Lifting operations on the Delhi metro were thrown into the spotlight last week after the project suffered two major accidents in two days.
Six people died when a concrete viaduct section collapsed on 12 July. The accident occurred where a steel cantilever was being raised to lift a 300t prefabricated concrete bridge segment.
Three truck-mounted cranes then collapsed while trying to lift a steel girder on the following Monday, but without injury.
According to reports, four cranes were trying to lift the 300t girder when one of them malfunctioned. This triggered the collapse of the other three cranes which were overloaded as they were forced to share the weight.
Delhi Metro chief E Sreedharan offered to resign to take “moral responsibility” for the accident, but his resignation was rejected by the authorities.
In October last year, two people died and at least 11 were injured in a similar accident. Then, mechanical failure in a launching gantry was blamed for the collapse (NCE 23 October 2008).
The metro currently has three lines covering 75km, and authorities aim to complete several extensions totalling about 100km before the October 2010 Commonwealth Games.