Elon Musk is best known for Tesla electric cars and SpaceX. But his new tunnel-making venture, aptly named “The Boring Company,” wants to revolutionize the way that Americans travel — not up in powerful space rockets this time, but rather beneath our cities. Here’s everything you need to know.

In the words of the Boring Company, “roads must go 3D.” Musk and his company believe that going underground is a better choice than mass air travel. “Going up” in flying cars will create a whole new set of problems including noise, weather concerns, and the safety of pedestrians below them. With tunnels, traffic is pushed underground, limiting noise and preventing the division of communities that a large multilane highway exacerbates.

Construction of these tunnels is all but invisible to those on the surface, and the Boring Company argues that as more capacity is needed, a new tunnel can be built to address it. He likes the idea of tunnels because they’re long-term, they won’t have much impact on current city structures, and (naturally) because it’s a little sci-fi. It also ties in well to Musk’s high-speed, long-distance transit passion (including dreams like the Hyperloop), and the possibility of connecting nearby cities to each other.

The Boring Company was founded to look into ways of making underground tunnel construction more feasible.

Humans have been digging underground tunnels for thousands of years, so at face value Musk’s idea seems a little bit silly. Why would a man who’s spent many years working on next-generation technologies focus on something we already do well? The simple answer is efficiency.

We might be able to construct tunnels better than we have in the past, but that doesn’t mean we do it efficiently or in a cost-effective manner. A great example of this was Boston’s so-called “Big Dig,” which pushed most of the highway systems through downtown Boston into tunnels. Inefficiencies and cost overruns inflated the cost of that project to $22 billion, and it took 15 years to complete. even worse, the end product was of questionable quality, even though it has had a generally positive effect overall.

The Boring Company hopes to prevent construction nightmares like the Big Dig. It’s not reinventing the wheel; what’s different here is they’re using old-fashioned underground digging more efficiently. Specifically, the Boring Company aims to vastly increase the speed at which tunnels can be dug and at a far cheaper rate than is now feasible. It will help dig the tunnels itself, using its own assets — with a bit of high-tech thrown in.

The Boring Company focused on several areas of tunnel digging to improve the process overall. Some of the advancements include:

Musk and the Boring Company have been doing real tunneling work for the better part of two years now. Construction of a small test tunnel wrapped up in June 2017, however it wasn’t ready for a public demonstration until December 2018. That tunnel is 1.14 miles in length.

The company did have plans to build a second tunnel that ran parallel with the 405 freeway (beneath Sepulveda Boulevard) along Los Angeles’ west side, but it was scrapped after community pushback. Other projects are still underway, including some pretty crazy ones.

The company proposed a loop system in August 2018 that would shuttle Los Angeles Dodger fans and concertgoers from the Los Feliz, East Hollywood, or Rampart Village neighborhoods to Dodger Stadium. The total trip is expected to cost passengers just $1 to ride, and would get them to the stadium in 4 minutes. Currently in the environmental review and permitting stages, no date for construction or opening has been set. Construction is expected to take less than 14 months.

It also was selected by the Chicago Infrastructure Trust to “design, build, finance, operate and maintain” an O’Hare Express loop service. This system will  connect Block 37 in downtown Chicago with O’Hare Airport Terminals 1-3.

Perhaps the biggest and most ambitious project is a proposed tunnel connecting Baltimore with Washington D.C., which would allow individuals to travel between the two cities in about 15 minutes. Construction of the tunnel is expected to take between 12 and 20 months depending on the speed of the TBM. The long-term goal is to build a tunnel between New York City and D.C. The trip is expected to take only 30 minutes.

Many of these projects currently are not much more than proposals, but a few have begun, and Tthe Boring Company is going to be busy for the foreseeable future.

There are a number of issues with digging new transportation tunnels, some that the Boring Company has addressed and some it has not. They include:

If you live in NYC, D.C., or another city riddled with public transit, you have probably noticed (especially in recent years) that the big problem with subways and similar solutions is maintenance. Tunnels may reliably stay the same, but underground equipment wears out very fast and is very difficult to replace or keep running on a reliable schedule over time. In other words, you can have the best tunnels in the world, but unless the city devotes enough resources to maintenance and updates, they are going to run into a whole lot of problems.