Discarding originally planned HST route Mumbai-Pune (150-175kms) and inlieu of this, going for Mumbai-Nashik-NGP (about 850kms) HST line appears surprising.
.
AHM-MUM-Pune was supposed to be first HST route as per study conducted by Japanese Rly experts based on traffic & economic feasibility. But Mum-Pune section was dropped due to higher construction costs involved in crossing mountainous terrain of Bhor ghats and only Mum-Ahm was considered.
....
more...

Construction of Mum-Nashik route shall also be a equally costly due to crossing of equally tough Thull Ghat. Mum-NK/NGP traffic is lesser than Mum-Pune and the HST line cost shall be about 4-5 times Mumbai-Pune route. Techno-economics totally favour Pune route. Looks like CM's home city getting undue priority over the much more deserving but ill fated Pune. Pune has already suffered a lot in the case of Metro train.
.
CMs push may lead to study of the route but the project economics shall no be favourable and project is most likely to remain on paper. On the other hand pursuing for Pune route is more likely to give concrete results.

Nagpur is second capital of MH, not Pune. That makes it more important, politically. there no biased decision there.
The CM frm NGP reportedly gave funds for the rakes of the expected CSTM-NDLS Rajdhani train, which gives no benefit to Nagpur.
You are comparing Mumbai-Pune with Mumbai-Nagpur.
The actual comparison should be Mumbai-Howrah and Mumbai-Nagpur.
A...
more...

big distance of Mumbai Delhi is getting upgraded to 160 kmph being a 'A' class route (potentials of 160 kph), that is real big distance in just one go.
Similarly, We have Mumbai Howrah amongst A class routes, out which Mumbai Nagpur might be done in first leg, be it upgradation of existing double electrified route from 110 Kmph to 160 kmph Nagpur-Igatpuri like for NDLS-BCT or separate new Corridor like for Bandra-Kurla C to Ahemdabad Bullet, using the same BKC terminal for both.
Nagpur comes in centre of 4 metros to be connected by High Speed out of which most economical for Nagpur, surely would be Nagpur-Mumbai route for obvious reasons, so, when opportunity strikes, why not it a consideration?
Besides, Just one route Mumbai Ahemdabad
how much will it benefit actually? Same terminal could be used for Mumbai Nagpur as well.
From Ahemdabad where would it get extended its unclear but if Mumbai Nagpur gets bullet, it can extended to Nagpur Howrah.
Ofcourse, great work would be required through the Thull ghats, but when Katra can get connected likewise, why cant this one?

09 Dec 2016
Received by : Ministry of Railways, ( Railway Board)
Forwarded to : Efficiency and Research
Officer name : SHAILENDRA N. JAISWAL
Officer Designation : Exec.Dir.Efficiency and Resear
Contact...
more...

Address : Room No. 515, 5th Floor,
Rail Bhawan, Railway Board.
New Dellhi110001
Contact Number : 01123388139
e-mail : eder@rb.railnet.gov.in
Grievance Description : Subject:- Upgradation of existing Mumbai-Nagpur route. The planned bullet train between Nagpur and Mumbai by state government has been called off. It is a well known fact that Mumbai-Nagpur route is the part of A class Mumbai-Howrah Route, having potentials of 160 kmph. Currently, What is the max permissible speed (mps) of Mumbai-Kasara-Igatpuri-Nagpur route? For start, the Igatpuri-Nagpur route should be upgraded to 130 kmph and subsequently, to 160 kmph. This would be very useful to cut down the travel time between the state capital Mumbai and second capital Nagpur. Currently, Mumbai-Howrah AC Duronto Express has the rake capable of 160 kmph. Further more mumbai-nagpur tejas or shatabdi could be given by Railway Board.
Date of Action : 28 Dec 2016