By the early 2000s, New Delhi faced severe traffic congestion and rising air pollution, underscoring an urgent need for efficient public transit. When the Delhi Metro opened in 2002, it represented a pioneering effort in urban rail development within a low- and middle-income country. Today, the system stands as a global benchmark for large-scale transit projects in developing contexts.

As of March 2026, the Delhi Metro surpassed New York City's subway system in length, with its extensive network achieved at an approximate cost of US$10 billion. This investment is notably lower than New York's expenditure on a 5.6-kilometer tunnel. The Delhi Metro has also been recognized as the first railway project awarded carbon credits by the United Nations, with 33% of its energy sourced from solar power and trains equipped to recover braking energy. In 2025, the system reported a punctuality rate of 99.9%, reflecting operational efficiency.

However, the project did not proceed without challenges. Early skepticism about the feasibility of rail-based mass transit in India stemmed partly from the difficult experience of Kolkata’s metro, which suffered delays and low ridership after its 1984 launch. Delhi's dense urban fabric added complexity to the project, as the metro lines had to be constructed through congested neighborhoods, marketplaces, slums, and areas near historic monuments. The construction phase involved the displacement of thousands, many from low-income and marginalized communities, prompting legal requirements for compensation and resettlement.

During construction, safety incidents occurred that resulted in fatalities and injuries. In October 2008, a crane malfunction caused a bridge segment collapse in east Delhi, killing two and injuring 17. A subsequent bridge collapse in July 2009 in south Delhi resulted in five deaths and 15 injuries. E. Sreedharan, then managing director of the Delhi Metro Rail Corporation (DMRC) and widely known as the "Metro Man of India," accepted responsibility and tendered his resignation, which was declined by the Delhi chief minister at the time, Sheila Dikshit. Under Sreedharan’s leadership, the organization maintained strict anti-corruption policies and cultivated a professional culture emphasizing punctuality and discipline. He prioritized knowledge transfer by sending deputies abroad to study global subway systems and hired contractors skilled in relocating infrastructure to minimize disruption.

Public acceptance was another critical element in the system’s success. Many Delhi residents were unfamiliar with subway travel, so the DMRC employed creative outreach, including street plays, to educate commuters on navigating escalators, automated turnstiles, and fare systems. The transition from tokens to paper tickets, smart cards, and eventually digital payments facilitated smoother transactions. Though early station amenities were limited—basic facilities like toilets were often located outside stations—improvements over time included the addition of restrooms, eateries, police booths, and retail kiosks. Enhanced signage and color-coded guides further improved user experience.

The Delhi Metro has had significant social and economic impacts, particularly for working women who benefit from its safety and convenience. The mostly underground or elevated tracks help reduce commute times by avoiding road traffic. With ongoing expansions, the metro network is projected to extend further, accommodating the capital’s growing population and economic activities. Its delivery showcases that rapid urbanization and public transit development can coexist, offering a model for other cities in India and beyond seeking to address infrastructure challenges while managing cost and efficiency.