I fully agree on your following point: Doubling between YNK-Penukonda and DMM-Kalluru should be done initially atleast as traffic gets distributed between Penukonda and Dharmavaram first and between Kalluru-GY/GTL.
While GTL-Kalluru (now BG) and GTL-Gooty-Kalluru can serve as double line one for uptraffic and another for down traffic. Kalluru-DMM section has just one BG track. So this needs to be doubled. Remember that there is currently
an abndoned MG track just adjacent to running BG between these stations. The MG track was active and was used for trains running from GTL-Pakala on MG...
more... strectch. While GTL-Kalluru and DMM-Pakala were converted to BG. MG track between Kalluru-DMM was just abandoned. The original plan of IR is to dismantle it. Since GTL-SBC doubling is very much required, I do not understand why they convert this MG to BG insted of abandoning it. Then we would have double track on some 78 km already.