Here are three facts to consider.
First, infrastructure spending has a higher bang for the buck than just about any other kind of spending. The San Francisco Fed, for one, estimates that every $1 of highway spending raises GDP by $2. Second, even if you don't believe in multipliers, infrastructure spending is something we have to do eventually—so we'd save money if we do it when interest rates are low. Third, investors are paying us 0.43 percent after inflation to borrow for 5 years.
Now look at the chart below, via Cardiff Garcia of FT Alphaville, of inflation-adjusted infrastructure spending in the U.S. the past decade. Weeping is optional.
This is what a disastrous policy error looks like. There wasn't enough infrastructure spending in the stimulus, and there really hasn't been enough since the stimulus ended—and since austerity-obsessed Republicans took over the House. President Obama has, of course, called for modestly more infrastructure spending now, but that's been a political non-starter.
This isn't even penny-wise and pound foolish. It's just foolish.