Kolkata Metro

The Kolkata Metro is a major rapid transit system in West Bengal, India.

It serves the city of Kolkata and the wider Kolkata Metropolitan Region. This system holds historical importance as the first rapid transit system in South Asia. Today, it ranks as India's fourth largest and fourth busiest metro rail system. The network is owned and operated by Metro Railway, Kolkata. This organization is the 17th zone of the Indian Railways. It is unique because it is the only metro system in India controlled entirely by the Indian Railways.

The system operates using five color-coded lines.

These lines consist of underground, at-grade, and elevated stations. The tracks use both broad-gauge and standard-gauge measurements. To move the trains, the system uses a 750 V DC third rail system. This means electricity is provided through a third rail on the track. The metro serves 58 operational stations across a total length of 73.42 kilometers. Trains run daily between 06:30 and 22:44 IST. Approximately 300 daily train trips carry a vast number of passengers through the region.

Building the metro required complex engineering methods.

For much of the Blue Line, workers used the cut-and-cover method. This involves digging a trench and then covering it to create a tunnel. In other areas, such as a 1.09 km stretch near Shyambazar, they used shield tunneling. This process used compressed air and airlocks to manage the environment. This specific section crossed a railway yard and the Circular Canal. Because this was an indigenous, trial-and-error process, construction took nearly 23 years.

The history of the metro began long before the first train ran. In 1919, a committee led by W. E. Crum recommended a metro line. This plan would have connected Bagmari to Salkia via a tunnel under the Hooghly River. However, the proposal was not undertaken in 1923 due to a lack of funds. Later, in 1971, the Metropolitan Transport Project prepared a master plan. This plan used help from Soviet specialists and East German engineers. They proposed five rapid-transit lines for the city. Construction finally began after Prime Minister Indira Gandhi laid the foundation stone in 1972.

The Green Line, also known as the East–West Corridor, includes impressive engineering feats.

This line includes the Howrah metro station. This station is the deepest metro station in India, reaching a depth of 35 meters. At its inauguration, it was also the largest metro station in the country. The Green Line also features an underwater tunnel segment. This was a major part of the plan to connect Bidhannagar to Howrah. Construction for this line began in March 2009 under the Kolkata Metro Rail Corporation.

As the system expands, new lines and stations are being added.

The Purple Line, or the Joka–Eden Gardens Corridor, opened in 2022. The Orange Line, running from Kavi Subhash to Beleghata, opened in 2024. The Yellow Line, connecting Noapara to Jai Hind, opened in 2025.

The Jai Hind station on the Yellow Line is significant. In August 2025, it became the largest metro station in India. It is also recognized as one of the largest metro stations in all of Asia. These new lines help connect more parts of the metropolitan area.

Connecting different lines is essential for a large transit network. The system uses interchange stations to help passengers switch between lines. For example, Noapara serves as an interchange for the Blue Line, Yellow Line, and Orange Line. Kavi Subhash also acts as an interchange for the Blue and Orange lines. The Esplanade station was upgraded to include a subway. This allows passengers to move between the Green Line, Purple Line, and Blue Line. Other interchanges exist at Salt Lake Sector-V and Jai Hind. These connections allow the metro to function as a single, integrated system.