The stiffest challenge so far is the construction of guide bunds on the turbulent Brahmaputra River within the short time of four to five months a year because of the rainy season and flood, a top official of the Northeast Frontier Railway said. (Agencies)
"Construction of guide bunds has been the most challenging task of this project as it has to be completed up to the safe level during the very short working period of four to five months," NF Railway General Manager, Construction RK Singh.
Singh said that early flood in the river restricts the working season to a very short period of approximately five months, from November to March only.
"It demands huge mobilization of equipment for execution of the massive work of the project," Singh explained.
Another major challenge is transportation of concrete across river channels of 600m to 900m width from both the banks. However, it has been overcome by adopting pumping of concrete through pipeline laid over buoys with multiple concrete pumps, he says.
"The width of the river at the alignment location of the bridge was approximately 10:30 km. Approach embankments inside the dyke up to the abutments of the bridge were constructed before placing the guide bunds at the approaches of the bridge," the railway official said.
The 4.94 km bridge, stated to be the lifeline of the North-East, will facilitate connectivity between north and south banks of the Brahmaputra in the eastern region of Assam and Arunachal Pradesh.
Situated 17 km downstream of Dibrugarh city, the bridge is being constructed for double line broad gauge track and a three-lane road, Singh said.
The national security of the country's Eastern region would also be further strengthened after commissioning of the bridge, he added.
The bridge was sanctioned in 1997-98 and its foundation stone was laid by former prime minister AB Vajpayee on April 22, 2002.
The pace of work picked up after the bridge got the status of a national project in 2007.
The project consists of construction of the bridge with 74 km rail link connecting the existing rail network and 29.5 km of road link as NH-52B from south bank to north bank.
The bridge will have 42 piers out of which 37 piers have been completed.
The rail link across the bridge will connect two existing railway networks running at south bank and north bank of the river with the present meter gauge railway network at north bank side undergoing conversion into broad gauge.
It starts from Chaulkhowa station and Moranhat station in south bank and joins in between Sisibargaon station and Siripani station of Rangiya-Murkongselek section at north bank.
Singh said that the bridge was designed to have a two-line railway track on the lower deck and a three-lane road on the top deck with the girder for the first time in the Indian Railways to have a ‘steel flooring system’ for railway and ‘welded steel truss composite’ with concrete deck for road on top.
He said that the existing dykes on both banks of the river to protect the areas in its vicinity from flood had also been strengthened and raised as per the model study done at Irrigation Research Institute, Roorkee.
The latest projected date of completion of the bridge is June, 2017 and the estimated cost would be Rs 4,996.19 crore.
The stiffest challenge so far is the construction of guide bunds on the turbulent Brahmaputra River within the short time of four to five months a year because of the rainy season and flood, a top official of the Northeast Frontier Railway said.