December 28th, 2009

Shenzhen China What is being reported as a crane collapse has killed five and injured one yesterday in China. The accident doesn't specify if it's a tower crane and details are sometimes hard to come by out of China. If I find more I will post.

November 21, 2009

Update to the Hawaii self-erector tip story. News in Hawaii isn't what I'd call complete. I wouldn't characterize US news in general as good as it's based on popularity. I asked around and got the story. You might say that this is the rumor mill, but it's reliable.

The model was an IGO 21 and not a 50. It's a little crane with only 3900 lbs capacity in tight. This explains the Jeep;s roll bar having the ability to shield the tourists from being crushed. As you might recall, two ladies were sitting in a Jeep when the crane fell over them, but the roll bar saved their lives.

The reason for the collapse is so shocking it's funny. To be clear, I don't know who was who here, or who was doing the work. The crane was purchased in the not too distant past. The assertion was that this was the first job for the crane. They are going to dismantle the crane. Instead of reading the manual and making a step by step checklist and putting someone who knows the process in charge, they just started working. (These manuals are very detailed, use great drawings and the steps are numerically ordered. For the most part, you don't even have to know how to read.) The first thing they did was remove the counterweight. The second thing they did is yell "No, No, No!" and watch some ladies luckily live.

This is one of those stories that leaves me feeling incredulous. Maybe I've just been spoiled, but I don't know what goes through someone's head that leads them to make these types of decisions. What would make a person pull the counterweight on a crane with 80 feet of boom standing out there? It's stories like this that must be shared, simply so that it can be prevented and we can be encouraged to do things right the next time.

December 4th, 2009

Dongguan City, China A Tower Crane from somewhere near the 50th floor of a planned 68 floor building. 3 people were killed with 5 injured. The story that I've found so far on it reports it as a "quality problem" with the crane already.

The Chinese cranes that I've seen here in Washington have reasonable workmanship. During a foundation load test, I was even concerned that maybe they were too strong, or underrated from the factory. You could see little deflection sighting up the tower. The tie-ins were very loose with pin play from the collar to struts as much as 11 mm from centerline. The response I got to this condition was that it was "acceptable" where as a German manufacturer only allows 1.5 mm for the same connection. There were many design issues with the crane such as having slewing gears inside the turntable (occupied space during climb) with no gear covers. The hook had no rating or data available to reference it's size or measurements. The wedge and socket had not markings on them to reference size of rope or manufacturer. There was an article in 2007 about dangerous steel from China being used in tower cranes. All of these things are required here in the US. I had other questions as well.

We can only hope that China continues to improve for the safety of it's people and anyone whom buys their cranes. If anyone gets more details, please share them.

Edit : Today reports are that the "power arm" broke. It's not clear to me if the mean the counterjib or jib. They speak about the counterweights breaking away, but it's lost in translation I believe.There are tremendous stresses behind the pendants of some counter jibs, of course depending on design. On some you have a lot of weight cantilevered out and counterweight placement is critical. it's not much more of an answer, but it's jib related either way. Link

December 1, 2009

Warsaw Poland, The Poles are building a new National Football (read soccer in North America) Stadium in Warsaw. They have multiple cranes both Mobile and Tower throughout the job site. Yesterday two workers died when they fell 50 feet in a elevator car attached to the crane. Story

This is a first for me. I've never seen an elevator on the side of a crane. For us in the US, the idea of an elevator is one of those mystical winged horse ideas. I've climbed over 600 feet of tower on a suspension bridge. I do think that it's a decent idea for getting tools onto the crane and for any rescue operations that may need to happen. But since I've never seen one of these elevators, I have to make some assumptions. If I'm wrong about their construction, please let me know. I'd love to learn about these.

I assume that the elevators were are talking about are similar to regular Construction Hoists that fall under ANSI A10.4 here in the US. A rack and pinion, electric (potentially hydraulic) drive system held to it's track by guide rollers. (For come quick background, in my part of the world, the crane erector often erects both the crane and Hoist as a package deal. I was a licensed Elevator Mechanic in Washington State and now inspect them as well as Tower Cranes.) Most modern (last 15 years) elevators have three electric motors on the car. The point is not just power but also redundancy. If all three were to fail, then there is an overspeed governor that should kick in at 125% of the cars rated speed. The old style is a cable driven clamp system that squeezes the tower legs until it grinds to a stop, and the new is essentially a brake on a gear that gets tighter as the car travels further, after it's engaged of course. The system should be tested after the install. The overspeed governors should be swapped out every four years or so. They do have dates on them. I wouldn't expect to see a counterweight system because they you are added load to the top of the crane whether the is at the top or bottom.

I certainly don't know what caused this accident. I bring up common designs just for understanding of how they work. I would suggest that if your operator is taking an elevator, he isn't inspecting his crane, so who is? Guys hop in elevators and run them because they are easy. Installation and maintenance of elevators is dangerous and important work. It should only be done with a very experienced supervisor involved.

Novemer 26th, 2009

Basel, Switzerland A Wolff tower crane jib, apparently being dismantled, was dropped due to stability problems with the mobile crane. The Tower crane jib will be a total loss, as well as the mobile crane boom and luffing jib. One woman was injured. It sounds as if she was in a room on the opposite side of the crane where a wall was destroyed in the impact.

