Tower Crane Accidents

January 27th, 2012

2012-01-28T08:05:00.000-08:00

College Green, NSW A man named Fen Joyce fell from a 45 tower crane jib at 12:30 AM after having been at a party. His friends are mourning the loss and note that he was a fun person to be around. You can read more in a newspaper article in the Manly Daily

It's not that uncommon for people to climb cranes at night. I've seen pictures show up on photo sites that are of people sneaking around. People have been passed out in cabs only to be found by the operator in the morning. Talk about a hang over. I've had the hook of my crane tangled in trees after fraternity pledge week near the University of Washington. I've even heard stories of people climbing cranes to steal power cables for their value in copper wire. One of those stories also involves two heel marks being drug out to a car due to apparent electrocution. One of my favorite stories involves a local operator whom decided to retire to his cab after going out with the iron workers on site to enjoy some brews. He awoke with lasers on his chest from police shooters and the cell phone ringing with the job superintendent on the other end asking him for any information about how to get into the cab.

We should take measures to keep people from hurting themselves. I'm back to running a crane after our long economic slow down. I'm working in a University District so I have the base walled off with razor wire at the top of the wall. Additionally there is a set of hatch doors on the tower that would force someone to crawl outside of the tower to continue up (top of second tower section). If they get to the top, the door to the cab is locked, but they could certainly access the jib. Short of positioning a MMA trained security guard on the tower, I'm not sure what else we could do to deter this behavior. In the crane being used on this job, a solution may have been simply locking the lower hatch door on the cab which would prevent a person from getting further than the turntable.

People are sometimes just determined to do what they want to do. We can't protect everyone from themselves, but we could do our level best with some efforts as simple as a pad lock.

December 24th, 2011

2011-12-24T07:49:00.000-08:00

Essex England. The boom of a luffing crane suffered a structural collapse and has been left hanging while crews assemble to disassemble the structure and make the site safe. At this time, high winds are expected so the nearby flats have been evacuated. Given the fact that the crane is not likely to weather vane properly, this seems like a prudent move.

I have only found one picture on BBC's website. Link The details are sparse at this point but it seems clear that the boom is being supported by the pendant. The cause of this accident could be varied. Structural failure due to weld failures. A pin backing out at a splice connection. Side Loading. Operating in high winds. It's a wide open until more details are released.

February 20th, 2011

2011-02-21T21:25:00.000-08:00

Stuttgart, Germany A Tower Crane collapsed inside of a 40,000 seat stadium. The crane was a mere 14 meters high, and the cab of the crane was dislodged in a way that it seapartated from the wreckage which allowed the 31 year old operator to clear himself from the cab with broken ribs. He was immediately taken to the hospital.

The crane appears to have broken away at the Cat Head to turntable connection. Sometimes these connections are made with through bolts. We have seen a number (1, 2)of Comedils come down due to poor bolting and bolts that have never been changed out after being torqued. I have personally found loose bolts on similar connections. I'm not familiar with the particular crane in use here so I can't really know what type of connection it is that we are talking about. Is it a pin that maybe had a keeper missing? A set of shouldered bolts that were not tightened due to being forgotten?

You should be putting your hands on the bolts of your cranes. I can't tell you how often I find hand loose bolts that should be tightened well beyond my physical ability to loosen them without a tool, let alone by hand. This is how we can prevent these problems from getting to the point of failure. Daily Checks should be done prior to each shift. Don't take the extra time your employer gives you to just go up in the crane and get yourself set up, walk that jib. Look at those pins. Put hands on those bolts. It's your life that we might be talking about.

Kran Unfall Stuttgart

February 19th, 2011

2011-02-19T07:58:00.000-08:00

Plymouth, Devon, UK A man in his 30"s fell from a tower crane. The fall was about 200 feet in length and resulted in death.
Vertikal reports the story as a man whom climbed over a security fence then climbed the crane without authorization. When he reached the turntable he found that he couldn't get any higher and then fell or jumped to his death.
The picture shows what appears to be a Liebherr 420 (US designation). These cranes have a hatch door from the turntable to cab transition. If you are the operator, you can place a lock that would prevent a person from getting past this area. The height of the cab and it's sheer sheet metal face would make it impossible to climb around without setting up ropes.
This is one of those things that we in the industry often endeavor to prevent, but it seems like a uphill battle. I've seen cranes with 10 feet of plywood walls built with razor wire at the top. The crazies still get by. People stealing copper show up to take the large power cords that feed 480v with a 200 amp service up to the crane. Operators will show up and find the cord gone. We've seen it where they've just taken bolt cutters and cut right through the live wires. I've heard a story about it happening at a crane service yard where they found drag marks as if the person who did it was injured and couldn't walk out. Sorry, I find that hilarious. Sometimes justice moves at the speed of light.
You should do what you can to prevent people from getting themselves hurt, but if they are jumping fences, clearing plywood walls while getting through razor wire, they are determined and short of putting a couple of trained pit bulls on the second mast landing, we can't save these people from injuring themselves. Even at that, they would certainly sue here in the US for the bites that they would receive, and sadly they'd often win.

February 13th, 2011

2011-02-14T07:35:00.000-08:00

Buenos Aires, Argentina (Palermo Las Canitas) A tower crane on a specially designed pedestal collapsed killing no one. It fell over four buildings, destroyed the ceiling of one apartment, which would have likely killed the occupants if they were in that spot, but everyone walks away from this one.

Looking at the design, I've never seen anything like it. It's a large concrete footing on top of four concrete pillars. At first my thought was that that they were trying to make it easier to finish the building at the end of the job. Normally you would pull the tower sections out, then go back and fill in the 3x3 meter holes in the floors that allowed the crane through. But if you had four concrete pillars close together like that, what could you put in that area of the building? So ease of removal couldn't have been the case. It actually looks like it would make it 100 times worse because you would have to remove all of that concrete. The only thing even remotely close to this that I've ever seen is a crane that was anchored to a large structural concrete beam that then had Aluminium Screw Jack Shoring for the next two floors down.

Looking at the base, I just don't like the way it's set up. You have a crane that is sitting on top of this large concrete block as if it's a raised footing. Then you have two floors of concrete columns. It would be one thing if the concrete portion had something to resist the torsional loading, but I don't see much that would resist that. I see some wood, but a compression or two on soft wood and you simply have wood sitting there and providing no resistance. We've all felt concrete floors move under us when a car drives by in a parking garage, and frankly a crane being loaded and torquing up to swing is doing the same thing to concrete. Since even flexible concretes are terrible in shear, what is stopping this concrete from moving? In the case of the crane on the large structural beam that I've seen, it was all tied into the floor of a building with enough mass to resist it. Here, there is little mass, and the mass that is there, only makes it worse because it's so top heavy.

For us in the field, this strongly points out the need to inspect your cranes, daily, and prior to your shift. Get out that flash light and look for concrete cracks. Don't show up to your crane and just run up the ladders. You might get the odd person whom doesn't understand. But here is the reality. That concrete, it didn't crack overnight. It was moving, and those cracks could have been seen. The same is true with most weld cracks. They spend a while moving and tearing just a bit more each time until enough of the weld has failed that it can't take the stress at all and let's go. Dig around, look. One other important thing, notice that the failure is on the side that would normally be considered loaded because the limited size of the jobsite on that side of the crane? The counterweights load that side of the crane nearly as much as the maximum pick on the jib side. So be sure to look at all sides of your crane thoroughly.

This story was brought to my attention by another blogger. Gustavo with Gruas y Tranportes (Cranes and Transports) alerted me to the story as it was in his home town. He has written a few blogs on it and there is some more information that can be found there. Thank you Gustavo.

This morning a video from inside one of the apartments came out on this website. Can you imagine the fear of watching TV while sitting on that couch! If you were under it, it might be deadly. I also found it interesting to see so clearly where the rebar was helping the concrete hold together.

Colapso de grúas en la Argentina

April 18th, 2009

2011-02-02T09:09:00.000-08:00

Harbin China. A Tower Crane Collapsed due to a broken bolt, apparently in the mast of the crane. The fracture was 20 meters below the turntable. The mass of the superstructure came down killing 1 and injuring 4 others. This may be a fortunate result considering the fallen scaffolding around the building. Many more could have been on the scaffolding.

Bolt inspection is often overlooked. It's been my experience that this was an area in need of improvement when I got into the inspection side. It has greatly improved since the problems were pointed out. I'll give a couple of examples.

Markings. ASTM standards in the US require that the manufacturer and the grade of the bolt be marked and visible on the bolt. I found some bolts had no markings at all. Over the years some of the bolts would get ruined or lost. Rather than purchasing new bolts which are quite expensive, one company was making their own. I don't know of it being a problem and the machinist whom did it is quite good. The quality of the materials is claimed to be adequate, but if that bolt fails, whom is now responsible? Certainly there isn't a manufacturer to blame or pay for the damages. So I chose to have them removed in every case.

Dings in the landings and threads lessen the cross section of the bolt. This lessens the ability of the bolt to withstand the load. Personally, If I found one, or two, I might not get too excited. But if I found lots of them, I'm going to start rejecting them. These bolts should be handled with a modicum of care.

I don't believe that I have a picture of these, but I found stretch bolts to be hour glassed in the threads once. Any hour glassing is an indication of failure and internal, if not external, cracking. The bolts have been tightened to their yield and cannot be used. In this case, it stopped the crane from being erected as the section with the bolts was not able to be inspected until it arrived on site, the day of the crane erection.

A crazy one that I found was soft washers under hardened tower bolts over a large loop bolt hole. The washers were dished out and collapsed in. Even after seeing the picture, the crane owner asserted that the washers were correct. It pissed me off so I went back with a saws-all and cut a section off. A hardness test showed that it wasn't hardened at all. We eventually replaced them all. The crane in question got so hammered by me that it was never erected again. I may have to blog just about this one crane one day. It was absurd. The tower leg had even been cut into with a torch and it was just painted over as if loosing a 1/2 inch of material was no problem.

Poor Install: Washer @ Yellow Arrow Belongs where Orange Arrow is.

But back to the bolts. Bolts should be periodically NDT tested. They should be cleaned, spin freely and have oil on them when torqued. It's not something to be overlooked.

Original Harbin Story Link
塔式起重機在中國哈爾濱因螺栓失效折疊

March 27th, 2010

2011-01-31T07:50:00.000-08:00

A forum in French had this photo included. The poster claims that it's the bent lacings of an MDT 178 that bent during a load test. If you look at this post and one at the bottom of the same page, the consensus seems to be that Potain is asserting that the lacings were damaged during handling and exposed by the load test. The point being that the load test itself was not the root cause. Since this happened, Potain has shortened the flattened section in what appears to be an attempt to not have such a long flattened area that would be subject to damage from lateral impacts, or loading, during shipment.

I don't know any of these details to be factual. They do make sense and I think that they are worth talking about and noting for those operating or inspecting the flat top Potains. The jibs are tall and narrow. Given the large flattened area, looking for deformation or any markings indicating a strike in this area would seem prudent.

November 28th, 2008

2011-01-29T09:25:00.000-08:00

Summerstrand South Africa (Port Elizabeth). A crane being climbed down from the Radisson Hotel was caught in the wind after it was already low enough that it was trapped next to the building. The tower is visibly being worked hard but no injuries were reported and I'm not finding any report of the crane actually coming down. Makes it a bit of a minor scare but the lesson is reportable.

Whenever you are going to climb, erect, or dismantle a crane, it's a good practice to use a reliable weather service. Here in Seattle, Weather Net has always proved reliable area by area. We have hills so and their maps and reports are great by elevation as well as general location. When we built the Narrows Bridge and were trying to get the cranes down, they were able to tell us exactly what the winds were going to be at 660 feet (200 meters) off the water and not just for the Tacoma area over the land. We had a few tight areas to get by that were so tight that we had to reconfigure the climber and it was going to take hours. All of that time was going to include an open climber which is when you are very susceptible to the winds. Find a good service wherever you are and use it. If you are going to put the crane down next to the building, you may want to know what the winds are going to do for the next two days.

If you can see that you are about to be caught, it may be a good idea to secure the crane as much as is possible. The the hook down and tie it off to something heavy at the tip that isn't going to slide. If you can rope the two jibs off to the building like you can in this case, if the wind changes direction, it can come by rather than in a case like this where you have the winds coming into that wedge between the crane and the building which is adding pressure on that tower and collar below. Since the crane can't move from there, the wedge is adding surface for that wind to strike. The height above the collar is allowing it to work that collar like a pry bar due to the leverage. The point on the jib is acting like a pivot, where as if it were tied off on both jibs, you would simply be more likely to have a jib fail ( beyond the tie off) rather than have the whole crane come down.

Having said all of that, the weather is never 100% predictable and we can all get caught. If you can't anchor the tip, get everyone safely away from the building and the crane.

The Day that Kroll Came to Town

2011-01-27T22:24:00.000-08:00

NOTE: Click on pictures for a larger version

Seattle Washington. No Accident, but a notable crane was erected. A Kroll K1800 was recently purchased and built for JCM Construction. The crane is by far the largest tower crane that has been up in Seattle. In the building of one of our sports stadiums we had a Liebherr 850 up and frankly the capacity at the tip of that crane isn't half of what the Kroll is capable of. It's a monster.

JCM is a joint venture between Jay Dee, Coluccio & Michels Construction. They have partnered up to undertake a tunneling project that is set to provide underground light rail (Subway/Underground) between Capitol Hill (residential area just East of downtown Seattle) to the University District where you'll find the University of Washington. The project has been dubbed the U-Link. It's a 3.15 mile extension set to be bored by a TBM. This is much needed project here in Seattle as our freeway system was not well planned out. We lack public transportation outside of busing. This is another step that is crucial to our city moving forward. When you think of any major city in the world, it must include trains to move it's people. So besides having a giant crane that gets guys like us all excited, this is a historic moment for the city.

On to the crane story. The crane was erected by Northwest Tower Crane Service. The parts started arriving on the 6th of January. Each truck load was an over-sized load. As is typical with many large Kroll's, the jibs are inverted with the trolley running on an I-Beam. Each of the jibs were 12 feet tall which is wider than the lanes of the road. With pilot cars in the lead and tailing, the crane was brought in bit by bit from Vancouver Washington, a scant 164 miles away, and the parts arrived and were assembled on site. The process ended up taking a total of 15 8 hour days to assemble. The crane was brand new and out of the box. If you've ever assembled a brand new crane, you know how many parts we are talking about and the time to locate each bolt and washer. It's IKEA on steroids and from Hell.

After the parts were assembled and staged on site, Ness & Campbell Crane (One Company) brought in their Grove GMK 7550 outfitted with the Mega-Wing. The 550 ton crane was ran by Doug Ukert, whom runs a hook as well as one can be ran. As of the 25th, the tower was stacked and everything else was ready to go. So on the 26th, the 124,000 lb turntable, cab, and tower top were hoisted into place.

Next came the Counterjib. Weighing in at 52,000 lbs with the hoist in place, you can see that the 550 when outfitted with the Mega Wing doesn't even deflect even though the full 197' of boom is out. The process took longer than most counterjibs because of the size of the pendants. There were four connections to make instead of just two. This is no Liebherr 154 where I could move the pendants and make the pins by myself. Then two of the massive 20,000 lb counterweights were put into place. Even at this point the erectors noted that the 100 feet of tower barely flexed. A far cry from 305 feet of PECCO S35 towers with a 400 on it on loose bolts where it looks like you are at the end of long ski jump and looking back up.

To make the 250 foot long jib pick, the 550 moved away from the tower. In the meantime, the crew sent down the load line and fully reeved up the crane. The jib was lifted off of it's dunnage and towers and hoisted into place. the entire process of hanging out the turntable, counterjib, and jib took nearly 11 hours. This is with a crew that when I worked with them we had erected, reeved, and load tested a Liebherr 630 in 14 hours. It's simply a long and slow process. But when you consider that it was reeved already, it's not a bad time frame for a new crane of that size.

