Source: https://www.financialexpress.com/business/railways-project-connecting-sikkim-to-railway-network-for-the-first-time-hits-major-milestone-only-9-of-project-is-on-ground-key-details-inside-3463153/
Publisher: Financial Express
A significant development has been seen in the Sivok-Rangpo Rail Project which is to connect Sikkim to the railway network for the first time. The project has seen the construction of an 855-metre-long emergency exit tunnel.
Where is the tunnel situated?
As per the officials, a 20-metre section of the tunnel is running under National Highway-10, along the Teesta river. The most challenging part of the whole project was mining through the soft and loose soil due to the high risk that it might cave in. Such an incident would have hit Sikkim’s road connectivity with the rest of the country.
NH-10 is the only road network that connects Sikkim with other parts of the country.
Ircon International is constructing the project. An official from the firm said, “It was a huge challenge for us to mine a tunnel 18 metres below the highway, because the soil is very soft and loose, just like the river sand bed (fine to coarse-grained), with alternate bands of pebble, cobble and boulders.”
Talking about the challenges of the project, the official said that mining only for a 20-metre distance, the width of NH-10 including the impact areas on both sides along the highway, has been the hardest part so far.
“We completed it successfully, without causing a single millimetre of deformation to the highway,” the official added.
Which method was used in the process?
The Railway officials have revealed that they used the rarely-seen method called secant-piling method. Following verification by the Indian Institute of Technology (IIT), Ircon officials compiled a case study detailing the innovative aspects of the mining operation.
Sivok-Rangpo Rail Project
The SRRP project spans a length of 44.96 kilometres between Sivok in West Bengal and Ranpo. It will have 14 tunnels, 22 bridges, including 13 major and nine minor. It also has five railway stations, namely, Sivok, Riyang, Teesta Bazar, Melli and Rangpo.
As per an official, the work on 10 of the 14 tunnels has been completed and the other four have seen the completion of the lining work. The project’s longest tunnel is 5.4 kilometres, while the shortest one is 538 metres.
“Of the 13 major bridges, 12 are ready with the substructure. The maximum height of the pier (of Bridge-17) is 85 metres, constructing which was itself an uphill task. The most demanding aspect of the project is that 86 per cent of the total rail line passes through tunnels and 5 per cent over bridges,” the official said.
They further said that only 9% of the project is on the ground.
The Indian Railway has set a new target of August 2025 for completing the Sikkim Rail-Road Project (SRRP), which will establish connectivity between Sikkim and the rest of the nation via the railway network for the first time.
