On the equatorial line of Europa’s Jupiter-facing inner hemisphere lies a massive, oblong platform that juts out of the sea at a shallow angle. Leading up to it, a long tunnel hidden beneath the waves is outfitted with a pair of magnetic rails designed to levitate massive cargo capsules, accelerate them to extremely high speeds, and fling them into orbit to be intercepted by the ark station.
The commerce rail’s position allows it to take advantage of the lowest gravity conditions on the surface, and the placement of the earliest colonies was heavily dictated by its construction; arguably to the detriment of the colonists, since the inner hemisphere is exposed to higher levels of radiation, volcanism, earthquakes, and the equator experiences the most dramatic tides of the entire moon.
Once the commerce rail was operational, exporting resources from the surface became trivial, though the high speeds and unpressurized capsules meant the system could not be used to transport humans.