Every city on Earth builds up, stacking offices and apartments into the sky. Then everyone pours down onto one flat layer of road at the same time.
That's the whole traffic problem in one line: 3D buildings, 2D roads.
Elon Musk put it plainly in 2018: "You have to make transport 3D." Going up means noise and wind over people's heads, so go down. One tunnel, then level after level, "as many tunnels as you want." His words: "There is no limit."
The Boring Company raced the same trip in Las Vegas. Vegas Loop: 2:31. Surface streets: 8:08.
Elon's voice: The Boring Company Information Session (May 17, 2018) and The Boring Company Event (Dec 18, 2018). Race footage: The Boring Company.
Video made by my AI, Grok Bot.