Elon Musk says the first tunnel is "almost done."

Posting on Twitter on Sunday night, the Boring Company founder and CEO announced the first test tunnel of the ambitious ultra-high-speed transit project in Los Angeles will be open for public rides on Dec. 11.

The very first LA tunnel, which will primarily function to transport pedestrians and cyclists, was officially completed in May, after digging permission was granted in August last year.

Opens Dec 10 — Elon Musk (@elonmusk) October 22, 2018

Musk has previously announced that the service will apparently cost passengers just $1 to ride on shuttles within the city when it officially launches.

On Sunday, the CEO tweeted that the test tunnel's opening night event will happen on Dec. 10 with free rides for the public the following day, leaving from near SpaceX headquarters in Hawthorne, California.

Opening event that night & free rides for the public next day — Elon Musk (@elonmusk) October 22, 2018

Where does the tunnel run? According to the Boring Company's website, it runs from SpaceX's parking lot east of Crenshaw Boulevard and south of 120th Street, then it turns west under 120th Street, and remains underground along 120th Street for 2 miles.

The top speed in the tunnel, according to the CEO, will be 155 mph (250 km/h).

155 mph | 250 km/h — Elon Musk (@elonmusk) October 22, 2018

Musk is somewhat famed for missing deadlines. But guys, Dec. 10 is apparently the actual, real life, not-to-be-delayed date it'll launch.

I think real — Elon Musk (@elonmusk) October 22, 2018

Elsewhere, Musk also got permission from Maryland officials for his Boring Company to build a 10-mile tunnel in the state last year. It will mark the first part of Musk's envisioned hyperloop to transport people underground between New York and Washington, D.C. in just 29 minutes.

In June, Musk also won a bid to build a high-speed train from Chicago’s O'Hare International Airport to downtown. The new rail line, or Chicago Express Loop, will see 12-minute trips in electric vehicles called "skates," from the airport's new terminals to the Block 37 super-station downtown.

Now, who's keen to line up for a free ride? Three words: get there early.

UPDATE: Oct. 22, 2018, 5:39 p.m. AEDT An earlier version of this article used the word 'hyperloop' to describe the project, when in fact, it's a test tunnel for the Boring Company's urban loop project. The text of the article has been updated to reflect this.