Pier No 67 in Zamrudpur was not the only one to have developed cracks. At least two more piers, no 66 and no 68, too had cracks and the Delhi Metro Rail Corporation (DMRC) decided to support the cantilevers —extended projection on the piers — with steel struts.
The cantilever on Pier No 67 — in the under-construction section of the urban village on the 20-kilometere Central Secretariat to Badarpur line — collapsed under the weight of the pre-cast segment and the launcher .
The mishap killed six people.
Sources in DMRC said the fact that three of the five cantilever piers on that curve had developed cracks indicated that there was a problem with the design of the piers. But how the design was approved by DMRC and why pre-cast segments were being put on them despite the cracks were questions that remain unanswered.
DMRC spokesperson Anuj Dayal said he had no knowledge about the cracks on the other two piers.
“In any case, we have already ordered review of all the piers,” he said.
DMRC formed a four-member inquiry committee to look into the possible causes of the accident.
Gammon India, the civil contractor, also formed a two-member internal committee on July 17. Nuclear scientist V.K. Sharma, president (Operations), Gammon India Ltd and SA Reddi, former deputy managing director of Gammon India, are part of the committee.
While the DMRC managing director E Sreedharan has accepted a design failure, no action has been taken so far against the people who were responsible for preparing the design and approving it.
“The design of the pier was prepared by Arch Consultant who were chosen by the contractor from a list of 10 consultants with detailed design who were pre-qualified by DMRC,” said a DMRC official.
The official said while the consultant was chosen by the contractor, DMRC approves the design.
The consultants were also responsible for suggesting that struts be put to support the cantilevers on the piers that had developed cracks.
DMRC chief engineer (design) Rajan Kataria, who is part of the DMRC probe committee, approved the strut design.
A senior DMRC official said if the design had failed, Kataria should have been grounded for approving the design.
DMRC spokesperson Anuj Dayal defended the decision to have Kataria in the committee and said it was still not certain if the accident was caused by a design failure. “Kataria is an experienced engineer and working as a convenor in the inquiry committee,” said Dayal.
He also said any action against the consultant would be contemplated only after the inquiry panel submitted its report.
Sanjay Jain and Rajeev Ahuja of Arch Consultants could not be contacted despite several calls to their mobile phones, office phone and a personal visit to their office in Rohini.