Elon Musk might be riding on a wave of electric cars and micro-renewable power generation, but that doesn't apparently preclude some pretty crackpot ideas from escaping the Tesla owner's mind, where they should have been securely restrained.
Take this one for example. Building a network of roads underneath Los Angeles because a) Los Angeles roads are really busy, b) Los Angeles residents need trains for their cars because they never do normal things like walk and c) the concept of a public transportation system has never been adequately solved in all of history.
Sorry, scratch that last one. Turns out that public transport has been solved by every major city in the world. Outside the West Coast, apparently.
I like Musk's idea of engineering new tunneling machines capable of boring and reinforcing at the same time, thus doubling the speed of current solutions. However the idea that this technology should then be used to construct a network of roads for cars in what are, when's all said and done, prams, is completely ridiculous.
Build your boring machines, build your tunnels, but build them for a world class mass transit system that works for everyone. Not just jerks who can't experience life outside of their cars.