You probably don’t want to look at this image.
(spoiler - no crushed bodies involved, just crushed truck)
For many years small volunteer fire depts would make home made water tank trucks. Frequently, they were the subject of rollover accidents that caused many deaths. The cause was almost always lack of interior baffles. The water would slosh back and forth, build up momentum and over the truck would go. NFPA regulations now ban this practice.
The article from whence it came. The problem was not the coil, it was the fact that it was inadequately secured. The truck didn’t hit anything - the driver simply applied his brakes, and the coil broke free from whatever piece-of-shit tie-down job he had done. He was ticketed for having an unsecured load.
Here was a similar incident involving steel i-beams rather than a coil. Same problem, i.e. inadequate tie-downs let the load come forward when the driver hit the brakes - except this time the beams pierced the cab and killed the driver.
Another steel-beam fatality, again due to braking, no collision at all.
Coils shifted and caused truck to overturn on cloverleaf, killing driver. This was not an issue of rolling into the back of the cab during braking/impact; the lateral acceleration of the turn caused the rolls to shift, tipping the truck over.
Moral of the story: 10,000+ pounds of unsecured cargo can be dangerous, regardless of its shape or orientation.
I remember a truck driving using the term “suicide coils” while telling me about his job. I just figured he was trying to impress me. Apparently, I was wrong. :eek:
Ahhh, now a weird accident scene I saw 20 or so years ago near an intersection in Orlando makes sense. Two apparently undamaged vehicles, a stopped car in front of a stopped van, and the car had a PVC pipe sticking in the crease of its rear hatch. I surmised that the van had braked and sent the PVC flying into the car, but now I know a bit more about why it might have not been secured well.
I’ve gotten nervous behind logging trucks. Seen logs that looked like they were shifting around. I have pulled off the highway to get gas or a snack just to let that truck get a few miles ahead of me.
I have no desire to get stuck behind a logging truck on a curvy road. Didn’t want to pass because I’d have to speed to stay ahead of it.
This isn’t a truck I want to follow for sixty miles.
https://images.app.goo.gl/tZY1RtCGxsUjnwq27
One of the most terrifying drives I’ve ever done was behind a logging truck in the switchback mountain roads of WV. I was in a Ford Econoline. Surely, I thought, I’ve got better handing & acceleration than a tractor-trailer laden down with large trees around these tight curves; there’s no reason I can’t hang with him. Granted I’d never been on that road before I didn’t know it at all (& it was in the pre-GPS days) & he probably drove it every day. Eventually decided I wanted to live & slowed down.
^this.
Take a look at the pictures provided by the OP.
See the quality of chains & restraints holding down the load.
Any collision violent enough to break those restraints, will result in a thundering mass of steel hitting the rear of the cab.
But this is true whether the steel load is a ‘suicide’ roll, stacked sheets, or lengthwise loaded beams.
The only difference is that beams would slide EASIER through the restraints, and sheets would cut through their restraints with less effort. The roll does not break the restraints as easily, but its center of mass is higher so it is more of a tipping hazard.
All trucking of very heavy metal loads is hazardous. A vertical roll no more so than any other configuration of similar weight and similar center of mass.
You want to talk dangerous, try putting the same mass on wheels on the truck, like when transporting wheeled construction vehicles.
Same mass, higher center of mass, on wheels, and usually filled with nice flammable fuel to immolate your crushed remains.
Yet you see them every day on the highways.
One thing not mentioned is that steel haulage is a fairly specialist job. The rates are higher and the drivers better paid, so the hauliers can be selective about the skill set of the drivers they employ. Okay - everyone has an off day and bad things happen, but it is generally accepted that those guys are something of an elite. The ones who haul construction equipment are at another level and the guys who lead the teams transporting oversize loads are at the top.
There is a haulage contractor near me who specialises in moving railway stock; frequently vintage steam engines. They also carry 300 tonne plus loads. The lead divers are on £100k and more which is over twice the rate that an ‘ordinary’ driver would earn.
Is there any reason why a coil can’t be secured properly - so that it doesn’t get loose in a crash?
Seems like you’d just need to pass a sufficient number of binder chains through the center of the coil.
Along those lines, is there any reason why they can’t lay it flat instead of positioning it so that it rolls when it breaks free? It would have a much lower center of gravity, and friction would make it much harder to slide than to roll like a wheel.
