stretch was built under very difficult geological conditions, with pressure as much as 2.3 bars. The planned deep-level station was abandoned due to difficulties in building an escalator tunnel. However, in 1980 the continued development in engineering techniques allowed for this to finish and the station was opened without any disruption to the service. Southwest In the late 1980s work began on the final section in the southwest, to the new suburbs of Konkovo and Yasenevo finally reaching the edge of the Bitsa Park in 1990. Timeline Transfers Rolling stock The line is served by two depots, Kaluzhskoe (№ 5) and Sviblovo (№ 10). Most of the trains are 81–717.5/714.5 models which were received new from 1987, however 12 of them are the new 81-717.5M/714.5M which were added to Sviblovo's park in 1996/1997. In 2017, the Moscow Metro began replacing the 81–717.5/714.5 and 81-717.5M/714.5M models with 81-760/761s (Oka). The 81-760/761s stopped being used on the line on 22 August 2018. In 2018, Moscow Mayor Sergey Sobyanin announced that the next-generation 81-765/766/767 (Moscow) trains would operate on the line from 2019, and within five to six years the old rolling stock would be entirely replaced. In May 2018, the first 81-765/766/767 train began operating on the line, ahead of schedule. In December 2020, the first 81-775/776/777 train began operating on the line. Subway car types used on the line over the years: Series G: 1958 - 1982 Series E, Ezh, Em-508 and Em-509: 1972 - 1996 Series 81-717/714: 1987 - present Series 81-717.5/714.5: 1988 - present Series 81-717.5M/714.5M: 1993 - present Series 81-760/761: 2017 - 2018 Series 81-760A/761A/763A: 2018 Series 81-765/766/767: 2018 - present Series 81-765.3/766.3/767.3: 2018 - present Series 81-765.4/766.4/767.4: 2019 - 2020 Series 81-775/776/777: 2020 - present Recent developments and future plans Currently the line spans through the entire city and no extensions are planned in the nearby future. However several projects exist. The first one was to connect the town of Mytishchi in the Moscow Oblast with the Moscow Metro, this was however declared unnecessary by the mayor of the city. Another one was to extend from Bitsevsky Park to Annino of the Serpukhovsko–Timiryazevskaya line, however it is unlikely this will be realized due to the preserved area of the Bitsa Park, and a newer project to bring the Butovskaya Light Metro line to the southern radius. The lack of transfer to the Serpukhovsko–Timiryazevskaya line has led to