To link the continents required the longest single-span suspension bridge outside the United States. The span stretches 3,542 feet, all the way across the straits. The only bridges with longer spans are New York’s Verrazano-Narrows (4,260 feet), San Francisco’s Golden Gate (4,200 feet) and Michigan’s Mackinac (3,800 feet).

Construction Features

One of the first jobs was construction of the two bridge towers. Eventually the towers rose on either side of the straits to 540 feet, the height of a fifty-five-story building. At about 150 feet above ground, the legs of a tower were joined by a thirty-two-foot crossbeam. It is upon the top of this crosspiece that the roadway now rests, high enough to permit the largest ships to pass beneath. Another crosspiece joins the tower legs at 330 feet and a third one does so at 500 feet, near the top.

The four tower legs are mammoth​—twenty-three by seventeen feet at their base. And they are hollow! Thus, inside each of them is an elevator large enough to carry twenty passengers to the road level. There is even a small elevator for carrying maintenance men from there right to the top of the towers.

After the bridge towers were up, the two huge suspension cables were strung, using 25,000 miles of steel wire. Each cable has nineteen strands. These strands are each composed of 550 wires. Actually these wires form a continuous loop that was strung back and forth across the straits 550 times to make one strand.

Each completed cable of nineteen strands weighs 2,700 tons, and is two feet in diameter! Connected to these two cables are hanger cables to which the roadway was then attached. The way this was done was most interesting to watch.

The six-lane roadway is composed of sixty 59-foot-long, 109-foot-wide prefabricated steel-box sections. Each section weighs about 150 tons. It was on December 7, 1972, that the first of these sections was lifted into its place high above the water from a barge in midstream. The roadway formed rapidly, as successive sections were lifted into place and welded together. Finally, on March 26, 1973, the last section was lifted and hung amid celebration.

However, there was yet work to finish. The roadway deck needed to be asphalted, suspension cables required painting and elevators had to be installed. Also, approaches to the bridge still needed to be constructed and paved.