Keep in mind that many of the heavy truck cab’s components are considerably heavier than what you may find in a passenger vehicle. These components will have to be fatigued, removed and lowered safely once they are displaced. Consider what will happen after the victims have been disentangled and have been packaged for removal; your crews will be used to lifting the victims out of their cars. In these cases, your crews will be accepting the victim over their heads, and will have to lower them onto a stretcher. The mere act of removing a somewhat larger victim will require a significant amount of manpower. Have the adequate personnel on scene and ready to receive the victim once they have been packaged.
Once we have identified the victim location and the plan to remove them, we need to consider the next point: Is there a need to displace or move the vehicle(s)? When we have to lift or move a vehicle (think under-ride or over-ride with a passenger car), we need to know the weight of what we will be moving. One quick way to get a rough idea of the potential weight of the vehicle involves counting the axles and adding the weight ratings together (photo 4). A good rule of thumb for axle weight is:
Steering axles with thin profile tires = 12,000 pounds/axle weight rating
Steering axles with wide profile (flotation) tires = 25,000 pounds/axle weight rating
Drive axles on tractor/truck = 20,000 pounds/axle weight rating
Tag axles/trailer axles = 15,000 pounds/axle weight rating (Note: this is an averaged assumption; some may be rated for more, but it will get you started.)
Taking the above numbers into consideration, we can add the Gross Vehicle Weight Rating (GVWR) for a vehicle. For example, consider a twin-drive axle dump truck, equipped with a tag axle and wide profile tires on the steering axle. Based on the estimations above, the potential capacity of that truck and contents can weigh around 80,000 pounds. What do you have in your resource caches that can lift/move/haul/hold these loads? Finding an answer to this question at the scene is not a good plan.
Don’t forget about the properties of the cargo; solids, liquids and gases all react differently when they are displaced, and some of them can provide enough inertia to cause vehicle displacement in an adverse direction (photo 5). Some container trucks must be off-loaded prior to lifting; be sure to check with the experts before trying something that may end in disaster.
Displacement and separation may be as simple as wrapping the vehicles’ suspension systems with chains and load/ratchet binders. Many rescue companies have opted to carry large flat-load straps on their rigs. These straps can be deployed much easier than grade 80 chains can, and are not as bulky to work with. These straps will have hooks and connection points on them to be utilized on frame rails, rims, suspension parts, etc… Wrapping the suspension systems tight will result in 5 to 6 inches of displacement in passenger vehicles, and up to 12 inches when lifting larger vehicles off of passenger cars (photo 6). When the suspensions are under compression, it may provide an adequate amount of displacement to separate the vehicles so that disentanglement procedures can begin. If not, then the larger vehicle will most likely need to be lifted or displaced from the smaller vehicle. If this is the case, you will need cribbing and associated strut supporting equipment that is strong enough to handle the working load limit of the vehicle. A combination of resources may have to be utilized in order to lift the larger vehicle. For example, a heavy-duty wrecker may provide the strength to raise the larger vehicle high enough to separate the vehicles, but will benefit from cribbing and support from the underside of the vehicle, if possible.
Once the lift is done, it may be necessary to separate the vehicle(s) and begin the extrication. This may require dragging the passenger vehicle back from underneath the commercial vehicle (photo 7). While I understand that this approach is a bit controversial, and this may raise an eyebrow (or considerably more) on a few rescuers, let’s consider two very critical points to this argument:
1. It is not recommended to be working underneath any suspended load. If your resources on scene cannot only lift, but stabilize the load in such a way that your crews will be protected while they work on the smaller vehicle, then go right ahead and begin patient care. However, it has been my experience that is not possible very often (if at all).