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By now you must have heard about the horrible #OdishaTrainAccident in which 250+ passengers have lost their lives.
As a lifelong train enthusiast, I believe this is one area where I have the knowledge and contacts to gather what happened. Here's an explanation thread (1/n)
As a lifelong train enthusiast, I believe this is one area where I have the knowledge and contacts to gather what happened. Here's an explanation thread (1/n)
https://twitter.com/serailwaykol/status/1664658547899236357
The station where the accident happened has two mainline tracks for trains to pass thru (called Up Main and Down Main) and two side tracks called "loops" used for stopping trains temporarily.
A train is accepted into loop by moving a switch which moves a piece of track. (2/n)
A train is accepted into loop by moving a switch which moves a piece of track. (2/n)
Some time before the accident, a freight train was accepted into the loop. Once the train is in, the switch is moved back to point to mainline from a route relay panel. Signals along the tracks are interlinked to panel to guide the loco pilot whether to slow down or continue(3/n)
In this case, the switch did not move back correctly, thus was still pointing towards loop but relayed to panel that it is set back to mainline. Accordingly, the signals on mainline turn green showing all clear.
We still don't know WHY this happened, but this is important(4/n)
We still don't know WHY this happened, but this is important(4/n)
The loco pilot of 12841 Coromandel Express sees green signals on mainline so continues driving at its maximum permitted speed of 130 km/hr.
However, since the switch is set towards loop, the train tries to enter loop at this high speed and in the process derails. (5/n)
However, since the switch is set towards loop, the train tries to enter loop at this high speed and in the process derails. (5/n)
The locomotive and several coaches of Coromandel Express smash into the freight train while some coaches spill over to the adjacent Down Main track. This impact causes a lot of casualties. (6/n)
To make things worse, exactly at this time, Down Main line has its signals green for 12864 Bengaluru (SMVT) Howrah Express to go in opposite direction, also at 130 km/hr.
Some derailed coaches of Coromandel hit 12864 and derail its last 3 coaches too. More casualties. (7/n)
Some derailed coaches of Coromandel hit 12864 and derail its last 3 coaches too. More casualties. (7/n)
Disclaimer: all this is informed speculation based on reports from railway officers, pictures, and train tracking data. The official investigation is still pending.
I hope this helps mitigate some wild theories thrown around by people who have no idea how trains work. End. (n/n)
I hope this helps mitigate some wild theories thrown around by people who have no idea how trains work. End. (n/n)
Question many are asking is: would having Kavach anti collision device prevented this?
No! Kavach is meant to stop a train when it senses another train on same track. It cannot sense a switch set wrong, nor can it stop a train from derailing. This was a freak accident.
No! Kavach is meant to stop a train when it senses another train on same track. It cannot sense a switch set wrong, nor can it stop a train from derailing. This was a freak accident.
How could the switch be set wrong and show green signal? Is there no failsafe?
There are failsafes, we don't know why and how this happened. Route interlocked signalling works fine millions of times every day across India. Why it failed this ONE time? We don't know yet.
There are failsafes, we don't know why and how this happened. Route interlocked signalling works fine millions of times every day across India. Why it failed this ONE time? We don't know yet.
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