Friday, July 16, 2010

July 15th, 2010

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.

1 comment:

MsLaura said...

My boyfriend is an Ironworker and he was in a work accident in March. The high call was given but the beam toggled on both ends instantly and the lag time on the crane brakes caused the choker to part. The beam catapulted towards him leaving him badly injured and with trauma, he will not be able to go back on the field.

So glad I found your site, I have so many questions. Like why is there a lag time on tower crane brakes? Do they have an emergency brake that can stop it dead? The accident could have been avoided, oddly enough there was/is no media coverage or mention of this accident, it has been very hush hush.