let me give an example what i saw with my own eyes.
just a matter of yesterday, BBS Bound Prashanti Express was at 85 kph or even more, came to halt in just few mins at SCM station when the red signal changed suddenly from green.
there was no emergency brake applied in this phase, they applied the brake completely and the train stopped without any issues.
and...
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secondly,
if a train is running at 110 kph, braking distance is 1 km as per Indian standards, the rest what u said idiots on track, the crew either has to ignore or else slam down brake to "continuous level til the pressure is full" and later emergency brake.
for 130 kph, its 1.5 km (braking distance)
for 160 kph or above, its 2 km (braking distance)
experienced LP's know exactly when and at which point to slow down/brake down, u too know that.

Goods train don't go above 100 at all, everyone knows that, u too know it.
they run below 70/80 only and they too have distance braking.
and now a days, when the braking system in Wagons are being modified, its quite possible.
but to bring to a sudden halt will eventually follow up some derailments, coz even if AEB is slammed...
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down, it'll take almost couple of meters for the entire train to stop.