Speculation as to ground stability, the operator swinging too quickly load, and the light counterweight configuration, have been put forth. I'm looking at the pictures and thinking that the load was relatively low in relation to the boom judging by it's landing. I'd be surprised to think that he was still swinging, and to think of swinging quickly in this tight area doesn't ring true to me. The ground doesn't appear to have unsettled the crane in an unusual way with one outrigger higher than the other. And the counterweight configuration being wrong is so elementary, that the crane's LMI would have to be disabled. Worse things have happened, but I find it hard to imagine this is the case. There is another option that rings true to me.

The reports are that the winds were 61 kph, or 38 mph. When you get a load like a 197' tower crane jib out there catching the wind, the loads on the crane affecting it's overturning moment grow exponentially. If you are anywhere near your limits on the stability chart, you can get into trouble quickly.

We push the limits in tower crane erection and dismantling. I've been on cranes where we've used tag lines secured to truck hitches to control loads being hoisted. 35 to 40 mph has been my limit. Not the smartest move of the day, but we pat ourselves on the back when we make it happen. This is what it looks like when it goes wrong. Washington State law and ASME B30.3 limits the crane erection and dismantle wind speeds to 20 mph. Crane manufacturers often have the same 20 mph limits. We should do better in striving to respect these limits. The same is true for Climbing cranes.

Story Link, Story with Video in German and good view of job.

November 21, 2009

Maunawilli, HI A self erecting tower crane that appears to be a Potain IGO 50 tipped this weekend landing on an occupied Jeep. Fortunately the two occupants lived apparently thanks to the roll bar. I would add also that and IGO 50 is a very light crane.

Hawaii has NCCCO requirements. The operator should be certified in tower cranes. Soils are a common problem for self-erectors. Hawaii has very solid ground under what is commonly a thin layer of Red Clay. Simple outrigger pads would generally be all that is needed.

In the video on this link to the news story, Ms. Oswalt notes that the workers screamed "No, No, No" and said that the "... almost killed you." The pictures are certainly inconclusive so far, but hopefully I can find more in the coming days. I would be very curious as to the potential of this being human err.

October 23,2009

(Update: Reports are that the Loadline parted causing a shock load.)

Toronto Canada. A PECCO (Peiner Electric Crane Company formerly out of Millwood NY) 355 or 225 has collapsed. The operator has survived with some bleeding from his head but it is reported that he is not seriously injured. The crane collapsed onto the new construction of a 6 story building that it was helping construct. There were no other reported injuries.

The crane failed in the turntable. Not unlike the New York collapse of the Kodiak tower crane, we have a crane approaching 30 years old still in use, that failed in the turntable. There are a litany of problems that can cause this.

There are sometimes up to 100 bolts that hold that turntable together. If they are not maintained, rust will accumulate. They do need to be periodically replaced. Cranes this old need to be torn down on a regular basis for through inspections.

Rotec or Rubella Bearings need to be disassembled and inspected regularly. Beyond regular wear and tear that can destroy the bearing, cranes get struck by lightning. The resulting electrical surge can arc across bearings and lead them to premature wear.

Metals bend and flex when put under stress. The ductility of the steel and the loads induced determine how much. after 30 years of use, microcracking can result. The cracks in this form are not noticeable and grow over time to the point of failure. All cranes have a useful life span.

Bearings being bought from companies that sell them cheap, may not be making a sound product. If a bearing isn't machined precisely, of the correct grade of steel, and hardened to exacting standards, this may be the result. The question of should I use a $15,000 bearing or a $40,000 bearing should never become a factor. The proper question is, is the bearing made well by a reputable company.

I was erecting a crane (PECCO 2000) that had a bearing not machined properly. As a result, we could not get the crane to spin because the bearing was simply too tight. Once we got it to spin, the operator got scared and stopped immediately. The bearing was so tight that the crane stopped slewing immediately as well. We were erecting the crane and only had the counter jib on. The counter jib bounced back and forth in a torquing motion for ten minutes while we discussed it. end result was that it was a cheap and poorly made bearing. We tore the crane down and started over. There was no savings and it's one of those times where I wasn't sure if I was going to survive what was happening. At least it was on December 23rd so the impact on our families wouldn't have been too much to bear.

I'm standing on a soap box here. If your crane is over 25 years old, stop using it. There are a number of variables that can lead to failure. In this particular crane, you have pendants that have been exposed to the weather for 30 years. What does the core of that cable look like? The outer pendant is 3 inches in diameter and as a result, you'll never be able to inspect that core. They don't have the common sense safety systems such as auto zeroing of the controls. you have to put the control into neutral. I would always look and the sheaves on a PECCO just to be sure everything stopped. In the dark it was simply ugly. The use of these cranes makes sense in business because they are paid for. The risk factors out the profits from a whole fleet of them. Insurance internationally for cranes has gone insane, and it's these old cranes that we have to thank. Go through my blog. We can't fix stupid, but we can certainly fix the structural problems and old design problems.

This operator was lucky. Canada has a great inspection system. But we can't be running these very old cranes. A couple of years ago I saw some old Lindens and Krolls from the 60's up and running in Victoria. I know it feels like a waste, but they have to go.

October 23rd, 2009

The July 6th Liverpool tower crane collapse operator survived. A report is out from the BBC about his condition. Iain Gilham paralyzed from the waist down after having been thrown out of the crane as it was collapsing. Since then he's missed his daughters wedding and the death of his mother. He speaks on the BBC link on a video about the accident.

It's surprising to see how many tower crane operators survive tower crane collapses. Some of the cranes are designed in a way that survivability in a collapse is surprisingly possible. The larger Liebherr's cab is built as a part of the structure. The operator sits in the center of the structure. As a result if the impact isn't great enough to cause extensive internal damage such as tearing the aorta, they may survive. Penetrations into the cab would be the other large concern.

