INTERCHANGE IS NOT THE SAME AS BUYING AND SELLING. Vaclav Smil takes a look at the electric power grid. "If you think about the chances of spending soon $100 billion to fix the grid think about this: the replacement value of concrete installed in America's crumbling highways, bridges, runways, pipes, canals and buildings is on the order of $6 trillion (or some two-thirds of annual GDP). As most of it was emplaced between the mid-1950s and the mid-1980s it is increasingly due for repairs, and the above estimate does not include the cost of disposal of the removed concrete as there is no practical way to recycle that mixture of hydrated cement, sands, gravel and metal. Clearly, fixing infrastructures is more daunting, and lot less glamorous, then putting them in place. We are yet to begin this challenging task." Be very, very afraid. To repeat: a detour used to mean you had reached the end of the new construction on the interstates (think late 1950s or early 1960s.) Today there are no construction detours as the road commissioner rebuilds the road under traffic. And just mention "high tension line" and watch the neighbors cringe.