largely during the 1990s, with the initial new sections opened in January 2000. Line 1 mostly runs at ground level and the other two (Line 2 & 3) routes run entirely underground. A fleet of 42 trains, using 252 carriages, operates on the network, with a daily occupancy of 1,353,000 passengers. Line 1 (Green Line) serves 24 stations, and is the oldest line of the Athens metro network. It runs from Piraeus station to Kifissia station and covers a distance of . There are transfer connections with the Blue Line 3 at Monastiraki station and with the Red Line 2 at Omonia and Attiki stations. Line 2 (Red Line) runs from Anthoupoli station to Elliniko station and covers a distance of . The line connects the western suburbs of Athens with the southeast suburbs, passing through the center of Athens. The Red Line has transfer connections with the Green Line 1 at Attiki and Omonia stations. There are also transfer connections with the Blue Line 3 at Syntagma station and with the tram at Syntagma, Syngrou Fix and Neos Kosmos stations. Line 3 (Blue Line) runs from Nikaia station, through the central Monastiraki and Syntagma stations to Doukissis Plakentias avenue in the northeastern suburb of Halandri. It then ascends to ground level and continues to Athens International Airport Eleftherios Venizelos using the suburban railway infrastructure, extending its total length to . The spring 2007 extension from Monastiraki westwards to Egaleo connected some of the main night life hubs of the city, namely those of Gazi (Kerameikos station) with Psirri (Monastiraki station) and the city centre (Syntagma station). Extensions are under construction to the western and southwestern suburbs of Athens, as far as the Port of Piraeus. The new stations will be Maniatika, Piraeus and Dimotiko Theatro, and the completed extension will be ready in 2022, connecting the biggest port of Greece, the Port of Piraeus, with Athens International Airport, the biggest airport of Greece. Commuter/suburban rail (Proastiakos) The Athens Suburban Railway, referred to as the Proastiakos, connects Athens International Airport to the city of Kiato, west of Athens, via Larissa station, the city's central rail station and the port of Piraeus. The length of Athens's commuter rail network extends to , and is expected to stretch to by 2010. Tram The Athens Tram is operated by STASY S.A (Statheres Sygkoinonies S.A), a subsidiary company of OASA (Athens urban transport organisation).