Transit Hub Beta spanned three hundred meters of heavy ferro-concrete, an underground transit cave connecting the monorail spurs of Mega-City 01 to the high-speed air-powered elevators of the Apex Spire. Beneath soaring arches of brushed steel and yellow emergency light, over three thousand civilian supply workers, customs officials, and foreign diplomatic escorts moved between self-running freight containers, luggage staging decks, and beast-holding pens.
The air in the underground cave was normally dominated by the clean, heavy-duty tang of electric linear-power-coil motors, the sharp ozone bite of magnetic braking rails, and the musky, leathery scent of resting draft-animals. Handlers from the Pan-African Shield were unbuckling the transport harnesses of their desert transport stock. Meanwhile, Eurasian wagon drivers in oilcloth aprons shoveled grain into the troughs of their shaggy mountain oxen.
Then, sixty feet overhead, the massive intake baffles of Exhaust Shaft 9 shuddered.
It began not with the violent blast of high explosives, but with three muffled, high-pressure thuds that shook through the steel support pillars. To the untrained ear, it sounded like a heavy valve slamming shut against high fluid pressure. But to anyone trained in heavy-duty chemical mechanics, it was the clear sound of rupture discs shearing under sudden gas spreading.