When I was an operator, collapse was a thought that would go through my head, along with the question of what would I do. Of course the answer of swinging the crane, running out, getting into the right spot, all would go out the window as it would happen too fast. Iain Gilham being in a Wolff (Wolff's are no longer distributed in the US so I haven't seen one newer than a 1986 model) the seats aren't designed in a way that would aid you in a accident. Why would you design seat for that? It would be assumed that you'd die in a collapse anyway. But that's not what we are seeing. In my blog alone I can think of a half dozen accidents where operators died that may have lived if they were secured in their seats. Iain may not be paralyzed if he would have been secure in his seat.

I want to suggest that maybe it's time to consider designing seats in a manner that would aid survivability in the event of a collapse. Seat belts just on the lap would add to this survivability. The operators wouldn't be flung out doors and windows and as a result dying from secondary injuries. We all know that most operators would never use them. In some cases in working close to the tower the operators stand up to see straight down. They would have to unbuckle anyway. This argument doesn't negate the value of this added safety in 90% or better of the operations. Seats could be designed with head rests to prevent neck injuries. It would simply be an option and the onus would be on the operator to use his personal protective equipment.

It seems silly to me to be able to survive the actual collapsing of the crane only to be thrown out from a height too great to survive as the crane stops falling. We as an industry should be calling for a change in this safety item. If you are the company that leased Mr. Gilham's crane, wouldn't you wonder why you are going to have to pay millions to settle his legitimate claim for a spinal injury when maybe he could have been 100% physically OK?

August 18th, 2008

I found this vid online and the text states that this demolition was to take down the building only. The location doesn't make any sense for anything that I can find. I would certainly hope that no one was in the crane at the time and that everyone was clear on the ground.

Unknown

Bogota Columbia A tower crane was being used to remove a tree. The tree cutters didn't know the weight of the pieces being cut off and overload the crane. Most crane manuals say no hoisting of "stuck" loads. Cutting away a tree while not knowing what the load is or will be fits in this category.

I don't know that the operator survived, but it looked like an easy fall into the tree, then the jib, then the tower top and stopped. We can only hope that all involved were all ok. Any details on these, pass them along and I'll post them.

Link to video of the accident

July 22nd, 2009

Russia? The title of this video indicates that Russia was the location of this accident. Russia is slightly large and just because it was a Slavic accent doesn't prove that it was Russia or establish where in Russia. But that's not really important.

The link is to a vid of a self erector tower crane coming down in the wind. It also strikes the luffing pendant of a second crane taking the jib down on it.

What I see are cranes weather vaned together. The winds are flat out howling. Then we have a quick change of direction that side loads one of the cranes. The side loading overwhelms the tower and/or it's connections and down comes the crane.

Tower cranes are designed to spin in the direction of the wind. The front jib should be pointing with the wind, indication where the wind is going. This allows the back moment of the crane to face the wind. Essentially the crane is leaning into the wind like you would when you walk in 60 mph winds. The change of direction at the rate shown in the vid appears to be incredible. Sometimes the brakes drag a bit but the crane normally weather vanes say after 20 mph. The rate of direction change may have simply been too much for this crane. Another possibility is that the crane was not put in weather vane mode and the crane was not spinning with the change of direction... or at least not fast enough.

It's a cool vid and if you can't see the link... go up to the word link above, and click on it. I know it's hard to see the highlight, but the link is there.

September 11th, 2009

I've found a crane accident from Regensburg Germany. A Self-Erecting Tower Crane has collapsed due to an apparent luffing rope failure. Unfortunately this is not an uncommon cause of self-erector accidents. The solution is simple, inspect the ropes during the crane erection. No one was injured and the damages are apparently are around 50,000 Euros. Sorry for the delay but only searching in German found the accident... Kran Unfall.

So the rope. The jibs on many of the self erecting tower cranes are pulled up via a luffing winch with a rope. The winch is locked in place and the jib is held up by the rope. After the crane is erected it's difficult to inspect the rope. It would require a man basket or other powered access such as a snorkel lift. While the rope is on the drum you are only inspecting a third of the visible rope. So as the crane's mast is being extended you have to inspect the rope. I like to stand over the hoist with a tower wrapped around the rope. The towel protects my hands from wires, yet it lets me feel the shape of the rope and any broken wires will snag the towel clearly showing the problem and it's exact location. This is the trick I use for hoist rope inspections as well. I can't tell you how much time it saves and how much more effective this is over a visual inspection of one side of the rope.

I cringe when I get a call to inspect self-erector tower cranes after they are erected. The luffing ropes are critical but the least inspected item. I spend extra time on site to see the whole crane erected because of this item. I sometimes spend more time on a small self-erector than I do on a large crane because of this time. It must be done.

Turmdrehkran Unfall

September 7th, 2009

The collapse of the Liverpool crane in July is focusing on the foundation of the crane. The claim is that the base is to be excavated so I am working on the assumption that the base is a concrete structure which would be common. There isn't a lot that we can do about this in the field, but let's talk about the issue anyways. (I apologize for the tardiness, I was on vacation.) Story

Generally accepted engineering practices, most manufacturers, and in the US ASME B 30.3 require that foundations for cranes be capable of supporting 150% of the intended load. Occasionally I'll see higher numbers, but 150% is the requirement. These numbers are developed off of Vertical Load, Torsional Moment (twisting induced in the horizontal plane) and Overturning Moment (the forces the structure apply to the foundation in the vertical plane in an attempt to become horizontal). The concrete foundation must have enough surface area for the given soil to resist the foundation twisting during operation and have enough surface area to spread the load along the soil provided. In the Liverpool case the crane appears to have changed from a Wolff 100 to a Wolff 500. While the torsional moment and vertical loads changed, the pictures indicate that the overturning moment is what was exceeded. If you increase the size of the crane, you have to increase the size of the foundation as well.

