NFPA 1670 Vehicle Rescue: Technician-Level Competencies - Part 7

Jan. 1, 2006

NFPA 1670 Vehicle Rescue, Technician-level Skills and Competencies

Advanced Hands-on Training Skill: Vehicle Underride

Create an extrication pathway to allow for removal of a simulated patient from a vehicle and large truck underride scenario

Given the scenario of a vehicle underride, create an opening sufficient to remove a simulated trapped driver, seated and belted

MORE IMAGES:Slideshow of Images From Article

When a passenger vehicle collides with the rear end (or side) of a large truck trailer, the smaller and lower vehicle becomes a wedge on wheels. Just like a wedge, a typical automobile is thick at one end and tapers to a thin edge at the other. In an underride scenario, the front of the vehicle acting as the thin end of the "wedge" travels beneath the undercarriage of the larger vehicle as the front end of the small vehicle is compressed downward towards the ground. The suspension of this vehicle lowers and the front tires may even deflate under the extra pressure as it jams itself under the truck. Because of its wedge shape, the car can lift the rear end of the truck or trailer as it forces itself under it.

The intrusion of the truck trailer into the passenger compartment that accompanies the underriding can cause severe head and upper body injuries to the car occupants and consequently results in a very high rate of fatality. Often, the car passengers are decapitated by the so-called "guillotine effect."

This University of Extrication column uses both real-world and training images to examine the challenges presented to responders arriving at an underride crash. Study the images and accompanying text to better comprehend the complexity of these situations and the decision-making process that is involved.

In an underride incident, there are several predictable tactical actions the responders should prepare to accomplish, based upon information gained from the scene size-up. These include:

  • Hazard control, including electrical system shutdown
  • Vehicle stabilization - auto, truck and trailer
  • Initial and sustained patient access
  • Disentanglement - pinned by position or condition
  • Extrication of the patient(s) - tunneling, sidewall or vehicle removal
  • Removal of patient

At one such vehicle underride accident in McKinney, TX, responders found a young man alive, seated and belted in the driver's seat of his Jeep. His vehicle had crashed at high speed into the rear of a stopped tractor-trailer in a residential neighborhood; a classic underride incident.


Ron Moore, a Firehouse contributing editor, is a battalion chief and the training officer for the McKinney, TX, Fire Department. He also authors a monthly online article in the "MembersZone" and serves as the Forum Moderator for the extrication section of the website. Moore can be contacted directly at [email protected].

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