A concept sketch for Elon Musk's proposed Hyperloop transportation system Elon Musk Suggested Hyperloop route, along with future route and station possibilities Musk Says It Could Be Built for Between $6 Billion and $10 Billion; Tickets Would Be Cheaper Than Airfare California’s $70 billion proposal for a high-speed train system left Musk “disappointed,” as he mentions in his blog post, adding, “How could it be that the home of Silicon Valley and JPL — doing incredible things like indexing all the world’s knowledge and putting rovers on Mars — would build a bullet train that is both one of the most expensive per mile and one of the slowest in the world?” According to Businessweek, “Musk figures the Hyperloop could be built for $6 billion with people-only pods, or $10 billion for the larger pods capable of holding people and cars. All together, his alternative would be four times as fast as California’s proposed train, at one-tenth the cost. Tickets, Musk says, would be ‘much cheaper’ than a plane ride.” In the PDF, Musk writes, “Transporting 7.4 million people each way and amortizing the cost of $6 billion over 20 years gives a ticket price of $20 for a one-way trip for the passenger version of Hyperloop.” Nobody’s Planning to Actually Build It Just a minor detail here, but someone has to step up and build the Hyperloop, which means raising a bunch of money, getting California to okay a big double-barreled tube to be built along I-5 between San Francisco and L.A., and a whole list of other details. Musk may have pitched the Hyperloop concept today, but he has no intent to actually do anything with it right now: during a Tesla earnings call last week, Musk said, “I don’t have any plans to execute, because I must remain focused on SpaceX and Tesla.” More Must-Reads from TIME