Billy D7 4T
New Member
Enr - Ny Crane & D.o.b.
It sounds like a master rigger was on site, I was wondering about what NY CRANE's arrangement was with the C.M./G.C., being leased hopefully will afford them some protection, as they are kind of indeminfied from means and methods, or should be if the G.C. had their own 14&15 O.E. on site. Have to wonder if there was a Master Mech. on site too, standby, like a shop steward, but many of them are highly experienced and would be another set of eyes to spot a problem.
The B.E.S.T. squad, a division or dept. of D.O.B. was on site too, with high rises, you can't leave materials on the decks near or close to the edges, I used to tie off all our materials to columns when faced with high winds, so they were given a stop work order on that, typical violation, also hints at the site management, if D.O.B. inspected the building, high wind warnings and there were violations on that, nothing to do with the crane though.
I agree with Jimmy Lomma, don't like nylon straps at all, the condition of them can be compromised, physical damage, and or even UV light weathering them, often times I used to have to go to a supplier on the lower west side, forget the outfit, they supply rigging, and get brand new slings, instructing my Ironworkers to use care with them and cut up any that are damaged. Abrasion and cuts to them was the #1 reason. 2 things come to mind, were the slings certified for the weights and the configurations used, choker, cradle or however they rigged the collar and were they defective when manufactured or compromised before or during use. I have always disliked the foreign manufacture of these items, we used to MFR quality rigging equipment, just look in old industrial catalogs, what criteria or reference standards do foreign manufacture adhere to and who checks it ??? I've seen these cranes installed and taken down many times, but don't recall the details of adding sections, it's always done off hours out of sequence of regular production work, the last place I want to be on a saturday is at work whenever possible, but as PM or super, running that job, you would have to be there and be right where the action was going on and you cannot be afraid to stop someone when you see something you think is wrong. That article states they usually set these collars in 3-4 picks, so I would imagine that each of the sections would attach to the tower at the specified point, to surround it, so when the last section goes on, it is also attached to the building and secures the crane as designed by the engineer.
My concern with this would be that when the tower is raised and requires additional connections to the building via the collar(s), with the previous multiple pick sequence to place same and connect it, is the tower at risk until it is connected, or it's working load limits, radius reduced enough and the jib must stay closer to vertical or at the opposite angle for balance, etc. until the connections are made, meaning you must be very careful and work within the reduced limits, kind of like a hydraulic R.T. when on intermediate outriggers, you are limited by weight and pick radius. If that is the case, one would think that some temporary connections could or should be made 1st, to secure the tower, prior to the sequence of placing the collar in pieces or as a whole, like they were doing at this site. It appears obvious that if there were some tiebacks above the collar, the tower could have been secured above the last collar, and also at the foundation. With this scenario, you wonder if both those connections would have been enough to keep it from getting motion, the counterweight and subsequent motion sure would have placed some serious moment arm type forces on it, once it gets moving. The key to it would be to have the tower secured enough to prevent it from getting motion in the first place. If what occurred at this site happens, and a collar falls, say the crane is compromised, but still tied off, it would seem to be a much better outcome, even if it had to be disassembled and re-erected, compared to what happened at this site, might have prevented what happened. Out of respect for all parties involved, it is unfair for me to really say, just speculation from a friend in the industry, this is a very tragic event.
I'm sure the temp connections would be a cost item, would have to design something that you could attach to the building as designed, coordinated with the structural drawings and engineer of record, problem being the last deck poured would not be 28 days cured in a 3 day cycle, so you would have to go as many floors lower or find an alternate detail, per the engineer, it is going to be a cost item especially if the superstructure is not going to be easily attached too for some reason should be coordinated into the structural drawings at the design stage. Some kind of back up connections is really something to consider. I'm sure a lot of buildings have been put up without any, similar to this one, but all it takes is 1 time, and we have that on this site, it is going to be the cause of change.
It sounds as if the crew wanted to place it in one pick, saving time, but if it does turn out to be the nylon slings, it is kind of clear as to the mistake made. That piece weighed 12,000 lbs, or 6 ton, according to the reports, no way would I be using nylon slings, too heavy to chance, a 4 way spreader, wire rope off of a ring to the headache ball hook, there is just no way when you compare safe working loads of these 2 materials, that nylon is even worth consideration for a pick like this. 5/8" wire rope, 4 lift points to spread out the live load, I'm sure just one would would hold that weight just from memory. I have used them for material picks up to 2 tons, but beyond that, no way.