The crane is fully erected and only has a few more hoops to jump through. Washington State requires that all cranes are UL (Underwriters Laboratories) Listed. A private company is coming in Saturday to do that work. On Monday, the plan is to load test the crane to get it fully certified. This is where the numbers are impressive. I have to admit that I haven't seen the load chart. So these numbers are my best good faith understanding of what they are. If anyone has more accurate numbers, let me know. The operator, Willie Steinberg, hasn't sent them to me yet. But as I know them, in 6 part operation (corrected from 4 part), it's good for 66 tons (corrected from 60 tons). This will facilitate most of the TBM load out. It's still not enough for the Cutting Head which will require yet another crane. The number that really impressed me was the tip capacity. 33,000 lbs! (corrected from 32,000) Liebherr 420 or Potain 485 maximum capacities... 250 feet out.

The base of the crane is right next to the edge of the hole that will be facilitating the TBM and keeping the work going. The concrete foundation is tied back. It's also been reviewed and accepted by two Registered Professional Engineers. The hole is maintained by lagging and steel H-Beams driven into the soil. The foundation will be tested at each 45 degree position for 10 minutes with the maximum moment load. The code normally reads as at the tip, but the site will not facilitate that and the load would likely be over a live street or apartment buildings. The next best thing is to just hit the Load Moment which induces the maximum overturning moment on the foundation anyways. This test is performed with the weights next to the ground. Once stable, a measurement is taken of the clearance from the ground. After the ten minutes has passed, a second measurement is taken. If there is any deviation, then we have a soils support problem. If not, on to the next point. Normally this is done over a 90 degree arc, but since this crane foundation has been judged to be non-standard, it will be done over 360 degrees as the job allows. In this case it really can only be done over about 180 degrees. Once all of the load tests are complete and the crane is signed off by the technicians, we'll be off and running in catching up to the rest of the world by having some underground service. Many thanks to Kroll and JCM for helping us rise up as a city by providing us a tall crane so that we can go underground.

I hope to get more pictures soon. I hope that you enjoy them.

Added Load Chart on 1.28.2011

April 19th, 2009

2011-01-26T21:39:00.000-08:00

Suzhou City, China During Dismantling operations a tower crane suffered a structural failure that killed 4 and injured 2.

It seems clear that the climber is on the tower near the top. The counterjib complete with weights hangs. The pendants of both jibs are connected to both the jibs and the tower top. What appears to be missing is the turntable. You can clearly see air between the tower and where the tower top is. There may be the smallest of turntables up there. If it still exists, are we looking at a turntable so thin and old that it is clearly pre-70's? Looking at the tower I don't even see any landings, nor can I make out a ladder which also makes me wonder about the age of the crane. But given the t-shaped counter-weights and the solid steel bar pendants, I would gladly let go of the age concern and assume that what we are looking at is a crane that suffered a bolt failure. Was it caused by the climber pushing into a weakened bolt or were the bolts removed prematurely? Both seem equally dubious claims, but where humans are involved, the likely cause is human err in removing the bolts, which has happened way too many times. This blog alone has it documented as happening as far back as 1985 in country after country. It never ceases to amaze me.

We have a Kroll K 1400 going up in Seattle today. I took many pictures today. The Counterjib was on, but the front jib was going to go up later in the day and I didn't want to wait around 6 hours. I'll be on the site tomorrow and get more pictures. It's a massive crane. I'll lay out the details that I can gather tomorrow, evening time here in Seattle.

September 26th, 2006

2011-01-19T05:39:00.000-08:00

Danang, Vietnam. Typhoon Xangsane made landfall in Vietnam late in the evening and made quick work of a tower crane breaking it in the mast. The crane was being used on the Hoang Anh Gia Lai Hotel project. When it snapped it came down losing it's counterweights which landed in a nearby house killing two children and seriously injuring the mother. The story is from a forum, so the details aren't confirmed. But there was a picture found to go along with the story.

In Hurricanes or tornado's, you can't do much other than make sure that the crane is weather vaned and hope that the winds don't climb over 140 MPH or so because virtually all cranes are in trouble at that point. This particular hurricane was a category 4, which puts it at 131 to 155 mph winds. I don't think that we can fault the crane or anyone when the crane is hit with such unusual winds. Just get back from it and house people away from it.

June 14th, 2010

2011-01-18T12:19:00.000-08:00

Найдите другие ролики на video.vefire.ru

Lyubertsy, Ukraine. A Tower Crane on a large project fell over backwards landing on a building's roof. Hopefully the building stopped the crane up high enough to prevent the operator from being killed.

The only source that I have of the accident is this video which appears to be from a cell phone. The pictures are terrible so here comes my wild speculation from what I can see. I see a jib laying on the ground in front of where I would normally expect the crane to be standing. It makes me immediately wonder if the jib structurally failed under load and caused the crane to be shock loaded backwards. Imagine being loaded heavily to the front and if the entire crane lets go, no all of the counter weight is on the back side pulling you back but you just instantly released the load on the front jib. This would cause the mast to fail at the base just as it appears to have done so in this video.

November 26th, 2008

2011-01-15T09:44:00.000-08:00

Kaluga, Russia (date listed is the date that the video was uploaded). A crane on rails found a support problem. It's an interesting problem. The crane was working when the underlying support under the bogies with the counterweights gave way. The crane was able to remain standing and I have every confidence that they were able to lift it and get it properly supported again. In the short term they added ecology blocks and wood under the counterweights to prevent it from sinking further.

But what was the cause? I'm actually not going to suggest that it was improper soils, but I'm not a geologist or soils engineer and I haven't seen the ground used because it is covered in snow. I'm going to suggest something else. Water combined with regular freezing and thawing can weaken soils. The water infiltrates the ground, then it freezes which causes the water to expand. As the water thaws and is able to escape, voids are created. Much in the same way pot holes are created in roads, the freezing and thawing cycles of Russia can pose a real problem to be addressed.

The best solution in climates like this is to have a reinforced foundation under the whole of the tracks. That's a bit of a dream solution for many projects around the world. Under cranes on rails for long term installations, I would certainly recommend a complete foundation under the rails. For construction, we just won't get to that level of spending everywhere in the world. Most contractors will have the supports designed to support the rails adequately for typical scenarios and not worry about the "what if's" as much as a professional complainer like myself.

When it comes to setting up cranes, "what if" should be your motto in the planning phase. Just like construction safety in general, always know your escape route before you get into a bad spot. In this case, you should know what your weather extremes are. The most common failure in tower cranes is knowing that wind maps exist, but putting up max free standing cranes in areas with high winds. It would be more appropriate to build it a bit shorter, tie in and climb it to final height if you are exposed to high winds. The point being, consider the weather in the planning phase and you'll save money over time. Safety isn't a sprint, it's a marathon.

You can see a video of the scenario here.

поддержка Калужской кран

January 11th, 2011

2011-01-13T14:49:00.000-08:00

Ho Chi Minh City, Vietnam. A tower crane collapsed killing it's 24 year old crane operator. The story notes that one person on site is already blaming the height of the crane, the length of the jib, and the soft soils. One part of the picture supports him quite well.

The Original report shows a green arrow with the picture. I'm not sure what they are they are getting at. I want you to see the red arrow. It's pointing at a large concrete base up in the air. One, or multiple problems has happened. The crane base is likely too small. In relation to the size of the tower, it looks very small in width. Not that I haven't seen this before. I had a job once where the base wasn't much wider than the tower itself. but the base was connected to pilings that went 80 feet into the ground. If the base is only 4.5 to 6.5 feet deep, I'm going to suggest that it's just too small and light. The base has to resist not only overturning moment, but torsional loads. If it's small with no surface tension to adequately resist the twisting induced on the tower by the slewing of the crane, the soil will eventually become dislodged and potentially not provide adequate underlying support.

If the base is too small, it might not have enough mass to hold the crane down. The concrete base should be sufficiently large with enough safety factor that it acts as an anchor. An anchor strong enough to prevent that crane from falling over. The only way that crane should fall over is due to structural failure. Good soils on a adequately sized foundation will always cause a crane to break before it overturns. You should never see a crane foundation up like a tree root ball. And we've seen it before in Prague, again with a visibly small foundation.

Cranes are designed to match their bases. Reactionary forces are listed based on height, tower used, and jib lengths. You must match them all together and make sure that you are starting with good soil, or this may be the eventual result.

Updated photos and link

Cần cẩu sập ở Việt Nam

October 6th, 2007

2011-01-12T09:15:00.000-08:00

Russia. A large Self-Erecting crane went down in Russia. The building that it was working on appears to be in the process of being built. I don't see a roof and the adjacent building that is of the same type of construction is a few floors behind it. Notice that there no crane down on that building, and the roof on this one doesn't appear to be complete. Is this just another Russian crane on rails that doesn't have the shut off ramp to prevent travelling too far? Did it hit buffers or stops or just run right off a set of rails? Of course the crane is destroyed, but I can't imagine that the chances of surviving a crash like one are very good. It hit hard enough to bend up a cab simply from the shock.

I don't know the exact cause. There is a video of the news coverage linked here. I wasn't able to download the RUTube video format, so you'd have to check it out there. If you speak Russian, maybe there is more information for you in the News Story.

Русские строительного крана падает в-стрит

February 3rd, 2009

2011-01-11T08:23:00.000-08:00

Malaysia A luffing Tower Crane suffered a boom collapse while lowering a load. In the report given, no injuries are reported.

The picture leaves the crane a bit distorted, but the lower crane was the Luffer. Apparently taller crane, the Hammer Head swung into the luffer while it (the Luffer) had a load on the hook. The contact caused the boom to collapse. It's not clear if the Hammer Head had a load on the hook and thought that he was clear or thought that just the hook was clear and was swinging past but the hook acted like a wrecking ball on the jib. A solid strike on a loaded boom chord with even an empty block could certainly collapse a boom.

As operators we get into a hurry. There are always pressures. The Hammer Head operator has a to be sure to be clear of the lower crane. He could certainly hoist over the lower crane, trolley out past it, or swing left rather than right. Contacts happen between very good operators. I've made contact with another crane that swung out of my area then back in with out announcing. I got myself in a hurry and I didn't double check. It's like not looking over your shoulder when changing lanes. I was relying on the radio (mirror) and not taking that half second to just look.

Another potential problem goes to job and crane planning. When using Luffers with Hammer Heads, it's important to keep the boom of the lower crane out of the air space of the Hammer Head at the slewing level. It might be difficult to plan around that, but it is a cost of having the two cranes on site. Certainly you can check the clearance on the forward jib, but with counter jib and weights hanging below the jib, there maybe little to not visibility, and even less forgiveness if you were to contact a heavily loaded crane boom.

December 13th, 2006

2011-01-09T19:05:00.000-08:00

Sienna, Italy. A tower crane collapsed killing the operator. The accident trapped the operator necessitating that hydraulic spreaders be used to free the operator.

The details are few and the only picture that I can find is the one included which certainly lacks clarity to help explain anything. For me, the idea of being trapped or crushed by my crane was the worst part of operating a tower crane. It would be one thing to crash due to a problem, it would be another to survive the crash only to be trapped. Maybe it's that I experience some clausterphobia when I'm squeezed and unable to move. For me, the idea of being trapped is ample motivation to inspect the crane.

Link

May 14th, 2009

2011-01-07T08:18:00.000-08:00

Crosio della Valle, Italy. While working on a housing project, a Self-Erecting tower crane suffered a structural failure at the base of the crane. From what I can see, it would appear that a outrigger failed while loaded directly over that leg.

The story notes fairly emphatically that that cause is structural failure. On the outriggers, the primary suspect for me is the transition from a box beam to the screw jack. You have a perpendicular structure that is welded on. Poor fusion, inclusions, ignored porosity, etc in this location are definite causes for repair. Unfortunately, any number of these problems could be buried in the weld which would make it difficult to detect outside of using Ultrasonic Testing. The only other things that would stand out to me is the need to verify that the proper counterweights were installed to resist the loading on the jib which would translate over that outrigger and that the load on the hook did not exceed the rating of the crane. This may have been one of those accidents that is not preventable using normal inspection and operating methods.

The original story linked above does have more pictures in case you were interested.

Crosio della Valle crollo della gru

December 25th, 2007

2011-01-06T14:13:00.000-08:00

Xi'an China a tower crane suffered what appears to be a structural failure. The mast has broken and torn just above the collar and landed on the building that it was building. The article doesn't give me good details and since I don't speak Chinese, I don't have any details as to the injuries. The crane appears to have hit the scaffolding so hopefully it was at least clear. I'm not sure if the accident occurred during a storm or during use. Since it's China, and the details are few, I'm not going to speculate any further. Link to story and video.

October 10th, 2010

2011-01-05T11:45:00.000-08:00

Linz Austria. In what is being shown as a tower crane, the crane operator was thrown from the crane and died of his injuries. The story indicates that the the crane was shock loaded but gives a confusing scenario as to why or how. It could be that the translation is bad or that the reporters understanding is poor. Either way, it would appear that the operator was standing in the crane when the shock load happened and he was tossed out the window. Or at least that's my inference.

I've ran a crane that had no floor window and required that you stand when you are within 50 feet of the tower with a load. If a load was in tight, you were literally required to lean out the window in order to see. Fortunately in cases like that, you aren't likely to shock load a crane. I can see how if a operator had a window open, and they were standing, and you shock loaded a crane you could be tossed out. It fits quite nicely into my argument against old cranes. New Cranes have guards and glass at your feet and up for visibility. They have seat to sit down in. I grabbed a stuck load once that as soon as I realized it was stuck and not just heavy I stopped. I got on the radio and told my bellman and in the mean time it broke free. The load went over his head, I began hoisting up as fast as possible because it was going to be coming back down and I didn't want to hit him. Had I been standing, I could have easily been thrown. This also fits nicely into having a new crane so that you can have a functioning load cell so that you can discuss loads that don't react as you would expect them.

I'm also a fan of the idea of seat belts in cranes. So many operators live with injuries that could have been prevented by not being tossed around in the cab in collapses. I know that they'd never get used, but that doesn't mean that they aren't a good idea. As a kid I never used a seatbelt, but they were certainly a good idea. In the end, this old crane likely doesn't even have a seat and the result is a standing operator. Standing in front of a window on a tower crane that has the potential to shift unexpectedly and without warning.

Source for picture and story.
Kran Unfall tötet Betreiber in Linz

September 23rd, 2008

2011-01-04T07:15:00.000-08:00

Italy. Built on the edge of the job site, a tower crane collapsed into the home of three families destroying the home. In the two stories that I have found, neither notes anyone being injured. The cause of the accident is noted at a burst water pipe which then washed out the soils. A second story indicated that a soils engineer says that the soil was not properly contained nor assessed.

Soils are often overlooked. Putting a crane on the edge of the hole requires that the bearing capacity be assessed. Non-native soils should also be a big red flag. Virtually every job uses a soils engineer, so what's the problem with having them assess where you are going to put the crane? Was cribbing, or matting, used to spread out the load under the pads? It's pretty straight forward that you should take advantage of spreading out the load at every opportunity. If you are putting the crane on the edge of the job site, you should consider reinforcing soils at least around the crane. Soils nails, sheet piling, lagging, air-placed concrete, CDF, etc. Find a way to slope the edge or secure the soil.

January 25th, 2009

2011-01-03T08:35:00.000-08:00

Bern, Switzerland. A man working around a Self-Erecting Tower Crane was killed when it "slipped" off to the side. He was killed in the accident.

The information shown doesn't give any clear indications as to potential causes. There is only on brief moment in the news story that seems to show the crane with out riggers folded out as if it were sitting on the outriggers. It's clear that there is considerable snow in the area. As a point of consideration in these scenarios, if you are going to set up over snow, you'll want a shovel. You should not be setting up metal outriggers on snow or even frozen ground. It's important to use wood in these cases. The reason it's important is not for compression, but rather torsion. A metal outrigger on frozen ground will have little resistance to slipping if the ground is not level, or sliding if the crane is slewed. There are torsional resistance requirements on cranes. It's rare that this becomes a problem, but this is a case where it may have been a concern that should have been heeded. So at the time of year when Europe and North America are covered in the white stuff, make sure you take the extra 5 minutes to remove the snow whether it's on a Tower Crane on pads or a Mobile. Do this both under the pads and or under the matting used.

Original Link to Story

November 26th, 2007

2010-12-29T22:13:00.000-08:00

Xi'an China. A Tower Crane suffered a structural failure injuring one worker. The crane broke from it's base and leaned into the scaffolding next to the building. The stop must have been very soft due to the scaffolding bending which may have been critical in keeping the crane as vertical as it was.

