July 11th, 2009

The Liverpool tower crane that collapsed is being removed.

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

cranes after collapse. They have a self erector to suspend

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

crane assisting the 800 ton crane. Clean up of this

magnitude can easily approach a million dollars. I was

involved with the clean up for the Belleve crane collapse

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

out process to figure out weights, closest center of gravity

for rigging, and methods of cutting that will prevent the

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

July 6th, 2009

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

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

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

July 6th, 2009

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

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

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

July 4th, 2009

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

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

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

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

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

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

June 22, 2009

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

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

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

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

June 16th, 2009

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

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

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

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

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

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

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

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

May 21,2008

Atlanta, Georgia - I learned today of a tower crane accident that didn't make national news during the rash of accidents in the US last year. A Liebherr 420 was being prepared to be climbed on an Atlanta jobsite. The collar appears to have been installed and the climber mounted on the tower. During the process the climber freed up and fell 70 to 240 feet (conflicting reports) to the building below. If you go to this link http://www.wsbtv.com/news/16354291/detail.html and watch the vid you'll see the end of a strut sitting on floor as if the bolts were all sheared off at the splice plate. There was a person on board the climber during the fall and they managed to survive with multiple injuries.

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