Wow! That is some machine.
Still it's only going through sedimentary material, "clay, claystone, sandstone & limestone. Neither the coastal mountains nor the mighty rocky's are based on such malleable materials. The article did mention something I'd skipped over, methane deposits. They've been pumping oil out of Southern California for a long time, but one little methane bubble could turn a boreing machine into rubble.
There are basically two types of tunnel boring machines: for soft soils and for rocks. A quick source is https://en.wikipedia.org/wiki/Tunnel_boring_machine - see sections 2.2 and 2.1, respectively.
The Gotthard base rail tunnels in the Swiss Alps have been made through very hard rock - with sometimes crushed salt deposits functioning as high pressure aquifers. Quite difficult work - but they managed. Under less complicated conditions, rock tunneling machines have been used in most continents.
Passing the San Andreas fault is certainly an issue, but otherwise there are no serious obstacles for boring Los Angeles - San Francisco. For efficiency, usually one machine is used for 10 - 25 km only (cf. the Channel Tunnel - boring from both ends). The hyperloop would likely consist of two tunnels (one in each direction) and probably a service tunnel in between - so that would be quite an investment in TBM equipment.
Thanks for your, and others wake up call(s).
After decades in Nevada I should have at least remembered the boring machine that was carving away at our infamous "Nuclear Suppository", as one of our brighter Senators had dubbed the Yucca Mountain Site.
Hardrock tunneling equipment certainly does exist, (my bad), but I hope you will agree that it's outrageously expensive, and that progress is measured in kilometers/year.
The viability of going from Los Angeles at sea level, to Las Vegas, at 2,000 ft requires tunneling under Cajon Summit at 4,000 ft., except that Cajon pass follows the path of St. Andreas's famous fault. North of there is Mount Baldy (above the tree line), and to the south Mount Arrowhead and Big Bear Mountain with their ski resorts and high altitude training camps.
Musk would either travel for 100 miles deep underground, or stay close to the surface and have such a roller coaster ride that pealing passengers off the ceiling would be a problem at speed. The trains creeping up and down Cajon do so at less than 30 MPH, and maintain a grade of less than 3% only by zig-zagging up the face of the cliffs. Zigging and zagging are not things that the Hyperloop is designed for, but it is the traditional way to scale mountains.
Wide sweeping heavily banked turns are certainly doable, but how does one adjust to up and down movements at speed? Pilots in G-Suits with barf bags, strapped tightly to their seats, have learned to adjust, but passengers might object to the 0 G sections of the ride.
Terry