The reason the Forest Service builds these roads, quite apart from the deep pleasure of doing noisy things in the woods with big yellow machines, is to allow private timber companies to get to previously inaccessible stands of trees. Of the Forest Service's 150 million acres of loggable land, about two-thirds is held in store for the future. The remaining one-third--49 million acres, or an area roughly twice the size of Ohio--is available for logging. It allows huge swathes of land to be clear-cut,