VB is faster and more comfortable(better priority also,less delays)than cramped DD,usually the pax of DD will be able to pay little extra for VB
Even SBC MAS VB DD used to depart within 15 mins ,still VB had 85% occupancy on weekdays also

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Any sector like MMCT-ADI, NDLS - CDG, NDLS - ASR which has demand for AC CC accommodation over Non-AC CC accommodation will see this trend unless a Shatabdi runs on same time slot.

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More to do with the priority and better maintenance of VB.
This month, I travelled ANVT-LKO by VB and returned LJN-NDLS by Shatabdi.
I could feel the difference between Shatabdi's poor condition/maintenance and VB's A1 maintenance and catering.
VB is becoming a first choice over Shatabdi/other AC class trains (when running immediately in morning/evening slots).

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Same case with MYS MAS VB And Shatabdi
VB gets clear run,Shatabdi trolled due to useless controlling which they won't do with VB

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