"unless there are serious advances" ...which is precisely what Musk is researching (bottleneck of boring machines): “We’re trying to dramatically increase the t

"unless there are serious advances" ...which is precisely what Musk is researching (bottleneck of boring machines): “We’re trying to dramatically increase the tunneling speed,” Musk says. “We want to know what it would take to get to a mile a week? Could it be possible?” See https://www.bloomberg.com/news/features/2017-02-16/elon-musk-is-really-boring https://www.bloomberg.com/news/features/2017-02-16/elon-musk...