10.12.2014

Manufacturing error blamed for fatal crane collapse

The Singapore state coroner has 'found' that the tower crane collapse at the city’s National Gallery last year was due to a manufacturing error.

The ruling was handed out yesterday by state coroner Marvin Bay who claimed that 'luffing jib sheave bores did not comply with design specifications, being 0.33 to 1.28mm larger than the parameters allowed, resulting in an excessively loose fit between the sheaves and the bearings. Investigators claim that this allowed the luffing jib cable to be caught in the sheave and break'.
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The crane after the incident

The operator of the luffing jib tower crane, Ismail Sias, was fully qualified and had performed all of the required checks before starting work. The crane then lifted a five tonne excavator - well within the crane’s 15 tonne capacity for the radius. According to the operator the crane jib started to vibrate as the excavator was lifted above the building. Sensing that something was badly wrong he pressed the emergency stop button, but almost as he did so the jib dropped onto the building and the part of the counterweight came off.

Somkhot Chanyut, 49, from Thailand was struck by the crane’s hook assembly, which amputated his left shoulder, dislocated his left leg and crushed him.

Ronju Ahmed, 28, from Bangladesh was killed after he was struck by the falling counterweight. Four other men were injured by falling debris. See original accident report

Vertikal Comment

We have not yet seen the full written report of the investigation, or coroner's 'findings', so while it is clear that the incident was caused by a problem with the jib hoist cable and its interface with the sheaves, it is not clear from what was said in court which tolerances were off. And if this was really due to an original manufacturing error or an incorrect replacement, non genuine spare part, or even excessive wear - the crane was, we understand over six years old. The three cranes on site were 24 tonne Comansa LCL500s supplied by Access Systems Technology.

We will of course update this when the situation is clearer.