Clearly you can see the base of the crane from the screenshots. It would appear that the base was fabricated, set in place for the concrete pour, and the tower was added later. You can see clearly where the red arrow is (photo below) pointing where the welds broke. It's certainly possible that the welds were simply poor quality and that's why they failed. but let me complicate this in order to help prevent this from happening in the future.

You'll notice that the legs are welded to the lower frame. Since you don't only have to hold the crane down, you have to be concerned about the torsional moments induced. The twisting forces. If you've ran a crane before, you know that it's substantial. The welding should include bevels with multiple passes. I would have added gusseting running at least off of the two sides. This will aid in absorbing that torsional force, but it will help reduce any flex in the structure vertically as well due to compression or tension in the over turning. It also adds more weld and who can complain about more glue? The other thing that I would do if it's feasible, is plan to bury this base in concrete to aid in stabilizing it. This would hold that base as stable as is possible and limit any potential cracking due to those movements over the life of the crane, or length of time on that job site.

I couldn't get the video to play on any other source than on the website. YouTube and blogger both reject it. The video loads horribly but the link is here in case you want to see the story or watch the new coverage of the accident.

塔式起重機事故在西安

April 30th, 2009

2010-12-27T18:48:00.000-08:00

Chernvtsi, Ukraine A small self erecting tower crane suffered what appears to be a structural failure during the dismantling process killing a man. These old self-erectors often dropped the jib tip of the crane to the ground then maneuvered the mast down and eventually the jib would be stored horizontally. In this one we see what appears to be a fresh structural failure. I don't know if it was the cause of the accident or a result. But what is clear is that some of the best practices aren't being observed in the maintenance of this crane.

You can see the clean gray steel that appears to have ripped and or fractured. The top appears to have a fractured drop forged piece of steel on what I assume is a top chord.

On this picture it's clear at the red arrow that the dead leg and the live leg are clamped together. This severely weakens the ability of the load line to sustain the load. If you look at the blue arrow, you'll see that it's pointing at a wedge and socket on the opposite side and it appears to be loose. I don't have enough details to see if that's due to a broken line or due to a luffing drum failure. Either way, this isn't the right way to do it. Add a slug of wire to the dead leg. Add enough length to the dead end to clamp it back to itself which would prevent it from being able to run. Or, even better, use a Crosby Terminator which takes most of the work out of the issue. Just maintain the cranes properly.

If you speak Russian, there is a lengthy News story here that might get more of the story out for you. If you want the original link, here it is.

June 25th, 2010

2010-12-26T09:39:00.000-08:00

Cessna, Italy. The jib of a tower crane came down shortly after it had been erected. The boom came down with a father and son team working at a height of 7 or 8 meters. The translation isn't clear about where the two were working. Were they in a suspended platform? arial lift, actually on the jib? Clearly the crane is taller than 7-8 meters, but I don't see any other place where they could have fallen from 7 or 8 meters. The story notes that they are basically the crane erectors and they were finishing up verifying that the crane was working well and certifying it. The father ended up on a Conex roof and the son was badly wounded on the ground. The son was transported to the hospital where he was treated but the father died on the job site. Link

The cause of the accident is listed as a "rupture or leakage" of a pin. I can only assume from the pictures that we are talking about a jib pendant pin and it would appear that it's at the Tower Top connection. Certainly looking for bent keepers on pins is one of the primary things that I get concerned about. They do get missed. People get into a hurry or distracted and simply forget to double check. In this case, a story came out two days later that another party was being investigated for Manslaughter in the matter. That could be due to many different laws, abdication of responsibilities like providing training, or a more serious charge.

It may seem interesting that a father/son team is working on cranes and gets injured together. But it's happened two other times that I know of. Here and Here. In all three cases it was the father that died.

November 20th, 2010

2010-12-22T22:07:00.000-08:00

Busan, Korea. A luffing tower crane lost it's boom on the Paragon Apartment project. It sounds as if no one was injured in this accident.

Looking at the video, The only things notable are that the gantry looks to be intact. Without better pictures, the number one suspect is the Luffing rope failing. The only effective way to really get a good look at these is while the crane is being erected. If you have a bellman, or an inspector available, make sure that they are running a towel over the line as it's being pulled out by the crane erectors. There are often six long parts of rope that you'll never get to on the drum after the crane is put into operation. After it's erected, you'll be faced with having to inspect it visually. Effectively if you could see 100% of the outside of the rope, you are really only inspecting 20% of it. A good inspection requires tactile inspection feeling displacements, bird cages, broken wires on the side opposite of where you stand and and potential displacements of the core.

Outside of the rope, be sure to fully load test the crane and visually inspect that luffing winch brake to make sure that it isn't glazed or simply worn out.

Link to story
부산 한국 타워 크레인 사고

April 14th, 2006

2010-12-21T22:06:00.000-08:00

Tampere, Finland. A tower crane operator was killed when his tower crane tipped. It didn't hit the ground, but it would appear that in the process the cab was struck by a collapsing jib, or at least deformed in the process.

The crane was on rails and properly counterweighted. There really doesn't appear to be anything wrong with the crane specifically. For some reason, the end of the rails were removed, taking the interlock ramp to shut down the bogie motors down out of the equation. At the same time, this removed the end of rail buffers as well. the crane ran off the rails and down it went.

This has been done at the end of the job before in St Petersburg killing 3 there. No Buffer or stop. I know of others that I just haven't posted as of yet. There are an extra few hours left in the schedule. There really is no excuse for this type of behavior, but we see it all too often.
Link

torninosturin romahtaa

December 11th, 2010

2010-12-20T23:11:00.000-08:00

Singapore. Vertikal is reporting that a luffing tower crane in Singapore lost it's boom in the backwards direction over the top of the crane. I have been unable to find any other stories on this and I've been searching since Friday. But at least they have someone confirming the story in the comments.

The crane appears to be a Potain MR 295. They have a up to 60 meters (197') of boom and with the largest hoist package and in 4 part operation they are capable of hoisting 50,000 lbs. I love luffing cranes in terms of operation but they are such a pain in the ass to erect due to so many things going up on a small space. But back to the story. I don't see anything obviously wrong with the crane. The crane is PLC (computer) controlled so I don't imagine that the limits on the boom weren't working. Setting up the upper and lower boom limits are critical and many PLC systems won't let the crane run properly until the limits are set. So there are three other thoughts that I have.

In Malaysia, we are talking about an island. So winds are always a concern. An unloaded boom up to 80 degrees or more with the crane pointed into the wind could be pushing it. I personally hate looking up at booms when my inclinator is reading more than 80 degrees. They look like they are ready to come over at any time. The booms get into reverse camber and it's just unnatural. I guess it's a Seattle thing where we don't see Luffers up too often. But each crane has wind limits and luffing crane operators really need to be aware of the winds on unloaded booms and the direction they are facing.

Wind is also a problem in making sure that you store the boom at night at the proper angle. In Seattle a few years ago we had a Kroll that was caught in the wind due to too low of a boom angle and the corridor effect in cities where the winds are channeled down the streets in between the buildings. The effect is that the crane cannot properly weather vane and point down wind. I suggest that you do go to the link to see the video to see how fast the crane was spinning. The core point of the boom angle is that at night if the crane does not weather vane and the winds hit the boom while it is up too high, they can be blown over.

The only other thing that occurs to me is the load line or rigging failing and inducing a shock load on the crane. The balance of the luffing booms that have failed seem to be from heavy winds. They find a way to get blown over backwards whether it's brakes dragging, high boom angles, or simply gusting winds. The issues seem to all be avoidable short of hurricanes, but the guys in the field want to get home and the job wants to get the crane up and running. Neither pressures are conducive to making certain that everything is done as well as possible.

October 28th, 2005

2010-12-20T07:38:00.000-08:00

Shenyang, China. It's not often that we get full reports on why accidents happen from anyone that investigated an accident. I ran across one that even though it's a translated article, it does a decent job of telling the story. It comes from the Safety Research Institute of Liaoning Province, Shenyang with the full report being found here.

A QTZ315 Chinese made tower crane was being climbed down in good weather. It collapsed with 5 workers on the crane. The report doesn't indicate the fate of them all, but given a nearly 100 foot fall and the volume of blood on the site, the prognosis isn't good. The crane was found to have what's listed as an "ash bucket" (concrete?) on the hook and a tower suspended on the armature. The accident investigators found that the "claws" (either resting dogs or climbing dogs) failed structurally due to what is called a scratch and uneven loading. The failure caused the superstructure fall and crash into the tower. At this point the lowest mast section just above the knee brace section collapsed due to the vertical overload. The crossbase stayed in place and the rest of the crane fell over.

Looking at the pictures of the "dogs" it would appear that it simply wasn't in far enough. I think that the report is trying to indicate the same, but it's lost in the translation. There is an armature that is also fractured and that's likely due to the failure and subsequent slamming into towers and lacings as the superstructure came down. In my experience in climbing, it's 3 guys trying not to sleep for 25 minutes between sections while one guy makes sure that the lower dogs are in tight with each stroke and a technician runs the pump. Buy always, you have to make sure that the dogs are in tight. They are only designed to work if they are all of the way in and even if they aren't all of the way in and can take the load, they can slip in with 300,000 lbs of load on them, and that isn't good for any structure.

February 10th, 2009

2010-12-16T23:54:00.000-08:00

Palencia, Spain. Juan Jesus Sanchez Chapels, 58 years old, was killed after being knocked to the ground by the crane working on his job site. The translation of the story makes me assume that he was hit by the block of the crane as it swung by. You are welcome to see if you gather something else out of it if you speak Spanish. Link

Job sites are constantly transforming as the job goes on. Operators are running at timing and speeds that they have been used to for weeks at a time. You might have been stuck on one floor for a couple of weeks depending on how it's going, it's size and the schedule. So you get lulled into habit operating just as you might fall into habit driving near your home. If something changes, you might not notice it the first time by. Well if floors are being built or scaffolding is going up and a man is standing on it to build it or work from it, and you are used to hoisting up for 17 seconds before you can swing, and are looking ahead for the location of your bellman instead of where your hook is, that man might be higher than you have seen and the next thing you know, you've knocked him off the scaffolding. Of course, I'm just talking this out from the limited details shown.

Grúa accidente en Palencia

October 23rd, 2010

2010-12-15T21:45:00.000-08:00

Yibin China. On October 23rd, 2010 there was a boom collapse in Germany. All of the way on the other side of the world, China lost an entire superstructure of a crane killing 3 and injuring 4.

Looking at the picture of the crane, Three things strike me as things that I really want to see in person.

Why does the tower go from nasty old tower with no corrosion protection (paint) on it to a new looking tower?
Why is just that one tower fractured and do we not see any other damage?
Was this crane being climbed or did the mast bolts snap without even damaging the one side of the structure?

Besides the obvious point that any self-respecting contractor would not be pleased with the obvious state of disrepair of the paint on the crane, The different color makes me wonder if the mast was a knock off by a manufacturer other than the original manufacturer. You can buy Korean Liebherr Mast sections. You can buy You can buy Chinese Comedils. Chinese Tadano's. What I'm getting at is that there are tons of knock off's out there. Do they do engineering or do they just mock up what they see? Do they use the same materials in terms of grade and quality of production? A mast section that fits and looks right, may not be right. (I'm not adding pictures or naming names for obvious reasons.)

I assume that the one tower is damaged because it was of poor quality. I can't imagine another reason that enough welds failed to leave the one side standing perfectly vertical but the other three sides look like toothpicks. We are talking about welds with incomplete fusion from the factory.

I have to go with the idea that this crane was being climbed at the point of the accident, and here's why. Mast bolts do break as a cause and during accidents. But again, we have a side perfectly vertical still. By contrast, In the first New York accident, the point that struck the building next door on the mast ripped the steel column off on one of the sides instead of breaking the bolts. The clamping forces on these bolts are designed to be so strong that there is no way you could fold the tower on three sides and have the bolts simply break on the one side left without buckling it severely.

China continues to make poor decisions on their cranes, but more importantly we see structural failures time and again. Not all of these cranes are that old either. They are just so poorly designed and the materials are subpar. My only regret is that I don't know the models and manufacturers to start tracking which ones are failing how and why so that they can be avoided. Until that's revealed, I would just recommend not going near a Chinese crane at all.

Original Link

宜賓中國塔式起重機收合

December 9th, 2009

2010-12-14T23:26:00.000-08:00

Liaoning, China In the process of being climbed, a tower crane counter jib lost support at the top pendant connection. It immediately fell crashing into the climber killing at least one and injuring two others. The dead man and the two other workers had to be rescued by the fire department. The accident is similar to another accident that I reported on just last week. Notice the pendants hanging straight down on next to the red arrows and the tower on the jib still on the where the yellow arrow is.

It's important to note the accidents on the counter jibs because you don't generally see them failing as often as the jib of the crane. I don't think of them taking the same level of stress, but clearly the can fail just the same. On this particular one, I'm not sure if it's a weld failure at the Tower Top of if it was a pin failure as if possibly it didn't have the keeper, or a proper keeper retaining the pin. I think of some of the older 390 and 550 Liebherrs that had pendants that had to be removed in order to be shipped on a truck. They had a single pin that was a pain to install due to lining up two pendants at once, but worse was trying to drive it out later. It could tie up an assist crane for 20 minutes on the seemingly simplest of project that just never seemed to work out well.

Look over the structure of the tower top, the keeper installation, the pin itself, and pendants including the welds. The vibrations sometimes induced by a bouncing climber on a pin that doesn't have the right keeper in place could cause that pin to walk all of the way out just like this accident's potential cause.

March 6th, 2009

2010-12-13T21:08:00.000-08:00

Mesero, Italy. A load on a tower crane dislodged while being flown on a job site. The load weighed approximately 300 pounds and appears to be have been on a set of flying forks. The load came off and struck a 33 year old worker in the chest whom was airlifted to the hospital to no avail. He died of his injuries.

The video shows the emotions of the workers involved. It's certainly not surprising but an emotion that we should think of when we are rigging up a load that is iffy. If you have a load on a set of flying forks using a ratchet strap to secure it to the forks would be a good idea. Another idea is simply engineering out the problem. We get used to the run of the mill solutions to rigging and throw up our hands when we run a new solution is required. It might be that you take the pallet and put it in a bin with a four point pick. Or it might be getting a manufactured solution that addresses the problem like this.

Boscaro makes a pallet bin that goes over the pallet. Then you place the tines through the pallet and all of the items are secured. If you have a pallet of bolt kegs for a structural steel building, the bolt kegs are secured inside the mesh. Even if a keg falls over, no one is in any danger. The bin is hoisted on a four point pick, so you couldn't unbalance the load enough to ever endanger anyone. These are the types of solutions that you should be looking for. In the US we are required to engineer out all potential hazards and I think that's a good way to go. If this solution is one that you need, you can contact www.boscarousa.com

Link to story
gru incidente + milano + 6 Marzo 2009

June 15th, 2008

2010-12-13T08:57:00.000-08:00

I had originally posted this video back on June 15th, 2008 but the link is now dead. So I've uploaded it to YouTube so that it won't go dead on us again. It's clearly a tower crane on a travelling cross base going over. I can't tell if it's intentional or not. You would think not, but was it just happenstance that someone was videoing? Why does the guy at the end start sprinting towards the crane? It seems that the two action are contrary to each other in making assumptions.

Clearly the crane hit something. It should have been the end stops on the rails. Many Russian cranes have gone down due to the rails not having stops at all and so the trucks just run off the rails and sink into the soils. It's possible that this crane was being operated at the time, but I can't imagine an operator being quite so unaware of where the end of the tracks are. Could it have been blown that way? Were the traveler brakes not working well and the rail clamps not added for safety? I don't have anything but the video to go off of.

February 28th, 2006

2010-12-12T19:31:00.000-08:00

Malnate, Italy. The load line on a tower crane ruptured which induced a shock load strong enough to separate the turntable. One worker was struck by the line and injured, but by in large, the crane came down in and area that did not have many workers in it.

The jib went over the top of the building and ended up leaving the turntable suspended on the side of the building. The building itself suffered minimal damage and so with the replacement of the crane, only one minor injury, the only real loss was the crane and the confidence of the workers.

