Metro reinforcement cage collapsed due to weak joints, says IISc report

BENGALURU: A team of the Indian Institute of Science (IISc), which studied the Metro pillar collapse near Nagawara, has found fault in the construction method adopted by the Bengaluru Metro Rail Corporation Ltd (BMRCL). The IISc has submitted a 27-page detailed technical report to BMRCL on the collapse of the reinforcement cage of an under-construction Metro pillar 10 days after the incident.

Professor Chandra Kishen from IISc said, “We have taken the test report on the quality of steel, sand and cement, which are used for the construction before starting the inspection of the construction. We had also taken reports on the quality of crusher stones and the soil”.

Prof Chandra Kishen of IISc said there is fault in construction method that was adopted by BMRCL.

“We have submitted a detailed report after analysing the incident. The Metro pillar collapsed due to poor joints in the middle. The 18-metre-tall pillar cannot be built at one stage. A normal steel rod is 12 meters long, and since the pillars are 18 metres tall, they join the steel rods. The entire weight falls on the guy wires, and if the cage bends where the rods are joined, two of the guy wires will slacken and the entire weight of the reinforcement cage will fall on the remaining two guy wires, which they cannot support. Hence, the cage collapsed. If they have used a box structure to support the reinforcement cage, it could have been better”, he added

Some Of The Findings of the Study:

The pillar collapsed due to the weight of the iron rods.

Supporting boxes could have been used to hold the cage in place along with guy wires.

Crusher stones, cement for the work are of good quality

Managing Director of BMRCL, Anjum Pervez said on Saturday, “I have not yet see the IISc report as of now. We have suspended three BMRCL officicers and derostered three NCC employees. We have asked IISc to suggest precautionary measures so that such incidents do not recur and we are also training our engineers. We have removed all pillars which are over 12 metres tall and we will continue the work on the advise of IISc. We will bring changes on the SOPs”.

MD of BMRCL Anjum Pervez said, experts are training BMRCL engineers on new construction techniques.

The second phase of Metro work on the Gottigere-Nagawara and RV Road- Bommasandra lines is going on in full swing. Also, the third phase of the work has received the green signal and preparations are under way.

Technical experts are training the Metro engineers on safety and technical aspects during construction and how to carry out the project during pillar construction and civil works. They will also impart knowledge on the height of pillar be raised during construction and supporting structure. Engineers have also been directed to inspect the site during Metro work.