A bold plan…but at what cost?

President-elect Obama has disclosed a few more details of his plan to rescue the economy, but left out key specifics — like how much it will cost.

But it will be big. Obama said it would be the largest public-works project since construction of the interstate highway system began in the 1950s. (For the record, the U.S. Department of Transportation in 1991 put the final cost of the system at $128.9 billion, almost all of it federal money.)

Obama did say that the largest part of his economic recovery plan — the label "stimulus" has gone out of fashion — would be rebuilding the nation’s highways and bridges, with the emphasis on projects that are "shovel ready," that is, can begin immediately.

The governors say they have $136 billion worth of projects ready to go and the chairman of their association, Edward Rendell, told The Washington Post that Obama "didn’t blink an eye when we talked about $136 billion."

Even larger figures are being talked about. House Speaker Nancy Pelosi is talking about having a package of $400 billion to $500 billion ready for Obama’s signature immediately after his inauguration. And some Senate Democrats are said to be thinking even grander — on the order of $1 trillion.

Other parts of Obama’s plan — still with few specifics — would make public buildings more energy efficient, renovate aging schools, build hospital databases of electronic medical records, install computers in classrooms and expand the reach of high-speed Internet. He would also save the middle-class tax cut and provide direct aid to the states.

Obama’s stated goal is to save or create 2.5 million jobs, an objective that attained new urgency last week when the government reported that 533,000 jobs had been lost in November, the largest one-month loss in 34 years, bringing the total job losses for the year close to 2 million.

While the desire for haste is understandable, a package this large and ambitious has huge potential for waste. To take one example, the last time we were in a frenzy to install computers in the classroom they were obsolete soon after they were installed. Compassion should be combined with healthy skepticism.