Respect for load lines and regular inspections are necessary. I'm a fan of going for a ride in the trolley basket to see the rope on the jib. not only do you get to see all of the line, but you get to hear the sheaves and rollers for their bearing conditions. I'd suggest that you need to inspect the ropes not only visually as many people do, but I would suggest that the right way to do it is tactilely as well. I do this by wrapping an old towel around the line in a safe spot and have the operator hoist it through your hands slowly. Any broken wires grab the old towels immediately and I can't tell you how many times that I've found broken wires on the opposite side of the side I was looking on. The notion that an operator has inspected a line by sitting in the cab and watching it go by is not an accurate or informed position. Certainly it's the most practical as a lone operator up there, but it's not the best that we can do. Get a bag of old used cotton towels that will tear easily. Wrap it around the line so that if it does hang up it won't immediately get dragged into a sheave. Hold on to it in a manner so that if it hangs up it won't tangle in your hand. And position yourself in a manner to be able to communicate clearly with the operator at all times, including by radio if need be. Don't let your load line develop a problem that you never see simply because the breaks are on the opposite side of the line that goes by your line of site.

Link to Original Story
Crollo della gru a torre a Malnate

September 16th, 2010

2010-12-11T01:49:00.000-08:00

Rosrath, Germany. A Self-Erecting Tower Crane Collapsed damaging multiple cars and the roof of at least one house. No injuries were reported. The report does note some wind and that's what the police suspected that wind was the cause. I'm skeptical of that claim in favor of looking at two other potential causes.

The ballast on the crane seems to be lacking in mass from what I'm used to seeing. Frankly, I've seen the smallest of cranes have more ballast than this. To be fair, I've never worked with this model of crane. It just strikes me as not enough ballast, but I have no real evidence that this is the case.

The other issue that stands out for me is the quality of the wood used. From the picture of the base of the crane it would seem that some of the wood is showing signs of rot. To make matters worse, the wood is spanning over some concrete blocking so there is no under laying support in the middle. This really shouldn't be done with suspect materials.

Both of the conditions that I have listed would affect the crane more than your standard wind. The crane was still in operation and anyone that has spent any time on a self-erecting crane knows that running them in the wind is anything but fun or easy, so you even shut them down earlier than a top slewing crane. I reject the claim of the officers and present the pictures as my reasoning.

Mobile Crane Unknown Date

2010-12-10T07:46:00.000-08:00

It's not a tower crane, but it's compelling. It's a mobile crane going over due to poor soils. It would appear that everything was intended to have been done right (matting layers are perpendicular), but the big picture is that you can't be so close to the edge on non-native soils without reinforcement of some sort. It would be best to use a soils engineer.

Operationally, guys noticed the soil giving way while the load was able to be landed back on the pilings. There really isn't a good reason why they didn't do that. Always take a moment to stop for safety. Even if there was no other injury, this is a 2.5 to 3 million dollar accident. How much would have it cost to set the load back down?

December 12th, 2008

2010-12-09T22:45:00.000-08:00

Lindenthal, Germany (suburb of Cologne). Two Tower crane erectors suffered leg injuries that were described as severe and were taken to the hospital. Looking at the pictures, I can almost promise that it's broken legs, and lets get to why.

In the picture we have a crane boom that has been set down on the ground. The journalist isn't sure if this crane was going up, down or was dropped. I would suggest that this boom was set on the ground that was uneven. Even at this point, it still looks like it's not all of the way down on the ground on the sidewalk.

The lower chord pin at the Red Arrow appears to have been removed while the jib was partially airborne with the jib touching at each end. The jib is under tremendous stress at this point. Either the jib should remain suspended by crane while only the lower chord pins beyond the rigging points are removed, or the jib should be set down on dunnage (wood) to support the jib at either side of each splice. If you have wood under each sectional connection, you can safely remove the pins. But even then, there are two measures the erector should do to protect themselves, and I don't think that they did either.

First, when you are removing these lower chord pins, stand on the lower chord. If you have your feet planted on the ground and the jib shifts violently, you become the target. If you are standing on the lower chords, you go for a bit of a ride and might end up smirking due to surprise only. The second thing is the hammers used. Yes, hammers, plural. Don't just use a sledge alone. When the pin gets close being ready to be driven out, if there is any tension on it, you should use a B&O (backing out) Hammer. With one hand hold the snout on the pin. With the second hand you swing the larger sledge on to the face of the B&O. The long snout protects the hole from being marred by strikes. Additionally, when the pin frees, the snout will follow through. This will prevent the radical shift of the piece. When you are dismantling, this tool is incredibly useful, especially in the air.

A quick story, a rookie Iron Worker was with myself and another journeyman. We set a jib down on uneven ground. We had a second (assist) crane so we were going to pull the pins after we had the jib supported by the second crane. I'm off disconnecting the fall protection. Keith is bending keepers so that we can move quickly when we start to work with the crane. The Apprentice starts to drive the pins at a point where there is significant clearance between the ground and the lower chord. I walk by and say, "Hey, get up on that jib. Your feet are in the bite." He gets in the right spot and I walk away. He's swinging away at this pin and it isn't moving well. He puts his feet back on the ground and Keith see's it. "Hey, didn't Gaytor just tell you to stand on the lower chord?" He gets back to where we told him to be. He swings a couple of times and again puts his feet on the ground. The pin comes free, the jib shifts down and breaks one of his feet. Sigh... In the US we have a saying, "You can lead a horse to water, but you can't make him drink" He's a nice guy, but he was one of those young Iron Workers who is the son of an Iron Worker so somehow he knew best through his genes.

Stand on that lower chord, support the jib, use a B&O and you'll never have broken bones in your legs and feet from a loaded jib.

Turmdrehkran Demontage Unfall

January 16th, 2009

2010-12-08T22:47:00.000-08:00

Monteprandone, Itlay. A Tower Crane fell over after being contacted by a second crane on a neighboring job site. It would appear that neither crane have operators cabs on the top of the superstructure. So neither operator is reported as inured. However, there was a Grandmother and her Grandson whom were lucky in their escape of injury.

Even when you have two jobs that are not related to one another, but they have the cranes have potential of making contact, you need to give the operators a specific radio to inform one another what you are up to. When you'll be in the other guys airspace. I have substitute operated quite a bit. I recall one job where I showed up in the morning on a Saturday. The neighboring crane was idle and I was clear of it. It was a luffing crane I was in a saddle jib. I got rid of a load and due to the clearance while hoisting up (It was a tall crane) I start my swing going around the long way. I'm paying attention to my clearance so that I can reach top speed on the swing. I was working with Iron Workers and no one likes speed in their cranes more than Iron Workers. As I get clear with the hook and have reached top speed in my swing I look out horizontally and notice the neighboring crane is not only now working, he's in my airspace! Fortunately I was on an old PECCO 400 Tower Crane that had three swing motors to get me stopped quickly with counter swing. No note from the regular operator, no note from a bellman, no second radio. I nearly swung into another crane because there was no crane to crane contact and I had no idea that he could even reach into my airspace, let alone that they were going to be working. I had no normal reason to look up. When you are 300 feet up, what is going to get in your way?

A second radio is a critical reminder to pay attention. There may be information that the operators can share that will allow for effective use of the cranes together. Maybe it's that I'm going to be swinging in and out of your airspace for a while so swing in the long way. The second radio may look costly on paper, but you'll make it back up in speed, if not in avoiding wrinkled cranes.

Link to story.

Monteprandone, Italia crollo della gru a torre

Unknown Date

2010-12-08T08:42:00.000-08:00

China. A worker was pinned and appears to have been killed during a climbing operation in China. The story only comes from a video that I found, but the scenario appears to be quite unique. The counter-jib appears to have structurally collapsed in the middle and come down simply to crush the man. Warning: This video may be beyond the normal tastes of North American's.

The crane is short with a climber on it. Since I don't see any tall buildings nearby, I'm presuming that the crane has just been erected and was going to be climbed to it's operating position. From the low height, I would even assume that the crane had not even gotten one tower section in yet. The excavator used to get the fire fighters into position seems to easily reach the lower climber platforms.

While climbers do get an ugly and uncomfortable bounce from time to time, could it really cause this? I suppose that you can't rule it out, but a more likely scenario is that the climber wasn't set properly and it slipped or structurally failed causing the crane to crash down hard on the tower. Let me draw it out a bit.

Normally the crane's counter jib has stresses that run down the pendants on the black arrows. From there, the pendants prevent the weight from dropping in the back which translates to force pushing in against the turntable or tower top depending on the design. If you drop the entire crane on to the tower itself during a climb operation, somewhere between the red arrow and the yellow arrow you are going to see significant downward deflection. At the same time the stresses on the pendants are going to increase multi-fold which also increases those inward stresses on the beams, but now on a structure that has deflected. In this case yield was found and the whole counter jib came down like a battering ram killing the man.

This isn't unique in the sense that we've seen structural failure in the middle of counter jibs. It's happened here, and here. You need to be looking there too for cracks in splicing plate welds and in the horizontal diagonal lacings. I've found cracks in those lacings before.

Again, the Video shows a body and the man trapped.

塔式起重機事故

November 25th, 2010

2010-12-07T00:22:00.000-08:00

Bolzano, Italy. In the north of Italy a Self-Erecting Tower Crane came down striking three cars and injuring none.

In the pictures of the crane, it would appear that structurally speaking, there is no failure that is notable. Certainly damage is present, but it appears to have been caused by the accident rather than before the incident. Looking at the base we see that weights fell off, so we can't get a count. I've never heard of the wrong number of weights being put on. In this case, it would appear that the crane simply tipped, so that possibility can't be ignored. But it isn't likely. The ground looks good. There are matts there that could be a bit better but they do look like they took some time in trying to get the crane level as well.

Looking at the jib of the crane just behind the first car visible, you can see that the location of the trolley shows that it's likely that the crane was carrying a "bunk" of plywood. Was the moment limit set on this crane? Was the crane load tested to 100% and the limit verified? Does the crane have a scale on it for an accurate reference? Certainly a good operator should be able to guestimate this weight with some accuracy if you are going to be closing in on the limit of the crane. 1/2" Plywood = 1.42 lbs per square foot. 45.5 lbs per sheet, etc. You can have these references in a book, in your smart phone, maybe on a card in your hard hat... I know that I have some buried around the office somewhere that I would put in the hard hat given I were a bellman again.

Load test your cranes. It's really not that difficult, expensive, or time consuming. All of these factors compared to the cost of replacing the crane.. not even close to being on par. The beauty of a tower crane is that if you've load tested it, you can have some confidence that the limits will work and keep everyone safe.

Original Link

consigli gru a torre in Bolzano

July 31st, 2008

2010-12-06T08:50:00.000-08:00

Original link

Milan Italy A tower crane was blown over during the night due to an apparent tornado. I don't have any report of any injuries, but clearly the crane and at least one vehicle was destroyed. Did the Volkswagen get spared? I'm not sure but it's close!

The same old story is true, that you need to make sure that your crane weather vanes and does so well. Sometime Technicians are OK with the idea of letting the brakes drag a bit even when they are open. I don't agree with this position. When you get into winds like tornado's, the wind can change direction very quickly and the best chance of survival is to have a crane that points downwind without hesitation. An example of hesitation and the eventual results...

Crollo della gru a torre a Milano

April 12th, 2009

2010-12-05T09:58:00.000-08:00

Donetsk Ukraine. A Tower crane collapsed while installed the "intermediate" section. It sounds as if the female crane operator was injured seriously and was taken to the hospital. Also, a nearby building was struck during the collapse.

The crane is clearly an older model. The jib is made of I beam construction and in my experience, you have to go back to the 70's to find this type of structure. But let's assume that it wasn't a structural failure. What are some of the other problems with cranes this old?

Do you have manufacturer support. The Kodiak Crane that went down in New York had no factory support and the weld repair was done poorly by someone unqualified. If you have an old Pecco crane whom do you call to find out the allowable deformation in a jib lacing on a 170? There are people whom know these things, but it's not like everyone can just pick up the phone and call the right person immediately like you would with a Potain. So problems get brushed over or ignored for years.

How about having a skilled and factory trained technician in charge of the crane erection? Is the technician 65 years old? How many of them are there? Is the technician on site working with the crane with second, third, or fourth hand training? How easily are mistakes made? It just doesn't seem like a good idea to be using cranes that could have structural problems hidden below 9 layers of paint. With a technician that may not have even been trained by someone with a factory background and does the manual even exist? How many old cranes have you been on where there isn't even a manual?

Link to Original story

баштовий кран аварії в Донецьку

2 Years Ago

2010-12-04T20:35:00.000-08:00

Zibo China, A tower crane was filmed as it was down after either moving gravel or concrete using a concrete bucket. The crane appears to be new in condition and design, but it also appears to be Chinese or Korean. What's interesting is that the link lists the video as the "kindergarten" accident from October 10th, 2008. Clearly it isn't the same crane, so I'm not sure where it's from. I couldn't get the video to load into Blogger or YouTube, so here is a link to the original.

What strikes me about the video is that the crane has the climber left at the top. Often crane manufacturers only allow this if the crane is at least two tower sections below its maximum free standing height either from ground or tie in. The added mass can overload the crane as well as the added surface subject the crane to more wind load. From an operational standpoint, I simply wouldn't want a climber in my line of sight. This is especially true if I were on a crane of significant height because it would block my view. Sometimes due to the tie-in schedule it's the way to go, but for most jobs, it would just be easier to send it down and grab it on the way up next time. What are we talking about, 30 minutes of work for it to be better for the crane and the operator?

淄博塔吊倒塌

August 1st, 2010

2010-12-01T08:09:00.000-08:00

Harbin, China. A Tower Crane being climbed in Harbin China collapsed after being erected. I don't have any details on the number of people injured or dead as the video is the only source that I have found on this. The link to the original video doesn't have an exact date on it and only lists it as about 4 months ago. So that date listed is just an approximate.

The tower sections are short, and so is the climber. Clearly the climber is broken, but likely that's from the side loading once the collapse began. What strikes me when I look at the tower sections that were bent is that even though they are short, only two are broken. Does this climber only reach down 12 feet or so? Does that allow the spread of the load across enough surface of the tower sections? Does that allow for enough ductility in the structure of the climber itself? Is this a design problem? The quality of Chinese steel is under question to begin with.

In terms of practice, the crane appears to have gone over to the side. So was the tower properly plumbed to 1:500? Was there wind at the time of the accident? It's noticeably calm during the report so that doesn't strike me as likely. Given that there is little twist in the tower, I wouldn't expect that the crane wasn't slewed off kilter. The only other thing that strikes me as a potential is the human error of running the climber over the top of the tower. Often there isn't a terrible amount of play given here, and if you went past the mid rollers, this would be a likely result. Original Link

中國哈爾濱, 塔式起重機倒塌, 塔式起重機事故

June 26th, 2008

2010-11-30T09:49:00.000-08:00

Portland, Oregon A Liebherr 100 struck power lines which electrified the crane but did not electrocute the operator. After the power was shutdown he climbed down the crane with the Firefighters. Source

The pull on the loadline looks as though the operator was swinging the crane with an empty hook at a radius that was too far out and with the hook too low. A lapse of thinking while operating?

The crane was clearly grounded well since he isn't dead. Potentially there could be quite a bit of damage done to the crane even with proper grounding. The motors could end up burned out due to the immediate surge. The issue that stands out to me is the condition of the slewing bearing. Cross arcing between the balls is a known problem on cranes that have received multiple lightning strikes and it leads to premature deterioration of the bearings themselves. The Loadline is destroyed on this crane. While you might be able to pick up a small line like this for a few thousand dollars, you'll have to have it installed, potentially wait for it and what does shutting the job down really cost? All of these consequences assume that there is not a load on the hook and that no one is touching the crane itself.

This is where I speak of the virtues of modern cranes over even a 10-15 year old crane like the one in this case. Most modern cranes have the option of what Liebherr calls a ABB system. What it does is allows the crane to block out areas of operation. In a case like this, you would trolley out to the tip and swing out to the limit of operation (10 feet away from 50kV and add .4 inches of clearance for every kV above that), mark that spot then travel to the opposite point, mark it, and the crane will prevent the operator from swinging into that area. It knows the virtual location as a straight line, or you could set it up for multiple direction changes. Almost every crane manufactured since 2005 has this option, so if you are going to work with a tower crane near power, I cannot recommend this feature enough. I've had older operators balk at the idea, but I frankly don't understand it. It's like being against a seat belt or Anti-lock brakes. Unless you are in a race car, why is that again? If it's my insurance on the line, the system will be turned on when I'm there.

