At the Trans-Alaska Pipeline, which is visible from the highway. Stretching more than 800 miles, from the oil fields of Prudhoe Bay to the dock at Valdez, the pipeline carries more than two million barrels of oil a day. It's 48 inches in diameter, insulated with three-and-three-quarter inches of fiberglass. All that is jacketed in galvanized steel and, in some sections, refrigerated with a brine mixture to keep the line from melting through the permafrost.