Indian prime minister Narendra Modi opened a vertical-lift rail bridge in the southern state of Tamil Nadu yesterday.
The 2km New Pamban Bridge connects the mainland with the town of Rameswaram on Pamban island, located in the Palk Strait between India and Sri Lanka.
It replaces a causeway built in 1914 that closed in 2022. That span had a double bascule, as used at London’s Tower Bridge.
The $640m bridge was built by state-owned contractor Rail Vikas Nigam with Spanish consulting engineer Typsa.
It has a 73m-long vertical lift section that can be raised by 17m in 5.5 minutes. While the original Pamban was India’s first bascule rail bridge, this is the first vertical lift design.
The structure is wide enough to carry two standard gauge lines, although to begin with it will have only one. This line will support trains moving at 160km/h, compared with the 10km/h that was considered safe on its predecessor.
Typsa said the new bridge must withstand a corrosive marine environment for 100 years.
To this end, it specified stainless steel and fully welded joints covered by a coating made up of a zinc base layer, an epoxy intermediate layer and a polysiloxane finishing layer. This is expected to last 50 years before requiring renewal.
The surfaces of the bridge were made as smooth as possible to reduce seawater pooling, and the height of the deck was raised 5m compared with its predecessor to avoid splashing.
The construction process had to take into account the strong currents in the strait, as well as the danger of cyclones and earthquakes.
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