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Tunnelling on Dhansiri-Zubza rail line begins at Chümoukedima village

Tunnelling on Dhansiri-Zubza rail line begins at Chümoukedima village
Ongoing tunnelling work at Kukidolong area, Friday. (NP)
Staff Reporter DIMAPUR, JUN 7 (NPN) | Publish Date: 6/7/2019 12:25:49 PM IST

As part of the Central government’s ambitious plan to connect all State Capitals with rail-head, tunnelling on the hilly area from Chümoukedima till Zubza began with the first tunnel dugout at Chümoukedima village on Friday. The 72-metre tunnel was dug using the conventional method of tunnelling using a hydraulic hammer attached to the tip on an excavator.

The proposed new rail route by Northeast Frontier Railway (NFR) in Nagaland will cover 82.3 km from Dhansiri to its terminal station at Zubza. Work for the project began in March this year and the arduous and long-drawn task of tunnelling, building numerous bridges and laying tracks is expected to be completed in two years.  

The 82.3-km stretch will have 20 tunnels spanning 26 km, besides 19 major bridges. The longest bridge to be built at Sirima village is estimated to be 700 meters long, while the longest tunnel measuring 6.4 km will be dug at Chaphema village. Once operational, the railway route will pass through Dhansiri-Dhansiripar-Shoxuvi-Molvom- Sirima- -Chephema-Khabvuma before culminating at Zubza, which is around 900 metres above the plains of Dimapur. 

An official from NFR explained that a railway station at Kohima was not feasible as it was situated around 1,444 metres above sea level, “too steep for a rail head”, adding that there was also the lack of space. He also informed the media that the route from Dhansiri to Shoxuvi was expected to be operational by December this year.

On Friday, Nagaland Post visited two sites where tunnelling was underway and another site where the next tunnel would soon be drilled. While the drilling for a 72-metre tunnel at Chumoukedima village was completed on Friday, drilling for a much longer 824-metre tunnel is currently underway near Kukidolong. A longer tunnel (3 km) from Chumoukedima village to New Chumoukedima will be drilled next.

The exaction method currently employed at Kukidolong is the New Australian Tunnelling Method (NATM), a method that is believed to have revolutionized modern tunnelling industry and currently used in many modern day tunnels. Also dubbed as the “design as you go” approach, NATM is based on the study of behaviour of rock masses under load and monitoring performance of underground rocks during construction. 

NFR has incorporated state-of-the-art machinery for its drilling with an imported boring machine from Switzerland.

Keeping in mind safety of the workers, NFR is in consultation with Geological Survey of India (GSI) to understand the landslide patterns and history on the routes. Also taking into account the constantly shifting tectonic plates and fault lines that can develop over a period of time, conscious effort is being made to ensure that the route is perpendicular and not along the tectonic plates.

The NFR official explained that unlike Rishikesh where rocks were blasted during excavation, the soil in Nagaland was primarily of stale soil or mud stone, as referred by geologists, which made tunnelling a difficult task as the soil easily absorbed water, making it slippery and thereby also increasing risks of landslides. This nature of the soil also increased the pressure on the walls of the tunnels, he added.

Another challenge is water pockets that can cause seepage during excavations. Taking cognizance of these challenges, engineers at the site have embedded pressure cells along the inner walls of the tunnel to check for increase in weight.

The NFR official claimed that contractors were determined to finish the project within the stipulated time. There are also currently no major hurdles except for the earth cutting and filling that had to be halted in Pherima due to the monsoon. The biggest hurdle so far had been the land ownership dispute in Sirema, though compensation had not been a problem, the official added.

 

Launched on December 3,1990. Nagaland Post is the first and highest circulated newspaper of Nagaland state. Nagaland Post is also the first newspaper in Nagaland to be published in multi-colour.

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