November 24th, 2010

2010-11-29T07:25:00.000-08:00

Downpatrick Ireland. Getting back after a long US Holiday weekend and I find that Vertikal.net is reporting a Self-Erecting Tower crane having suffered a jib collapse. It's one of those stories that never made the news and is only known because of a reader. Likely the accident caused no injuries, but what could have caused it?

Vertikal notes that winds can cause this. It's true. When you have the jib only partially folded out or stacked, the torsion on the jib is higher than when it's profile is lessened and the entire jib is folded out. But this isn't what sticks out to me. The jib being partially folded in or out is relevant, but what really sticks out to me is the trolley position.

If this were an overload, the hook would not be at the jib. If it were winds at night and the crane were simply weather-vaned, the trolley should be back next to the mast. But the position of the trolley and hook height leads me to think that the crane was being folded up to be removed from the site. The position is where many popular models require the trolley to be placed during erection or dismantling. If a person were to become complacent, and not put that trolley in the right place and span both the eventual horizontal and vertical jibs and continue to fold up the crane, you could easily bend that small jib section.

An odd potential is the Queen's Post suffering a structural failure due to binding during or an undetected detected defect. The big picture is that Self-Erectors need to be treated with care as well. Often contractors and users view them as a toy, but the reality is that they can be dangerous if not handled with care. You have to carry out maintenance and inspection. You need qualified operators and technicians. Follow the manuals and make sure to go back and read it periodically. We get used to doing things one way and a refresher from time to time may expose that you are making a mistake that could be avoided.

Vertikal notes that open discussion is critical to crane safety. I couldn't agree more and that's why I do this blog. It's not to cause fear or hesitation but to insight thought in the process of handling cranes. To cause the operators, and those responsible, to realize that laziness and complacency leads to death. Take that extra moment to do things right. In the end everyone wins. First and foremost, everyone goes home. The equipment lasts for decades. Insurance rates are kept to a minimum which means more money available for tools and wages. And finally, no one's reputation is damaged which can be a really large and unseen expense.

November 13th, 2010

2010-11-22T22:29:00.000-08:00

Bejing China A tower crane being climbed, apparently down, collapsed killing three workers and injuring two including the operator. The Operator was asked some questions in the hospital and seems to be indicating in this blog that the hydraulic pump may have had an issue.

It seems that few climbers are fast and smooth. Often I've been on climbers that caused the jibs to bounce. Overtime the bounce becomes a rhythm which is hard on the jibs and pendants. Sometimes the technician needs stop and let the bounce settle then get going again in hopes that he can get the fluid flowing smoothly. The only other thing that strikes me as likely to be within the hoist mechanism is in the ram. If a person were to not have a positive acting check valve, a failure of the pump to create pressure or a hose bursting could quickly drop the entire superstructure which can certainly be a serious problem as it endangers the integrity of the crane itself.

There is more information in this article as well, but the translation is terrible and so I cannot make heads or tails of it.
塔式起重机倒塌北京

November 20th, 2010

2010-11-22T07:55:00.000-08:00

Dandong China A tower crane being climbed suffered a failure killing 6 people and injuring one man on the ground. The crane was up at 50 meters reported to be on the 25th floor (does China count from below ground floors?) and Vertikal reports that one report they found has the crane as being dismantled but it's not confirmed. They also have the injured person on the ground listed as a woman, but two stories that I have found have the victim listed as a man. Either way, it's a innocent by stander being struck by falling parts.

Chinese news often doesn't come out with pictures, but I find them later. I'll keep an eye out for them and add them as soon as I can. Story links Here and Here

塔式起重机倒塌中国丹东

November 16th, 2010

2010-11-18T20:16:00.000-08:00

Studen, Switzerland. A 45 Meter Tall Wolff Tower crane on a cross base fell injuring two people on the ground and the operator of the crane. Also a building that was occupied has been virtually demolished and surprisingly no one was reported as injured. Two cars were struck by the jib of the crane and were certainly a total loss. They were virtually pancaked.

The crane fell backwards onto it's counter jib which had punched into the building. It stayed partially airborne because of this but the quick stop dislodged the cab from the crane tossing the operator in it on to the other side of the building. The operator is listed as seriously injured but I'm not finding any listing of the extent of those injuries.

In one of the pictures it's pretty clear that the cross base was sitting on soil that was under water. The concern with that is any under mining and is the soil staying compacted while it drains? I have had one crane that had a base below the water table during the winter. I showed up and the base was completely under water and the water was moving. The soils engineer had used sand and gravel to achieve his desired compaction in my case and I can only hope that they did the same on this site. Even with the soils engineering being done, I spent that entire winter thinking about that crane. As I look at the base though, one side of that cross base does appear to be lower than the rest which makes me really want to see if the soil has eroded over there. Clearly ballast was on the cross base and hopefully that was the correct weight.

Potentially everything was intended to have been done right but water is simply not something you want moving around the base of your crane because it's unpredictable in nature.

You can see more pictures Here
Turmdrehkran Zusammenbruch, Grue à tour l'effondrement

November 12th, 2008

2010-11-18T08:01:00.000-08:00

Lasi Romania, A small Self Erecting tower crane tipped and fell during the dismantling process. I managed to strike four cars but did not injure anyone. The jib and likely the mast, are a loss but possibly the base is salvageable.

With the crane coming down, I'm reminded of an accident in Hawaii where the crew dismantling the crane got a step ahead of themselves and removed the weights prior to getting the crane adequately folded down. Without more information, I can't understand why a crane that was used to work on a job for months would fall over during the dismantling process. The ground certainly would be compacted. But if you remove the weights without the crane being adequately folded down, this may happen. Some of the small Potains have weights bolted to the frame to prevent this sort of thing. Mistakes always seem to have a way of happening anyways.

Link
macarale turn accident

October 22nd, 2010

2010-11-17T12:26:00.000-08:00

Ming Pao China A luffing tower crane boom was blown over backwards in a typhoon. Fortunately, the area where the boom fell was a no-work area due to safety and the cab was no struck by the boom so no one was injured.

The translation makes it sound as if the crane was no able to be weather vaned for one reason or another. I think that we've all been caught in winds that were above our chart, but don't you have full warning that typhoon is coming in? I know that in Hawaii I was always aware. Maybe it was a long pick and they were supposed to have been missed?

The crane is clearly a loss from the boom and gantry stand point. Much of the rest of the crane may be salvageable. Link

塔式起重機倒塌

1980 and Earlier Australia

2010-11-16T08:47:00.000-08:00

I ran across a forum at Skyscraper City that has a number of old accident pictures in it. For the most part I don't have dates or much information. The pictures are interesting nonetheless. So I thought that I would throw them up all in one post and note that it comes from that forum so you could dig in to the forum if you like and see how the Aussie Crane Operators love their Favco's. They almost reminisce about each crane by serial #. I'll put up a link to the source for the photos and you will be able to see a larger format at the source than on my blog.

Listed as St Kilda Road, this accident is with a crane that is well before my time. It appears to be a early Luffer that could date back to the 50's. It seems to have lost stability at the base. It may have the record for the most cars gotten in one accident! Link

If you haven't seen a GCI before, you should check them out. They set up in 20 minutes, come self contained with motors instead of needing 480v 3 phase power, and have capacities up to 60,000 lbs! They also had fixed jibs available or lattice conversions for greater capacities. Manitowoc still has a spec sheet available here. The claim in the forum was that they crane was swinging too fast with to large of a load. I'm not sure if that means that it was torsionally overloaded or the stopping of the load caused the load to swing so far out of line with the counterweights that they were ineffective. Large picture Link

More Accidents after the Jump

This Favco is listed as having been on the Gold Coast. It would seem that we have tie-in failures here. If you look at the failure points you'll see that the collars have collapsed in the towers. I don't have any experience with Favco's. The last one up in Seattle was around 30 years ago. What I'm reminded of is internal bracing. The collars are squeezing in on the towers. What you are generally required to have is internal added bracing to resist this squeezing and potential collapse. The picture shows why, but this may not be the cause of this accident as I have no idea if they are required on those giant and heavy Favco towers. The operator survived this accident as his cab came to a rest just before the cab struck the ground. Large Picture link

In Adelaide a Favco fell nearly perfectly between two buildings. The story as told in the forum was that the bolts from the climbing frame to the turntable were removed at the end of work Friday after climbing the crane down. The assumed plan was that the crane was going to be dismantled and not used again. The operator not knowing that the bolts were removed went to operate the crane when it simply fell off of the mast. A rigger was injured in the accident but was able to carry on with his career. Link 1, 2

There are other great photos at the forum that many crane geeks can enjoy. Even a ringer boom being blown off the ring. Go check it out!

January 26th, 2009

2010-11-15T09:00:00.000-08:00

Turkey, A Self Erecting Tower Crane was dumped over in an apparent overload. The only source I have is the video itself which lists the upload date of the January the 26th 2009, and the language of the type is Turkish. I don't know any other details.

Looking at the accident I notice that the person taking the video is standing off to the side in a smart location behind another building. Why would he be standing there, videoing at random, unless they knew that they were about to overload the crane? You would need someone to back off the Over Turning Moment limits, intentionally. Then you might have someone scale out the load and assume that you are within the limits. The difficult part is that when you ride the theoretical limits on a Self-Erector, you aren't likely to account for shock loading. Most self-erectors are anything but smooth operationally. I've watched the outriggers get light during a limit test at the tip. The crane was cutting out and the operator kept trying to hoist up and the perfect frequency of the hoist up and cut out began leading to a bounce that made my hair stand up. Fortunately the technician with him told him to stop it because he was abusing the crane. Even then, make an effort to be smooth about it.

Rely on the limits at 100% of the rated load only.

kule vinci kaza, kule vinç çöküşü

September 10th, 2008

2010-11-10T07:55:00.000-08:00

Koksijde Brussells A counter jib for a tower crane snapped while being handled killing one man and breaking the hip of a second. The accident was immediately blamed on metal fatigue by the Office of Verune.

The crane appears to be going up. The pick points used look to be substantial and the counter jib is being lifted off of the truck apparently to have it fully unloaded while all of the horizontal structure is prepared to be erected. Often when you have counter jibs consisting of one piece the pick points end up being a wide spread. It would seem that the only things to take away from this in the field is to not choose the widest pick points for stability purposes, and when you ship the piece, be certain that the center of gravity is well supported. If you send a counter jib down the road over bumps, speed bumps and more with no support under the Machine Package, over time it will be weakened. Inspectors should be sure to look at the beams for cracking and stress as well. Sight down the beams to make sure that they aren't twisting or developing creasing as a tell-tale that the stress has weakened the structure. There doesn't seem to be much else to beware of other than to be clear enough of the piece in the event of failure.

Sometimes the accident doesn't have anyone to blame, just ways to be sure that you are protecting yourself. Link to story

April 30th, 2010

2010-11-08T08:31:00.000-08:00

Magnitogorsk Russsia A self erecting tower crane was being dismantled when the truck crane being used to assist was apparently overloaded and tipped. No one was reported as being injured in the accident.

The crane appears to have been climbed down at which point many of the older style self-erectors would lower the jib tip on to the ground. From here the pendants would have been disconnected, the truck crane connected to the top chord of the jib, and when sufficient load is pulled off by the truck crane, the lower chord pins at the mast would be pulled and the jib lowered to the ground.

Looking at the picture of the truck crane, it doesn't appear that there is a soils issue as the ground is quite rocky. The outriggers swing out and lock into place so it wasn't as if the outriggers were only at the mid extend point. My suspicion would be that the crane was scaled out to be able to pick the load of the jib, but someone forgot that either the truck crane would have to boom down to clear the tower, or boom up to to clear the tower. In reality, sitting farther away and booming up would be the way to go if you think that you are close to a stability or structural limit. By being farther away, you can have the truck crane hoist up to about the proper load and read the pins (see if the pin is sitting down hard in the hole or riding up) and even pull one pin to see how the jib hangs and the truck crane is performing. At this point, if you have a problem you can re-make the pin and get a bigger crane. By doing this, when you cut the jib free, it would be booming up towards yourself which would eliminate the stability problem. If you are going to boom down and away, you better be sure that you have the right weight and radius figured out.

If you are close on weight, it would also be better to be closer to the butt of the jib near the mast. It's marginal, but you want to keep as much weight on the jib tip as possible.

The tower crane may have only received minimal damage to a few lacings or potentially dents in the box chords. Easy repairs. The truck crane would really need to be torn town and fully inspected, even to the bearing. I don't know if that's worthwhile in a crane that old, so it may be a loss. Looking at this accident and thinking about how it likely happened, I'm reminded of a saying that my first iron working boss used to repeat often, "Know your escape route." You have to plan for the worst in this business and by doing so, you'll likely avoid it. Link to story

November 7th, 2010

2010-11-07T07:00:00.000-08:00

Penang Malaysia. A tower crane operator had to be rescued due to running across a hornet. Apparently a single hornet incapacitated the man from being able to climb down. The story doesn't note if he's allergic and went into Anaphylaxis Shock. News being news, either he's allergic and had a severe reaction, or he actually found a full on hornets nest which can take down even an adult and this wouldn't be a first on a tower crane.

The rescue of the man did not go well. The incident was originally reported at 2:30 PM. When the Fire Department arrived the initial thought was to use a "Super Gyro Skylift". I believe this is a aerial work platform mounted on a truck from. However this wasn't quite tall enough. So a crane was brought in and a dumping bin was used to remove the worker. The rescue was finished at 4:30 PM, 2 hours later.

Serious incidents do happen on tower cranes. Operators have medical emergencies. Here in Seattle we had a brand new technician get sloppy with a wrench and drop it in a live electrical panel which then blew up in his face and all over his hands. He was able to climb down. In LA, the story as I know it, was that a crane erector was dereeving a Liebherr 630 and rolling up the trolley line when it went over the side. As it ran his leg was in the bite and running and eventual snap of the trolley line severed his leg. You don't have 2 hours to get that man down. Heart Attacks, Strokes, trauma, etc are all cases where 2 hours is not an acceptable time frame. Especially in a city of 1.7 million people. The Fire Department should be prepared for this and be able to rope that man down.

It just illustrates the need for planning ahead. I really do believe that you should have rescue kits on the crane, training in how to use them available for enough workers on the site. It's really not that difficult. There are times when it will make the difference between life and death.

Link to story

July 9th, 2010

2010-11-05T09:24:00.000-07:00

Chaohu China A QTZ63 tower crane collapsed on a job site killing the operator in the cab. The Report on the accident simply notes the Manufactuer, crane used, and the job known as Country Garden Pheonix Hotel. In addition to that it does note that China is requiring that cranes be inspected and everyone on the crane through out the job must be "trained". Hopefully this will be taken seriously over time and China will improve.

The crane itself is a modern PLC controlled crane. It's a small crane with a maximum capacity of 13,200 lbs. and a maximum jib of 148 feet if I'm understanding their data. Considering the limited pictures and the depth of the video found, it would appear that no fault occurred in the structure that is visible. However, we can't see the base. The PLC controlled cranes from France and Germany are difficult to fool even if you wanted to. In order to properly run, they must be put through a load test, or at least I don't know a short cut. I can only assume that Chinese manufacturers set up the same parameters for the own protection if not keeping up with the European manufacturers. Combine this with the fact that the accident happened at 7:20 AM and I would wonder if there were a soils problem and rain and or wind in the cranes recent past. That's my wild speculation anyways.

Video found on the crane. If you speak Chinese, maybe you'll understand more from the story.

塔式起重機事故

September 25th, 2008

2010-11-04T10:54:00.000-07:00

Molfetta, Italy A tower crane collapsed injuring no one. The cause is listed a mechanical, but given computer translations, that could mean anything. The crane appears to be a small crane sitting on a modern cross base complete with ballast, knee braces and even a climber down at the base. The counterweights sitting on the tower appear to be an older design, shaped like an inverted T. These older weights were often found on Older PECCO or Peiners on the 170's and some 180's (US Designation). The rest of the counter jib and the Tower top don't match that model or anything else that I would recognize.

