Saturday, January 29, 2011

November 28th, 2008

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.

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