There's another Elon Musk vision that's much closer to becoming a reality: Loop, a more localized, subway-like project from The Boring Company. (Musk is the founder).
Subway construction has slowed in the US due to high building and maintenance costs, but Loop's futuristic concept is making progress in Los Angeles. The company has nearly finished building its first stretch of a tunnel in the city that will transport people in their own cars or pedestrian "pods" at speeds up to 150 mph.
The high-speed system will allow people to bypass traffic and get around the city faster.
The company also announced plans to build a regional Loop network connecting close citiessuch as Baltimore and Washington DC.
However, experts warn the tunnels could become congested, too. In theory, more people could gravitate to cars and wait in traffic jams at tunnel entry points.
Musk recently said it will offer free rides on the Loop in the coming months.
