Tumbling down

As I am sure most of you heard, last Saturday at crane collapsed in Manhattan. And then yesterday we find out that a city building inspector was arrested for failing to inspect the crane.

This whole incident is a horrific tragedy. And there is a whole lot of information out there about what occurred. And since I take an interest in this sort of stuff (no I am not sadistic, (ok, maybe a little) but a big part of my job is in safety, including work around cranes).

The crane that collapsed was a tower crane, which has a vertical tower supporting a horizontal boom. It was being employed in the building of a new high-rise, that would be 40 stories tall when completed.

Common practice in the erection and use of a tower crane is to brace them back to the building for stability. This was the process that was being done on Saturday when the crane toppled. Workers were extending the erection of the crane.

The process involves the use of 6-ton tie-backs that attach the tower to building. While installing the tie-back at the 18th floor, somehow, the tie-back fell. At the ninth story, it struck the tie-back anchoring the tower and damaged it. When the 9th floor tie back was damage it caused the stability of the crane to be compromised and the counterweight on the back of the boom pulled the entire unit over.

The tower landed on top of the an penthouse condo, which is where the woman from Miami was killed. Several other building were damaged. 6 construction workers were also killed, and I have not been able to figure out what the circumstance was in their deaths from news reports I have read. I assume that they either fell off the tower or were crushed when the tower hit the apartment building.

Some people will try to blame the collapse on the inspector. The important thing to remember is, the inspection that should have occurred was on March 4th. The collapse was on March 15th, and caused because the crane was being built taller. The odds of seeing anything on the 4th that was tied to the 15th collapse are slim. As far as I can tell, it is a freak accident that ends in tragedy. Obviously, the inspector failed to perform his duty, but that is not what caused this incident.



The incident reminded me of the "Big Blue" collapse in 1999. "Big Blue" was a 1,500 ton lattice boom gantry crane, that collapsed in a 26 mph wind while lifting a roof section onto Miller Park baseball stadium in Milwaukee, WI. 3 iron workers were killed in the collapse. They were in a suspended man basket hanging from another crane at the time of the collapse. The boom of "Big Blue" hit the cable and basket as it fell, breaking the basket loose and sending the men to their death.

In a strange coincidence, OSHA inspectors were on site at Miller Park the day of the collapse and had a video camera filming the lift, capturing the horrific collapse.



The screeching sound you hear is, I believe, the brakes on the cables. The loud pop/bang is a pin shearing, which triggered the collapse. Right after the guys filming move and look back to the boom, look just to the right of the vertical cable in the center of the screen, you will see the boom of the second crane and the small black spot is the man basket. Watch the basket and the boom of the second crane as well.

This incident was preventable. The lift should never have taken place in those kind of conditions.