Did we ever find out who gave the order to blow those tanker cars up in the first place?.................
The railroad decided it was the least of all evils. Trials had been done in Canada using a propane tank, and results were good if not completely guaranteed.
Blasting caps punch holes in the tank at strategic locations, and usually some sort of flare is lit to ensure the liberated gas ignites.
The article is stupid scary about phosgene, which comprises a miniscule 0.004% of the vinyl chloride monomer combustion product. About 3% is Hydrogen Chloride, which is the worst of it. CO2 is about 6%, CO is <1%, and carbon soot is about 6% by weight.