Experts to monitor metro pillar for 30 days

Experts from IISc will monitor the “health” of pillar 155 near Trinity Metro Station for 30 days from January 1 to ensure that the structure will remain safe as per the global standards.

Prof Chandra Kishen J M from Indian Institute of Science, who inspected the repair work on Sunday evening, declared that the structure remains safe. But they will keep a tab on it for a month to ensure that its integrity remains uncompromised.

“We have been involved in the repair work to avert the possibility of a crack in any part of the structure due to the strain put on it during the lifting of the viaduct. This includes the crossbeam, which had developed honeycomb (gaps in concrete). High-pressure grouting (filling of concrete) has been done to reinforce the strength of the damaged part,” he said.

He said 27 censors, called Electrical Resistance Strain Gauges, have been installed on the affected structure. “The viaduct has been lifted for grouting work. It takes 24 hours, for the epoxy material (concrete) to harden, the viaduct will be lowered. Each gauge has been installed on a critical part of the structure and will help us track the strength of the structure,” he said.

Trial run

Led by Kishen, a team of research scholars is working in tandem with officials from the Bangalore Metro Rail Corporation Limited (BMRCL) to ensure that the pillar returns to the ‘design condition’.

“Once the viaduct is lowered. The experts will examine the strength of the repair work once again. After their approval, the rails on the viaduct have to undergo refitment. After the track is ready, we will conduct a trial run on Monday evening,” a BMRCL official said.

Asked about the reason for the defect, the IISc professor said honeycombing in concrete structures was a common feature.

“It’s a two-metre deep crossbeam, where the concrete has not been compacted properly. It’s a kind of construction defect that should have been rectified in the construction stage itself,” he said.

Meanwhile, BMRCL Managing Director Ajay Seth has asked the IISc experts, who are monitoring the design work on Phase 2, to come up with measures to further improve quality control mechanism in Namma Metro.