From 4 April 1993 trains along the Sognsvann Line were connected to the eastern part of the metro, initially connected with the Østensjø Line.
fɹʌm fˈoːɹ ˈeɪpɹəl nˈaɪntiːnhˈʌndɹɪd nˈaɪnti θɹˈiː tɹˈeɪnz ɐlˈɔŋ ðə sˈɑːɡnsvæn lˈaɪn wɜː kənˈɛktᵻd tə ðɪ ˈiːstɚn pˈɑːɹt ʌvðə mˈɛtɹoʊ, ɪnˈɪʃəli kənˈɛktᵻd wɪððɪ ɑːstˈɛnsdʒoʊ lˈaɪn.