Musk's true hyperloop design isn't a train like the Hyperloop One company is proposing, but a sort of low-pressure ramjet hovercraft in a hose. On Mars, you do

Musk's true hyperloop design isn't a train like the Hyperloop One company is proposing, but a sort of low-pressure ramjet hovercraft in a hose. On Mars, you don't need the top half of the hose because it's already low-pressure, so the ramjet hovercraft could run in an open-air trough.