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Kolkata Metro

Rapid transit system in Kolkata, West Bengal, India

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The Kolkata Metro was initially planned in the 1920s, but construction started in the 1970s. The first underground stretch, from Bhawanipore (now Netaji Bhawan) to Esplanade, opened in 1984. A truncated section of Green Line, or the East–West Corridor, from Salt Lake Sector V to Howrah Maidan, was opened in 2020. Purple Line, or the Joka–Eden Gardens Corridor (currently truncated in Majerhat), opened in 2022, Orange Line, from Kavi Subhash to Beleghata, opened in 2024. The Yellow Line, from Noapara to Jai Hind, opened in 2025.

As of 2025, the Kolkata metro has the deepest metro station and largest underground metro station in India. Howrah metro station of the Green Line is the deepest metro station in India with depth of 34 m (112 ft). Also at the time of inauguration, it was the largest metro station of India. In August 2025, Jai Hind metro station of the Yellow Line became the largest metro station in India, as well as one of the largest in Asia.

Metro Railway, Kolkata and Kolkata Metro Rail Corporation are the owners and operator of the system. On 29 December 2010, Metro Railway, Kolkata, became the 17th zone of the Indian Railways, completely owned and funded by the Ministry of Railways. It is the only metro system in the country to be controlled entirely by Indian Railways. Around 300 daily train trips carry more than 800,000 passengers.

History

Early attempts

In the September 1919 session of the Imperial Legislative Council at Shimla, a committee was set up by W. E. Crum that recommended a metro line for Kolkata (formerly Calcutta). This line was supposed to connect Bagmari in the east to Benaras Road, Salkia, in Howrah in the west via a tunnel beneath Hooghly River. The estimated construction costs were £3,526,154, about ₹36.4 crore (equivalent to ₹77 billion or US$800 million in 2026) based on current exchange rates, and the proposed deadline was 1925–1926. The proposed line was 10.4 km (6.5 mi) long, about 4 km (2.5 mi) shorter than the current Green Line, which would connect East Bengal Railway in Bagmari and East Indian Railway in Benaras Road. The tickets were priced at 3 annas (₹ 0.1875) for the full trip. Crum also mentioned a north–south corridor back then. An east–west metro railway connection, named the "East–West Tube Railway", was proposed for Kolkata in 1921 by Harley Dalrymple-Hay. All the reports can be found in his 1921 book Calcutta Tube Railways. However, in 1923, the proposal was not undertaken due to a lack of funds.

Planning

Then the Chief Minister of West Bengal, Bidhan Chandra Roy, reconceived the idea of an underground railway for Kolkata from 1949 to 1950. A team of French experts conducted a survey, but nothing concrete materialised. Efforts to solve the traffic problem by augmenting the existing fleet of public transport vehicles hardly helped, since roads accounted for only 4.2 percent of the surface area in Kolkata, compared with 25 percent in Delhi and 30 percent in other cities. To find alternative solutions, the Metropolitan Transport Project (MTP) was set up in 1969. The MTP, with the help of Soviet specialists, Lenmetroproekt and East German engineers, prepared a master plan to provide five rapid-transit (metro) lines for the city of Kolkata, totaling a length of 97.5 km (60.6 mi), in 1971. Three were selected for construction:

  • Dum Dum – Tollygunge (Blue Line. Presently operates from Dakshineswar to New Garia.)
  • Bidhannagar – Ramrajatala (Green Line. Presently truncated till Howrah Maidan.)
  • Dakshineswar – Thakurpukur (divided into Blue Line: Noapara to Dakshineswar and Purple Line: Joka to Eden Gardens)

The highest priority was given to the busy north–south corridor between Dum Dum and Tollygunge over a length of 16.45 km (10.22 mi); work on this project was approved on 1 June 1972. A tentative deadline was fixed to complete all the corridors by 1991. Though the idea of an underground railway in Calcutta was first explored during the British era and later envisioned by Dr. Bidhan Chandra Roy, the then Chief Minister of West Bengal, it was ultimately Shri Siddhartha Shankar Ray who transformed the dream into reality. Shri Siddhartha Shankar Ray was the driving force behind turning the Calcutta Metro from a decades-old plan into a living project. As Chief Minister of West Bengal, he revived the stalled project, ensured land acquisition, and persuaded the Central Government to release crucial funds. Under his leadership, the foundation stone of India's first underground railway was laid in 1972 by the then Prime Minister of India, Smt. Indira Gandhi. The Kolkata Metro, earlier known as ‘Patal Rail’, remains a lasting testament to his foresight, determination, and developmental legacy.

Construction

North-South Metro

Since it was India's first metro and was constructed as a completely indigenous process, a traditional cut-and-cover method and driven shield tunneling was chosen and the Kolkata Metro was more of a trial-and-error affair, in contrast to the Delhi Metro, which saw the involvement of multiple international consultants. As a result, it took nearly 23 years to completely construct the 17 km (11 mi) underground railway.

