By GREG PRINCE
When I began my fire service career, there was only one brand of rescue tool, spreaders weighed 80 pounds, air bags were unheard of, extrication was based on brute force, and we conducted drills on “perfect” cars at the local towing company. Today, we have many brands of tools to choose from. Air bags are in every car, and extrication knowledge and techniques have replaced the days of slamming and banging. But what about training? Do you still drill on perfect cars? Probably a good majority of you do.
The Snohomish County (WA) Fire District has a huge auto crushing yard in its response area that allows us to drill there all the time; the yard will crush and position vehicles to create the most realistic scenarios. Training on crushed and impacted autos can hone our skills for when we work on actual incidents.
Five years ago, the “Two Doors and a B Post” technique, used on four-door sedans involved in a significant accident with critical patients in the front and back seats, was documented in the various journals. The evolution involves opening up the entire side of the vehicle as a single unit—two doors and the B post—on the front door’s hinges, giving total access to both patients quickly and efficiently. On hearing of this new technique, my crew and I went down to the yard to try it out. The results were pretty encouraging, but when we attempted the evolution under realistic vehicle conditions, there were complications. We modified the original technique using the following steps, with more positive results:
1. Force open the rear door, latch side, with spreaders and/or cutters (photo 1).
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| (1) Force the rear door using whatever technique you want. The rear doors can be tough, so try a couple of times with the spreaders. If you have no luck, cut the nader bolt. (Photos by author.) |
2. Cut the top of the B post (photo 2).
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| (2) Cut the top of the B post. Remember to check for hidden pressurized gas cylinders and seat belt pretensioners by stripping the inside plastic before cutting. If you find one, modify your cut location to work around the cylinder, and ensure someone cuts the seat belt. |
3. Open the door all the way, and then crib under the B post.
4. Cut the bottom of the B post as deep as possible (photo 3).
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| (3) This is a difficult cut. Make sure you are aware of the patient’s location. Make certain you choose good positioning for tool control. Cut about one or two inches above the seam, and make it as horizontal as possible. Take extra care to ensure proper placement of this cut. It will pay off later. |
5. Place the spreaders as shown and spread to tear apart the B post (photos 4, 5).
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| (4) This is the initial spreader location to begin tearing out the B post. Note the step chock directly under the spreader tip. Make sure you direct all energy toward the spreader’s upper arm. Try to catch the curved corner of the door (we were slightly off here). This location is curved metal and thus is stronger than the surrounding flat area. |
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| (5) Spread the area. Here you can see the tearing begin. Watch both tips to ensure that they are firmly in place throughout this process. If you notice that the upper tip is slipping or tearing through the door, stop and reposition the spreader. The best new tip location is right in the middle of the lower hinge assembly. This is a very strong location with a thick backing plate underneath the door skin. Keep spreading until the post tears all the way across. |
6. Open the entire unit by the front door’s hinges (photo 6).
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| (6) The entire side of the car is opened on the front door hinges. On a side-damaged car, two- to three-minute cutting times are possible. |
Sometimes, the B post tore out cleanly; sometimes, for unknown reasons, it did not. Instead of tearing across the base, it would tear down to the vehicle’s underside, leaving the B post intact. After repeated failures, both the cause and solution became apparent. It turned out that the procedure’s critical point is the location of the B post cut made in step 4. The key was understanding the car’s structure.
Cars, like people, have anatomies—structural strong points, welded seams, crumple zones, and integral structural members, to name a few. The B post itself is comprised of two metal parts, formed and bonded together vertically. This fits over a metal support that sticks up from the bottom of the door sill. The B post is then spot welded to the sill at that joint, forming a horizontal seam. The seam is the weak point, and the sill below provides the structural integrity.
CUTTING MORE ACCURATELY
Think of the door sill as an anchor. When left in place, it diverts forces back up. Think of the spot-welded seam as a perforated tear zone. When you cut the B post above the seam and apply force, the metal will tear down to the seam, as desired. Next, the seam simply tears apart, popping each successive spot weld (photo 7). The operation works as designed, and the whole side of the car opens up.
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| (7) Ideally, position the cutter two to three inches above the (door sill) seam. This seam was rather low, about the same level as the floor pan, but the cut can be as high as three inches above the base of the B post. Keep the cutters as parallel as possible; one good cut is all you need. In this situation, the cutters could not get any closer than about three to four inches from the seam, which was too high for the metal to tear down, then across, the seam’s length. Because we had a proper, parallel, well-placed cut, the metal tore cleanly. |
Problems occur when you do not take care enough when you position the B post cut in step 4—you make the cut on an angle through the seam or, worse yet, below the seam. Since you bypass the seam, the tearing force applied by the spreaders then follows the direction of the cut. It flows downward, tearing the thin metal in a curved path under the car, leaving the B post intact and in place.
What happened is simple: We bypassed the tear zone, so the “anchor” was compromised, losing all structural integrity in the zone. (Note: Some cars cover up the seam line at the bottom of the B post, making it impossible to see. In these cases, make your cut about four inches above the post’s bottom.) Always cut horizontally and about one or two inches above the seam.
We probably would have detected the problem on a perfect car. However, the problem’s potential was magnified on a damaged vehicle. The bent metal and crushed door created a reduced work area that tempted us to cut across the post’s bottom, which would have been too low. This simulated situation led us to learn to make the “real cut for success.” We learned that, whenever possible, you must drill on damaged vehicles to simulate real accidents.
GREG PRINCE is a 24-year veteran and lieutenant with the Snohomish County (WA) Fire District #7. He specializes in truck operations and auto extrication.
