The 5 step discipline for overturns and underrides
Uprighting a loaded cement mixer, perhaps lifting the rear of a loaded van trailer is an everyday task for heavy recovery operators. Place someone who is injured and trapped in an auto underneath such a vehicle and the challenge begins. While heavy recovery operators may easily overcome this task it may prove a formidable challenge for fire/rescue responders. This challenge may be a matter of life and death for the victims of the collision, and prove dangerous to emergency responders also.
To provide a guideline for success regarding overturns or underrides, I promote a 5 Step Discipline. An overview of this discipline is in the information that follows. It is an effort to provide fire/rescue responders a simple list of steps to follow when faced by such an intimidating incident.
Identify the cargos of all vehicles involved/Hazard Mitigation
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. Responders should understand the characteristics of the fuel (s) involved and be prepared to mitigate the associated hazards. Undeployed SRS also present a problem, generally in the smaller vehicle in an overturn/underride situation. Promptly de-energizing the electrical system in all vehicles involved is a critical task. Big rigs typically have a bank of batteries wired to offer greater starting amperage. The location of the battery banks varies according to rig itself. There is no definite location of battery banks for each rig. The battery cables of big rigs are larger than that of autos, nearly the size of 00 gauge wire. The cables may be disconnected at the terminal or double cut using a cutting tool.
Calculate resistance/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 very useful they simply may not be able to provide the support needed. This may be due in fact to the construction of the larger vehicle or the damage inflicted upon it during the collision. The optimum in this circumstance is using a heavy wrecker as a stabilizing tool. Typically there is sufficient force and tools needed to perform this task on a heavy wrecker. Moreover it is important that fire/rescue responders realize the limitation of their equipment in this type of collision. Fundamentally they must understand the weight involved, construction methods and materials of various trucks and trailers in order to appreciate these limitations. Struts may be used very effectively with big rig incidents due to the vertical stabilization height needed and resistances imposed upon them. The use of chain slings with struts is also very effective. A minimum of Grade 80 (or greater) chain is recommended during extrication operations. Preferably ½” link diameter chain is used to maximize the support provided by the strut. Generally this requires the use of alloy steel strap shackles used with strut attachments.
Lower the smaller vehicle
Typically this isn’t possible, as the heavier vehicle has crushed the smaller one to some extent. Simply deflating the tires may provide a few inches of lowering.
Generally the suspension of the smaller vehicle will compress upon heavy vertical loading, creating an added problem during lifting the larger vehicle. As the big rig is lifted the suspension will relax thus allowing the smaller vehicle to rise. Actually this will decrease the total amount of lift gained nearly 5-6”. Suspension compression may be helpful, and can be accomplished using a ratcheting load binder strap (minimum of 2” width). For example when the front of an auto has struck the rear of a tractor trailer, the strap is connected to the front wheels of the auto and the strap tightened. As the larger vehicle is lifted the suspension will remain compressed. Alternative extrication techniques may be performed, i.e. trunk tunneling. Perhaps this technique will be of benefit and offer the opportunity to maintain axial spinal alignment. Responders should learn and frequently practice alternative techniques for such incidents involving overturns/underrides.
Lift the larger vehicle
This is best accomplished with a heavy wrecker and its associated equipment. When lifting such weight it is vitally important that fire/rescue responders understand their limitations when using common extrication equipment. I urge responders to seek out training providing details of lifting physics, timber cribbing capacities, big rig anatomy, rigging, and heavy lifting operations. Once the load is lifted, it should be fully supported by equipment that is within its WLL. Herein lays the benefit of timber cribbing, vertical strut systems, and heavy wreckers. Obviously continuous observation must be provided for any lifting or uprighting operation to increase the safety for all involved. The area completely surrounding the vehicles should be under constant surveillance by responders who can sound a command to halt the lift. This command must be established prior to any lifting, and understood by everyone on scene.
Separate the vehicles and extricate victims
Although controversial it provides increased safety for victims and emergency responders. Depending upon the type of big rig it may provide increased safety to upright the rig rather than operate under it while suspended. Once the lift has begun it is safer to continue until the overturned big rig is uprighted. After lifting the larger vehicle, the smaller one is attacked similarly to a common extrication problem. It is inadvisable and dangerous for anyone to work beneath a suspended load. A thorough knowledge of timber cribbing, struts, and heavy rigging is paramount to provide safety for all involved.