The base is being left as it was according to the report. I can only assume that the base did not significantly dislodge. What can happen here is the underlying soil is not able to resist the overturning moment while the luffing crane is boomed up. If the crane starts to overturn ever so slowly, the mast sections of the crane may eventually buckle and foundation may drop right back into place with minimal disturbance to the soil.

Cranes are to be erected to a degree of 1:500 in the vertical plane (commonly called 1 inch in 40 feet in the US). Geometry makes this true for the foundation as well. So if the base goes out of level by just a couple of inches, with the boom at a high angle, the base doesn't have to move much to induce forces on the mast beyond it's designed intended load. The crane that collapsed in Bellevue Washington was out of horizontal by 1 inch in 8 feet. That translated to 28 inches in the vertical, not include the normal tower deflection of around 10 inches. So you can see how two or three inches out in the horizontal would quickly cause some buckling.

The base of a crane whether on steel or concrete, foundations must be properly sized, as near horizontal as possible (I've always used 1/8 inch for 8 feet to stay safe), and they cannot be moving beyond this while in use either. The design of the foundation isn't the only relevant factor. The design of the crane's mast is for the plumb factor of 1:500 as well. No engineer designs both, so without the manufacturer issuing a letter, saying it's ok to be out of plumb, you cannot erect the crane out of plumb.

If it's a base design issue as noted, then the finger must be pointed at either the engineer of record, or the contractor for changing the crane after the base was designed. It's like building a building foundation for a ten story building then throwing a 30 story on top of it. Who made that choice and who will write the check?

I look at the foundations as far as exposed size, concrete breaks, and soil reports. Beyond that, I'm not the engineer or contractor and it's difficult to determine if things were done correctly.

August 9th, 2009

Abu Dhabi A man fell from a 132 foot tall tower crane and the circumstances are suprising. A crane operator called an engineer crazy for a desicion being made about the project. The engineer took offense and climbed the crane to discipline the operator. He was angry at the time. I lead to an altercation and the operator struck the engineer with a steel bar. The engineer fell to his death.

Due to long hours and pressures, things can get heated in construction cranes. Issues about whether or not fights should ever happen, you need to take it to the ground. A punch or scramble to the deck on a crane is almost guarenteed to lead to a fall. Even during the climb down, it might be just enough time to actually calm down enough to not feel the need to make it physical.

The crazy description might have been dead on.

July 28th, 2009 Mother of all Near Misses

Blue Cross/Blue Shield in Chicago was adding 24 floors onto their existing 33 story building downtown Chicago. The building was entirely being constructed out of structural steel sans concrete core. The hoisting was being done by two Potain MR605’s which are big luffing tower cranes. One of those cranes nearly came tumbling down from over 600 feet. Great decisions prevented that from happening. This is the story of the nearest miss I’ve ever seen. And I’ve seen a few.

The crane operator had an unloaded hook. He’s running the crane when he hears a loud bang and feels movement from what feels like the tower. He stops to assess what has caused it. The Bellevue crane that survived in the above story, Same thing. Unusual noise and shutter… stop and go see what that was. The crane that collapsed in Bellevue it happened during the crane erection, but we couldn’t get anyone to believe that it was a problem. I had an intermittent popping in a cross base once that wasn’t showing what the cause was. Eventually my ballast started spalling on the frame and cracks were developing in the concrete. We decided that it was torsional loading causing the base to flex. We called in an engineer to design a stiffening method and the problem went away. The commonality… stop and assess.

The towers are connected by pins. The upper section is hollow (with reinforcing) angles with holes milled to accept a set of pins, and from the tower below, a dowel of sorts also milled to accept the pins. It’s a tight positive connection. This dowel which cannot be viewed once the tower is connected is what failed. A crack caused a full separation in the leg connection. This crane was effectively three legged instead of four at this point. Private discussions that I’ve had with some that were there claim that engineers familiar with the equipment said that the engineering numbers showed that the crane should not be standing.

The crane was secured by welding a box frame to the outside of the tower leg. The project was nearly finished so the other tower crane was used to dismantle the nearly fallen tower crane within a few days. Since then all of these towers have had their connections reviewed and NDT tested at a cost to Manitowoc. The Technical Service Bulletin asks that pitting corrosion, cracking, and even scratches in the paint in this dowel area are cause for further review. This article has some decent pictures of what to look for.

So what caused the problem. There is a hypothesis that has been developed. The building was again made of structural steel. Structural steel flexes quite a bit. A job in Portland years ago had a Liebherr 630 tied into it’s structural steel building. In order to plumb the building, they had to balance out the crane first to remove it from pushing or pulling the entire building around. If you have two tower cranes tied into structural steel and don’t have all off the steel as rigid as possible, including diaphragm, then you raise the crane, and add more steel which you will make plumb and rigid, you are likely to add loading to the crane’s mast by pushing it around, and out of plumb. Additionally you have two cranes pushing that steel back and forth on each other adding loading that is unintended in the tower design. We may never know 100% why, as it could have had inclusions in the steel, Porosity, pitting, etc… we can only learn from the potential problem and seek to prevent it in the future.

