Details about both startups' systems - the exact materials in particular - are scarce, though.
The Hyperloop concept has captivated me and a lot of other people who just want to freaking get there already. From Elon Musk's white paper three years ago through now, I've been unabashedly optimistic about this insane plan. But the challenges are enormous, and deserve mentioning.
Hyperloop Vs. High-Speed Rail
California-based engineer Kristen Ray offered a thoughtful critique on Quora in 2013. She noted that thermal expansion was a problem because a 20-degree temperature change outside would cause an expansion of 600 feet across the proposed steel tube's length. Ray also questioned Musk's structural simulations for areas with seismic activity, and estimated that Hyperloop bearings alone could cost $4 billion.
Clearing those and other splintery hurdles is now in the hands of the competing startups, and student teams working on Hyperloop pod designs. Musk set this all in motion, but other smart people will have to get the system up to speed and over the finish line.
Maglev Pod Wins Hyperloop Design Competition
Last December, Hyperloop Technologies CEO Rob Lloyd wrote that his team was working toward achieving a "Kitty Hawk moment" this year. I'm still holding out hope that Hyperloop does land in history up with the Wright brothers rather than down with the Hindenburg.