DP writes that for extending the Green Line with double track, a TBM of diameter 10 meters is necessary. Just like the one Metrostroy has. The TBM Nadezhda had been used to excavagte a tunnel from the Tourist and Zenith stations. It was planned to build another tunnel in opposite direction. But when it was cancelled, it was taken to Moscow. Now it will be brought back from Moscow.

DP writes about the bureaucracy required for the Green Line double track extension with all different departments etc.

https://m.dp.ru/a/2021/09/24/Pojdut_dvumja_putjami