3 Line or Line 3 may refer to:
Public transport Asia Line 3 (Chennai Metro), or Purple Line, under construction in India Line 3 (Hanoi Metro) or Văn Miếu Line, under construction in Vietnam Line 3 (Riyadh Metro), in Saudi Arabia Aqua Line (Mumbai Metro), India Pink Line (Pune Metro), under construction in India Purple Line (Kolkata Metro), India Ampang Line or Line 3, in Klang Valley, Malaysia Circle Line (Kuala Lumpur), or MRT Line 3, in Klang Valley, Malaysia MRT Line 3 (Metro Manila), Philippines Busan Metro Line 3, in South Korea Daegu Metro Line 3, in South Korea Seoul Subway Line 3, in South Korea Taipei Metro Line 3 or Songshan–Xindian or Green line, in Taiwan
China Line 3 (Beijing Subway), a subway line in Beijing Line 3 (Changchun Rail Transit), a light rail line in Changchun, Jilin Line 3 (Changsha Metro), a metro line in Changsha, Hunan Line 3 (Chengdu Metro), a metro line in Chengdu, Sichuan Line 3 (Chongqing Rail Transit), a monorail line in Chongqing Line 3 (Dalian Metro), a metro line in Dalian, Liaoning Line 3 (Dongguan Rail Transit), a planned metro line in Dongguan, Guangdong Line 3 (Foshan Metro), a metro line in Foshan, Guangdong Line 3 (Guangzhou Metro), a metro line in Guangzhou, Guangdong Line 3 (Hangzhou Metro), a metro line in Hangzhou, Zhejiang Line 3 (Harbin Metro), a metro line in Harbin, Heilongjiang Line 3 (Hefei Metro), a metro line in Hefei, Anhui Line 3 (Jinan Metro), a metro line in Jinan, Shandong Line 3 (Kunming Metro), a metro line in Kunming, Yunnan Line 3 (Nanchang Metro), a metro line in Nanchang, Jiangxi Line 3 (Nanjing Metro), a metro line in Nanjing, Jiangsu Line 3 (Nanning Metro), a metro line in Nanning, Guangxi Line 3 (Ningbo Rail Transit), a metro line in Ningbo, Zhejiang Line 3 (Qingdao Metro), a metro line in Qingdao, Shandong Line 3 (Shanghai Metro), a metro line in Shanghai Line 3 (Shenzhen Metro), a metro line in Shenzhen, Guangdong Line 3 (Shijiazhuang Metro), a metro line in Shijiazhuang, Hebei Line 3 (Suzhou Metro), a metro line in Suzhou, Jiangsu Line 3 (Tianjin Metro), a metro line in Tianjin Line 3 (Wuhan Metro), a metro line in Wuhan, Hubei Line 3 (Wuxi Metro), a metro line in Wuxi, Jiangsu Line 3 (Xiamen Metro), a metro line in Xiamen, Fujian Line 3 (Xi'an Metro), a metro line in Xi'an, Shaanxi Line 3 (Xuzhou Metro), a metro line in Xuzhou, Jiangsu Line 3 (Zhengzhou Metro), a metro line in Zhengzhou, Henan
Europe Line 3 (Athens Metro), a metro line of the Athens Metro, Athens, Greece Line 3 (Budapest Metro), a subway line of the Budapest Metro, Budapest, Hungary Line 3 (Madrid Metro), a metro line of the Madrid Metro, Madrid, Spain Line 3 (Metrovalencia), in Valencia, Spain Line 3 (Moscow Metro), the Arbatsko-Pokrovskaya line in Moscow, Russia Line 3 (Saint Petersburg Metro) Île-de-France tramway Line 3, a modern tramway in Paris Paris Metro Line 3, a line of the Paris Metro rapid transit system in France U3 (Vienna U-Bahn), a subway line of Vienna U-Bahn, Vienna, Austria
North America
Canada Line 3 Scarborough, a former intermediate capacity rapid transit line in Toronto Line 3 Red (Montreal Metro), proposed but not built Line 3 Ontario, an under construction subway line in Toronto
Mexico Mexico City Metro Line 3, a rapid transit line in Mexico City Mexico City Metrobús Line 3, a bus rapid transit line in Mexico City Line 3 of the Guadalajara urban rail system, Mexico
United States Route 3 (MTA Maryland), a bus route 3 (New York City Subway service), a rapid transit service 3 (Los Angeles Railway), former streetcar service 3 Line (Sound Transit), a future light rail line in Seattle, Washington
South America Line 3 (Metrovía), a bus route in Guayaquil, Ecuador Line 3 (Rio de Janeiro), a proposed metro line in Rio de Janeiro, Brazil Line 3 (São Paulo Metro), Brazil Santiago Metro Line 3, in Chile
Oceania Australia L3 Kingsford Line, light rail line in Sydney, New South Wales T3 Liverpool & Inner West Line, Sydney Trains service, New South Wales
See also Enbridge Line 3, a proposed tar sands oil pipeline 3 Train (disambiguation) 3-line, a name for the Russian Mosin–Nagant rifle Three-line whip, an instruction from a whip to vote in the UK parliament List of public transport routes numbered 3