India's Longest Railway Tunnel Is Not What The Search Results Will Have You Believe

Updated: Thursday, June 19, 2025, 9:57 [IST]

The longest tunnel in India if you look at the official search results is the Pir Panjal tunnel in Jammu and Kashmir at 11.2km long. This result pops up, even though Tunnel T-50 in the same state is around 1.5km longer.

However, both of these tunnels are nowhere close to what is the longest railway tunnel in India. This tunnel is twice the length of Tunnel T-50 and has been used in its entirety for nearly 15 years, with millions of people using it every year.

The Actual Longest Railway Tunnel In India

So, just what is this tunnel and where is it located? Well, the tunnel in question is a section of the Delhi Metro's Yellow Line that starts before the GTB Nagar station in north Delhi and pops out of the ground just before the Qutub Minar station in south Delhi.

This underground stretch of the Delhi Metro measures 24 kilometres long and features 20 stations under the soil of the nation's capital. Constructed in four sections, India's longest transportation tunnel was first thrown open to the public in December 2004. This section runs between Vishwavidyalaya and Kashemere Gate ISBT and features four stations while covering 4.06km.

The next section of the tunnel to open was in July 2005 when the line extended south to the Central Secretariat metro station, adding 6.62km of tunnels and six more stations to the line.

The northern extension towards Jahangirpuri started operations in Feb 2009 and added a single underground station in the form of GTB Nagar with the underground section extending a few more hundred meters further before the Yellow line ramped up into its northern elevated section.

The final section to the south, which ends up joining the elevated southern section of the Yellow line just before the Qutub Minar metro station opened in September 2010. This section added nine more underground stations to the Yellow line and saw the underground section top out at 24km.

The Importance of India's Longest Railway Tunnel

The underground section of Delhi Metro's Yellow Line serves important parts of the nation's capital including the North and South campuses of Delhi University, Kashmere Gate ISBT, Connaught Place, Old and New Delhi Railway stations and also features the second deepest metro station on the network - Chawri Bazar - which is located 25 metres below ground level.

The underground section of the Delhi Metro's Yellow line also features interchanges at 6 stations - Kashmere Gate, New Delhi, Rajiv Chowk, Central Secretariat, Dilli Haat INA and Hauz Khas - with other lines of the Delhi Metro. Two of these stations also provide interchanges with the Indian Railways network - Chandni Chowk (for the Old Delhi Railway Station) and New Delhi (for the New Delhi Railway Station).

Why Is It Ignored By The Tunnel Lists?

The reasons why the underground section of the Delhi Metro Yellow line is ignored by those who collate such lists are not really known. A few reasons that pop into our mind are:

This is a Metro line and therefore not part of the actual Indian railways network (despite running on the same broad gauge track setup).
It was constructed and opened in sections - therefore not a proper tunnel in the eyes of the Railway and tunnel snobs.

Whatever the actual reason may be, it just doesn't match up to the facts - The underground section of the Delhi Metro's Yellow line is the longest transport (rail or road) tunnel in India.