Train No Train Name Runs From Source Runs On
12319 KOAA AGC EXPRES KOLKATA WED

SNo Stn Code Stn Name Route No. Arrival Time Dep. Time Halt Time (In Minutes) Distance Day Remark
1 KOAA KOLKATA 1 Source 13:10 0 1
2 DGR DURGAPUR 1 15:30 15:32 2:00 161 1...
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3 ASN ASANSOL JN 1 16:13 16:18 5:00 203 1
4 DHN DHANBAD JN 1 17:10 17:15 5:00 262 1
5 GAYA GAYA JN 1 20:12 20:17 5:00 460 1
6 MGS MUGHAL SARAI JN 1 23:00 23:20 20:00 663 1
12319/12329/12379 have same slot between SDAH and MGS.
If 12319 reach Gaya at 20.12 then 12329 and 12379 too should reach the same time at gaya. Also note the distance between Dhanbad and Gaya which is 198 KM and as per your time if it reach 19.45 then it reach Gaya within 2.30 Hours at the avg speed of 78 KM. as Rajdhani it self take 2.31 hours to run between DHN and Gaya you think it run at the speed of Rajdhani.
This train reach gaya at 20.12 only but not halting there, There is no technical halt there. Here is working timetable detail I got from my friend . Check yourself.
84 TANKUPPA TKN DHN ECR 19:38 19:38
85 BANDHUA BNF DHN ECR 19:5419:54
86 MANPUR JN MPO MGS ECR 20:02 20:02
87 GAYA JN GAYA MGS ECR 20:12 20:12
88 WEST CABIN GAYA WCB MGS ECR 20:22 20:22
89 KASTHA KSTA MGS ECR 20:24 20:24
90 PARAIYA PRY MGS ECR 20:28 20:28

Could be but what i said is from my experience which i can't deny.
Though it stopped at Gaya and i asked the PC Staff as to why it had stopped at gaya, he told me they needed to load Food items from Gaya.
I travelled in this train 2 yrs back and now probably the stop has been given away.
@ UG. Look...
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at the timnigs of 2381 Poorva express and you can estimate how much Slack timings are there in 2319 AGC Express.
HOWRAH JN 08:20
ASANSOL JN 11:00 - 11:05
DHANBAD JN 11:58 - 12:06
PARASNATH 12:41 - 12:42
KODERMA 1 13:32 - 13:33
GAYA JN 1 14:50 - 14:55.
Clear 15 mins Slack timing.Poorva takes 2hrs 40 mins from DHH to Gaya while when i travelled (it was 2329 then) , it took 2hrs 30 mins(+/- 3 mins) to reach Gaya which is nothing Amazing at all.