Pictures:

http://www.nytimes.com/slideshow/200...ANE_index.html


This was a "CLIP-ON" crane. These are vertical trusses, similar to antenna towers, that are stacked on top of each other and "clipped on" to the side of a building while it is being constructed. The hoist sits on top and it can raise itself by adding more sections and jacking itself up.

The crane ripped off the building while it was lifting something heavy and it demolished a 4 story building across the street and ripped off a sheer wall on the apartment building next door.

Estimates are that this accident killed 4 people.

The crane was working on a 44-story condo tower.

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Buh-bye.

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The Lord is my light and my salvation; whom shall I fear? The Lord is the strength of my life; of whom shall I be afraid? - Psalm 27:1

Is this the same thing?

http://www.youtube.com/watch?v=vx5Qt7_ECEE

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Sort of.

Clip-on cranes have a Y-shaped boom and they are "clipped" to the side of an existing tower. That YouTube video shows a standard Kangaroo crane where it is completely free-standing. Clip-On cranes are similar, but their booms are structured differently.

If you were near the Comcast Center while it was going up, there were two Clip-On cranes that were used to build the building past the 20th floor. When the concrete-steel reinforced core was completed on the building, a Kangaroo crane was added to the Comcast Center to assist with the construction and was also used to dismantle the other two Clip-On cranes, attach all the glass windows to the building, and de-conctructed the Clip-On elevator towers that were used for construction workers to reach all the floors of the building. All the Clip-On towers (there was a total of 4 of them at one point), where all socketed to the concrete core of the Comcast Center, so all the lateral forces affecting the Clip-On towers were transmitted to the Comcast Center's core tower... keeping everything stable.

You can only put so much load on a kangaroo crane that has no lateral truss braces. Buildings shorter than 25 stories usually are built with free-standing kangaroo cranes.

According to the NYT, the crane operator caused the accident. The construction foreman on site witnessed the accident:


- While carrying up a steel beam, the beam snapped off the suspension clips when it accidentally hit the building.

- As the steel beam fell, it followed a path to the ground that was the most disadvantageous to the crane operator: it went down between the crane tower and the building, slicing through all the clip on braces that hold the lateral forces between the crane tower together and keep it upright on its trip to the ground.

- Without the clip-ons, the tower loses all of its bracing to keep it upright while it is holding a load. When the tower has no weight, it can stay upright on its own, but when there is a load over the side of the crane, the forces are transmitted through the clip on brackets and into the building's core tower which is being constructed at the same height.

- The top 1/5th of the crane started to teeter the rest of the crane tower over. As the crane was slowly tilting, the bottom 4/5ths of the crane struck a 27 story apartment tower on 51st Street and Lexington, transferring most of the weight of the crane into the apartment building. There were eyewitnesses in the apartment building interviewed on WCBS (check their site) who witnessed the thing smash into their apartment building.

- The disaster was the top 1/5 of the crane, with the cab still attached to it. The joints between the top of the crane and the rest of it obviously cannot take those kind of forces, so the top part of the crane with the cab snapped off and continued to fall. This completely destroyed a 4 story townhouse near 51st Street and 2nd Avenue.

- As the crane was falling it sheered off walls on several nearby buildings, and a pre-war apartment building next to the townhouse had its SE-corner completely sheered off the building, exposing apartments on the top 3 floors of the building on that corner.

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Buh-bye.

This scene is right near where I work, buy newspapers, food and pet supplies. The construction site has been a major mess for months, blocking traffic on a bus route, creating large puddles that freeze, etc. I wasn't surprised to find that this was where it happened.

Excellent areal coverage:

http://video.wnbc.com/player/?id=229438

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Buh-bye.

You commute from Kensington to the far UES of Manhattan to work everyday?

Jeez. Hopefully your employer is paying the $1,000 AMTRAK a month.

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Not every day; I abuse my car a lot though.

Totally astonishing NBC footage btw, especially the patter about "was there a bulding there? no--yes, a 4-story building" obliterated by a piece of crane.