Metro Line M4 (Budapest Metro) Metro Line M4 (Budapest Metro) Line 4 (officially: South Buda–Rákospalota (DBR) Line, Metro 4 or M4, and unofficially: Green Line), is the fourth line of the Budapest Metro. It opened on 28 March 2014. The first section, 7.4 km in length and consisting of ten stations, connects the southwestern Kelenföld vasútállomás located in Buda, and the eastern Keleti pályaudvar in Pest, under the River Danube. While three additional sections — one an eastern extension to Bosnyák tér, the second west to Virágpiac, and a third further east to Újpalota — have been planned, these remain unfunded by the Budapest city
Budapest Metro in a limited state, with the gates opening as one approaches. Ticket validators have been installed on a bus and at the terminus of line H6, but are not being used. Lines run from approximately 04:30 to 23:30 every day, though times vary slightly between lines. The Budapest Metro is completely electrified and standard gauge in operation. Three different types of rolling stock are currently in service: Budapest Metro The Budapest Metro () is the rapid transit system in the Hungarian capital Budapest. It is the oldest electrified underground railway system on the European continent, and the third-oldest electrically operated