Since mechanical failure is listed, it could run from a run away trolley that overloaded the crane to a broken weld in the cross base. From what is shown, I don't see a way to tell, I'm just glad that no one got hurt in the accident.
Link

Edit: I found that I didn't look at all of my info that I had found before I posted this. As I was closing it out, I realized that it isn't Balice Poland as I had originally noted but it was in Molfetta Italy in a area known as Balice. I also noticed that I have a video about the accident as well that may lend some clarity. At one point it sounds as if the reporter is talking about a computer and then I hear quatro. If anyone speaks Italian, and can clear it up, have at it. But was the crane overloaded due to a computer or computer set up issue?

April 16th, 2009

2010-11-02T23:21:00.000-07:00

Klagenfurt, Austria. Most Self-Erecting tower cranes have a derricking crane off the mast that allows for counter weight removal. In most cases it's slow and clumsy and requires that the weights be double handled. So in every case but one, (we were 19 stories up on a building) we have always used an assist crane or fork lift to add or remove weights. In this case, they were using a articulating crane with a fixed hook to remove the weights. During the operation the weights were caused to topple injuring one worker and destroying the cab of the crane.

The crane appears to be a Potain HDT 80 (U.S. Designation). Each of the weights weighs 6300 lbs or roughly 2860 kg and there are 13 of them. On the side they have ladder rungs that form a ladder that becomes quite tall and those rungs lead to the top where you'll find two picking eyes. The picking eyes are embedded into the concrete on top of a raised section that mates to a recessed area on the bottom of the next weight. This eliminates the needs for tie downs and aligns the weights automatically.

The difficulty in removing these weights is that when you use a fixed hook on the end of a boom, you must be cognizant of the boom angle and keeping the picking eyes from binding on the recessed area. The higher up the weights, the steeper the boom angle is. So as you boom up to lift the weights, you decrease the radius quicker than you gain clearance. The solution is to extend the boom in order to gain clearance. The same is true with Tele-Handler Forklifts. In this case it would seem that someone wasn't paying enough attention to the boom angle on the load an pulled the remainder of the load on to the truck crane itself. The concept is basic, but if it's your first time, it's better to ask questions, give up a modicum of appearance of expertise, and have everyone go home healthy and alive. Link to story.

March 29th, 2009

2010-11-01T12:29:00.000-07:00

Miass, Chelyabinsk Region Russia As a tower crane was being disassembled the jib collapsed. fortunately no one was injured in the accident and it sounds as if only the crane was lost.

The collapse happened after the counterweights and what sounds like the base ballast were removed. The contractor is asserting that a unforeseen Gale Force wind came up causing the crane to fail. They are being forced to assert this as the insurer is questioning the collapse. Article about the insurer's concerns. Then there is a second article a few days later that asserts that the winds never occurred. (The picture is from the second article and I'm not clear if that's the crane that went down or just a stock photo because it doesn't match the story exactly.)

What strikes me as relevant is I don't know of a manufacturer that would, or does, suggest to remove the ballast prior to removing the horizontal superstructure. I mean really, we are talking about the the greatest overturning stresses on the crane being induced during this process and you want to remove the ballast that is designed to prevent that? Shy of removing the knee braces (if so equipped) and the final tower section, the ballast is the next to last thing to remove. Remove all but the final tower, pull the ballast, braces, tower then the cross base. This is the normal process for the four different manufacturers I've seen with cross bases. So if you remove the ballast, you certainly won't need a gale force wind to cause the tipping of the crane.

More importantly, I have a question about what is going on in Russia. They seem to be acting as if wind is always an excuse for losing a crane. Here we have two downed in a legitimate wind storm. Here we have another just a few days later downed in what may have been a wind storm. Wind will occasionally happen and down a crane. There are weather events that you cannot prepare for. In this case, it sounds as if it's a easy reach for a crutch rather than simply fessing up to the reality, that you removed the ballast out of sequence.

крах башенный кран, аварии башенного крана

December 9th, 2008

2010-10-28T22:01:00.000-07:00

St Petersburg, Russia. A saddle jib tower crane that appears to be a Kroll suffered a structural failure that is interesting. I was wondering at first if it was an inner pendant failure. The only pictures that I can find are the ones I've screen captured from the video so they are poor resolution photos. You see how the jib is hanging down but not pointed straight down indicating that it still has support from above. You look at the top chord and you can see the single pendant still under tension. Give it's location in terms of distance from the tower, it's likely that it's a single pendant jib.

Moving back you see that the #1 jib section is twisted and has broken lacings. It really appears that the jib has structurally failed. While that in and of itself isn't something new, take note of the hook and rigging... it's empty. No side loading, no overloading, nothing is written about heavy winds but could it be in the video in Russian?

This accident reported no injuries. It was over, or adjacent to, a medical center that had to shut down as much as possible. Cranes seem to spread out enough of the load that they rarely take out entire buildings, save New York with Massive Favco's coming down on brick structures. But counter weights will punch though multiple floors. if not all of the way to the basement. That being, it's prudent to move as far away as possible.

This may be a clear example of why you should be looking at your crane and walking the jib periodically as the operator. There are good bellman that can do it, but the operator is responsible for a safe crane and I'm here to tell you, riding the trolley doesn't do it. You must see both sides of the jib. You have to look for deformations in the lacings. You have to look at the welds and expose the metal under new paint cracks. If you find them, put primer on them. The primer will crack very quickly if the metal is moving and the metal is likely to move long before it fully fails. That being, I'm pro riding the trolley to review the trolley lines, seeing the load line and knowing how the trolley is performing. The core point being that simply riding the trolley is a lame inspection, and that's putting it politely.

Side note: New FLV downloader, dealing with learning curve. Find full vid and text here. I couldn't find any other stories on accident.

аварии башенного крана, крах башенный кран

August 11th, 2010

2010-10-27T09:32:00.000-07:00

Sukhumvit Soi, Thailand This story comes from a personal blog and is understood from a translation, but here it goes. A tower crane operator decided that he wanted a energy drink. So he had the guys on the ground put one in a bag for him. The story has describes the operator as agitated or irritable. He sends the hook down without worrying about it being under control. The guys on the ground place the drink in the bag and the operator immediately begins to hoist up. As he was hoisting up, he hung up on some scaffolding. Since the crane was small he soon became overloaded and the jib failed.

With a modern crane, the computer, moment rails and or hoist limits would shut down the crane. The crane being used clearly isn't modern. Likely, it wasn't being maintained properly. So as the operator hoists up quickly, instead of shutting down at 100% of the available load with another 50% before failure should happen, the crane simply failed, and collapsed killing two and injuring 3 others.

The operator was clearly in the wrong. You aren't clear of obstructions, so what are you doing hoisting up? You have people under your hook and you can't give them the courtesy of sending them a stable hook? You didn't pack for the day properly so others must suffer your wrath? What kind of training did this operator have? He knows that he was in the wrong. He ran from the job site and was being looked for by the police. I would think that he would have been safer with the police, but I don't know Thailand. He killed two people over a energy drink. Yikes. Link to blog.

October 23rd, 2010

2010-10-25T08:10:00.000-07:00

Cologne Germany What appears to be a Speirings 599-AT5 has suffered a jib failure causing about half of the jib to fall into a tree and dangle from the pendant. No injuries were reported in the accident. The building was struck which will require some repairs.

The Speirings Cranes are mounted to an All Terrain Mobile crane frame. They are very convenient for jobs that don't need a crane full time. If you have a wood frame building maybe you only need a crane a couple days a week. The Speirings Self-Erecting Tower Cranes can drive in, set up in about 30 minutes, make your picks for a few days then be off the payroll while the carpenters frame the floor.

The downfalls to using a crane in this manner come in the form of wear and tear on the cranes. In particular, if you have jibs being folded over and over, what kind of wear are you putting on the connecting pins on these lower chords and through the pendants? Are you looking at them every year or so to be sure that you aren't getting wear that wouldn't be visible without dismantling the connection?

At the end of boxed jib chords you'll find that the male and female pin connections are welded into place. often these welds are ground smooth so it's hard to notice that it's a weld, but it's a weld nonetheless. Cracking can certainly occur there and since it's not an obvious place to look, it can be overlooked in a normal inspection. You have to also be cognizant that you have layers of steel moving at these joints. they can bind on one another or drag also causing undue stress that you may be unlikely to see during the normal crane erection process.

I prefer to walk the jibs of self erecting cranes after they are folded out. Trust me, I don't like it because the jibs are tiny, not designed to walked on so foot placement is akward, and the bouncing at the tip is interesting at times. But I've found trolley ropes out of their sheaves and other problems that are likely to only be found after folding out. The picture is low resolution, but I'd like to see a close up of the but of the jib section that broke. I really wonder if there might have been pin walk. It's something that I look for. Pins in holes have a tendency to walk in or out during "action". Tie in collars pins are really bad for this. Sometimes tower pins do this as well. Even with a keeper in place, you'll want to see if the keeper is deforming or marring showing that it's under stress during the folding process. Since no obvious structural damage is evident on the lower chords, from the poor picture quality, is it possible that one of the pins simply sheared it's keeper than walked out? Just a final concern and something to watch for.

The likely crane that failed.

Turmdrehkran Unfall

July 17th 2009

2010-10-23T09:53:00.000-07:00

Bellach Switzerland. I got some updated information about a self-erecting tower crane that went over. The internet was kind enough to send me some pictures that really show the story. In the original story I was concerned about the ground and support under the crane. It turns out that was exactly it.

Rather than building up the ground and compacting then using matting, they chose to span over a void to sit on a pre cast concrete vault or man hole. Who made this decision? I find it hard to believe that they could move over 5 feet or even just rotate the base to avoid the void. Sometimes we get focused on doing something one way and we fail to see options. In this case it was to the crane's demise. Was it a $100,000 mistake? I often see self-erectors on buildings. Frankly, if no one were to provide me a engneer"s drawing, I'm out. In this case, I would have required that the void be filled in and substantial matting be implemented. You can't reliably rely on pre-cast with unknown reinforcement.

You have to see one more photo in here too. Not only did they come up with their own bridge design, but they used inferior materials. Look at the quality of this wood at the break. It's split along it's length due to age and at the fracture you can see the dry rot. There were other pieces where the dry rot was clearly evident where there were no fractures. If you are going off the script for what would be sound practices, at least use sound materials.

December 16th, 2009

2010-10-22T20:47:00.000-07:00

Graz Austria A Self Erector fell over with the 49 year old operator in the crane injuring him.

The crane was lifting 1.5 ton concrete tanks at the time of the collapse. Short of making the pick at the tip of the crane, most K type cranes should be fine with this type of weight. Even if the weight exceeded the capacity, it would have to do so by quite a bit to legitimately pull over the crane. Of course I've seen cranes pulled over. We had one go over here in Seattle a few years back. The crane could not make the pick so a forklift was used to help the crane make the pick. When the forklift was pulled away, the crane gave way. Sadly I cannot find record of this accident and might have to go to the public library to find it.

I share the Seattle story not because I think that this is what happened here, but because a sound self erector just doesn't fall over, just because. You'll notice the luffing rope appears to be intact. You don't see any bends in the tower sections indicating failure. The jib indicates that it's going straight out as if it was not a pendant failure. But the base is overturned. This doesn't appear to be a crane failure but rather a set up failure.

In the reports filed in the inspection in the month prior "defects" were noted (Link to story). My guess is that the defects weren't addressed. Maybe it was a lack of a soils report. Maybe it was poor matting and frankly it might take the majority of a day to fix the problem. Here in Washington State, if I state that there is a defect, it must be addressed prior to continuing or commencing operation. I'm annoyed that we don't have the option for a correction period because there are times where little problems are not going to cause an accident, but it will take time to get parts. Time to reschedule me and the technician and the test weights. Let's say it's a bad sheave that is still functional for example. But if contractors are allowed to ignore the Notice of Deficiencies, and the result is a crane falling, endangering many lives, maybe it's an annoyance that I can live with.

August 13th, 2005

2010-10-20T14:24:00.000-07:00

Caracas Venezuela A tower crane erected on a cross base (cruciform) that appears to be the manufacturers design tipped over and crashed on to the job site. Two workers were injured can needed treatment. Link to story.

There were two potential causes noted. One was the crane fell out of a plumb condition. It would be odd, but not unheard off. You should always have your soils checked prior to erecting a crane even if it were being installed in the most reliable concrete footing. Through out the job you have to protect the integrity of the foundation as well. I've seen jobs that needed to be shut down due to a dirt contractor becoming over zealous and undermining the crane foundation. The big concrete block doesn't do you any good if it's sitting on air.

The other potential speaks loudly and is much more common. It was indicated that a large I beam may have been hoisted and overloaded the crane. This would be a significant overload of 30% or more. While it's true that some tower cranes don't have scales, an overload of this amount is clearly noticeable to anyone whom has load tested a tower crane. I've been on a crane that was approaching 117% or so and it was flat out uncomfortable. Sadly it took protesting loudly to point out that we were way past what the crane was rated for. This was a case of over reliance on the computers. We had no alarms going off, the display had noted the overloaded condition due to yet the technician wanted to continue on with the test. The next morning they came back and found the problem. That desire to get everything done rather than having to come back literally endangered my life.

Load tests on cranes must be carried out. You must test the limit switches to be sure that they are in good working order and that no overload can happen. Tower Crane operators trust their limits as a habit, good or bad, and we owe it to them to get the limits properly set. Don't scrimp and assume that the limits are still working since the time that the crane was erected.Test the limits properly. Adjust them as needed. Then we can all go home!

August 15th, 2010

2010-10-18T08:31:00.000-07:00

St Petersburg Russia. Two Tower Cranes were blown over in windstorms noted as "hurricane's". Considering how often I see the translation to hurricane I wonder if big winds or heavy storm simply translates that way. In both cases the operators were in the cranes and injured. In one the female operator was hospitalized with a brain injury and she suffered a broken leg. Link

The picture of the downed crane appears to be a bottom slewing crane with the machinery at the base, and it's on rails. The failure is structural and in the in the mast. As you look at, what strikes me is that it would appear that the crane was still in operation. The machine deck is opposite of the jib, but it's blow over backwards. The assumption for me is that since the tower doesn't look twisted, it was facing the wind instead of away from the wind. Sometimes operators assume that this is OK because you are getting hit with a crosswind that catches the surface of the jib. But this doesn't take into account the whole picture. Tower cranes weather vane with the jib down wind also because they lean back into the wind when they do so. Imagine walking in heavy winds and leaning backwards instead of forwards to drive through the wind. If your crane is in operation during heavy winds, you are asking it to not only deal with the winds, but lean backwards at the same time. On many cranes the jibs also have positive lift when the jib is unloaded so you also might be losing a portion of the weight of the jib that normally holds it down due to the wind exposure on the bottom surface.

Don't be a hero in the wind. Most tower cranes are to be shutdown by 70 KPH or 42 MPH. Some are sooner. Adhere to it. You may be able to be the guy that runs into the 50's (MPH) for a career, but you only endanger yourself, and everyone else around your crane. There is no warning in structural failure. It will be immediate and unforgiving. Shutdown the crane, find out what the weather is likely to be doing from a reliable service (In US eg. NOAA, Weather Net) and if it's not looking good and going to get worse, why would you stay in the crane? The climb is not that difficult.

крах башенный кран, аварии башенного крана

Historical Tower Cranes

2010-10-15T11:27:00.000-07:00

Liebherr TK8 Circa 1948

I love history. I complain about the safety of the old cranes, but I have to say that I love them. I've operated a Peiner PC 1200 from 1968. No counter swing, controls weren't standardized, single speed trolley that only ran fast due to lack of parts... try threading 10 meter I beams through a doorway with a crane that has only a fast trolley and no counter swing or positive acting brake! While I don't like to see them on sites, I find the history intriguing. Seeing the evolution from small tilt up TK 8's to the massive Kroll K10000 makes me smile like I did when I was a kid getting into my grandfather's old crawler that he had in his junkyard.

Old Portal Crane, Peiner 1200 (US designation), &TK25?

The best website that I know of that has assembled the history of tower cranes is Kran-Info. They have photos of cranes from the 40's with Hans Liebherr's TK8 to the large Wolff portal cranes that began to change how we constructed buildings. Pictures of them in use, pictures of the old controls that may make you scratch your head, and pictures of them being restored. These guys even have a museum that you could visit if you end up in Germany!

