Closingthe gaps
India has been on a bridge-building mission, speeding up city commutes, boosting border defences, offering hope in areas long ignored. Here are some of the biggest projects
The way Vinay Gupta, president of the Indian Institution of Bridge Engineers, sees it, Independent India is living through its golden age of bridge-building. In the last two decades, we’ve dreamed bigger than ever. The country’s longest bridge, the 9.1-km Dhola-sadiya, opened in 2017, linking Assam and Arunachal Pradesh and allowing troops to smoothly reach the border with China.
With construction over Kashmir’s Chenab Valley in full swing, we’ll soon operate the world’s highest railway bridge. In Tamil Nadu, a section of Pamban’s new sea bridge will rise, like an elevator, so ships can pass beneath.
Building a bridge is not easy in India. The rivers change course, seas swell in the monsoon, states such as Kerala and Goa have several water bodies, complicating construction, Jammu’s mountains are quake-prone, the subsoil in Assam is different from that in Kerala. “What worked in one place will not necessarily work in another,” says Gupta. “You have to innovate from the bottom up.”
India has stumped engineers since the colonial years. Our rivers were wider and wilder than those in England. Piers would sink into the silt. Well-style foundations were developed especially for India, in which cylinders of brickwork would be sunk deep into the sand until they hit rock. Over these well clusters, piers could stand firmer, allowing iconic structures such as the old Naini Bridge in Prayagraj, Uttar Pradesh, to stand.
More recently, builders have found a way to compress concrete with high-strength steel wire. The resulting pre-stressed girders can withstand more pressure better. “It cuts building time; you can do it on site,” Gupta says. Combine them with a design in which a central tower connects cables that hold up the bridge deck, and it becomes possible to build longer, sturdier bridges, such as Mumbai’s sea-link, that hold up against wind and tide too.
Regardless of where they’re built, India’s bridges are connectors in more ways than we realise. When remote villages get a tangible and weather-proof link to cities, opportunities, markets and ambitions expand. Neighbouring districts, once so distant and strange, are suddenly an hour’s drive away, and not so different after all. Troops can reach conflict zones faster. Often, residents become tourists in their own states. And everywhere, a bridge sends out the message that movement matters; that getting somewhere is worth it.
India’s bridge-building spree is linking even those who’ve never travelled on them. When pictures of the Chenab valley bridge, went viral this year, Kashmir felt closer even to those in Mumbai and Chennai. With the closure of the Lakshman Jhula in Rishikesh comes news that a new glass-bottomed bridge will be built further up the Ganges. Every bridge we build near our borders sends the message that we’re serious about defending our territory.
“It’s a golden age in terms of how quickly we’re learning too,” Gupta says. India’s milestones have piled up quickly, largely because India is learning from China, West Asia and the US, which are building the world’s longest and most-advanced bridges. They’ve innovated to create new techniques to locate damage while a bridge remains in use. Drones fly over sites, using infrared thermography to identify problem areas. The Chenab bridge uses Tekla, a sophisticated AI program that analyses existing data and usage projections to create a speeded-up simulation, anticipating errors and damage even before they occur.
“India’s bridges are beautiful, many of them created against great odds,” Gupta says. “People travel over them every day, never realising their role in holding India together.”