It sounds like a master rigger was on site, I was wondering about what NY CRANE's arrangement was with the C.M./G.C., being leased hopefully will afford them some protection, as they are kind of indeminfied from means and methods, or should be if the G.C. had their own 14&15 O.E. on site. Have to wonder if there was a Master Mech. on site too, standby, like a shop steward, but many of them are highly experienced and would be another set of eyes to spot a problem.
The B.E.S.T. squad, a division or dept. of D.O.B. was on site too, with high rises, you can't leave materials on the decks near or close to the edges, I used to tie off all our materials to columns when faced with high winds, so they were given a stop work order on that, typical violation, also hints at the site management, if D.O.B. inspected the building, high wind warnings and there were violations on that, nothing to do with the crane though.
I agree with Jimmy Lomma, don't like nylon straps at all, the condition of them can be compromised, physical damage, and or even UV light weathering them, often times I used to have to go to a supplier on the lower west side, forget the outfit, they supply rigging, and get brand new slings, instructing my Ironworkers to use care with them and cut up any that are damaged. Abrasion and cuts to them was the #1 reason. 2 things come to mind, were the slings certified for the weights and the configurations used, choker, cradle or however they rigged the collar and were they defective when manufactured or compromised before or during use. I have always disliked the foreign manufacture of these items, we used to MFR quality rigging equipment, just look in old industrial catalogs, what criteria or reference standards do foreign manufacture adhere to and who checks it ??? I've seen these cranes installed and taken down many times, but don't recall the details of adding sections, it's always done off hours out of sequence of regular production work, the last place I want to be on a saturday is at work whenever possible, but as PM or super, running that job, you would have to be there and be right where the action was going on and you cannot be afraid to stop someone when you see something you think is wrong. That article states they usually set these collars in 3-4 picks, so I would imagine that each of the sections would attach to the tower at the specified point, to surround it, so when the last section goes on, it is also attached to the building and secures the crane as designed by the engineer.
My concern with this would be that when the tower is raised and requires additional connections to the building via the collar(s), with the previous multiple pick sequence to place same and connect it, is the tower at risk until it is connected, or it's working load limits, radius reduced enough and the jib must stay closer to vertical or at the opposite angle for balance, etc. until the connections are made, meaning you must be very careful and work within the reduced limits, kind of like a hydraulic R.T. when on intermediate outriggers, you are limited by weight and pick radius. If that is the case, one would think that some temporary connections could or should be made 1st, to secure the tower, prior to the sequence of placing the collar in pieces or as a whole, like they were doing at this site. It appears obvious that if there were some tiebacks above the collar, the tower could have been secured above the last collar, and also at the foundation. With this scenario, you wonder if both those connections would have been enough to keep it from getting motion, the counterweight and subsequent motion sure would have placed some serious moment arm type forces on it, once it gets moving. The key to it would be to have the tower secured enough to prevent it from getting motion in the first place. If what occurred at this site happens, and a collar falls, say the crane is compromised, but still tied off, it would seem to be a much better outcome, even if it had to be disassembled and re-erected, compared to what happened at this site, might have prevented what happened. Out of respect for all parties involved, it is unfair for me to really say, just speculation from a friend in the industry, this is a very tragic event.
I'm sure the temp connections would be a cost item, would have to design something that you could attach to the building as designed, coordinated with the structural drawings and engineer of record, problem being the last deck poured would not be 28 days cured in a 3 day cycle, so you would have to go as many floors lower or find an alternate detail, per the engineer, it is going to be a cost item especially if the superstructure is not going to be easily attached too for some reason should be coordinated into the structural drawings at the design stage. Some kind of back up connections is really something to consider. I'm sure a lot of buildings have been put up without any, similar to this one, but all it takes is 1 time, and we have that on this site, it is going to be the cause of change.
It sounds as if the crew wanted to place it in one pick, saving time, but if it does turn out to be the nylon slings, it is kind of clear as to the mistake made. That piece weighed 12,000 lbs, or 6 ton, according to the reports, no way would I be using nylon slings, too heavy to chance, a 4 way spreader, wire rope off of a ring to the headache ball hook, there is just no way when you compare safe working loads of these 2 materials, that nylon is even worth consideration for a pick like this. 5/8" wire rope, 4 lift points to spread out the live load, I'm sure just one would would hold that weight just from memory. I have used them for material picks up to 2 tons, but beyond that, no way.