Rahami may have thought he had good reasons for allegedly stuffing the Chelsea bomb inside a large metallic dumpster. It meant the bomb was hidden from police and passersby. It also meant that the dumpster itself could have been torn into pieces of jagged white-hot shrapnel in the ensuing explosion, dramatically increasing the amount of damage to anyone unlucky enough to be standing nearby.
That’s not what happened. Instead, the dumpster appears to have contained much of the blast, ensuring that a bomb capable of potentially killing dozens of people ultimately wounded 29 but caused no fatalities.
John Goodpaster, a forensic chemist at Indiana University–Purdue University Indianapolis, said that placing a bomb into a container where it is surrounded on all sides except for one — think of a box with its top removed — leads to so-called “focusing.” That, he explained, “means the blast is largely contained and nearly all of the explosive force will be directed out of the opening of the container.”
Since the dumpster was open on the top, he added, “the explosive force was directed upward — which is exactly the opposite of what one wants for maximum casualties.”