Is Elon Musk's plan for a road network beneath LA more than a pipe dream?

Cities attract wild ideas, from Qinhuangdao’s straddling bus to London’s bike lanes in the sky. As Musk’s Boring Company starts tunnelling, could his plans for underground roads and Hyperloop trains prove the doubters wrong?
Read more: https://www.theguardian.com/cities/2017/sep/04/elon-musk-hyperloop-boring-underground-la-traffic?source=Snapzu