200 bridges, 19 tunnels for Dimapur-Zubza railway line
Eastern Mirror Desk
Dimapur, Sep. 11: The ongoing construction of the Dimapur to Zubza railway line, known as the new broad gauge (BG) Line under the Northeast Frontier Railway (NFR), is slowly but surely getting underway as engineers and labourers have been working round the clock for the project which is expected to be completed by 2021.
The Deputy Commissioner (DC) of Dimapur, Kevekha Kevin Zehol along with Extra Assistant Commissioner (EAC) of Chümoukedima, Thejavizo Nakhro and other officials visited the site of the ongoing construction of a bridge and tunnel near Kukidolong (Khuokhi River Bridge) on September 11. The DC inaugurated the construction of ‘bridge 88’ at Kukidolong which will connect with “Tunnel No. 3”.
The tunnel is said to be approximately 824 metres long. An engineer at the site told Eastern Mirror that there will be 19 tunnels and 200 bridges along total length of the railway line. The railway line, which will be around 82.3 km, is expected to be completed in three phases.
“By December 2019, 17 km is expected to be completed as the first phase, 17-44 km by December 2020 as second phase, and 44-82.3 km by December 2021 as third phase,” the engineer informed.
The engineer mentioned that one of the biggest challenges faced while constructing the bridge and tunnels, was the issue of adverse soil conditions. “We are encountering soft soil in almost all locations which makes it very difficult to move at a fast pace,” the engineer said, adding that instead of blasting certain areas with detonators, excavators are being used instead.
“We are blasting off certain areas in small magnitudes but it isn’t helpful as the soil is soft,” disclosed the engineer. He further informed that the mountains along the sites contain ‘stale’, which is a type of clay becomes very sluggish and gives a muddy texture when mixed with water.
The engineer informed that due to this problem, the method of the New Austrian Tunnelling Method (NATM) has been incorporated for the tunnels. He said that the main idea was to use the geological stress of the surrounding rock mass to stabilise the tunnel itself.
It was also reported that ‘aquifer’, a body of permeable rock which can contain or transmit groundwater, is also hampering the progress of the work. While digging the soil, water flows through such layers which turn the tunnel road soggy, making it difficult for workers and vehicles to move about, he said. Boring pipes are drilled on top of the tunnel to puncher the water pockets, he added.
Apart from poor geological conditions, another engineer revealed that the unfavourable weather is also a big hindrance. “The weather makes it very difficult to work throughout (the year) as we can work properly (sic) only for 5-6 months; but we are trying our best,” said the engineer.
The longest tunnel will be located at Chaphema and is informed to be 6.4 km long. Tunnels alone will cover 26 km of the entire railway line.
Led by the NFR and several railway construction companies, the project began in March this year and is expected to be completed by 2022.
The new BG line will take off from the existing rail line at Dhansiri railway station in Karbi Anglong district in Assam, 19 km short of Dimapur, and will reach Zubza, which is 16 km short of Kohima.
This new line will have a speed of 100 kmph and will touch Dimapur and Kohima districts of Nagaland. According to the NFR, the railway line project has been allocated INR 500 crore in the recent Railway Budget 2019-20.