I applaud the operator for his wise decision making. I’d name him, but I’m not sure that he wants that kind of attention. Dogging everything off and finding that problem was exactly the right answer. Potentially hundreds of lives were saved. To gasp the scope of this… the crane is 600 feet up with 160 feet or so of jib. The break is 20 meters of tower down. So if the crane fails entirely, you have about 250,000 lbs of steel and concrete coming down from 600 feet 230 feet long into a busy street an hitting occupied buildings. Locals 1 Ironworkers and Local 399 Operating Engineers proper training saved lives even though most never knew about it.

July 17th, 2009

A Self-Erecting Truck Tower Crane toppled this week in Switzerland. Storms and heavy rains were reported and the ground does appear to be wet. I also look at this photo and see poor soil conditions for setting up a crane. The ground clearly isn’t level, but I can only assume that the properly leveling of the crane was addressed. Something that simple isn’t happening is it? I wish that the picture was taken from a little further back so that we could see if there was good cribbing (dunnage, mats) or not.

It’s not often that we see Self-Erecting Truck Tower Cranes go over. They are a great piece of equipment, but the operators need to be aware of all of the same problems that come on both the tower cranes and truck cranes.

There were no reports of injuries in this accident.

I found the last two stories on www.Vertikal.net. It's a great site and magazine (Crane and Access) that keeps track of trends in the industry. Based in Europe, they sometimes find stories that my normal alerts miss.

July 17th, 2009

Oetwil, Switzerland A self-erecting tower crane that appears to have been well set up had tipped over while being used in a concrete pouring operation. !5 workers were on site but fortunately no one was injured.

The immediate thought given the clear stability of outriggers and number of counterweights is the limits. Is it that the limits were never tested or set up? Usually self-erectors limits are contained and once set up for the crane, they won’t need to be re-set unless the configuration of the crane is different. In Washington State the cranes are treated as tower cranes and the limits must be retested during each crane erection. Under the not yet released ASME B30.29 (new self-erector standard) the cranes also must be tested after each crane erection. Of course this is the US standard and even that is voluntary… at least until you have an attorney in a deposition asking you why you didn’t follow it as he stares at your wallet. Then it doesn’t feel so voluntary.

Self-erectors are a great tool, but they need to be operated by competent people. Running it rough and not catching loads near the limit can lead to problems. Imagine trying to run fast on an older crane. You are trolleying out and not paying attention to how heavy the load is or the load chart. From top trolley speed the over-turning moment limit goes off and stops the trolley instantly. The load has 60 feet of line out and now it just stopped at 100% of its capacity. The load swings out 20 more feet before stopping which is now at the toppling capacity due to dynamic loading. I personally think that this is the type of thing that causes most self-erectors to topple. Just an opinion.

July 16th, 2009

Chattanooga Tennesse. A 41 year old Tower crane operator suffered a medical emergency while in the crane. From 105 feet the fire department had to rescue the operator and lower him to the ground using a ladder truck with a man basket on it.

Something that we don’t talk about much on tower cranes is how to rescue operators, and sometimes others, when they suffer a medical emergency. On a tower crane 300 feet in the air it becomes difficult and time consuming for figure out on the fly. As an erector we always had long ropes for tag lines and if one of us were injured, we would get them down via rope immediately. It would violate everyone’s policy to do so, but sometimes common sense and Bureaucracy don’t mix. I’m gonna save someone’s life and worry about the consequences later.

Contractors should develop rescue plans and talk about it. Materials such as good climbing ropes, possibly a block, harness, carabineers, should be available. If you don’t have a rescue plan in place, you may find yourself with a man in trouble and a fire department trying to figure out how to get someone down as they are literally dying. In the US these emergencies happen 3 or 4 times a year. With some simple planning, this problem if figured out ahead of time might save a life.

Additionally, something that I’m an advocate of is Trauma Suspension Straps. If you fall into your harness and are waiting for the Fire Department to rescue you, you might be killed by your harness due to heart failure (low blood pressure) Worse, the blood that pools in your legs cannot circulate and if you hang for too long, the cells will have de-oxygenated and become poisonous. When you are taken out of your harness, you have the potential to die anyways. For guys like me working on my own, that’s a miserable prospect. The straps roll up in a small packet and remain on your harness. If needed you unzip the packet, connect the straps into a loop and they allow you to stand taking the pressure off of the leg straps allowing the blood to flow and preventing a heart attack or toxic blood. $20 might save your life one day.

July 11th, 2009

The Liverpool tower crane that collapsed is being removed.

It's a good showing of what it takes to remove these

cranes after collapse. They have a self erector to suspend

the workers cutting the crane apart. There is a 500 ton

crane assisting the 800 ton crane. Clean up of this

magnitude can easily approach a million dollars. I was

involved with the clean up for the Belleve crane collapse

and the cutting apart of the crane and it is a long drawn

out process to figure out weights, closest center of gravity

for rigging, and methods of cutting that will prevent the

shock loading on the crane. It's dangerous work for certain.

July 6th, 2009

Seoul, Korea A Luffing tower crane collapsed in Seoul Korea killing the operator. No one else is reported as being injured. The 50 meter crane collapsed while hoisting 300 kilo items. Those of us in the crane world know that luffers are capable of much more capacity than that. Even a shock load of that magnitude would not take down a structurally sound tower crane.

