The value of smooth roads

From today's Star Tribune: State of our roads is getting bumpier

The article says "Department officials say they don't consider the condition of the roads a safety concern," and there is no evidence unsmooth roads (at least in the range considered in Minnesota, where roads are much better than, say, Africa), reduce capacity, so what is the rationale for smooth roads?

The answer seems to be to prevent future deterioration.

""You can reconstruct the roads already in poor condition or you can keep the roads that are about to go into the poor category from ever getting there by doing something first," Janisch said. "It's cheaper to keep them up.""

But is there a value to smooth roads? How much of a premium would travelers pay, all else equal, to have a smoother ride?

-- dml