The foundation stone of the project was laid by Indira Gandhi, the Prime Minister of India, on 29 December 1972, and construction work started in 1973–74. Initially, cut and cover along with slurry wall construction to handle soft ground, was recommended by the Soviet Union consultants. Later, in 1977, it was decided to adopt both shield tunneling and cut and cover methods for the construction of underpopulated areas, sewer lines, water mains, electrical cables, telephone cables, tram lines, canals, etc. The technology was provided by M/s NIKEX Hungarian Co., Budapest. In the early days, the project was led by the Union Railway Minister from West Bengal, A. B. A. Ghani Khan Choudhury, often against the prevailing socio-political stance of his contemporaries in the West Bengal government. From the start of construction, the project had to contend with several problems including insufficient funds (until 1977–1978), a shifting of underground utilities, court injunctions, and an irregular supply of vital materials. In 1977, an injunction for the allocation of new funding was passed by the newly elected Jyoti Basu government.

Despite all the hurdles, services began on 24 October 1984, with the commissioning of a partial commercial service covering a distance of 3.40 km (2.11 mi) with five stations served between Esplanade and Bhowanipur (currently Netaji Bhavan). The first metro was driven by Tapan Kumar Nath and Sanjoy Kumar Sil. The service was quickly followed by commuter services on another 2.15 km (1.34 mi) stretch in the north between Dum Dum and Belgachhia on 12 November 1984. The commuter service was extended to Tollygunge on 29 April 1986, covering a further distance of 4.24 km (2.63 mi), making the service available over a distance of 9.79 km (6.08 mi) and covering 11 stations. However, the services on the north section were suspended starting 26 October 1992, as this small, isolated section was little used. The Blue Line was almost entirely built by cut and cover method, while a small 1.09 km stretch between Belgachia and Shyambazar was built using shield tunneling with compressed air and air locks, since the alignment crossed a railway yard (now Kolkata railway station) and Circular Canal.

After more than eight years, the 1.62 km (1.01 mi) Belgachhia–Shyambazaar section, along with the Dum Dum–Belgachhia stretch, was opened on 13 August 1994. Another 0.71 km (0.44 mi) stretch from Esplanade to Chandni Chowk was commissioned shortly afterward, on 2 October 1994. The Shyambazaar-Shobhabazar–Girish Park (1.93 km [1.20 mi]) and Chandni Chowk–Central (0.60 km [0.37 mi]) sections were opened on 19 February 1995. Services on the entire stretch of the Metro were introduced from 27 September 1995 by bridging the 1.80 km (1.12 mi) gap with Mahatma Gandhi Road metro station in the middle.

In 1999–2000, the extension of Blue Line along an elevated corridor from Tollygunge to New Garia, with six stations, was sanctioned at a cost of ₹907 crore (equivalent to ₹43 billion or US$440 million in 2026). The section was constructed and opened in two phases, Mahanayak Uttam Kumar to Kavi Nazrul in 2009 and Kavi Nazrul to Kavi Subhash in 2010. In the north, the line was extended till Noapara from Dum Dum on 10 July 2013. The latest extension opened was the 4.1 km (2.5 mi) stretch from Noapara to Dakshineswar on 23 February 2021.

East-West Metro

The master plan of the metro corridor was made in 1971 along with the North–South Corridor, connecting the office district of Bidhannagar with the twin city and transportation hub Howrah via another transport hub of the city, Sealdah, and the central business district Esplanade by an underwater metro line. It is a ₹4,874.6 crore (equivalent to ₹150 billion or US$1.5 billion in 2026) project, sanctioned in 2008 by Prime Minister Manmohan Singh. The foundation stone was laid on 22 February 2009 and construction started in March 2009. The autonomous Kolkata Metro Rail Corporation (KMRC) was formed to implement the project. The Government of India (Ministry of Urban Development) and Government of West Bengal each had a half-share in it. Later, the Government of West Bengal pulled out from it, and the shares were transferred to the Ministry of Railways.

The realignment led to many other issues and delays. Some of the biggest issues were the H-piles under the Esplanade metro station and the Bowbazar mishap. Per the 1971 master plan, the East-West Corridor was supposed to pass under Central metro station, so the square foundational beams in Esplanade were not removed. Since the tunnel boring machines cannot cut through steel, another small tunnel was dug using New Austrian tunneling method (NATM) and the H-piles were cut manually. This extended the tunneling process by one and a half months. In September 2019, during the construction of the eastbound tunnel (from Esplanade to Sealdah), a machine hit an aquifer under Bowbazar, causing a major collapse in the area, delaying work in that section for several months. Around 80 houses were damaged and many buildings were declared unsafe, affecting more than 600 people. Later subsidence in the area was checked using grouting.

Expansion planning

By 2011–2012, the Railway Ministry had announced plans for the construction of five new metro lines and an extension of the existing north–south corridor. These were:

Major modification and interchanges

A new four-platform interchange station was constructed at Noapara and Kavi Subhash. This acts as an interchange station for the Blue Line with the Yellow Line and Orange Line respectively. After the opening of the Yellow Line, all four platforms are now operational, whereas, from 6 March 2024, all four platforms of Kavi Subhash were in operation, until 28 July 2025, when the Blue Line platforms were temporarily closed for reconstruction.

The existing Esplanade metro station was upgraded and a subway was constructed to the new metro station to provide an interchange among the Blue Line, Green Line and future Purple Line. Additional interchanges were built at Salt Lake Sector-V (green line)-IT Centre (orange line) and Jai Hind (Yellow line-Orange line) metro stations. In 2009–2010, the Blue Line underwent upgrades of services and amenities, and many stations were renamed after famous personalities by then Minister of Railways Mamata Banerjee.

Interchanges

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