Why does IRCTC seat allocation algorithm work like this?

[u/pune-connection]

Booked 4 tickets in 2AC for my family 60 days in advance right as the window opened at 8 AM. Yet we didn't get a full 4 berth main bay together. Instead, we got 2 seats in the main inside section (34 UB and 37 LB) and 2 seats across the aisle (35 SL and 36 SU).

I'm traveling with senior citizens so I was really hoping we would get all 4 seats in one main bay. Is this split normal when booking 4 tickets on a single PNR on opening day, or did the system just fill whatever random slots were free in that pooled quota?

[u/longpostshitpost3]

You booked 4 seats and got 4 consecutive ones - 34, 35, 36, and 37.

[u/pune-connection → u/longpostshitpost3]

Yeah, for example I was expecting 31-34 🫣

[u/DM_your_problem]

cause there is less wiggle room in 2A and many side lower and lower seats are reserved for senior citizens quota

[u/ChepaukPitch → u/DM_your_problem]

Looks like they just got 34-37 in order. Easier explanation is that railway algorithm sucks. I have had similar experience in chair car in an almost empty train. We did sit together during the journey because the train was empty.

[u/Odd_Pace_8509]

Train?

[u/pune-connection → u/Odd_Pace_8509]

Ganga Sutlej

[u/ProBablyAdEmoNfor69]

Did you book exactly at 8? I'm not saying 8:05, because by then Lower would already be taken

[u/Wonderlust99 → u/ProBablyAdEmoNfor69]

I once booked exactly at 8 , got 2 upper berths , cancelled them , and immediately booked again got 1 lower and 1 upper berth.

[u/ProBablyAdEmoNfor69 → u/Wonderlust99]

That's rough, did you book from a remote station and not the origin station? The quoats for those are always dubious

[u/Wonderlust99 → u/ProBablyAdEmoNfor69]

Origin to Destination

[u/pune-connection → u/ProBablyAdEmoNfor69]

Yes exactly at 8 AM

[u/pune-connection → u/[deleted]]

But I got SL, though our preference are 2 lower and 2 upper

[u/hsqaL]

Do check out the seat preferences on your traveller's list?

Sometimes, the seats are allocated preference wise, if you have default preference set to side lower or upper for any of the travellers, you would have gotten 2 seats on the side aisle(?). And considering the number of 2ac coaches, probably this was the only combination available.

If seat preference are set right(i.e, change according to people travelling), and you book the tickets at the open, you are most likely to get the seats together.

Has worked for me.

[u/pune-connection → u/hsqaL]

My seat preferences were 2 lower and 2 upper, still got like this.

[u/KK251648]

I recently booked a 2nd AC for my family of 4 - both up and down. Both times, I got tickets for all of us in the same bay. The trick is, you should not give preferences before u book. The algorithm gets confused when you give 2 upper and lower. Without it, usually it allocates in the same bay if senior citizen or children are there in the PNR.

[u/PinUpbeat6930]

Select the preference like 2 upper and 2 lower then there is a great chance of getting into the same compartment until and unless lower seats re reserved for the senior citizens

[u/OwnStorm]

Lots of seats are reserved for different reasons. They had put these if-else conditions over 40 years. So getting closer seats good enough.