similar experiment already done with 12015/16 NDLS-Ajmer Shatabdi where locomotive used in both directions . In result the time was reduced nearly 20 mins in 440 km journey. As the time reduced was not good, so railway drop this idea.
As the distance between stations are less and between them also so many TSR and PSR , so fast acceleration and retardation are not good because there will be too much jerking.

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Thank you for this detailed input. Really appreciate it.
If first generation ICE trains (like the one pictured) can do this since ages in Germany, providing comfortable (jerk-free) rides at much higher speeds, surely this should be possible here as well. Could these not just be technical challenges that can be overcome. Personally, I think that a saving of 20 minutes is worth it. If other trains are also "upgraded", there shall be an all round knock on effect, resulting in greater time savings.

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as 20 mins are worth ... but at the cost of loco+440km diesel , 20 mins are not looks worth ...
to overcome this , IR is planning to roll out train-set/upgrade version of MEMU which can run @160kmph in 2019
hope it is solution of your query on electric line (but i have no solution on diesel line)

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same thing can be done on diesel as well... demus are being run aplenty... but your post is extremely informative. yes, my question has been answered fully. thank you.

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