PM Modi to inaugurate 5km-long, 120-year-lifespan, 3-lane-2-track, strategically important Bogibeel bridge across the mighty Brahmaputra in Assam. Here are 10 things you need to know

Prime Minister Narendra Modi will inaugurate India's longest rail-road bridge -- the Bogibeel bridge in Assam -- on Tuesday, which also happens to be the birth anniversary of former PM Atal Bihari Vajpayee under whose government construction work on the project had kicked off all the way back in 2002.

Here are ten things you need to know:

1. Location: The Bogibeel bridge is located in Assam and increases access to Dibrugarh via the mighty Brahmaputra river.

2. Length: The bridge is 4.94 km long (was revised from the earlier planned length of 4.31 km). It is Asia's second-longest rail-road bridge.

3. Lifespan and technology: An engineering marvel, the bridge is expected to have a lifespan of about 120 years and is fully welded, along European standards, thereby entailing a lower maintenance cost.

4. Functionality: The bridge will have a three-lane road on its top deck and a two-line railway track on the lower deck. The girder has a steel floor for the railway track and a concrete surface for the road. The Prime Minister will also flag off the Tinsukia-Naharlagun Intercity Express, which will run five days a week

5. Construction materials: Eighty-thousand tonnes of steel plating, including 35,400 tonnes of steel from maharatna SAIL were utilised for constructing the bridge, plus a 1,000-tonne hydraulic jack and the use of pipelines to pump concrete.

6. Effect: The bridge will result in a significant easing of hardships for the people of the region by reducing the time and effort required to cross the Brahmaputra. Travel time from Assam to Arunachal Pradesh will be reduced to four hours as a 170km detour via Tinsukia would become superfluous. The Delhi-Dibrugarh train journey will also be reduced from 37 hours to 34 hours.

7. Strategic Importance: The bridge also has strategic importance and is likely to play a crucial role in defence movement along the India-China border in Arunachal Pradesh. Travelling from the furthest-most point on India's border with China will be shortened by several hundred kilometres. It will facilitate swift movement of forces and equipment, and in case of emergencies, fighter jets can land on it. 

8. Origins: The foundation stone for the project was laid by former PM HD Deve Gowda on January 22, 1997, while work began on April 21, 2002, when Atal Bihari Vajpayee was Prime Minister. The UPA  government had declared the construction of the bridge as a National Project in 2007, thereby assuring the availability of funds for speedy construction.

9. Cost: Construction of the bridge cost Rs 5,960 crore versus an estimate of Rs 3,230 crore.

10. In the North-East plan: The Bogibeel bridge is part of a number of infrastructure projects planned 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

(With agency inputs)