This past year we have looked at the types of trucks on the road, such as the specialty trucks. We have looked at the weights and construction of large trucks, and discussed the different types of trailers they pull. We talked about the weights of these trailers and what they may weigh loaded. So where do we go from here? Since we have pretty much covered all the basic anatomy of the heavy vehicles on the road, I guess we need to start looking at the rescue aspects of what we will be expected to do. One of the most important considerations in our rescue efforts will be to stabilize all the vehicles involved. Now do not get me wrong, the scene assessment and hazard control is first and foremost, but we will look at the assessing role and the ICS in another article.
After the initial assessment has been performed, we need to look at how to make the vehicles safe to work in and around. Stabilizing the vehicles to allow us to lift and cut is paramount. Now, we have to look at the vehicle and its possible weight. Normally when there is a crash involving a large, heavy vehicle, the large vehicle usually ends up on top. This in turn means that it will have to be lifted in order to remove those trapped or pinned in the vehicles underneath it.
We have already looked at what needs to be considered when it comes to the trailers, how much they may weigh, and any special considerations we may have to take into account. Once we do this size-up, we can start looking at what needs to be done and what equipment it will take. Can we do everything with just cribbing, and if so, is there enough and do we have the sizes that will be required? Will airbags be required and are the ones we have adequate? Stabilization struts and jacks may also be needed. If the vehicles are substantially off the ground, you may need to utilize cables and straps and bring in a large wrecker. The extrication aspect of heavy vehicle rescue will not be much more involved than standard vehicle extrication, except for the height. However, stabilization can require a lot of equipment and the use of heavy wreckers.
We need to first take a look at the equipment that will be needed when doing heavy vehicle rescue and if we don’t have it, where is a resource to get it on scene. Cribbing is probably the big item we look at. Keep in mind that a wood cribbing stack of 4X4’s is good for 24,000 pounds based on a two crib stack, and 54,000 pounds based on a three crib stack. Each point of contact is rated at 6000 pounds, with a built in safety factor. The rating is based on 500 psi of crush strength. Some woods depending on the grain and type of wood can go up to 1000 psi. On the other hand, plastic cribbing has a rating of 700 psi to 1200 psi. This can give you an increased capability for stabilizing the vehicles involved. If we move into 6”X6” wood cribbing, we can increase our strength to 60,000 pounds on a two crib stack and 135,000 pounds on a three crib stack.
Next we need to look at how much cribbing it may take for an average heavy vehicle stabilization. If we need to do four cribbing stacks at three feet high, it will require 88 pieces of 4”X4” cribbing based on a two stack box. If we need to add to the capability and do a three-stack box, it will take 132 pieces of cribbing. Looking at doing our stacks with 6”X6” cribbing, the two-stack would take 56 pieces and the three stack would take 84 pieces. This being based on doing four stacks, the crash could even require more. The problem will be are you going to have this much cribbing, and if so, is it on your rescue truck? It would take an area almost six feet by six feet to stack this much cribbing, not including step cribs, 2”X4”cribs and wedges. The average department cannot and does not carry this much cribbing on their truck. If relying on cribbing alone, you will need to consider calling in some other resources to add to your crib base. I did teach a heavy vehicle rescue class down toward the coast where they had set up a really neat mutual aid arrangement.
One of the county departments had a pull flatbed trailer with sides filed with 4X4 and 6X6 cribbing, along with a toolbox in the front of the trailer that had at least a half dozen 20 ton bottle jacks. They pulled this trailer to any vehicle crash that was requested in the county. I thought this was a really great arrangement and set up, and proves what mutual aid and working together is all about.
Next issue we will continue to look at stabilization equipment needed for heavy vehicle rescue. The weather will soon be getting warmer and we all need to squeeze in as much training as we can. Make the most of your training time. Until next time, stay safe out there and be the best you can be.