After skewering the proposed system («one of the most expensive per mile and one of the slowest in the world»),
Musk issued an
open - source design
challenge: a 28 - passenger solar - powered pod capable of levitating through a system of tubes almost at the speed of sound, with a one - way ticket price of $ 20 and a total building cost estimated at $ 6 billion, less than a tenth of the budget for California's high - speed rail project.