The last time Elon Musk was asked to speak at a TED conference was in 2013. He sat down with TED founder Chris Anderson to talk about his many big ideas, including a mass-market electric vehicle, a new way for homeowners to generate and share solar power, and a reusable rocket for space exploration. Four years later, Musk has brought all of those projects to market (or, just outside of Earth’s atmosphere, as it were), so it made sense for TED to bring him back this year to update the world on his projects and inspire us with an ambitious new vision. He didn’t.

What did we get in this year’s TED Talk? A really bad, really old idea for fixing traffic.

Yes, Musk thinks tunnels—specifically, dedicated freeway tunnels for cars where vehicles are parked on “skates” that somehow suck them below the street and propel them underground—are the answer to our traffic woes. This is why he founded a tunneling company named the Boring Company (get it?) to accelerate the development of this project.

One part of Musk’s plan is sound: Tunnels are a great way to move people quickly through busy cities. Which is why we build tunnels—for trains and other high-capacity forms of transportation. What Musk’s concept video shows is what looks like a modern-day, traffic-clogged street where a handful of vehicles elect to slip below the surface to travel below ground. Assuming all of these vehicles are electric Teslas to address any environmental concerns, the fact remains that car congestion is caused by just one thing: cars. What Musk’s video doesn’t show is the gridlock created when all these vehicles try to “merge” down into the subterranean highway at the same time. It’s no different than an above-ground highway. At all.

For one local who works on transportation solutions, hearing Musk’s talk on Friday was almost too much to bear. Brent Toderian is the former chief planner for the city of Vancouver (where TED is held) and took to Twitter to air his concerns, namely the fact that Musk’s proposal was distracting from the very real issues cities are facing.

.@elonmusk @CBCVancouver Not only would #ElonMusk's idea induce more driving if realized, it would further increase the already significant inefficiency of cars. pic.twitter.com/Y7n3zmH3Fs — Brent Toderian (@BrentToderian) April 29, 2017

.@elonmusk @CBCVancouver It's related to the proven tendancy for new freeway capacity to quickly fill up, referred to as #inducedtraffic or the #lawofcongestion. pic.twitter.com/Otr101mXwG — Brent Toderian (@BrentToderian) April 29, 2017

.@elonmusk @CBCVancouver Altho #Musk's car tunnel idea won't be realized, in my experience the danger of such hyped ideas is they can distract from real solutions. pic.twitter.com/6MsllJVvE0 — Brent Toderian (@BrentToderian) April 29, 2017

The perfect example of why Musk’s idea would not work is illustrated every day by the very reason Musk is so frustrated with LA’s traffic. He commutes from his Bel-Air home to the SpaceX headquarters every day along one of the most congested corridors in the country: the Sepulveda Pass section of the 405 Freeway. I’m sure it’s an awful drive, and there’s not a good public transportation solution in place that would help him get there faster.

But one of the reasons that the area around the 405 Freeway is so congested is because Los Angeles spent $1.1 billion adding more lanes to the freeway that now lures more cars to it instead of focusing on a car-free transit solution that would help more commuters avoid it (a mistake the city is now trying to remedy). The widening project did not magically fix traffic and studies show the commute is now one minute slower.

Designing cities around subways and light-rail, as well as the walking and biking infrastructure that connects people to them, means less space is required for cars and more space can be dedicated to people. Redesigning a city for cars, even cars that travel mostly beneath the street, means you will still end up making more room for cars, both above and below ground. Possibly the worst part of this idea is that it relies on the preservation of on-street parking, which already takes up a staggering 13 percent of land in cities like Los Angeles that could be used for parks, office space, or housing.

Redesigning a city for cars, even cars that travel mostly beneath the street, means you will still end up making more room for cars, both above and below ground.

This is not to say that Musk’s idea for improving tunneling technology would not be good for the transportation world. The work performed by tunnel boring machines (or TBMs) is very expensive and very slow, and finding a way to chew beneath our cities twice as fast for half the price could dramatically change the way we build and finance infrastructure. He does say he’s working on developing a TBM that simultaneously digs and reinforces tunnels, one of the big engineering challenges for tunneling. Musk should have given his TED Talk on that instead of this surprisingly archaic idea for addressing vehicular congestion.

Sadly, this has become a typical pattern in the world of transportation tech. Startups routinely dispatch a flashy diversion to distract from the fact that they’re not solving the real problem. Just last week Uber announced its plan for flying on-demand cars—okay, helicopters, really—but in reality the company is exacerbating the vehicular congestion that it wants to sail above.

Hey, where’s that electric autonomous minibus you said you were making, Elon? Now that would really help us solve some transit problems.