It was noted in the article that the cause of the collapse appears to be in the tower. My first inkling would be to look at the clearance of the tower to the floors or formwork. I often run across jobs that have formed so close to the crane that the crane moves into forms. When you do this you create fulcrum point over a small area that isn’t designed to take these forces. Nearly everyone knows that you can’t touch the boom of a crane to any fixed object. The same is true for tower crane masts. Carpenters or other workers don’t know this, then you have operators climbing on to cranes at the top floor and not inspecting as they climb. The result is the guy at the base of the crane can kill you out of simple ignorance. Climb your crane daily. If it’s too hard, that’s all the more reason to be doing it. It not just about the belly, it might just help you from becoming a carbon copy of this operator. Additionally dislodged connecting members and lacing failures are items to be looking for during those climbs.

The crane crashed across a rail line and caused major traffic problems as well. That’s two collapses and one lost load in two days. We must be vigilant in continuing to improve.

타워 크레인 붕괴

July 6th, 2009

Liverpool, England A luffing (assumed to be a Wolffkran from the design) tower crane has collapsed backwards into a apartment building adjacent to the jobsite. The operator was thrown from the cab onto the building and is in stable condition. No one in the apartment or jobsite is reported to be injured other than the operator.

Possible reasons for this collapse are numerous off of the one picture. No limits on the boom allowing the boom to be taken past 86 degrees or so can cause this. Poor soil conditions giving way under a base can cause this. Structural failure in the tower would be obvious given more pictures. Shock loading due to poor rigging or load line failure also can cause loss of rear overturning moment.

The crane is an obvious loss. The project will be at a stand still. The apartment next door may have to be evacuated long term. We can’t say what the cause is from the one photo, but preventing it looks awfully cheap now.

July 4th, 2009

Melbourne, Australia. A crane hoisting drywall lost the load at about 15 stories causing a near miss accident. The load narrowly missing striking a car as you can see in the picture. The article isn't clear about how the accident happened outside of the claim that the load must have "snapped".

Rigging failures due to improper rigging are not uncommon. New York had one that permanently disabled a architect late in 2007. Many others happen that we don't hear about. The US is finally getting testing on national rigging standards that will allow for standardized testing. It should be helpful in making sure that loads are more secure and this happens less often. Having a qualified rigger in charge of attaching a load is critical because often an operator can't see the load. I picked a load in the blind once using four way rigging with self closing hooks. The rigger on the ground could not get the hook in the picking eye. He chose to close the hook with the load resting on hinged portion of the clasp. The load was 180 feet in the air before I could see what he had done and my only recourse was to have everyone stop and clear out until the load was safe again.

Another instance was a guy using a chain for rigging put a lock in the chain instead of finding the right rigging. That was the jobsite foreman. A rigger in the blind with no education or supervision can endager the entire jobsite and the public.

Another point, you shouldn't be hoisting over the public. You really need to find another way and this is accident is a great example of why.

Make sure that you have someone educated rigging your loads. If you are in the states or Canada look into NCCCO certification. Unions, Crosby puts on good classes. Call your rigging supplier and I'm sure that they can point you in the right direction

http://www.news.com.au/heraldsun/story/0,21985,25731861-661,00.html

June 22, 2009

Graz, Austria Today's story does have a point, but it's more about the shenanigans of drunk students. In Austria this weekend a student walking home from the bar drunk decided that the tower crane was closer than his bed. He climbed the 150 of ladder and caught some sleep in the cab. As you can imagine it's not a healthy idea to climb ladders 150 feet up while drunk. So drunk that you don't even remember it. But all's well that ends well. The crane operator found him sleeping in the cab the next morning. I'm sure that a good laugh was had by all.

In Seattle there is an unnamed operator whom years ago went out drinking with the Ironworkers on the jobsite. (First lesson, don't go drinking with Ironworkers.) Rather than driving home just to have to come back, he decided to climb up to sleep in his crane. Someone noticed him in the cab and called the police. He awoke to his phone ringing and laser pointers on his chest from the SWAT team which is a whole other political topic. Virtually all of us who know give him a bad time about it everytime we see him. His phone was ringing because the contractor wanted to know something about getting up there. "Uh... It's me up here. I'll be down in a minute."

I had a crane in the University of Washington area. The first week of school I came in on a Monday to find the crane hook in the middle of the tree near street level. It's likely that on Friday or Saturday night someone got into the crane and was playing around. Leaving the hook down, dangerous for everyone, but the person had trolleyed out far enough that the hook was hung up in a tree preventing it from swinging into the street.

The lesson is that we should secure our cranes. Many cranes have locks on the hatch or door. If they are utilized you are less likely to have protestors reach the top of your crane and turn it into a billboard. We put a lock on my crane. It was a small tower crane so if it had gotten onto the street, a passing bus could have easily pulled it over. Just make sure that you don't add windloading to the tower with your method of blocking access to the tower if that's the route that you go. Oh, and don't turn your crane into a drunken motel. Sleep in your car if you have to.

June 16th, 2009

Montreal, Quebec A story from last year about an erector death left me a little confused. A gentleman has pointed me to a link that helps clear it up. It's a report by the government as to how the accident happened. They have video animations which I will link to here.

The crane shown is a Piener 405 or 415. The crane was being disassembled. They were taking off the outer jib when it shifted, coming back and striking the erector in the head and pinned him to the top chord of the jib. You have to imagine that this piece weighs possibly 30,000 lbs, depending on length. The jibs rarely come in level, and often you don't want them to. You want to be able to make one connection, adjust the piece and make the next connection as it's easier to make a double connection, or single connection then allow the metal or gravity do the rest of the lining up.

