Editor's Note: This post was originally published on December 4, 2017, and has been updated with the most recent information.

Elon Musk’s mysterious plans to construct underground tunnels aimed at cutting down on Los Angeles gridlock are becoming a little less murky.

City documents obtained today by Curbed include a preliminary map showing an extensive network of tunnels called “Loop.”

Riders could eventually use the tunnels to travel between Long Beach Airport and Sherman Oaks or from Dodger Stadium to LAX. Smaller tunnels would take passengers to other destinations to the east and west, including Santa Monica, Hawthorne (where the company is based), and the beaches of the South Bay.

An updated version of the map just released by the Boring Company features additional stops at Leimert Park, South LA, Echo Park/Silver Lake, Venice, and Union Station.

Both private vehicles and larger shuttles with “between 8 and 16 passengers” would be ferried through the tunnels on sled-like “electric skates” that will travel up to 150 miles per hour (though the plans note they could eventually go faster), the documents show. In May, Musk offered a glimpse of what that might look like.

Does this sound a bit like a conventional subway? The Boring Company suggests in the permit applications filed last month with the Bureau of Engineering that its system would be better because separate tunnels would be constructed for each stop (kind of like a freeway off-ramp), allowing vehicles to move close to top speed until they arrive at their final destination.

But before any passengers can use the system, it will need to be tested extensively.

According to plans, the project would be constructed in two phases. The first would create a single 6.5-mile tunnel parallel to the 405 freeway. It would travel beneath Los Angeles and Culver City, running roughly between the Inglewood border and Olympic Boulevard to the north.

This tunnel would initially be used for testing, but could be incorporated into the larger network if and when that becomes possible.

The second phase of the project would add new tunnels close to major destinations like LA Live, USC, and the under-construction NFL stadium in Inglewood. Planning documents note that those projects would be permitted separately and that the Boring Company plans to solicit feedback from LA residents on where new stations should go and how the system should function.

So far, the privately-funded transportation system has transformed from a cryptic social media post to a huge and nearly construction-ready infrastructure project with alarming speed. And, with the support of key local officials—including Mayor Eric Garcetti—it seems likely that Musk’s test tunnels will be up and running soon enough.