I still think that shatabdi concept may not work.
1. Indore-BCT is 828 km to be precise. The track between Ujjain-Indore is single line with MPS of 70KM... SO it will take 1h 10m. ( current best 1h 20m )
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2. Then Ujjain Nagda is double line electrified, but with not very high MPS. So it will take about 40 min to cover...
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a distance of 56KM. ( current best 45min )
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3. Now the Nagda BCT section, where BCT Rajdhani runs. It takes exactly 9 hours from Nagda to Mumbai. So lets say our very fast shatabdi takes 8h 15m.
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Then also it sums up to 10h 05min. Or say 10hours. So still for a round trip it will require 20h 30 min minimum. So I dont think that this is possible.
This can be done only if it gets two rakes.
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To cover 828 km in 8 hours, which even Bhopal Shatabdi, or Sealdah duronto is unable to do, the track and signalling system will require a huge upgradation. The average speed has to be 103.50KM/hour, which is far greater than that of Bhoapl Shatabdi or Sealdah Duronto. There is no section in whole of Indore Mumbai section with an MPS of 150.
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Please correct me if I am wrong in any of the stats.
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Plus we should not forget that Indore Duronto shares rake and time with Jaipur duronto.
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I completely agree with the concept of duplicate train. And evening 5PM departure from Indore will be the best. In that case we may see the new train even overpass Avantika in terms of demand, atleast in winters.
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Comments and Suggestions awaited.

Yuva Express should be cancelled and 12909/12910 Garib Rath should be made daily as it has CC coaches(same as Yuva)
Coaches of Yuva Express can be given to 12909/12910.
And
Introduce a Daily Intercity train to Vadodara with following time table (as there is not train from Vadodara after 4 PM to reach Mumbai directly, This will also be useful for daily pass holders,...
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last intercity from Vadodara is 19060/12936 Jamnagar-Surat-Bandra Intercity).
Halts should be as follows: Dadar, Borivali, Virar, Palghar, Boisar, Dahanu, Umergaon Road, Bhilad, Vapi, Valsad, Bilimora, Navsari, Udhna, Surat, Kim, Ankleshwar, Bharuch, Miyagam Karjan, Vishvamitri.
19021/19022 Mumbai Vadodara Intercity Express
CC: 2 SLR, 2 AC Chair car, 8 DD Chair car(1 for ladies), 6 DD General(1 for ladies)
BCT - 09:45 AM
BRC - 04:00 PM
Return
BRC - 05:00 PM
BCT - 11:15 PM

Hmm...
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But still I would reiterate, that Indore requires a night train to mumbai and not a day train.
This is because there are many many people from Indore working in Mumbai. So everyone prefers to come to Indore on weekends, and go back on Sunday. And this is where the timings of avantika are so useful.
Evening...
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7PM departure from Mumbai, so that people finish their work and board the train.
And 4 PM departure from Indore, so that people can reach early morning to mumbai and then have sufficient time to reach to their offices.
Indore still does not have as much demand as Ahmedabad.
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Once again comments and suggestions awaited.