Elon Musk has often stated the need for fast public transportation, which can also be clean. Buses, subways, and even trains have their limitations [don't even ask about taxis].
Elon Musk’s Hyperloop idea is actually a conglomeration of several ideas, “the Concorde, a rail gun, and an air hockey table,” according to him. Put another way, a combination of bullet trains and magnetic levitation in an airless environment.
Resembling the Hyperloop, ET3 is a tube from which air is evacuated. No air means no drag, so even a brick would be as aerodynamic as the Concorde. Second, the individual cars inside the tube are suspended by, and propelled by, magnetic levitation. Again, no friction, so the estimated speed can go up to 4,000mph or Mach 5.2 [the speed of sound is a measly 761mph].
The idea sounds grandiose, but ET3 already has mockups and prototypes and could test a 3-mile section of the Hyperloop-like system by the end of the year. If successful, it could pave the way for efficient and quick transportation across the US and even other continents. ET3 estimates that the system might cost a tenth the price of a dedicated high-speed rail line and a quarter the cost of a dedicated highway.
Put in perspective, California’s $70bln high-speed rail project could get passengers from Los Angeles to San Francisco in three hours. Be it Elon Musk’s Hyperloop, or the ET3, if one of them successfully built and operational, could do the same in just about half an hour.
[Editor's note: this reminds me of the latest Total Recall movie, where they had this hole across the Earth and a tube carrying people back and forth]