Sunday's accident occurred on a particularly tricky section, where a metal cantilever was being raised to lift a 300-ton prefabricated concrete segment of a bridge, Delhi Metro Rail Corp. chief E. Sreedharan told reporters.
Four truck-mounted cranes lifted the massive orange girder off the ground when one sustained a mechanical failure in its boom — the long arm used to lift weight, Dayal said.
The sudden shift of extra load caused the booms of two cranes to snap while the third crane toppled over, Dayal said. "It was a very tricky, very difficult and dangerous operation because the space was limited," he told reporters.
Live television coverage showed two of the booms shearing off the multi-wheeled trucks. The third crane keeled over and ended up in a vertical position with its underbelly in the air. |