The 6km-long steel-built Padma Bridge is a game-changer for Bangladesh, connecting 21 southwestern districts to the capital of Dhaka and boosting the country’s economy.
The Padma River is a sprawling major distributary of the Ganges, which originates in the Gangotri glacier in the Himalayas before flowing through India into Bangladesh and emptying into the Bay of Bengal.
One of the most frequented waterways in the world, the Padma has a very wide riverbed which splits in multiple channels dotted with shifting islands and sand banks. While traversable all year round, the rainy season makes it increasingly difficult for river vessels to navigate.
During heavy downpours this could essentially isolate Bangladesh’s entire southwest from the nearby capital and the rest of the country for all but the bravest and most skilled of travellers.
With this in mind, the Bangladeshi government embarked on a massive infrastructure drive to ensure safe, year-round crossing of the Padma, as well as connecting road and rail networks to improve access to and from the southwest.
Making connections with steel
Constructed at a cost of $3.6bn, the Padma Bridge is 22m wide and 6.15km long, making it the longest spanning the Ganges. It comprises a two-level steel truss bridge that supports a four-lane highway on its upper level and a single-track railway on its lower.
The bridge doesn’t just provide rail and road connections, it also carries vital utilities, with telecommunications lines and stainless steel high-pressure gas pipes fitted along its length. There are even plans for the bridge to house seven 400kv steel-latticed interconnector towers so that it can carry electricity.
Padma Bridge is a triumph of steel-built engineering that is expected to add between 1-2% to the country’s GDP
The bridge’s structure is made up of 41 connecting spans of 150m in length. These are supported on 42 piers whose foundations are formed of 262 high-strength steel piles. These 3m diameter steel tubes are driven up to 100m into the earth so that they can support the bridge’s massive length as well as the weight of road and rail traffic.
This steel core means that the piers and their foundations are able resist every conceivable strain, from liquefaction of the riverbed to impacts from river vessels, all the way up to earthquakes – a vital aspect in seismically active Bangladesh, which sits at the at the meeting point of multiple active tectonic plate boundaries.
Representing a sea change for Bangladesh’s infrastructure, the awe-inspiring Padma Bridge is a triumph of steel-built engineering that is expected to add between 1-2% to the country’s GDP and sets a high watermark for investment.
Images: Nahian Bin Shafiq – Own work, CC BY-SA 4.0, Jubair Bin Iqbal – Own work, CC BY-SA 4.0