Eighteen piers in three different under-construction Metro corridors have been detected with cracks. While the Delhi Metro Rail Corporation (DMRC) maintained that the cracks were "minor", it is unwilling to take any chances and has directed an expert team from Shirish Patel and Associates to re-check the design of all 18 points.

"During inspection, Delhi Metro engineers have found hairline cracks on eight piers of the Central Secretariat-Gurgaon corridor, two piers on the Noida corridor, and eight on the Central Secretariat-Badarpur corridor," DMRC spokesperson Anuj Dayal said.

For now, DMRC is awaiting the final report from the consultants. Officials said corrective action will be taken once the locations are examined. While pier 67 and a couple of adjoining piers at Zamrudpur, where the recent accident occurred, will be demolished, a decision on other piers will be taken after details of design and nature of cracks are studied, DMRC officials said.

But if the piers are found with design faults and need extensive work, it might delay commissioning of the lines, DMRC officials said. Trial runs on the Noida corridor began on Saturday and the line is slated to be opened in a month's time. The Gurgaon corridor is scheduled to open in January 2010, and Badarpur in late 2010.

"But there is no reason to panic as similar testing was done during Phase-I of the construction as a precautionary measure whenever required."

CRACKS: WHERE?Noida corridor: Gammon India

Central Secretariat-Badarpur: Contractor Gammon India

Central Secretariat-Gurgaon (elevated section from Qutab Minar-Gurgaon is elevated and has cantilever structures): ITD CEM JV

(Note: contractors engaged only on sections where cracks have been found, not on entire corridor)* 100 years: estimated life of a pier * DMRC has a maintenance wing that undertakes checks for structural and operational systems on regular basis but DMRC officials maintain cracks were never noticed earlier