#1 Somewhat true, at first place extension to ROK opened its scope for further/future extension too.
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#2 Dedicated trains to Delhi, Mumbai, Howrah, etc are certainly expected and deserved.
But unlike Mumbai and Howrah which are termini, Delhi has scope of extension when compared to aforementioned stn. Other reasons might include lack of space, higher TAT, etc.
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#3 one more topic to raise is new terminal (to reduce load of NDLS/DLI) to be located north of NDLS/DLI is still missing. Some new terminal dere was on the cards but don't know where it got lost.
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#4 Interestingly, we dont see demands of trains of/from J&K, HP, Punjab, Haryana to Delhi area to be extended further from Delhi area to MTC/GZB/MB/BE/ALJN/FDB/MTJ/AGC/GGN/RE/AWR/JP etc etc. (Avoiding to mention any train name)
But what could be the reason ? (Within Northern Railways ?)
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#5 For an example, jst as an example only, consider 12046/45 CDG NDLS CDG to cud have been easily extended to aforementioned stn for optimum utilisation. May b a little tweak in TT wud have been required though. Also, Dere may b more such and better examples.
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#6 back to Gorakhdham topic,
Though when GKP's train to Delhi got extended to HSR was pinching. May b when upto ROK was kind of fine and adjustable. But it's extension of BTI is pinching more. It no more gives the feel of GKP's train to Delhi. It's need/ purpose/requirment is all lost.
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#7 One sec, while I was re-reading the above para(s), I realised, I have missed one POV (point of view; learnt a new abbreviation recently as written by GenZ on insta. :P)
POV - Ofcourse, people enroute NDLS-ROK-HSR-BTI might need a proper morning ICE but perhaps NR sud look into the new demand as per requirement/need/feasibility. Extension in this case, isn't a very good approach. Why are people after some1 else food/right ? Demanding own right/food doesn't mean to snatch another's.
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#8 Another POV
As optimum utilisation is talked about.
I think, there sud have been 2 trains from GKP to NDLS/DLI
X train UP GKP 1600/1700 hrs NDLS 0500/0600
Y train DN NDLS 1700/1800 GKP 0600/0700
Y train UP GKP 2300 NDLS 1200
X train DN NDLS 2300 GKP 1200
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#9 let both X and Y trains have RSA, owned by NER and maintained at GKP.
Infact Y train cud have termini as DLI instead as anyways NR will park the rake somewhere bit faroff Stn. So rake layover, TAT, lack of space gets solved. And GKPians get trains to dedicated Delhi.
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#10 Another imp point - let X and Y have different routes.
Jaise one via BST - LKO - CNB - NDLS
Another via BST - LKO - MB - NDLS
More routes, via BUW-STP or via BNY
I wish I remember PnC se aur bhi koi route possible ho. Current trains using different routes 12555, 12571, 15057.
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Thank you for reading. :)

Extensions is basically something by which Bihar Politicians justified their existence. Instead of providing better infrastructure they simply extended an existing service or demanded halt of same. Something which Politicians of NWR have totally adopted and totally implemented. Now it's almost impossible for NWR to have a less stoppage Normal Superfast in Delhi Jaipur Section look at the condition of Delhi Barmer Express.
See, it can all be resolved by having a simple Shramshakti Express- Sogaria Intercity Express scheme.
A separate train service using the same rake can be introduced which in turn...
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ensures:
1. Freeing up of yard as rake will be in use.
2. Retention of original Quota for originally intended section.
This should've been done much before with Gorakhdham Express so it wouldn't be in this situation now.
With respect to Chandigarh Shatabdi: Yes, even I support the demand for it's further extension to either Agra or Rewari both will be useful for people of Chandigarh and Haryana.
New Terminal in Delhi won't be of much use as NR has found a much better way to get rid of Off Zone Rakes coupled with Greed of Politicians. It has become a matter of pride for these idiots to get trains having rich history like Poorva Express, Shiv Ganga Express, Prayagraj Express, etc.- something for which inspiration is taken from Politicians of Bihar.

As far as last 3 Points are concerned these people know that Zones can arrange for extra rakes, since they have to park it only and not do any maintenance they happily take over the extensions and stable the rakes for 20+ Hours (now rakes won't get wasted according to their insane logic 😂)
So they won't even think about minding about demanding extensions for your proposed trains.
ER had to arrange it for Sealdah Duronto extension to Bikaner. NCR had to arrange for Prayagraj Jaipur Express extension to Bikaner, they very well...
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know other Zones can do it too.
So your proposals won't simply hold good in the long run.
There should be a provision of making stations demanding extensions as primary maintenance points of those respective Trains. Half of these idiotic demands would stop automatically as people want to enjoy benefits without any responsibility. 😂
Mathura Allahabad Express was introduced for providing overnight connectivity to Stations of NCR. Now in Bikaner Prayagraj Express, people of Mathura, Agra can't even think about getting a seat- all because people of Churu, Jhunjhunu wanted a connection to Mathura 🤦😂. They want extension of Mathura Chambal Express as well. 🙏🏼
Other Zones don't have any work other than to arrange for Extra Rake and Train Numbers for different routes they have.
*Not intended as an offense to NWR or Jaipur Divison.*