Two Delhi Metro cranes topple over, 2 injured
NEW DELHI: Two cranes of the Delhi Metro toppled over at a construction site in New Delhi on Saturday. The accident occurred on the Connaught
place-Gurgaon metro line in the Saidullajab area.
The accident, blamed on "mechanical failure", took place at the proposed Saket metro station in south Delhi.
Although Metro officials claimed that no one was injured, police said two workers suffered injuries and were taken to a hospital.
"The incident took place at the Saket station. It appears that one crane developed a mechanical snag and lost its balance," a Delhi Metro official said.
Two fire tenders have rushed to the accident site.
On July 12, an accident at a metro construction site in Zamrudpur in south Delhi caused the death of six workers, including an engineer.
This metro line is set to open in March 2010.
Delhi Metro skipped vital quality checks
The inquiry report into the July 12 incident at the Metro construction site in Zamrudpur is a damning indictment of the way Delhi Metro Rail Corporation (DMRC) has been cutting corners to meet deadlines, or even stay ahead of them.
What DMRC made public on July 28 omits critical observations and conclusions in the report that put a huge question mark over DMRC's functioning and safety of the structures it has built.
A shocking observation made by the inquiry committee on the reasons for collapse of the concrete girder resting on Pier-67 — TOI has a copy in its possession — is that the drawings followed for construction of the pier were just ‘‘advance copies’’ which were ‘‘not authenticated by DMRC’s design section’’.
Much more disturbingly, the report states, ‘‘on occasion, work commences without ‘Good for Construction’ signed drawings to avoid delay in construction; at a later stage the project team authenticates the calculations/drawings with DMRC’s designers. In case of Pier-67, authenticated designs are yet to be finalised.’’
In many cases, checks are completely bypassed, says the report. Not all designs prepared by the contractors in ‘design and build contracts’, common in Phase II, are checked by DMRC’s design team. The report says ‘‘DMRC’s design cell is not equipped to proof-check each and every submission in detail though they generally check designs of critical items.’’
The callousness of DMRC is even more evident in the bypassing of seismic checks. The inquiry committee found that a seismic analysis that was required to be carried out on the viaduct (concrete portion joining piers on which the tracks are laid), in accordance with Indian Standard IRC6:2000 clause 222, was never done. This, according to the report, is a ‘‘mandatory provision to improve the performance of bridges during earthquakes in seismic zones IV and V.’’ Delhi lies in Seismic Zone IV.
The design defect in P-67 had been acknowledged by DMRC managing director E Sreedharan at a press conference. ‘‘The main top reinforcement (ssteel rods) in the cantilever (bars no 1 and 2) are not extended into the cantilever-pier joint to have the requisite overlap with the main reinforcement of the pier,’’ the report observes.
But what DMRC didn’t let out was the fact that the joint of the cantilever and Pier-67 was ‘‘not checked for integrity’’ i.e whether they were unified and strong enough. The committee found that the ‘‘minimal transverse reinforcement of the pier extends only 300mm into the joint’’.
The probe panel has, in fact, questioned the very design document based on which the pier cap for cantilevers are being constructed. The document (dated 30 December, 2008), says the report, is ‘‘a first submission which contains only crude calculations with overestimated loads which does not ensure a safe design. It does not include estimation of all loads (eg seismic, temperature etc) and their combinations to be used for design...The same has been implemented on the site.’’
That the quality of concrete used lacked strength had been made public by DMRC but the report says ‘‘the concrete fails to meet the strength criterion by a wide margin’’. It cites the reports submitted by Shri Ram Institute for Industrial Research Test House in this regard.
The panel, which submitted its report to DMRC on July 23, didn’t find any major flaws in workmanship. The members of the committee included Dr AK Nagpal, professor, department of civil engineering at IIT Delhi; Dr PR Bose, professor at Delhi College of Engineering; Steve Lowry, project director, general design (DMRC); and DMRC design head Rajan Kataria, who was later removed from the panel.
Pier-67 was cast on December 22, 2008, and the cantilever on the pier on January 28, 2009. The span between Piers 67 and 66 on this line was launched on March 28 this year. Construction work on the Metro section was stopped after engineers observed diagonal cracks on the pier cap on April 1 this year with the maximum width measured at 0.4 mm. Work was resumed three months later.
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