Can we please consider couple of more factors here - so that your proposal can be integrated well with other trains and regions?

1. All major long distance trains have already gone LHB, rest whichever are left will become LHB soon. But making LHB also means doing away with Slip-Coaches/Services, We no longer have Slip Trains/ Link Trains under LHB Era (which was possible during ICF Era).
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2. Now why I am raising this point? This is for one critical train from WB which still uses Slip Coach service, as long as it still has its ICF Rakes - 12311/12 Netaji Express (erstwhile HWH Kalka Mail) , but very soon this train too would have to face the hammer of LHB-fication. That time no Slip coach attachment/detachment will be possible.

3. Let us look at 12311/12s coach composition - out of its 24 coaches (aside from the HCP), only 13 coaches are allowed to go till KLK beyond CDG. (KLK does not have the capacity to handle more than 18 coaches - that's why KLK's longest trains currently now are 12011/12 and 12005/06 Shatabdi express trains with 18 coaches each - including EOGs). Out of those 13 coaches of 12311/12, we have CC of 1st AC cum AC 2 Tier - 01, AC 2 Tier - 02, AC 3 Tier - 03, Sleeper - 05, General - 01, SLR - 01. Remaining coaches with combination of AC 2 Tier, AC 3 Tier, Sleepers and General compartments are attached/detached at CDG - because we have a significant movement of commuters from WB/JH/Bihar to Chandigarh/Haryana/Punjab and vice versa.

4. Now, if say 12311/12 is made into an LHB Train - granted it will mostly comprise of AC Coaches - at least one 1st AC, 2-3 AC 2 Tiers, rest all AC 3 Tiers and 3 Tier Economy coaches. Even if we say that complete end-to-end 12311/12 will be a single rake with no Slips, at max will get 18 coaches - there will be little to no room for Sleepers and General compartments. So where do the thousands of people travelling from WB/JH/Bihar to Delhi/Haryana/Chandigarh and back go - how to solve their commuting crisis?

5. Hence my suggestion - sorry it's such a long detailly explained one - is that let 12311/12 become a fully AC Superfast train, connecting HWH-DLI-CDG-KLK, and meanwhile to cater to passengers of Non AC Classes - let us have 12329/30 WBSK Running 5 DAYS a Week (instead of Weekly - West Bengal probably the only state in India with just a Weekly SK!). Once 12329 reaches DLI around 9 am in the morning, it has ample time and slot to be extended to CDG (long before other CDG-bound Maharashtra trains all coming around 10.30/11am). Similarly in return direction, 12330 can start from CDG after the VB Gang from CDG (around 15:45/50) and reach DLI around 8/8:15 pm, and leave for SDAH. Many states in India (Goa, KA, KL) have SK Trains to CDG, no reason why WB cannot follow the same.

6. This train can have ample no. of Sleepers and General Compartments, so as to cater to the poor/those who cannot afford to reach Delhi/Chandigarh and back quickly in Premium Trains. Now why 5 days (and NOT DAILY) - is so that rest 2 days, instead of West Bengal Sampark Kranti Express, we can have a new NBSK - North Bengal Sampark Kranti Express starting from either NJP or NCB. Follow same route between CDG and DDU, then NBSK can take the PPTA route - shortest route out. We can also figure out / think about possibilities of route of NBSK via Malda, then we would need to avoid PNBE. But Noone in their right minds would travel from North Bengal to Delhi or back via Asansol-Durgapur - it would be HUGE WASTE of Precious Time!

Now these trains can be run either by a combination of ER (5 days) and NFR (2 days), or better still, be completely taken over by NR - why not many NR trains to WB? But whether Railway Board would be interested on taking this to table - only God knows! Would love to know your thoughts on this.

Thank you for your invaluable time, patience and replies.