President Barack Obama has pledged $8 billion in tax dollars to build a national network of high-speed rail—trains that can carry passengers at speeds in excess of 150 MPH.

But the Supertrain fantasy was a mistake back in the 1970s, when it gave rise to one of the most expensive—and rotten—TV shows in history. And it's just as much of a wreck in the 21st century for at least three reasons:

1. The lowball costs. CNN estimates that delivering on the plan could cost well over $500 billion and take decades to build, all while failing to cover much of the country at all. Internationally, only two high-speed rail lines have recouped their capital costs and all depend on huge subsidies to stay in operation.

2. The supposed benefits. "We're gonna be taking cars off of congested highways and reducing carbon emissions," says Vice President Joe Biden, an ardent rail booster. But most traffic jams are urban, not inter-city, so high-speed rail between metro areas will have no effect on your daily commute. And when construction costs are factored in, high-speed rail "may yield only marginal net greenhouse gas reductions," say UC-Berkeley researchers.

3. The delusional Amtrak example. Obama and Biden look to Amtrak as precedent, but since its founding in 1971, the nation's passenger rail system has sucked up almost $35 billion in subsidies and, says The Washington Post's Robert J. Samuelson, "a typical trip is subsidized by about $50." About 140 million Americans shlep to work every day, while Amtrak carries just 78,000 passengers. There's no reason to think that high-speed rail will pump up those numbers, though there's every reason to believe its costs will grow and grow.

"Supertrain 2010" was written and produced by Meredith Bragg and Nick Gillespie, who also hosts. Approximately 3 minutes.