AIUI a single tunnel doesn’t scale, sure, but part of the Boring Company’s mission is to make the tunnels super cheap, so scaling up the system consists of adding additional parallel tunnels.

I guess it’s like adding lanes to a highway, but instead of being limited to “make it wider” you can think in 3D and “bundle” tubes together with a honeycomb cross section.

Spitballing more, “reversing the polarity” of a single lane tunnel in such a bundle would be trivial to account for burst traffic (like they move the center divider on the Golden Gate Bridge).