Opened in June 2022, Padma Bridge is Bangladesh’s longest bridge to date, spanning 3.82 miles (6.15 kilometers) over one of the largest rivers in the world. It has immensely enhanced the connectivity between the country’s southwestern region to the capital city of Dhaka via road and rail, significantly cutting travel time.
However, designing the landmark infrastructure was no easy task as it presented considerable challenges, particularly the threat of monsoons and seismic activities in the area. Dr. Robin Sham, director of global long span and specialty bridges, and our Hong Kong team accepted the challenge and was appointed as the lead design consultant of the project.
The Padma Bridge features many engineering highlights, notably:
- The longest bridge over the Ganges River by both span and total length
- A monsoon-defying, seismic-resilient and scour-tolerant bridge design
- Prefabricated 492-foot-span (150-meter) steel truss modules which act compositely with prestressed concrete deck slabs
- The longest and deepest piling among all bridges in the world
- A two-level road and heavy (freight) railway river crossing, consisting of a dual two lane carriageway on the top deck and a single-track freight railway on the lower deck
- Support of a 29.5in-diameter (750mm-diameter) gas main and fiber optic communication cables
Designed to withstand earthquakes and monsoons
To develop the advanced bridge design, Dr. Sham and the team conducted extensive engineering studies and computational analyses to determine the best approaches and materials. Tubular steel piles measuring 9.8 feet in diameter (3 meters) were driven at an angle over 400 feet (122 meters) down into the riverbed to withstand scouring around the bridge foundation from the strong currents of the river, especially during monsoon seasons. Meanwhile, friction pendulum bearings were innovatively utilized between the superstructure and the pier tops for seismic isolation. This helps mitigate the impact of earthquakes as analyses indicated that seismic forces can be greatly reduced using isolation bearings rather than conventional pot bearings.
Faster and safer travel
The railway on the lower deck of the bridge connects to the Trans-Asian Railway Route and enables cargo movement between India and the container ports at Chittagong on the south coast of Bangladesh, while land travel between 21 districts in the southwestern part of the country and Dhaka will also significantly improve. Previously, trips took 15 to 22 hours by ferry, sometimes extending up to 24 hours due to long lines at ferry stations. Severe weather conditions, fog and extreme river currents have also caused delays in the transport of people and goods, resulting in rotten produce, and other economic and social setbacks.
The direct route via the Padma Bridge is expected to reduce these problems and provide a gateway for the agricultural and fishing industries in the southwest to the Dhaka-Chattogram economic corridor. With its completion, the bridge is expected to help increase the region’s annual gross domestic product (GDP) by 2.5 percent and the nation’s overall GDP by more than 1.3 percent.
The innovative design of the Padma Bridge will not only ensure that it will withstand the forces of nature for many years to come, but will also strengthen the economic and social ties of the regions separated by the mighty Padma River.