. 223 and 224, NHTSA concluded that single unit trucks and buses, including school buses, should not be included in FMVSS No. 224. The agency pointed to a number of facts:

  • single unit trucks and buses represent a very small portion of the rear underride safety problem;
  • the potential benefits of rear impact guards on single unit trucks and buses are small; and
  • the variety, complexity and relatively low weight of many single unit trucks and buses could require much more sophisticated and expensive rear impact guards, which seriously effects the net benefits to society of requiring rear impact guards on single unit trucks and buses.

Underride Accident Legal Help

If you or a family member was severely injured in a tractor-trailer underride accident, you should contact an attorney who can help you protect your legal rights. In such cases, the scene needs to be photographed, the vehicles inspected, all responsible parties identified and the insurance companies or other representatives put on notice. Additionally please keep in mind that there may are time deadlines that must be adhered to in filing claims against the responsible entities. If such filing deadline are passed (statutes of limitation expired), then you ability to bring a lawsuit may be forever lost. Contact an attorney to learn your rights. Call or e-mail us for a Free Confidential Consultation at 1-800-883-9858

Injured in an accident? Talk to a Lawyer about your legal options and rights!
Get Help Right Now