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The Nicoll Highway collapse in Singapore was possibly the greatest civil engineering disaster of the last decade.
Inadequate temporary works and design and construction errors all led to the fatal collapse of Singapore's deepest ever cut and cover tunnel in April 2004.
The collapse hit a 110m section of tunnel being constructed for the city's new Circle Line, adjacent to the six lane Nicoll Highway. Four workers died when steel struts supporting the excavation's diaphragm walls failed, causing the tunnel to cave in.
Failure lay with a connection between horizontal struts and waling beams. The official report into the disaster concluded that critical design...