Subway in Kolkata passes under Hoogly River after construction of 520-meter-long tunnel 

Commuters ride on a decorated coach at the newly inaugurated metro line between Esplanade station to Howrah Maidan, in Kolkata, India, March 6, 2024. (PHOTO / AP)

Indian Prime Minister Narendra Modi inaugurated India's first underwater metro services in the eastern city of Kolkata, the capital of West Bengal state, on Wednesday, marking a significant milestone for the country’s metro infrastructure.

The Howrah Maidan-Esplanade section of Kolkata Metro's East-West Corridor comprises the first transportation tunnel under any major river in India. The stretch also has the deepest metro station in the country – the Howrah station – at a depth of 33 meters. 

The underwater tunnel passes under the Hooghly River – and connects Kolkata and Howrah, situated on the river’s east and west banks, respectively. This section of the metro will reduce travel time between Howrah and Kolkata.

The under-river section of the tunnel is 520 meters long, and a train will take around 45 seconds to cross it, metro officials said. The trains will have an operational speed of 80 km per hour.

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The 4.8 km stretch of the East-West Metro between Howrah Maidan and Esplanade, built at a cost of $51 billion, is a vital segment of the East-West Metro corridor, according to an official statement.  

This stretch will boost the mass transport scenario of the region by providing a fast train connectivity. It will also solve the perennial traffic congestion and improve air quality by reducing the carbon footprint.

Kausik Mitra, Chief public relation officer of Kolkata Metro Railways 

The project has been implemented by Kolkata Metro Rail Corporation Limited, or KMRCL, under the federal Ministry of Railways.

The prime minister took a ride on a metro train from Esplanade to Howrah Maidan and interacted with school students during the journey that passed through the underwater transportation tunnel, according to a statement.

“It’s a very special day for the people of Kolkata as the city’s metro network gets significantly enhanced. Connectivity will get a boost and traffic will get decongested. It’s a proud moment that the Howrah Maidan-Esplanade Metro section has the first underwater metro transportation tunnel under any major river in our country,” Modi later said in a post on X, formerly known as Twitter.

"This stretch will boost the mass transport scenario of the region by providing a fast train connectivity. It will also solve the perennial traffic congestion and improve air quality by reducing the carbon footprint," Kausik Mitra, chief public relation officer, Kolkata Metro Railways told China Daily.

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The East-West Metro corridor starts from Sector 5 in Salt Lake, on the eastern flank of Kolkata, and ends at Sealdah at present. From Salt Lake, it will be extended to Howrah Maidan and cover a total distance of 16.6 km, out of which 10.8 km will be underground. There will be 12 stations along the entire route.

People coming from distant parts of West Bengal, as well as other states, will be immensely benefited when they use the metro services after getting down at Howrah station, Mitra said.

The railways have constructed walkways on both sides of the tunnel, which are connected to ventilation shafts every 25 meters. During an emergency, passengers can be evacuated through these shafts, Kolkata Metro officials said.

Rail authorities have installed special illumination for the inner walls of the tunnels, with blue lights, to provide a feeling of being underwater.

East-West Metro now runs 9.4km from Sector 5 to Sealdah and between Esplanade and Howrah Maidan. Work was stalled at the next 2.5 km section between Sealdah and Esplanade because of repeated incidents of subsidence. 

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This new section will soon connect Howrah and Sealdah stations, two of the busiest stations in the world, metro officials said. They said metro services will be operational along the entire stretch by October or November this year.

From north Kolkata's Shyambazar, the metro service to Howrah station takes only twenty minutes. Earlier, it took around an hour to travel this 7 km distance by bus, said Prosenjit Dasgupta, a resident of Shyambazar who took the metro ride on Wednesday.

It is a big milestone not only for Kolkata but also for the entire country, Biswanath Dewanjee, former general manager of KMRCL, told China Daily.

Commuters arrive at the newly inaugurated Esplanade Metro station in Kolkata, India, March 6, 2024. (PHOTO / AP)

The construction for the first phase of the East-West metro corridor commenced in 2009. The project suffered several delays and faced many challenges. Construction of the underwater stretch commenced in 2017 and was completed within 66 days, said Dewanjee.

Modi inaugurated and laid the foundation stone for multiple connectivity projects for various cities of the country, worth $187 billion, on the same day.

Modi inaugurated and laid the foundation stone for multiple connectivity projects for various cities of the country, worth $187 billion, on the same day

It successfully completed its trial run from Howrah Maidan to Esplanade and vice versa in April last year.

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Japan International Cooperation Agency, or JICA, is a major funding agency for the East-West Metro project.

The metro service has reduced travel time for millions of commuters and it will significantly reduce traffic congestion and improve the city's air quality as commuters will opt for this metro service daily instead of any other mode of transport, Snehasis Chakraborty, transport minister of West Bengal state government told China Daily.

It was in 1969 that the Metropolitan Transport Project was conceptualized and, after much deliberation, five separate routes were decided as Kolkata's Metro network. The network also includes the East-West Metro corridor.

Modi inaugurated and laid the foundation stone for multiple connectivity projects for various cities of the country, worth $187 billion, on the same day.

The tunnel is an important milestone in the nation’s infrastructure landscape, said G. Raghuram, a railways and infrastructure expert and former director of the Indian Institute of Management in Bengaluru.

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The experience would help in construction of more underwater tunnels in the future, and could help reshape urban mobility in the country, Raghuram added.

On Wednesday, Modi virtually inaugurated or laid the foundation stones for several other rail connectivity projects, worth some $187 billion, for various cities in India.

In 1984, Kolkata became the first city in India to have operational metro services. Metro rail lines are now available in 15 cities across the country, with the Delhi Metro covering an extensive 393 km across the national capital region.

The writer is a freelance journalist for China Daily.