During disassembly it's the same process in reverse. The jib is not coming out level. The crew that I worked on would hoist the piece sometimes mutiple times until we liked how it was positioned just off of the ground. Then we would paint mark the rigging locations and note, 10 feet tip heavy, or 10 feet "butt heavy" (flattering term, no?). The intention was that the dissasembly crew could visualize how this jib is going to free up and know that the rigging points are correct.

In the computer animation here, and here, you see the jib come up and strike the man. Note how the jib moves out then comes back and hits him. Here's how that happens on a Piener. That connection at the top of the lower chords has some flat bar that extends over the connection. So the male connection from the outer jib has a little area where it could hang up if the mobile crane is under-boomed. The jib is horizontal (nuetral) instead of tip heavy. As the guys get the piece free, it shifts nearly instandly and since the crane was under-boomed itcame back and hit the worker.

My suggestions are the same as my first blog, plus some more. #1, Use a B&O (Backing Out) hammer to drive pins on tower crane jibs. #2, after the pins are removed and before the B&O is removed, a sleever bar or Spud wrench needs to be in the hole to control the load. You move the mobile until the piece floats and you do not remove that tool until it floats, period. #3, the Mobile crane operator should be aware, or the "phone man" in the air should ask if the crane is under or over boomed if questions arise. Fianlly, #4 Mark you jib pick points and the attitude at which the peice flys naturally using those pick points. As a back up a guy can take a 15 foot rope, tie the horizontal members together by looping the rope twice, then twist the free ends until it is snug. If the piece jumps then the person can start to loosen the twist and manually float the piece. You'd be surprised how effective this is.

The report does not change the fact that this death was preventable. With a tool in the hole, the phone man should have seen that the piece was not moving, asked the ground man if it were over boomed, then boomed down until it pops free. At that point you adjust the hoist until it floats, pull the tools and the mobile crane now safely has the piece.

Crane work is unforgiving. If you think that you are on a crew that is unskilled, you probably are. If it takes you more than a day to put up the average crane, quit today. I see things travelling around to cities all over the US and simply shake my head. Someone on the site must know what they are doing, and they are incharge, period. Please, use the proper tools. Contact me if you don't know how to do it.

Thanks to the person whom sent me the link. Updates are part of what I'd like to get so that this blog is as accurate as possible. Journalists don't know what they are talking about in this arena and any solid info only makes us better, and safer.

May 21,2008

Atlanta, Georgia - I learned today of a tower crane accident that didn't make national news during the rash of accidents in the US last year. A Liebherr 420 was being prepared to be climbed on an Atlanta jobsite. The collar appears to have been installed and the climber mounted on the tower. During the process the climber freed up and fell 70 to 240 feet (conflicting reports) to the building below. If you go to this link and watch the vid you'll see the end of a strut sitting on floor as if the bolts were all sheared off at the splice plate. There was a person on board the climber during the fall and they managed to survive with multiple injuries.

The details are few and far between. Hopefully details will be released at some point so that we can all learn from the problem(s) that lead to this accident and prevent it from happening to us.

May 16th, 2009

Amman Jordan On May 16^th a tower crane collapsed while building the Jordan Gate Project. Working on the 44^th floor at a reported 220 meters the horizontal superstructure suffered a massive failure. This weekend the crane is to be dismantled in a planned three day process.

As you might imagine, this dismantle is going to be tricky to say the least. The jib is folded in multiple directions and will require securing as the sections are cut free with a torch. Often these types of operations are done from the safety of a second personnel basket from a second crane. Given that this is 220 meters up, the logistics of setting up a ground crane with that much boom and a derrick are daunting. As a result it’s likely that just to get this down one guy is going to have to be on what remains of the crane to make the cuts. Shifting loads, bound loads releasing energy, and falling items are going to keep this man in peril throughout the operation. If there weren’t other buildings around it would be better to tie a rope to it and cut it down like a tree leaning the wrong way. Alas, we are never that lucky.

I haven’t found any reports as to a cause of this accident. Often when the jib of a crane collapses the counter jib stays put. As a guy who has installed and removed thousands of counterweights, that’s impressive. In this case it failed as would be intuitively expected. You could expect that there was a tower top failure, but the shock of a pendant failure on either jib might cause this as well. It’s impossible to narrow it down without further information.

It might be important to note that this job has suffered other problems. 3 stories collapsed killing 4 and injuring 15 in 2006. A fire on the eighth floor broke out in the same year but no injuries were reported. The current crane accident left no one physically injured (an operator survived this?) but an Egyptian man was treated for shock. The crane dismantle is expected to take three days. Day one might be over at the writing of this blog. My thoughts are with the men faced with this task.

انهيار رافعة برجية

June 5th, 2009

Malta is one of the smallest nations on the planet. With a population of 410,000, It’s smaller than most major cities. Just off the coast of Italy there is something this tiny island nation is having no shortage of this year, tower crane accidents.

On February of this year Malta had their first tower crane accident that I knew of. It was a self-erector that collapsed without a specified cause. Two weeks ago (May 20^th) they had a second tipping, again from an unspecified cause. This weekend the crane that fell on the 20^th was being replaced. During the crane erection either a rigging failure or pendant failure occurred and the piece being hoisted into place was damaged. There are no reports of injuries.

I don’t think that I quite understand the lacksidasical attitude towards safety after the first accident. Wouldn’t you have a master rigger there and expect them to inspect the rigging? If it were a pendant failure, did you really decide against bringing in a crane inspector? Don’t you want an honest 3^rd party opinion as virtually all manufacturers suggest?

