Elon Musk has been the subject of public scrutiny for his comments on Twitter, but on Sunday the Tesla CEO used the social network to share a positive development. Musk announced on the site that The Boring Company will open the first test tunnel for a rapid transit system on Dec. 10.

Musk said the tunnel will host an opening event that night of Dec. 10 and will offer “free rides for the public” the next day. The announcement means Southern Californians could ride The Boring Company’s nearly three-mile tunnel before the end of the year.

The tunnel starts underneath a SpaceX office in the Los Angeles suburb of Hawthorne. It runs north for a bit before turning west for two miles, according to The Boring Company website.

The idea is to eventually use the company’s Loop technology to facilitate fast, underground transit between major cities, which would theoretically allow vehicles to avoid traffic. Passengers would travel in groups of up to 16 in what Boring calls “autonomous electric pods” that can travel at speeds of up to 155 miles per hour.

Alternatively, single-passenger vehicles could travel on the same tracks. The tunnels can be entered using what the company calls “Loop Lifts,” or elevators that are small enough to potentially fit in riders’ homes, according to Boring.

“Looking forward, one could have a lift in the basement of every office building, allowing extremely convenient commutes,” The Boring Company said on its website.

The test tunnel would, ideally, be a proof-of-concept for the company’s three other tunnel projects. One will take passengers between some neighborhoods in Los Angeles and Dodger Stadium, while another will provide fast transport between downtown Chicago and the city’s O’Hare airport.

Finally, the third tunnel would provide quick transport between Washington, D.C., and Maryland. Musk has previously expressed interest in tunnels connecting L.A. and San Francisco, as well as a line between Washington, D.C., and New York.