60 Minutes rewind. Rarely is a public works project built anymore without a huge price tag. But we've come upon a road that may be breaking all the records.It's costing more than a billion dollars a mile. And if you think that's ridiculous or outrageous, consider this. Onethird of the cost has little or nothing to do with building the road.What we're talking about is what they call the big dig. the most expensive road ever built. It's a seven and a half mile,10 billion dollar stretch of highway in downtown ...