Use of crane to support metro reinforcement cage could have avoided collapse of structure: IISc expert

Meeting likely next week to discuss investigation outcome and safety measures that need to be followed during construction of huge pillars

The Indian Institute of Science (IISc) expert, who has completed the investigation into the collapse of a metro reinforcement cage, which claimed the lives of mother and her two-year-old son, said the incident could have been averted had the structure been supported with the help of a crane or through other safety measures.

J.M. Chandra Kishen, the expert from the Civil Engineering Department of IISc, is likely to hold a meeting with the higher-ups of the Bangalore Metro Rail Corporation Limited (BMRCL) next week to discuss the outcome of the investigations and safety measures that need to be followed during construction of huge pillars in the coming days.

The accident happened on January 10 near HBR Layout. The construction of the pillar was part of ORR-Airport metro line of Namma Metro project. The BMRCL is constructing a 55 km elevated line from Central Silk Board to Kempegowda International Airport (KIA) via K.R. Puram, Nagawara and Hebbal.

Prof. Kishen told The Hindu, “The reinforcement pillar that collapsed was 18 metres tall. The steel bars are manufactured in 12 metre length, which means they have to lap steel bars (connecting one rod to another). While doing this, to provide stability to the weak links, guy wires are used, which they have put for reinforcement structures that collapsed. The bar benders do reinforcement tying by using scaffolding. Once they are done with the work, they have to remove the scaffolding to create space for column boxes.”

“But while removing the scaffolding, the stability of the reinforcement cage gets distorted. They should have provided a proper support system for the reinforcement cage with the help of a crane or so, which was not done. This resulted in the slow bending of the reinforcement cage putting pressure on the guy wires. One of them got cut and eventually the structure collapsed on the road,” he further explained.

After the incident, the broken reinforcement structure was held by a crane. The weight of reinforcement ranges from 10 to 12 tonnes.

“In the report, I have spelt out reasons for the collapse of the under-construction structure based on the data collected and analysis made. To prevent such incidents, suggestions have also been made about enhancing safety mechanisms that need to be taken in the process of constructing the tall metro pillars or special structures. The need for training engineers, especially when they are new to the construction of such special structures, on safety and making them face examination on safety protocols is also stressed. We are constructing the metro pillars on the roads that carry traffic; there is movement of people nearby the construction sites. Considering these factors, several suggestions have been made,” Prof. Kishen said, adding that there is a need for employing construction workers having expertise in constructing these kinds of tall structures, training workers and making them aware about the safety guidelines in the local languages.