Don't Blame NR now for the GREED of Chhattisgarh and Nagpur people & politicians.
Check the TT of BSP Rajdhani. Its sharing Slot 2 more Rajdhanis and 1 garibrath. But all these terminate at NZM itself , but only BSP is sent to NDLS. If BSP/NGP demands for a early termination at NZM itself , then NR will happily do this. But neither BSP nor NGP has demanded this.
Now i still didn't got your logic of South Rajdhanis.
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far as i recall , South rajdhanis are these:
TVC rajdhani: terminates at NZM
MAS rajdhani: terminates at NZM
SBC rajdhani: terminates at NZM
SC rajdhani: terminates at NZM
SC duronto , MAS duronto , MAS GaribRath , ERS Duronto ...All these also terminates at NZM only.
BUT
only BSP is stretched forward to NDLS , and its not just a coincidence , but a well planned demand by BSP/NGP to have Direct connectivity with New Delhi.
You saying Why BSP rajdhani is not given Pf 3 or 5 for arriving just like BCT rajdhani/Duronto , but i think you missed out the time Slot at which BSP arrives NDLS. It is entering NDLS with a tight slot with ZERO Permissible delaying. If BSP is given some "extra" shifting , then this will also hamper the next incoming Rajdhani which is RNC rajdhani. The n here only one thing is left to do , and that is Changning the arrival time at NDLS but this is also impossible bcoz NGP won't permit it to do. Only 2 things are possible for this train:
1. GET IN LINE and let yourself terminate at NZM itself just like on other days same slot trains do.
2. GET OUT OF LINE and give a dedicated earlier slot between NGP-NDLS.