They were kind enough to allow me to promote their site and I thought that some of you may enjoy the site as much as I do. So go check it out. You might be there for a few hours!

August 20th, 2010

2010-10-13T21:05:00.000-07:00

Nizhny Novgorod Russia, a Hurricane blew through blowing a crane over and into a home damaging it. Also damaged was an apartment building. If you have an event like a hurricane as a once in a life time event for where you are, then maybe the accident is understandable. Clear all humans away from the crane as the storm approaches and if it fails, we can always fix wood.

The operator was killed in the collapse. How could an operator be killed in a hurricane? What was he waiting for? If it were a Tornado with much less warning, as soon as you saw it coming wouldn't you cut the load free, weather vane the crane, get down and get away from the crane? Are you really hoping to make a pick or two when the eye of the storm passes over? I don't understand it. Link

аварии башенного крана, крах башенный кран

August 9th, 2010

2010-10-12T20:48:00.000-07:00

Salvador, Brazil A crane collapsed with three workers on it killing two and burying one whom was rescued and appears to have survived. The employees are employed by the crane erector whom was also responsible for the operation of the crane. Unfortunately nothing indicating a potential learning moment crops up from the story.

The crane appears to be a small top slewing crane and from the two pictures that I've found I don't see any mast, yet both the tip and the counter jib of the crane. It should be safe to say that the entire super stucture has dismounted the tower. There are a number of things that can cause that. Old technicians have told me uncomfortable stories about testing the slewing brakes on the old cranes. On some of the old cranes you'll see "toppling hazard" stickers in reference to closing the brakes without slowing the swing. Well, that used to be a method of testing the brakes on some cranes. You closed all of the brakes simultaneously and timed the braking. Fortunately I've never seen that... intentionally. I've seen a faulty bearing cause an immediate stop and I don't ever want to see that again. We had five of us up top and before we swung a second time, three of us were below the turntable... of course we were just listening and not terrified... right? We dismantled that crane and installed a new bearing.

The crew may have been inspecting the crane to determine what the problem was. Bearings and broken welds are often difficult to determine. We often hear noises in our cranes and we should pay attention to them. Having a second set of eyes is critical to seeing the whole picture. I had a crane on a cross base once that was fracturing the counter weights because the base was flexing excessively. Age and slop on the pins? I don't know. We welded in some beams that ran horizontally and stiffened the structure. The popping stopped when the beams were added and I ended up being safe. Is it possible that they were searching for a problem and were too late in finding it?

colapso do guindaste de torre

October 6th, 2010

2010-10-11T22:15:00.000-07:00

Seoul Korea, I think that we have at least two cranes involved in an accident with two people dead. I have found video of the site, but it only leaves me with questions. The Video is slow to load at this site, but it will get there. This screenshot, at the top of the blog, is from another video that I couldn't get to load and it shows a crane that appears to have collapsed at the turntable. Assuming the timing of the videos are similar, and they are according to the dates loaded, it would seem that we must have had one crane collapse at the turntable, fell, and in the process struck the other tower crane boom.

The immediate reports are that this is a Comedil flat top crane and the Cat Head bolts are to blame. The suggestion according to the translation of the article is that the bolts should be periodically replaced. There seems to be questions about the type of bolt used and the manufacturing of them. Admittedly, this is from a terrible translation. You can read the article here.

I don't have a Comedil manual on hand to verify whether or not those Cat Head to Turntable bolts must be changed out each time. If they do, well, you should, obviously, change them out. The type of bolt that I'm used to seeing is of the same finish and visually appears to be the same material used in the tower bolts. I don't know if they are tightened to their yield, but I doubt it because they are tightened with a torque wrench if I'm not mistaken. Either way, follow the manufacturers plan on bolts and do not skimp on what bolts to purchase.

UPDATE: This is a copy from a translation of a Japanese story on the Korean Collapse. The short version -TLDR: Cat Head bolts were changed out to a smaller and weaker version. Link to story

June 10, killed two西橋dong (Inc.) GS GS survey construction tower crane accident in question involved the construction of the outsourcing company.

This accident investigation committee, the National Institute of Scientific Investigation, Korea Occupational Safety and Health Authority under the Ministry of Labour, (stock) to participate in Korea Occupational Safety. The only private research organization of these (strain), Korea Industrial Safety, GS outsourcing company that has itself as an institution per year utility construction inspection. So construction union "has been the case study happens to leave the outrageous murderer" has been criticized.

Moreover, the construction union member organizations other than the State Department worried that the investigation of the case as it hides all interested parties. Industrial Safety and Health Authority, was passed by the tower crane design approval of an improved type of low strength bolts.

The tower crane accident happened CTT 561-1A is, CTT equipped modified after being imported into the country 516 models are equipped, they were equipped with low-grade deformed bolt type type type from the pin. However, occupational safety and health corporation on September 17, 2004, approved the design of this equipment grated pass.

Oh Hiteku construction union chief external relations, "features a thin bolt is true, from a pin method / 3 about the weak" and "accident happened in 1997 was broken bolt so well," he explained. Tower cranes are used in particular crash site, which currently is running 10 in the nation, adding that the situation can not exclude the disaster.

Despite the structural flaws of the equipment, occupational safety and health approved by the corporation and thus inspection, GS will be participating in the Korea Occupational Safety and Accident Investigation of construction contractors, the survey results were unbelievable. Construction union said: "We can expect comedy and transparent investigation" and that "this field study is likely to be concealed as bad management of equipment suppliers," the statement said.

In addition, the investigation into the accident that eliminated many trade union advisory experience in the field, see the construction union can not cover up the incident because the suspect] has been refuted. Oh Hiteku director, "the union could not accept requests to join the investigation continued," and "on the tower crane accident in a foreign country is not too hard, but must also resolve the fundamental problem we will of Not enough, "his voice raised.

Currently, the union construction tower cranes on a frequent accidents "are mushrooming hundreds of equipment leasing company, from maintenance and repair of equipment are not investing in the competition by dumping blood" has been said.

Since construction equipment management law in 2007, has been designated as one reason to be delegated to private bodies entrusted inspection from the Land.That the rampant money because loose testing private inspection organizations in the field.

For this construction union "of the Land, the test should be leaving any time of the accident-prone company and get to present a comprehensive management plan for the introduction of a demerit system," he said.

Aya Hara (Chamusesan)

Translation / censure: Yasuda (Yu)

Use of copyrighted material, pursuant to authorization fromsharing license version 2:

타워 크레인 붕괴

September 13th, 2008

2010-10-10T09:38:00.000-07:00

Turin Italy, An apparent tower crane operator found himself hanging from his load line by his knee. The fire department managed to rescue him by repelling down to him then continuing down to the ground with the operator. This might be the closest to a Darwin Award recipient I've seen on a crane.

The article doesn't seem to indicate how he got there. One thing is certain, he was on the jib without being tied off or secured if you will. I suppose if he thought that he saw a problem with the load line and leaned down to see what it was and lost his balance, the accident becomes plausible. Paint oxidation on lacings can make the cranes slick to walk on. The day does look like there maybe moisture in the air. If condensation has built up on a tube lacing and he's crossing in the middle, it's another way that you can slip. I have to say, after 8 years of walking crane jibs, I'm as uncomfortable on a wet oxidized lacing as I am on a icy or snow covered one. To make matters worse, it looks like he's wearing rubber boots. If you don't have the proper foot wear, being a flat bottomed, firmly supported, yet soft rubber soled boot, leather upper boot, what are you doing there?

The weight of the block is likely to be the thing that saved this man's life. As his load would have been added, the block would have been raising at a relatively slow rate decelerating him. The block weighs more than he does so as it came up due to his added weight, it prevented a sudden shock from the fall and must have been the difference between him being able to hold on during the deceleration and not being able to hold on. He's very lucky and this is a clear reminder to tie off at all times. Enjoy the video

1955

2010-10-08T21:28:00.000-07:00

Heidelberg Germany Maybe the earliest photos of a tower crane accident. I've hesitated in posting this accident before because I'm not sure of what this crane is that is down. It's clearly from 1955 and from the Heidelberg Water Authority. It's clearly a bottom slewer on rails. The rails are not secured against the torsional moment induced by the crane because they have slid all over the place. But from the pictures, I can't tell if this is technically a derrick or a tower crane. If the boom mounts at the base, I'd call it a derrick. if it mounts up above, I'd call it a tower crane. Either way, it's very early and the crane in the background appears to be a Liebherr TK10 on the same rails.
As a learning note, the rails should be secured well enough to resist the torsional (twisting) moment of the crane. These rails shifted significantly indicating that this was a serious problem, if not the cause of the accident. Interesting photos either way! Link to the orignial.

Turmdrehkran Unfall

January 30th, 2010

2010-10-08T20:47:00.000-07:00

Starnberg Germany, A Self Erecting Tower tipped slowly enough that all of the construction workers except for one managed to get to safety. One of the workers was caught and suffered a renal contusion (bruise of the kidney). The cause of the accident is not listed. Could it be an over load? Were the appropriate counter weights installed? Was the base set level within 1% of level? Was the soil reviewed prior to the installation? These are some of the major issues to address and watch for in dealing with Self-Erecting cranes besides the obvious boom rope which clearly performed well in this accident.

Turmdrehkran Unfall

May 6th, 2010

2010-10-08T17:25:00.000-07:00

Tubize France, A Tower Crane lost one of it's counterweights while operating. The weight crashed through a school that the weight was suspended over going through the roof, through the floor and into what appears to be a parking structure. One counterweight remained attached. The combination of the trolley being all of the way in and apparently no load being on the hook and the weight remaining attached may have been the difference between collapse and remaining standing. Had the second weight dropped off suddenly I have a hard time believing the crane would stand. On the other hand, it's certainly happened a number of times where one jib of the other has collapsed and the crane remained vertical. If you've ever been on a crane while being erected or dismantled, you'd no doubt be with me and not understand how that can be. Link to original story with more pictures.

July 22nd, 2010

2010-10-08T11:44:00.000-07:00

A blogger posted some pictures of a 33 story tower crane that suffered a collapse in the superstructure. It's not clear if this is a pendant failure or the tower top, but the whole superstructure is totaled and they report at least two dead.

The location of the accident isn't clear. I found the blog with Traditional Chinese but Google Maps brings up a Chhang Road in Cambodia. I unfortunately don't have a clear understanding of where this accident took place.

August 16th, 2010

2010-10-08T11:19:00.000-07:00

Inner Mongolia, A tower crane being climbed down for dismantle failed in the mast. Four workers were present on the crane during the climb and three were thrown from the crane receiving injures such as broken backs. The fourth was trapped in the mast, pinched on his leg by the collapsed structure.

The rescuers can be seen in the picture. It really shows the standards of safety required. We have rescuers wearing no fall protection up 20 meters and fully exposed. no High-vis, No work boots... PPE is non existent here.

The man that was trapped was released after 40 minutes and taken to the hospital. Link to story with more pictures.

August 31st, 2010

2010-10-08T11:00:00.000-07:00

Changchun City, China A tower crane collapsed killing 4 and injuring 1. Link No details are really given and the pictures don't share enough to see the exact cause, but one picture is worth 1000 words.

The tip of the crane in the accident shows that the Load Line is improperly terminated. Normally you would see the wedge and socket running to a swiveled connection that would allow the rope to spin out and prevent the block from ever twisting up and allowing the rope to work as a non-rotating rope. These applications vary, but look at the termination closely. It appears that the rope is simply ran around the tip, turned into an eye, then three wire rope clips have been added. Even the tip of this rope appears to not be secured from fraying. The strength of the rope is compromised to an assumed 75% of capacity with the clamping method since it includes the live end. The bending of a rotation resistant rope around a boxed tube puts it well outside of the D/d ratio allowed further weakening the rope. The prevention of the rotating of the rope will only lead to the twisting of the block and potentially core failure. This may well be the dumbest, or at least equal to the dumbest, thing that I've seen an erector ever do. I can only dream what the actual cause of the failure is. Homemade mild steel nuts on the mast bolts?

塔式起重機事故

August 11th, 2009

2010-10-08T10:39:00.000-07:00

Nanchong, China I found a second crane Nanchong that collapsed in August of 2009. Link No notes were available on the number of injured involved.
The crane was clearly recently installed and being climbed to it's working height. You can see the climber, the tower hanging from it, and the additional towers on the ground. It's not a common practice to use a small crane to erect a tower crane then climb it later. In the US, most of the cranes are erected to the needed working height and climbing is a less common practice except when the height of the crane will be beyond the maximum free standing height.
Two things stand out to me in this picture. first and foremost, the tower doesn't appear to be plumb. Is that an illusion? I hope. Was the soil not adequate? Was it built out of plumb, I don't know but the appearance is that the mast failed on the side that it's leaning to. That could all be a coincidence.
The other thing that stands out points back to my last post, also about Nanchong and Climbing accident. The hydraulic ram is visible and partially extended. It's on the opposite side of the apparent structural failure. So if the ram is pushing up, the rollers at the bottom of the climber are not tight, and the climber and super structure are allowed to lean too far out of plumb, then you have loading beyond the engineers intention and the point loading (fulcrum) on the side of the tower at the bottom rollers exceeds the design strength and you have a failure just like this one. Add in the potential of the crane being out of plumb to begin with and it's a recipe for failure.

塔式起重機事故

June 22nd, 2010

2010-10-08T10:18:00.000-07:00

Nanchong, China A tower crane collapsed killing two and injuring one. Link The accident appears to have been a climbing accident where the mast failed. When I zoom in on the picture (certainly is grainy as I don't have CSI enhance capability) I see what appears to be a gap between the mast and the turntable with a climber in between.
Generally when you climb a crane, it's to be balanced. There is a rocking back and forth as the hydraulics push at a slight angle on most models. but the amount of overturning moment induced on the tower should be minimal and certainly not enough to cause the tower to buckle. It should be vertical loading almost exclusively.
The cause of the buckling, being unbalanced, wind, or improperly adjusted rollers (some older models had rollers that had to be adjusted on each climb) are my primary suspects here.

塔式起重機事故

August 27th, 2010

2010-09-11T13:50:00.000-07:00

Warsaw Poland - A Self Erecting Tower Crane collapsed when it's outrigger beam folded in. The story comes from Vertikal.net and no details of any injuries were available.

The basics of Outriggers on Self-Erectors are that the beams are folded in during transport. Obviously you can't drive around with a 4.5 meter x 4.5 meter square. You might catch a few cars and power lines if you do. The beams are folded out and pinned in place as a part of the crane erection process. I've never noted a pin on a self erector "walking up" during operation, but let me lay out a potential cause. The pins are meant to be kept in place with a keeper. It's not as if the pressure of the pin being driven in or gravity is guaranteed to to hold it in place. The action of the crane swinging will cause small movements in this joint. With at least two layer of steel working back and forth, the rolling of the pin in the hole can cause the pin to move upwards. Normally I see this in Tie-In pins on larger tower cranes. The strut to collar pins often try to walk up and I've even seen them attempting to shear off the keeper. So if the pin is not keepered in place properly, this accident could happen with in a few days at the fastest or over a much longer period. Pin "walk", as I call it, is common and should be watched for. Double check your keepers when you assemble cranes!

July 10th, 2010

2010-07-18T12:04:00.000-07:00

Ulyanovsk Russia A Self-Erecting Tower crane on rails collapsed killing the crane operator. There is a short video that really doesn't add much to understanding the accident unless you speak Russian. I don't know what else I can add to explaining these accidents in Russia given that I cannot find more info on this accident. I think that I've hammered these rigs enough in the last week doing the Russian searches.

Original Article

крах башенный кран, аварии башенного крана

September 28th, 2009

2010-07-18T11:50:00.000-07:00

Tver Russian - A Self-Erecting Tower Crane collapsed after running off it's rails. The collapse didn't actually happen until the next day, and so fortunately no one was injured. This is not a rare occurrence in Russia. Cranes seem to run off the rails on a regular basis. So why and how is what comes to mind for me.

Examples of cranes running off the rails.. St Petersburg 2007, Minsk 2008, and I've ran across another one that ran off the rails, but they successfully got it back onto the rails so I didn't put up a post on it. In St Petersburg, the rails were removed prior to dismantling the crane. They just got ahead of themselves and then the operator ran off the end. In Minsk the brakes failed. But more importantly, where are the stops on these rails? Why is it that these cranes are able to run off the rails? They are supposed to be level, have a mechanical shutoff prior to the stops... oh, and have functioning brakes to safely stop the crane.

