The Red Line was the first one of the subway when it opened. It connects Shaheed Sthal in the east to Rithala in the west. With a total length of 34.69 kilometers, the part of the line is elevated, and the part is at grade, crossing the Yamuna River between Kashmere Gate and Shastri Park stations. The inauguration of the first stretch between Tis Hazari and Shahdara led to the collapse of the ticketing system because the line was overloaded with the number of people that exceeded the capacity to four times.
After the red one, the Yellow line was second to go. It was the first underground line in Delhi Metro. Currently, the line connects Samaypur Badli with Huda City Centre that is 49 kilometers from each other. The southern and northern parts of it are elevated when the central section runs underground. The line includes the second deepest Metro Station of India. Chawri Bazar is situated 25 meters below ground level.
The third line of the metro was the first to connect areas located outside Delhi. The most elevated line covers 56.61 kilometers and connects the satellite city of Noida in the east with Dwarka Sub City in the west. The first section between Dwarka and Barakhamba road was inaugurated in 2005.
The fifth line of the Delhi Metro opened in 2010. It was the first line on standard gauge. The route runs between Inderlok and Brigadier Hoshiyar Sing with a branch line connecting the Ashok Park Main station with Kirti Nagar station that lies on the Blue line. The line consists of 23 stations and is completely elevated with a length of 29.64 kilometers.
The Violet line represents the second standard-gauge corridor after the green one. It covers 47 kilometers distance and connects Raja Nahar Singh that is situated in Ballabgarh with Kashmere Gate located in New Delhi. Twenty-six kilometers are overhead when the rest is underground. The first section between Sarita Vihar and Central Secretariat was inaugurated in 2010. The construction was finished in just 41 months.
The Orange Line is also known as the Airport Express line. It runs for 22.7 kilometers from New Delhi Railway Station to Dwarka Sector 21. The line was constructed at the cost of $800 million. It includes six stations with several check-in facilities, eateries, and parking. Rolling stock consists of six-coach trains that are operating at intervals of approximately ten minutes and having the highest speed of 135 kilometers. The line was opened in 2011, after a delay of five months.
The Pink Line represents the second new line of the third phase of the metro that was partially opened in 2018, with a further extension opening in 2018. At the moment, it is paved between Majilis Park to Shiv Vihar, both located in North Delhi. When the line was completed, it covered 58.59 kilometers and became the longest line in Delhi Metro. It includes 38 metro stations and is mostly elevated.
The Magenta Line represents the first new line of the third PhasePhase of the Delhi Metro. Part of it was opened in 2017 and connected Botanical Garden and Kalkaji Mandir. Currently, the line consists of 25 stations from Janakpuri West to Botanical Garden.
The grey line is also referred to as Line 9. The track was opened in 2019, and it connects Dwarka with Dhansa Bus Stand that is located in the western part of Delhi. The line covers 4.295 kilometers and includes only four stations.