Bogibeel bridge: Amazing! India's longest rail-road bridge has massive lifespan

Bogibeel, Asia's second longest rail-cum-road bridge that will be opened to traffic by Prime Minister Narendra Modi on Tuesday, has a serviceable period of around 120 years, senior officials said here. 

The 4.9 km-long Bogibeel Bridge on the Bramhaputra river is India's only fully welded bridge for which european codes and welding standards were adhered to for the first time in the country, said Chief Engineer Mohinder Singh. 

Singh said a fully welded bridge has a low maintenance cost. The bridge, constructed at an estimated cost of Rs 5,900 crore, has a "serviceable period of around 120 years", he said.

The bridge reduces travel time from Assam to Arunachal Pradesh to four hours and will cut out the detour of over 170 km via Tinsukia. 

It will also reduce Delhi to Dibrugarh train-travel time by about three hours to 34 hours as against 37 hours presently.

Modi will open the bridge to traffic, 16 years after it was announced by then prime minister Atal Bihari Vjpayee.

The bridge has a two-line railway track on the lower deck and a three-lane road on the top deck. For the first time in Indian Railways, the girder has steel floor system for railway tracks and concrete for road.

"Early flood in the river Brahmaputra restricted the working season to a very short period of approximately five months (from November to March) and demanded huge mobilization of construction equipment," said Singh.

Transportation of concrete across river channels of 600 metre to 900 metre width from both the north and south banks was the biggest challenge, he said. 

To overcome this, concrete was pumped through pipeline laid over buoys. "Eighty-thousand tonnes of steel plates was delivered for the project via a combination of rail and road transport, while a 1,000 tonne hydraulic jack and strand jacks linked with the substructures were used for moving steel truss over the pillars," he said. 

'Most 2D' automatic nesting software was used to generate efficient two-dimensional cutting plans for fabricating the steel superstructure for the bridge.

After December 25, people, especially patients from Assam Medical College located here, can travel straight from Dibrugarh from the other side of the river instead of using the ferries. 

The bridge is part of infrastructure projects planned by India to improve logistics along the border in Arunachal Pradesh. This includes the construction of a trans-Arunachal highway on the north bank of the Brahmaputra, and new road and rail links over the mighty river and its major tributaries such as the Dibang, Lohit, Subansiri and Kameng.