While still sorely short on funds to actually get built, California's high-speed rail project reached a regulatory milestone on Thursday, with full approval now secured for a rail line linking San Francisco to Los Angeles.

The final segment that had been awaiting approval was a 38-mile stretch connecting Palmdale to Burbank, and as KTLA reports, that approval came on Thursday from the California High-Speed Rail Authority Board of Directors, which approved the final environmental impact report and route.

This segment is potentially going to be one of the costlier and more logistically complex in the high-speed-rail system, as it involves 27 miles of tunnels that burrow under the town of Acton, through parts of the Angeles National Forest, and beneath the San Gabriel Mountains National Monument — linking the San Fernando Valley to the Central Valley. From there, trains will travel over and under Tehachapi Pass to Bakersfield — a 79-mile segment approved in 2021 that involves nine separate tunnels and 15 miles of aerial structures.

The entire 463-mile route connecting San Francisco to Los Angeles is now cleared for construction, however we are still more than a decade away from seeing most of this completed. See all the segment maps here.

The current completion timeframe for the only segment currently under construction, the relatively useless Central Valley link between Merced and Bakersfield, is 2030-2033 — and that segment is still $7 billion short on funds.

The entire project is about $100 billion short on funds — and that's actually just the SF-to-LA route. Phase 1 of the larger project also includes a segment between Los Angeles and Anaheim, which is expected to get approved by next year. And then we have the later phase, which no one is even talking about, that reaches Sacramento and San Diego, for a total of about 800 miles of train track.

As the Chronicle reports, details about the actual design and earthquake safety of the many tunnels that are going to need to be built are still years off.

"We are at a very preliminary stage of design only for environmental purposes," said High-Speed Rail Authority CEO Brian Kelly to the board of directors, per the Chronicle. "The next steps on this are to bring that design work forward, further geotechnical work, understand exactly what the challenges are in construction, and make sure we’re doing the remedies correctly."

For the Palmdale-Burbank segment, Kelly says the cost is now estimated at $28.6 billion, with inflation bringing up the original estimate of $22.5 billion. But even that estimate is preliminary.

Kelly is set to retire next year as CEO of the rail authority, as KTLA notes. But he remains a champion of the project.

In a news release touting the milestone in the design phase of the latest segment, Kelly said, "It’s also transformational for Los Angeles County, connecting Palmdale to Burbank in a way that’s never been possible before."

On the plus side, the federal government has offered up a $3.4 billion grant for extending Caltrains tracks under SoMa to Salesforce Transit Center. And the work on the electrified tracks needed for the high-speed rail between SF and San Jose, which will be shared with Caltrain, is largely complete. As we learned this month, Caltrain will be rolling out its first electric trains in September.

Previously: Feds Pony Up $3.4 Billion for Caltrain Extension to Salesforce Transit Center, Which Is Now Being Called ‘The Portal’