Elon's hyperloop is extraordinarily different. It uses an electric hovercraft in an soft-vacuum sealed tube that is integral to the design in order to achieve

Elon's hyperloop is extraordinarily different. It uses an electric hovercraft in an soft-vacuum sealed tube that is integral to the design in order to achieve high speeds for intercity travel. This is just using stock subway cars on a stock subway track with a stock compact subway station platform. Inna tunnel. In order to get a regular route travelling from inner suburb to city center to inner suburb. The only distinction from a normal subway is that it eliminates at-surface options like shallow trench-and-cover tunnelling, and near-surface concerns about subsidence, soil composition, and underground things, in favor of having the only horizontal cut being the deep tunnel, entering the Earth on one side of the city and exiting it on the other at terminal stations. Tunnel boring machines have only gotten big enough to fit both tracks and a station platform and elevators, recently, so previous deep-tube tunnelling had to do two or three single-train-diameter tunnels, and separate excavation of stations using manual techniques, which is a whole other degree of difficulty compared to digging the equivalent length of tube with the single TBM.