For all of his other futuristic endeavors, serial inventor Elon Musk hasn’t spent much time on flying cars. Instead, he’s going to build tunnels as a solution to congested city traffic. As he revealed in April, Musk wants to build an intricate network of underground tubes through which cars will travel (really) as they sit perched on large electric skateboards (yes, really).

On Monday, Musk published a list of frequently asked questions for the Boring Company, his official entry into the world of urban mass transit. The FAQ included a seven-step plan to make cheaper tunnels, as well as a concise summary of Musk’s biggest point: tunnels rule, flying cars drool.

“Unlike flying cars, tunnels are weatherproof, out of sight and won’t fall on your head,” the blog post, which definitely seems like it was written by Musk, deadpans.

Musk realizes that the only way to get rid of traffic is to expand transportation corridors — like roads and train lines — into three dimensions. The ride-sharing giant Uber is betting it all on “going up,” as Musk puts it, with plans for an urban air mobility service that would replace some commutes with short-hop flights. But “flying cars,” per se, have a number of problems that prevent them from being a feasible, efficient mode of transportation.

Tunnels, on the other hand, offer a number of definite advantages. The Earth’s crust is deep enough that Musk says “there is no practical limit to how many layers of tunnels” that the Boring Company can build. If existing tunnels get congested, we can just go down another level. Tunnels are also, obviously, pretty much weatherproof (though the New York subway struggles with Hurricane Sandy point out that they’re not perfect).

Musk also points out that tunneling, and operating tunnels, is pretty much silent for people living on the surface, unlike flying cars buzzing around overhead.

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The general plan is to transport cars or other pods on super-fast electric sleds, like a short-range, non-vacuum version of the Hyperloop, which Musk also says will be integrated into the system for longer journeys.

Another benefit that Musk points out is one people may not think of as much. Roads and train tracks often literally divide communities — the old phrase “from the wrong side of the tracks” comes from a very real grounding where communities were often segregated on class or racial lines by physical barriers like train tracks or major highways.

Tunnels, on the other hand, run under the surface and out of sight, without disrupting the communities above them. While flying cars certainly transcend physical barriers as well, housing prices underneath airports or air corridors are noticeably lower because of noise pollution and the general anxiety of things falling out of the sky, tensions that flying cars would certainly exacerbate.

As Musk put it on Twitter today, “there’s nowhere to go but down.”

Photos via Elon Musk