National Geographic : 1968 Feb
Master of a mountain, a double barreled tunnel for 1-80 burrows 1,135 feet through a bluff at Green River, Wyoming. During the bore, engineers used electronic devices to measure stress. They found that steel-rib supports could be placed farther apart than planned. A century ago stockmen wel comed the Union Pacific Railroad, right background, the Nation's first transcontinental line. Now ranchers truck many lambs and calves to feeder lots in Nebraska and Colorado, only hours away on the Interstate. and 1-70 with Route 157. The 33 acres brought nearly $29,000-about $883 an acre. "Then we sat tight and waited," said Mr. Brinkhoff. An oil company began negotiating, and the first service station soon opened. Parcels of land subsequently have changed hands often. One well-located acre last sold for $50,000. In the past few years some 70 acres adjoining the interchange have been sold for a total of a million dollars. All this proved a boon to Collinsville, which 214 soon annexed the booming area. This is typical of the Interstate's Midas touch in many parts of the country. highways, engineers must cope with wildly varied extremes of weather and geography. Where climate is benign and traffic loads are light, Interstate routes may measure less than a foot in thickness. But Maine's rigorous winters can frost-heave roads apart, so Interstate 95 there has to be a colossus. Top to bottom, it extends nearly five feet: 9 inches of pavement; 5 inches of crushed, processed gravel; an 18-inch layer of coarser gravel; and a 24-inch sand-and-gravel base. Broad stretches of water pre sent still another natural ob stacle that road builders must overcome. In New York City, I marveled at the beauty and efficiency of the new Verrazano ELDPARKS© N.G.S. Narrows Bridge (pages 218-19). Longest suspension bridge in the world, the 4,260-foot span outstretches San Francisco's Golden Gate Bridge. It links the Boroughs of Brooklyn and Richmond, and, as a segment of 1-278, its six lanes help channel heavy through traffic between the Middle Atlantic States and New England around Manhattan's jammed streets. "But already," an engineer told me, "so much traffic is using the Verrazano-Narrows Bridge that we'll have to complete and open the six-lane lower deck by late 1969."