Tragic collapse of under-construction bridge in north east India prompts questions over methods

The bridge was being constructed near Sairang, in the state of Mizoram, as part of a project to connect it with a town further north, Bairabi.

Northeast Frontier Railway, which operates the railways in the zone of India where the incident occurred, stated an inquiry committee had been established to investigate what caused the failure.

Independent bridge consultant Richard Fish believes attention will have to be paid to the methods of construction used for the bridge.

He said: “Although the bridge seems to have been a fairly conventional truss design, attention will need to be given to the method of construction which appears to have been launching from one abutment.

“In which case, loads in some of the truss members in the launching condition are likely to be much higher than in its permanent state, even under live load.”

Although Fish is happy to see an inquiry has been launched, he believes a wider study of the construction culture apparent in India is needed.

He continued: “It is good to see that another investigation has been promised but, as well as the site-specific details, it really needs to look into the wider design, construction, and safety culture in India as this seems not to be an isolated incident, looking at the record of bridge collapses in the last few years.”

The second collapse in just over a year of a £170M bridge over the River Ganges in India this June, in which fortunately nobody was injured, was a stark reminder of the need to follow safe working practices in all phases of a project. The October 2022 collapse of a pedestrian bridge in Morbi, India, which killed 135 people was found to be a dereliction of duties by the local authority as it had not taken care of the bridge maintenance contract and left it to a local electronics company. The authority was dissolved following an investigation into its failures.

A similar tragedy occurred in Bangkok, Thailand in July when an under construction road bridge collapsed, killing two.

UK bridges board chair Hazel McDonald believes there are many questions that needed to be answered where the Sairang bridge failure is concerned.

She said: “My first thoughts are, apart from the tragedy of lives lost and serious injuries, were the temporary load cases that the structure would experience during construction adequately considered in the design? Were the materials as specified and was the construction following the agreed plan and method statements?

“Suitably qualified and experienced people must undertake the design and checking, ensuring all the temporary and permanent load cases are identified. If this is the case then it could be a problem with supervision, a problem with the quality of materials or a failure in the agreed construction methodology.

“Whatever has happened, the collapse has to be thoroughly investigated and the conclusions shared with the international bridge community.”

In May of this year, Northeast Frontier Railway celebrated the completion of the tallest pier for the bridge in the approach of Sairang station. It is 104m tall and hollow.

The Bairabi – Sairang New Line Railway project was aimed at connecting the state of Mizoram to the rest of the country by rail with 51km of line planned to be installed.

Northeast Frontier Railway believes the construction of the railway “will mark the dawn of a new era in terms of communication and commerce” in the north-eastern region of India.

Indian Prime Minister Shri Narendra said: “Pained by the bridge mishap in Mizoram. Condolences to those who have lost their loved ones.

“May the injured recover soon. Rescue operations are underway and all possible assistance is being given to those affected.”

Northeast Frontier railway, meanwhile, is completing the world's tallest pier railway bridge in Noney, Manipur.

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