A Bridge Between Two Continents
By “Awake!” correspondent in Turkey
IN LESS than two minutes a car traveler can now cross the famous Bosporus Straits that separate Europe from Asia. Making this possible is the beautiful new Bosporus Bridge, opened here at Istanbul last October 31. It is the only permanent span ever built to link two continents.
Once before the continents were bridged—temporarily. That was in the sixth century B.C.E. On that occasion the Persian king Darius the Great lashed boats together near this location to form a pontoon bridge, permitting his army to cross over from Asia to Europe.
Since that time, many plans have been made to build a more permanent bridge here. About two hundred years ago the French proposed a masonry-arch bridge. Then in 1860 the French designed a five-span bridge with colossal supporting towers, each topped by a mosque. A German bridge proposal was made in 1905. In the 1930’s a European technical congress proposed bridge plans, and so did the Turkish government in 1953. However, none of these plans materialized.
But why all this concern about a bridge? The location and growth of Istanbul are responsible.
Istanbul straddles the Bosporus, making it the only city in the world built on two continents. At this strategic crossroads of East and West, the city has been prominent ever since it was founded early in the sixth century B.C.E., when it was called Byzantium. Renamed Constantinople after Emperor Constantine about 800 years later, it became the wealthiest city in the world. In 1453 it was captured by the Turks, who embellished it with mosques and palaces and changed its name to Istanbul.
The principal part of the city is on the European side. Until recently relatively few lived on the Asian side. But Asian Istanbul has been growing rapidly, and about 25 percent of the city’s more than 2,000,000 population now live here.
Many workers commute from Asia to Europe each morning and return in the evening. However, bad weather causes ferry delays. Also, before the opening of the new bridge the increasing volume of traffic placed a terrific strain on ferry service. A wait of an hour or more was not unusual. But now the long lines of cars waiting for a ferry have disappeared.
The Bosporus Bridge forms the center link in thirteen miles of expressways that will eventually form a beltway around Istanbul. This will permit between-continents travelers to skirt the congestion of city traffic. Thus more commercial travel between the European and Asiatic parts of Turkey should be encouraged.
A Mammoth Project
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 of the Bosporus Bridge began in February, 1970, and was completed in 1,345 workdays. The cost of about $40 million was paid for mostly with foreign aid. However, it is estimated that the borrowed money can be repaid within four years.
The toll for a passenger car is 10 Turkish liras, or about 70 cents. Other vehicles pay more according to weight and size. With an anticipated traffic of 20,000 to 22,000 vehicles a day, the bridge could soon be earning a handsome annual income. After the loan has been paid off, revenues are scheduled to flow into the coffers of Istanbul.
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.
Now this is all completed, and traffic is flowing. Already 28,000 vehicles in a single day have crossed the bridge! For many in this growing country, the bridge, like television and other modern marvels, is something they wonder at as they stand nearby, craning their necks to see a tower top.