In this Tver case, the brakes were not working on the traveler. What I found really interesting in the article is this quote, "Tower Crane, who worked at the construction site, was built in 1991, the term of such equipment is 10 years. Accordingly, the life of the crane expired 8 years ago." I don't know where the writer is getting the information and he notes that with maintenance the life can be extended. Do we have maintenance records? Was it maintained? Was this the first time that the brakes malfunctioned?
Original Article

Russia is clearly not respecting any standards set by manufacturers. You can have the rules in place, but if no one enforces them due to open corruption, what is the point o having regulations? I have family in Eastern Europe, and they can't believe how business is done here. There needs to be a fundamental change before these accidents will come to an end over there. When government officials are wearing $300k watches, we can easily see what the real source of accidents like this are.

крах башенный кран, аварии башенного крана

July 2nd, 2010

2010-07-16T16:16:00.000-07:00

Amstetten Austria A crane operator was returning to work from having taken lunch. The operator tripped and lost control of the remote control to the crane. The crane apparently had a load on the hook. The control of the crane was knocked into hoisting down quickly. The load came down and struck another worker killing them.

A couple of things. If there was a load on the hook and this isn't a translation or reporter issue, then why is the operator not with the crane? We should never be leaving a load on the hook and walking away from the crane. Secondly, why is the remote activated if the remote is not attached to us? If the remote is not activated, it could fall anywhere and this won't be an issue. Third, was the control set up to auto zero. Most modern cranes cease to function when the controller is released. It's the standard that we have by law. I concede that it's possible for the remote to land on sometime which held the function on, we just want to be sure that our controls do auto zero and this is a prime example of why.

I see a series of question all that may have led to this accident occurring. The intent sounds like it was clearly an accident. I'm just thinking of the things that should have been in practice to prevent this.

June 22nd, 2010

2010-07-16T16:00:00.000-07:00

Passau Germany A Self-Erecting Tower crane collapsed onto a farm roof in Passau. The operator was only slightly injured due to some falling tiles. He was operating the crane remotely and so he was not subjected to the falling of the crane.

The crane was being used on a farm to build a silo. While it is dry in the summer months in Germany, the soils may not be as firm as required. It would be important to have out outrigger pads as well considering the soft fertile soil often found on farms.

Have you noticed that there were three accidents on June 22nd and 4 in the last two days? Are we back to our old bad habits? Are we forgetting about crane safety because we haven't seen a "major" accident in a while? Make sure that you are keeping a close eye on your cranes and the practices surrounding them. Just because work is slow and you need the job, doesn't mean that we should be allowing unsafe conditions to go on.

Turmdrehkran Unfall

July 15th, 2010

2010-07-16T15:40:00.000-07:00

Wels Austria. A man operating or signalling a tower crane was knocked from the scaffolding he was on by the crane. He fell about 50 feet. When help arrived he was still conscious and speaking. An hour and a half later he died of his injuries.

Anyone can make a mistake and get themselves in a pinch. More commonly though, guys are put on the radio to signal cranes without any real training. This is a problem in our industry. I'm going to talk about a few signalling concepts. If you know how to stop a load from swinging without touching it (catching the load), then this isn't for you. This is for the guys that don't know about that concept. If you don't know this concept, you should. It will make you money, make the operator happy, and maybe save your life. Not knowing this concept may be what killed the man in this story.

I'm going to run with the assumption that he was signalling the crane. Maybe via radio in the blind. Something that I do besides crane inspections is Signal Person Certifications. One of my clients needed it done on site for just one job so I stepped up to the plate. I came up with a game plan to have guys rig various items. I put in sharp items with choices of rigging, regular items, loose, etc. The person would be asked to choose the best way to rig then I would have them proficiently signal the crane. Part of that is making someone signal in the blind in tight areas. We were looking for "qualified" people to signal the crane. Not the minimum, but guys that would be able to get the job done and done safely.

Guy after guy with 20 years of experience could only pass with minimal proficiency. For me it was an indication that we aren't doing enough to teach in this area. Our leadership in many places aren't any good at signalling the crane so they assume that it's easy. Sure, if you do a poor job, it's super easy. In fact signalling a crane is not that hard. But there are concepts such as catching the load that are lost on many. Testers were coming down into a stairwell with good sized pieces when I'd have to call off the crane operations and ask them to "catch" the load (prevent it from swinging too much). The common response was, "But the tag line isn't long enough." Sigh.

Swinging loads are prevented by good operators or signal people. If you haven't ever seen it, or don't know what I'm talking about, go get a fishing pole and put a string and a weight on it. Now swing around like a crane. When you stop, the load continues to drift out because it's a rope with a weight on it. So you can do three things to prevent that. Slow down the swing prior to getting to where you want to stop. In Seattle I would say "easy swing" and the load will drift out ahead and to the side of the boom due to momentum. Then I watch until the boom and the load are just about in line with one another and then say "swing". By the time the boom fully stops I should be directly over the load and have it in control. If you have lost control and need to get it back under control, you wait until the load passes under the center of the boom then call for swing in the same direction until you are dead center over it, then stop the swing. As an operator, what I would do is get the swing or boom moving slowly, then pick up the pace of the movement as the load swinging got close to the center. That way I would stay over the load and it didn't swing. As I came to a stop on the swing I would counter swing the crane getting the load drifting out (reasonably of course) and allow the momentum of the crane to move over the load at about the same pace then stop the swing when you are over it. We all have slightly different techniques, but the principles are the same. It's all very simple, but the timing and practice with your operator takes time. Talk about your signalling. Ask what they like and don't like about it. Some operators want to be left alone. Other's want every signal there is. When you operate with a good iron working crew the day's fly by because you are doing very little thinking, just pulling the levers as told and keeping track of the three or four functions going on at a time. Get out that fishing pole and get the concept down. Then go put it into practice. you can also use that fishing pole to learn about boom deflection. That's another concept that you need to know if you are signalling cranes.

July 16th, 2010

2010-07-16T15:02:00.000-07:00

Regensburg Germany, A Self-Erecting Liebherr K Crane tipped slightly injuring one worker. The crane tipped at the base and does not appear to have any structural causes in the super structure. From the translation of the story I'm not clear as to whether or not it was caused by overload but it does sound as if they were bucketing concrete. As a cause of Self-Erectors going over, this seems common. Does anyone set moment limits anymore? Check them with a known weight and tape if need be? I would hope that's standard practice.

The base of the crane is only seen in a video from this article. Hitting the pause only gives a better view of the base and it's still not a good view to see if there was a failure there. It sounds as if the crane was placed up on concrete, so the only question there is was there enough padding to spread the load if it were thin concrete?

There was a fourth accident in the last two days that I am now trying to hunt down. Vigilance gentlemen... don't get lulled back to easy street because the market has slowed down .

Turmdrehkran Unfall

July 15th, 2010

2010-07-16T14:46:00.000-07:00

Laussane Switzerland, A Self-Erecting Tower Crane collapsed today. No one was reported as injured. One driver was startled as his car was just barely struck on the mirror. He was very close to being involved in the accident. No operator was noted as being injured.

Looking at the pictures, I'm a little surprised at what I see. I see a set of pins missing on the rear of the crane at the tower. Is it possible that the crane was erected without these pins? When I zoom in on the picture I don't see any damage to the dowel coming out of the bottom tower or the pocket on the upper tower. Could it be that they were dismantling and they moved the tower up only to find that the pins weren't in at all? Could it be that they were erecting for this site a second time and the pins were forgotten (reported as a 9 AM accident)? or possibly when they slackened the luffing rope to let down the boom to touch the tip to the ground it got enough movement that it just fell forward and has been like this since the crane was erected? This last scenario is the one that speaks to me since the job is enclosed.

This was a very lucky incident that the crane appears to have survived an entire job missing a set of tower pins and no one was killed. Don't get in a hurry and it never hurts to have someone double check your work. We all have made mistakes, but this one is easily avoidable.

The story online has many more pictures.

July 16th, 2010

2010-07-16T14:19:00.000-07:00

Erlangen Germany A mobile crane tipped over backwards during what sounds to be a tower crane dismantle at a sewage treatment plant. The mobile crane operator was sent to the hospital be ambulance. The damage was already listed at 1.5 million dollars.

The crane was said to have tipped over backwards. The picture doesn't quite show that, but appears to have been overloaded or had poor support under the outriggers as he was booming down to set the load down. What sometimes happens is a job is scaled (panned) out for where the crane needs to sit in order to make the pics off of the tower crane. If the person doing the scaling doesn't consider where the load must be set down as a factor, and the operator is willing to turn the key in order to get the work done, you may end up in this situation.

To be fair to the Mobile Crane Operator, the pictures don't show the ground and the article doesn't talk about cause. It's quite possible that the ground he was sitting on was back fill and not compacted enough. He easily could have been given poor information as well which would point the finger at someone else.

Turmdrehkran Unfall

January 31st, 2007

2010-07-16T10:51:00.000-07:00

Omsk Russia A 20 meter tall tower crane fell. The female operator survived the crash with a broken leg and was taken to the hospital.

The collapse again happened from the base area of the crane. The mast is clearly laying down on the ground. The article notes that the cause is presumed to be overloading. So let's suggest that these cranes in Russia are dropping due to limit failures. Why are they not addressing that? The beauty of running a tower crane was always, either the crane can make the pick, or it can't. There is no turning the key to make things happen. If everything is working properly, you cannot over load a tower crane.

One of my favorite over load stories comes from my area. The story as it's been told to me is that a self erector was unable to hoist a pallet off the ground. So the solution was to load the crane with a fork lift, then pull the fork lift out from under the load. This is ill-advised. You have hoist and moment limits for a reason. In this case, the load was far enough out that it existed for stability reasons. Shortly after getting the forklift clear, the crane tipped and came crashing down. Now I know that this story has a lot of validity. But I can't even find it locally in the news or otherwise. How many of these are we missing? Have there been 400... 500 tower crane accidents in the last decade? Sadly we'll never have the accurate number so that we can address it methodically.

July 3rd, 2007

2010-07-16T10:34:00.000-07:00

Veliky Novgorod Russia, A Large Self-Erecting Tower Crane collapsed killing one person, presumably the operator. The failure happened near the base of the crane. The article does not note any cause such as overloading or a cracked structure.

We seem to have a theme here in Russia of cranes dropping like flies. You would think that they would seek out the most common causes and address it. Are the cranes being used properly? If not, how do you change that? Certify operators? Scare the industry into change? Require newer cranes? Require NDT testing? Government inspectors? You can't just have these cranes dropping every few months and not do anything about it. It's simply irresponsible and shows great deference to life. The article notes that a crane fell in the same town only 6 months prior. Something isn't working.

June 22nd, 2010

2010-07-16T10:19:00.000-07:00

Petropavlovsk-Kamchatsky Russia, A tower Crane collapsed during the dismantling killing three crane erectors and injuring the crane operator. The crane was on a cross base but the crane superstructure managed to rip away from the mast bending and destroying the mast.

This article notes "refused Hydraulics". Looking at the video from this page it isn't clear as to whether or not the crane was a climber or not. There is no climber on the mast. When I watch the video I see blue and what appear to be platforms with the wreckage. The damage, the noting of hydraulics, and the platforms near the turntable lead me to believe that they over extended the climber for one reason or another. Many climbers don't leave a lot of margin for error. If the person operating it weren't paying attention or the valve stuck, this could be the result. I've never heard of a valve sticking on a climber, but I suppose anything is possible.

March 27th, 2010

2010-07-16T09:58:00.000-07:00

Saransk Russia, A luffing tower crane tipped, hitting, and wrapping over the building it was working on. The article (video of the crane in article) notes that no one was injured in the accident. 6 cars were damaged and fortunately the cars at the intersection were all stopped.

The second article that I found also has video and can be translated in Google Chrome. This article notes that the crane "cracked almost at the base".

The overall design of the crane is very old. I hesitate to say that the crane is old because large luffing self erectors seems to be the norm in Russia. Inspection is also common in Russia according to some articles that I have been reading. For me it raises the question of usable life of cranes. If the crane was inspected like many of these older Russian cranes, how old does a crane get before you say it's reached it's design life and shouldn't be used anymore?

November 11th, 2008

2010-07-15T14:19:00.000-07:00

Moscow Russia A Tower Crane collapsed killing the 50 year old crane operator by throwing him out of the crane. Only one picture was found and it accompanies this post. There is a video as well on this page . I picked up that the crane is defective. Beyond that, I don't understand a word he's saying.

As you can see, There are plenty of Russian crane accidents. I'm only scratching the surface because the accident's don't stay up forever. The languages used are not my own and I can't even type the characters used unless I download software that may cause me grief, so I'm not interested. I've found old pictures of early self-erectors down that I can't find any info on. I found a German crane that appears to have dropped it's load on it's rails and it caused itself to go down in 1955. This is more of a derrick, and that's why I didn't put it up. I'm closing in on 200 posts with all but 10 to 15 of them being tower crane collapses. I hope that the message that this is something to take seriously daily is resonating.

May 25th, 2008

2010-07-15T13:59:00.000-07:00

Minsk Russia A Tower Crane on Rails tipped over. The operator was not in the crane but running the crane remotely. Because of this, he was not injured by the accident.

The crane is older and it's assumed in the article that the traveler brakes failed. This would cause the crane to strike the end plates/buffers too hard and the collapse would be imminent. I heard of a new crane being ran with only one motor working on the traveler. The common position that "I'll make due." is not a wise decision. Most of the time you'll be just fine with that attitude. But the time that you aren't correct, you may be taking someone else's life in your hands, and you don't have that right. One of my favorite safety signs is "Just because you've been doing it for 20 years, doesn't mean that it won't kill you in 20 seconds." make sure that your equipment is operational. If it isn't, get new gear.

December 25th, 2009

2010-07-15T13:48:00.000-07:00

Kirov Russia - A Self-Erecting Tower Crane collapsed during operation killing the operator. An adjacent 9 story hospital suffered some damage to the roof but no patients were injured.

The cause of the accident was being listed as under investigation. There was a second accident in Kirov in August of 2009 that I suppose I will have to go find.

April 29th, 2008

2010-07-15T13:40:00.000-07:00

Kemerovo Russia - Tower Crane Collapsed killing the operator and injuring one other.

I don't recognize the type of crane at all. It almost appears as of the smaller tower sits inside of that base and is locked in there somehow. It does look like a clean break from this angle. I don't know what the mechanism is or what caused the accident so I'll just leave it at that. but don't forget to note how modern it is.

July 14th, 2009

2010-07-15T13:00:00.000-07:00

Saratov Russia A mason was injured with a broken leg due to the collapse of a tower crane. The collapse was apparently caused by negligence (undisclosed) by the crane foreman. He even admitted to the negligence while being interviewed.

Looking at the picture, it appears that we have a clean separation between the turntable and mast. If this is the case, then it must have been a bolting issue. There are 8 bolts that torque up to 4300 ft lbs that and if they are not tightened properly with the counterweights over the corner being torqued or prior to going horizontal with the crane, then you will end up with bolts loosening up. If the others were pre-stressed correctly, it could be that one corner loosens up and gets a gap going unbeknown to the operator. If that gap grows, then the other have added stress and can eventually fail quickly in a zipper like fashion, one after the other.

What I used to do on bolted towers is note the position of the crane before I climbed. As I climbed I would put a hand on the bolts under compression due to the counterweights. Both corners on that side. Then when I climbed down, I would put the weights on the opposite side (wind allowing) and check the other side as I climbed down. This was a once a week operation at a minimum. It adds very little time to either climb and is simply common sense.

August 6th, 2007

2010-07-15T12:51:00.000-07:00

St. Petersburg Russia A Self Erecting Tower Crane collapsed during a dismantling process. The 25 year old owner of the crane was on the top of the crane when the failure happened. He was thrown a reported 50 meters and was transported to the hospital with multiple injuries that were life threatening.

The cause of the accident wasn't official, but the story at the release of the article was that somone whom was charged with removing the lock nuts, removed the whole nut to some bolts. As you may expect, we appear to have human error as being the cause of this crane failing during a dismantle.