I can’t imagine that Maltans are going to put up with this. There were articles speaking out against the problem after the 2^nd accident, so certainly the rhetoric will only become louder as 3 accidents in 4 months on an island of 410,000 people is ignorance on display.

(Picture is of May 20th Accident)

http://www.timesofmalta.com/articles/view/20090605/local/second-crane-accident-in-sliema-in-two-weeks

June 4th, 2009

Tokyo, Japan a Luffing Tower Crane being climbed down for dismantle appears to have suffered a hydraulic failure in the climber that caused the boom to collapse killing a worker and person on the ground.

Often tower cranes are climbed down to allow for a smaller truck crane to either reach it or allow for using a smaller truck crane to perform the work which can save tremendous amounts of money. The climb is achieved via a climbing frame that surrounds the mast then connects to the turntable. It is connected to electrical power that runs a hydraulic pump that pushes a ram into climbing dogs (of various designs). The hydraulics are supposed to have check valves in case of hose or pump failure. The check valves should hold the ram in place during a hose change out if it were necessary. From the sound of the description I hear that the turntable fell, crashing hard into the tower below, while being climbed down. This could have been from one or two meters and would have been violent.

So what could have caused the climber to fail? Three causes come to mind. If the Check Valves were not in place or simply weren’t the right size, or the valves failed themselves. This could be the result during massive pump or hose failure. Stranger things have happened, but this would be a new scenario to me and I would want to see the maintenance records on that climber. Were the check valves ever changed out to possibly the wrong ones? The second stand out potential is the climbing dogs slipping. In many designs a person has to physically or mechanically pull the ram in to proper position. If a guy got lazy it could be off and a slip could happen allowing the crash. My third and final suggestion would be climbing dog failure. These structural members are welded into place just like any other piece of the crane. If you had a weld or metallurgical failure, again, this would be the result.

This is an odd scenario. I have 100+ crane accidents on my blog with maybe a dozen climbing accidents and no climber slips that led to this. In New York a tower was thrown off due to a slip, but the result was the tower being thrown off the platform and landing on a passing cab, not killing anyone, luckily. The solution there is to secure the tower to the climber via rigging while climbing. Past similar accident link.

Another possibility, from looking at the pictures, is that the tower crane came apart from the climber. The climbers are either pinned to the turntable, or bolted. This type of accident has happened twice that I know of, in Seattle in 1985 and in Croyden, England in 07. If you do not bolt or pin the turntable to the climber, only balance would hold the turntable on the climber. The idea that this could have happened again is beyond comprehension and murder charges would be the appropriate result. This is simple speculation in looking at the pictures and not based on the stories that I’m reading.

Hopefully we’ll hear the cause of this accident. Climbing a crane is some of the most relaxed work in tower cranes, if you have experience. It’s 15 minutes of fury followed by 30 minutes of trying to stay awake. But the guy running that pump needs to pay attention and every move that you make is critical. Sequencing and experience is critical even though it can seem so simple. The most spectacular accidents happen during climbs. This one may not even be human error, but you must have the right people in place for a climb. If you don’t… Seattle in 85, San Francisco in 89, Manhattan in 08, Hong Kong in 08, New York in 06, etc.

タワークレーン事故

June 2nd, 2009

In Dallas Texas yesterday there was yet another crane accident.Link . I normally don’t have much to say about mobile crane accidents, but this is becoming egregious and obvious as to what the problem is down there. If you look at the last year in Dallas, I can point to six accidents causing injury and making the news. How many didn’t make it on my radar?

The cause of four of the incidents is quite simply lack of inspections. The Dallas accident yesterday was due to a lattice boom rope failure (1 injured). The Huston Oil Refinery 2500 ton crane had allegedly the wrong bolts in the turntable (4 dead). A Tower crane operator wasn’t paying attention and the hoist limits had failed. As a result the crane two-blocked, parted the load line, and the block landed on a concrete truck driver. (1 dead). At Dallas Stadium a boom rope parted while attempting to lift the boom off the ground (3 injured). The other two accidents that come to mind are over turning accidents (3 injured). Save the over turning problems, the other 4 accidents are clearly preventable with inspections.

In May of 2008 I was contacted by the Dallas Fire Department Fire Prevention Officer. We discussed the possibility of me performing inspections on tower cranes and teaching them how to do it to protect the Dallas citizens. The follow up phone call was a disappointment to us both. The City had balked at the idea. The following month three of these accidents happened in one week.

Counting the dollars is a ridiculous way to decide safety measures. Many large entities argue that inspections and operator regulation are not necessary. ABC represents contractors all over the US. C-DAC (Cranes and Derricks Advisory Committee) is a proposal by OSHA to begin crane inspections as a compulsory item. Robert Hirsch, Director of Legal and Regulatory Affairs for ABC spoke before OSHA about C-DAC. His intention was not in support of protecting the long-term bottom line and or safety of workers, but rather he had this to say “…and to eliminate, or at the least significantly lessen, burdens that the proposed rule would otherwise needlessly impose.” Inspection to the standards laid out by the manufacturer should not be a decision that is hard to support. The manufacturer has their reason for wanting things done and it should be done, period.

The bottom line is not money. The bottom line is life. If the construction industry in the U.S. cannot safely hoist, or even choose to inspect cranes after six accidents in one state in one year, then OSHA is charged with the responsibility of stepping in and changing the practices of the industry. I may not be impartial since I am a crane inspector, but maybe right-to-work states such as Texas should look to California and Canada to see what the benefits of inspection and a skilled work force are? Maybe if you compared the cost of inspection and repair to the cost of lawsuits it would be a clear no brainer?