I’m not a trucker/loadmaster, but I’ll speculate.
From what I’ve read, the coils are up to 7 feet in diameter and can weigh as much as 40,000 pounds, perhaps more. Photos suggest that they are commonly chocked fore and aft using 4x4 timbers. Frankly, I don’t think those timbers will maintain their shape if a 40,000-pound roll tries to climb onto it; I suspect they’re just there to keep the roll in place until the chains can be applied.
So let’s assume it’s just the chains keeping the roll in place during a frontal collision. Roughly speaking it looks like the line of action for a hold-down chain passes through the center of mass of the roll, and is about 45 degrees from horizontal. Assume we want it to tolerate 2 Gs of deceleration; that means 80,000 pounds horizontal, which means our angled hold-down chain (and its anchor points on the sides of the trailer) needs to exert 113,000 pounds on the roll. The chain is pulling at both sides of the roll, so let’s say 57,000 pounds of tension in the chain. The biggest chains and binders I saw during a quick web search were rated for about 10,000 pounds, so you’d need six of these. Plus, your flatbed trailer would need six anchor points on each side, with each one capable of withstanding 10,000 pounds.
I suspect that last point - the strength of the anchor points on the flatbed trailer - is the limiting factor. And FWIW, the 2 Gs that I mentioned isn’t a whole lot of deceleration.
See post #12: depending on what the steel mill puts out, and on what the customer’s factory needs, you might end up needing a coil rotator at one or both ends of the journey.
Surely a trailer designed to carry a certain load should also be made capable of adequately restraining that load.
Machine Elf has made an assumption of 2g forward force, but EU/UK requirements assume 0.8g.
The 4x4’s are not simple chocks but are placed to support the weight of the coil clear of the deck. They would normally be nailed down to stop any movement. The three chains are arranged with the front and rear at less than 45 degrees and the central one vertical - to roll forward the coil would have to lift over the front chock and there are two chains resisting this movement, both forward and up.
Usually, trailers used for this work would be designed with proper anchor points. It is true that these are crucial to the security of the load. If a regular trailer is used, then the chains would be anchored to the chassis rather than the deck frame.
Last year I saw a picture of a trailer with a 20-tonne coil still firmly attached after running off a road and ending up on its side in a ditch. Annoyingly I can’t find it now.
0.8g would cover a maximum-effort braking stop, but Xema was asking about keeping a coil restrained during a frontal impact. In the latter case, 2.0g is minimal; it would require either a modest initial impact speed, or a great deal of crumpling of the front end of the truck to keep decel this low.
Well, there’s the vertical load due to gravity and road bumps, and then there’s the lateral/longitudinal loads due to acceleration. As bob++ points out, EU standards don’t even require 1g of lateral restraint, let alone the 2g that I was looking at.
ISTM that heavy steel chocks (like conventional wheel chocks, only much, much larger) could be used to prevent rolling. With the right material choice and geometry, these could use friction against the trailer bed to provide restraint under a 2-g decel. The downside is that the vendor would have to purchase/fabricate/stockpile these, and handling them would be an extra step to deal with during the loading/unloading process (IOW, the cost of a roll of steel would go up).
Bump: New footage
Friend from high school lost his father to a “homicide coil”. It broke free from a trailer, no accident, just improperly secured, it rolled down the road until it hit my friend’s father’s car
I recall a story told to me by a friend from Hamilton (Ontario), a steel mill town… that one time as a load was being trucked out of town the restraints on one such coil broke; but it was thin spring steel, and instead of rolling, it unrolled - quickly. You did not want to be in the way as it unrolled itself down the road.
I addressed this in the OP: it’s much easier to roll them on/off the truck.
It’s not the case that the CG would be lower anyway. The diameter is rarely greater than the width. The only way to lift these coils is to use the centre hole. Standing them upright would be a risky procedure - not only for the people doing it but for the likely damage to the edges of the coil.
Suitably chocked and chained, they are no more risky than any other load. In my own experience, flat sheets are more problematic; whether steel or wood - they are prone to slide.
I also doubt that these coils are allowed to roll anywhere. Controlling that weight would be difficult and the risks considerable. An overhead crane would be by far the safest method.