Metro authorities may have dismissed as minor the flaws in the civil structure of the Airport Express Link, but only four days ago they had found a fault at pier No 17, which was dangerous enough to have caused derailment.
"During inspections on Tuesday, the DMRC had identified the line's most critical point and observed that grouting of one bearing on the pier had been disturbed completely and could have caused derailment," a source said.
The DMRC on Saturday started repairs on the pier opposite Buddha Jayanti Park on Ridge Road. A source at the site said: "The bearings are in bad shape and need immediate replacement."
This is the stretch on which trains run at the lowest speed of around 15kmph, said sources.
The DMRC has informed the Delhi Airport Metro Express Pvt Ltd (DAMEPL) about its findings in a letter on the same day.
Metro chief Mangu Singh said on Saturday: "There are some minor problems on the stretch and would be rectified soon."
However, sources claimed that the DMRC had made repeated requests to the DAMEPL, the concessionaire company, to identify the spots where bearings required replacement or repairs.
"We have told the DAMEPL that in case further deterioration was noticed, the speed restriction should further be reduced. But they had decided to suspend the service temporarily," an official in the project section in the DMRC said.