All you need to know about the Mizoram bridge that collapsed, killing 23

The bridge is one of 185 bridges part of the 51.38 km long Bairabi-Sairang railway project. The piers — or columns — of the bridge had been erected at the time of the incident, which took place while one of the steel girders was being launched. The work was being carried out as a joint venture between ABCI Infrastructures Private Limited and BBJ Construction Company Limited, a Government of India enterprise, both based in Kolkata.

According to Sabyasachi De, Chief Public Relations Officer at North East Frontier Railway, the cause of the collapse is currently being investigated by a four-member committee constituted by the Ministry of Railways. A press release from the North East Frontier Railway announcing the completion of this pier earlier this year had stated that the pier was one of the “most critical parts of the project”, since it is in the middle of the river Kurung and the foundation had been built in the running stream.

The Mizoram bridge collapse

This prevalence of tunnels and bridges is typical of railway lines in Himalayan regions, explained De. “These railway lines can’t be made along the surface and the reason that a bridge that high is required is that we need to maintain a certain gradient in a railway line. Our limitation is that our gradient is fixed, and all railway lines anywhere in the world are built in a fixed gradient. In order to maintain that, all these kinds of infrastructure are necessitated. In hilly terrain, if we need to cross a low valley, then naturally a tall bridge will be required,” he said.

However, these massive structures in the hill state’s terrain are being viewed with some concern by observers. “The pillars for this railway track are being erected very high in this terrain. Here, the topography is very rugged. In terms of geology, the terrain is very unsaturated. This means the soil is soft and swells very easily because of rainfall, making it not very stable,” said Jimmy Lalnunmawia, the head of geology department at Mizoram University.

The project has been in the making for more than a decade now. However, officials said the August 23 incident is unlikely to lead to an extension in the timeline since the substructure was not damaged. The current deadline for its completion as per the Indian Railways is March 2024.

The proposal for land acquisition was submitted to the state government in 2011. The land was handed over to the Railways by early 2014 and the foundation stone laid down later that year. The Railways has cited a number of factors that slowed down the project, including long and intense monsoon; frequent landslides along access roads that stopped the movement of workers and material; the need to bring in materials from other states; the absence of local labour for heavy construction work; the shortage of workers elsewhere willing to work in the state’s hilly terrain; and COVID-19.