December 29, 1994: In preparation for the model 600 electric cars' direct operation into the Kyoto Municipal Subway Tozai Line, which was then under construction, preparation work for the voltage increase of the Otsu Line to 1500V was completed.
1994年（平成6年）12月29日-600形電車の建設中の京都市営地下鉄東西線への直通運転開始に伴う大津線の電圧の1500V昇圧準備工事を完了。