Highly unlikely. We'll probably be able to get twice the usage out of existing roads because the distance between cars will shrink dramatically.

In my cynical opinion SDCs will likely precipitate a ten year pause in new road construction as drive times drop dramatically. But at some point we'll catch up to the additional capacity and spend another five or six years suffering as roads are built and expanded.

But the newly constructed roads will be more efficiently utilized than roads at present, so it will be cheaper per passenger mile.