4 points
I don’t think TNT is used at all, I’m pretty sure it’s some explosive compound, as you said. However, explosives are still measured in terms of TNT, called Net Explosive Weight (NEW).
For example, one pound of C4 has a NEW of about 1.25 pounds.
3 points
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Looks like it’s something like 6-12kg of net explosive content so if that’s the same as NEW then it seems that the train has it beat by a fair margin, though I doubt the trains impact is as tightly targeted.