Big-Rig Overturns & Underrides

Uprighting a loaded cement mixer or lifting the rear of a loaded van trailer are everyday tasks for heavy recovery operators. Place someone who is injured and trapped in a car under such a vehicle and a challenge begins. While heavy recovery...


Uprighting a loaded cement mixer or lifting the rear of a loaded van trailer are everyday tasks for heavy recovery operators. Place someone who is injured and trapped in a car under such a vehicle and a challenge begins. While heavy recovery operators may easily overcome this challenge, it may...


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Uprighting a loaded cement mixer or lifting the rear of a loaded van trailer are everyday tasks for heavy recovery operators. Place someone who is injured and trapped in a car under such a vehicle and a challenge begins.

While heavy recovery operators may easily overcome this challenge, it may prove formidable for fire-rescue responders. This challenge may be a matter of life and death for the victims of the accident and prove dangerous to emergency responders.

A "5-Step Discipline" provides a guideline for success regarding overturns or underrides. An overview of this discipline is in the information that follows. It is an effort to provide fire-rescue responders with a simple list of steps to follow when faced by such an intimidating sight.

STEP 1. Identify the Cargos Of All Vehicles Involved

Many training programs offer specific information regarding cargo identification and the responder is urged to complete a hazardous materials training program in order to be prepared. Sources of information available on scene are: shipping documents, placards, container shapes/sizes/colors/labeling, the vehicle operator, the vehicle owner and the shipper. Certainly this affects the safety of all involved and is the first task performed.

Hazardous material releases are best handled by appropriately trained and equipped personnel. Also included in this step is mitigation of hazards involved with the vehicles themselves. This is common practice among responders to vehicle collisions and includes: scene assessment, fire/fuel hazards, de-energizing the electrical system, searching for victims and calling for additional resources. Typically, big rigs carry 100 to 150 gallons of diesel fuel in each tank. Usually, there are two tanks mounted alongside the tractor known as "saddle tanks." It is common for at least one tank to rupture during a substantial collision, perhaps both. Responders should understand the characteristics of the fuel(s) involved and be prepared to mitigate the associated hazards.

An undeployed supplemental restraint system (SRS) also presents a problem, generally in the smaller vehicle in an overturn/underride situation. Promptly de-energizing the electrical system in all vehicles involved is an important task. Big rigs typically have a bank of batteries parallel wired to offer greater starting amperage. The location of the battery banks varies according to rig. There is no definite location of battery banks for each rig. The battery cables of big rigs are larger than those of cars, nearly the size of 00-gauge wire. The cables may be disconnected at the terminal or double cut using a cutting tool. The preferred cutting tool is a hand-held ratcheting cable cutter such as used by industrial electricians.

Once an assessment of the scene is completed, additional resources are usually requested. Incidents involving big rigs versus smaller vehicles may require such resources as heavy wreckers, urban search and rescue (USAR) trained responders and their gear, heavy rescue squads and extended-incident traffic-control devices. Ideally, these resources will be responding on the initial alarm. Pre-planning for the dispatch and response of special resources is fundamental when faced with big-rig collisions.

STEP 2. Stabilize the Larger Vehicle

This is critically important to increase safety for responders and prevent further injury to victims. Generally, fire-rescue responders attempt to accomplish this using timber cribbing and strut systems. While these tools are useful, they may not provide the support needed due to the construction of the larger vehicle or the damage inflicted on it during the accident. The optimum in this circumstance is using the heavy wrecker as a stabilizing tool.

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