Hanoi Metro Line 3

Hanoi Metro Line 3, also known as the Line Nhổn - Ga Hà Nội, is a medium-capacity rapid transit service of the Hanoi Metro network, operated by Hanoi Metro Company. Colored dark red on transit maps, the line currently runs from Nhổn, a suburb in Bắc Từ Liêm District, west of city center, to its current terminus in Cầu Giấy Bus Interchange, located in Cầu Giấy district. When fully operational, the line will continue eastbound toward Hanoi Station, providing a direct connection to downtown Hanoi and the city's main railway station. The line operates between 5.30 am and 10pm, with headways of 6 minutes during peak hours (7 am - 8.30 am and 4.30 pm to 6pm), and 10 minutes during off-peak hours. All trains on Line 3 operate with a 4-cars formation.

This line was the first to be built in Hanoi Metro network, starting construction in September 2010 with an expected completion date in late 2016, with a budget of 18 trillion VND (US$1 billion in 2010) However, the project was plagued with delays and budget overrun, total about 34.532 trillion VND (US$1.46 billion) in 2022.

The line is divided into three segments: The first segment, which runs from Nhổn to Hanoi Station. This segment is 12.5 kilometres (7.8 mi) long, consists of 12 stations in total, with the first 8.5 kilometres (5.3 mi) (between Nhổn and Cầu Giấy) running elevated, while the last 4 kilometres (2.5 mi) (between Cầu Giấy) and Hanoi Station running underground. In addition, there have been plans for a southern extension (second segment), which will run from Hanoi Station to southern district of Hoàng Mai, and a northern extension (third segment) toward Sơn Tây. Currently, only the elevated phase of first segment (between Nhổn and Cầu Giấy) is operational. About 20% of Hanoi's population in 6 districts Ba Đình, Cầu Giấy, Đống Đa, Hoàn Kiếm, Nam Từ Liêm and Bắc Từ Liêm can benefit from this line.