Watch Elon Musk's Underground Sled Reach 125 mph A video depicts a test run inside one of the tubes Elon Musk hopes to spread across Los Angeles, offering sleds for cars to bypass congestion on roads overhead.

Get ready to bypass congested city streets by putting your car on Elon Musk's underground sled, which can travel at at 125 mph.

The serial entrepreneur and founder on Friday offered the first glimpse of his idea for a new network of urban transportation tunnels via an Instagram video of what appears to be an actual test run performed in Los Angeles. In the test video, an electric sled accelerates gradually to 125 mph before its forceful brakes kick in and bring it to an abrupt stop.

Musk didn't offer any details about the test other than a brief caption on his Instagram video (which, by the way, is potentially seizure-inducing, so watch it with care). He did, however, post a few more photos of the tunnel test site, including some shots of a tunnel boring machine (TBM) being lowered into the access pit.

[Warning, this may cause motion sickness or seizures] This is a test run of our electric sled that would transport cars at 125 mph (200 km/h) through the tunnels, automatically switching from one tunnel to the next. Would mean Westwood to LAX in 5 mins.

A post shared by Elon Musk (@elonmusk) on May 12, 2017 at 5:48am PDT

TBMs are frequently used in large underground tunnel projects, including new sewer mains and the Channel tunnel, and their name also gave rise to the moniker for Musk's project: the Boring Company. Musk initially teased his tunneling plans last fall, explaining that they were born partly out of frustration over persistent Southern California gridlock.

The first tunnel will run from the Los Angeles International Airport to Culver City, Santa Monica, Westwood and Sherman Oaks, Musk wrote on Instagram. He plans to build more tunnels that will cover the entire LA area, but he didn't announce a timeline.

In a video posted to YouTube last month, the Boring Company explained that drivers would pull their car onto a metal platform on the side of the road and the vehicle would then be lowered into the underground tunnel system. Once the platform is connected to the sled, it would take over, propelling the driver and his or her car to the tunnel exit point closest to their destination.

The Boring Company isn't the first high-speed underground tunnel idea Musk has put forth. He also helped create the technical underpinnings of the hyperloop, a magnetically levitating underground train that travels at jetliner-like speeds.