A Bridge Named After Vasco da Gama
BY AWAKE! CORRESPONDENT IN PORTUGAL
THE Portuguese newspapers were replete with the news—one of the longest bridges in Europe had just been inaugurated with a display of fireworks. March 29, 1998, marked the opening of the 10.7-mile-long [17.2 kilometer] Vasco da Gama Bridge. Named after the Portuguese navigator who opened the sea route from Western Europe to India in the 15th century, the new bridge opens new routes to the industrialized north of the country, to the white beaches of the south in Algarve, and to Spain.
The bridge, the fifth longest in the world, spans the Tagus River estuary from Portugal’s capital, Lisbon, to the town of Montijo, on the south bank. Its 2,710-foot- [826 meter] long suspended section permits the passage of large seagoing vessels 150 feet [45 m] below.
A Festive Beginning
The opening ceremony actually started as a massive party a week before the official inauguration. Yes, excitement was high on Sunday, March 22, as 15,000 people were invited to a traditional Portuguese meal of feijoada, or bean stew. Where would so many be fed? Naturally, on the new bridge! What a sight to see a table stretched out over three miles [5 km] of the bridge! The meal was a success, and the people were appreciative of the gesture.
A Growing Need
Why was such a bridge necessary? Since 1966, Lisbon had been using the 3,323-foot [1,013 m] 25th of April suspension bridge. The average daily traffic was about 130,000 vehicles. Can you imagine the congestion at rush hour and on weekends? It was not uncommon for commuters to spend one or two hours to make this crossing between Lisbon and the south of Portugal. Thus the need for an alternative. The six lanes of the new bridge, located about eight miles [13 km] farther up the river, have brought some relief. It is designed so that when traffic on it reaches 52,000 vehicles a day, an additional lane can be added in each direction. It is hoped that traffic will move along quickly with a speed limit of 62 miles per hour [100 kph].
Crossing the Bridge
Join us as we enter the bridge from the south, in Montijo. Leaving the land and marsh behind, we are now on the six-mile [10 km] Tagus River section. It is high tide, and we are totally surrounded by water. The antiskid pavement gives a secure feeling together with the 1,500 pillars supporting the bridge’s length.
We now arrive at the suspended section of the bridge. This span is supported by tension cables flaring out like triumphant sails from the top of two 500-foot- [150-m] high towers. The foundations of the support pylons are sunk to a depth of from 160 to 210 feet [50 to 65 m]. For further security, the bridge was built to withstand gusts of wind up to 140 miles per hour [220 kph] and seismic shocks four and a half times greater than the earthquake that destroyed much of Lisbon in 1755.
As we reach the end of the Vasco da Gama Bridge, the northeast edge of Lisbon greets us with palm trees. If we wish, we can now continue on to the superhighway that takes us to the north of the country. The new bridge makes it possible to travel on a fine highway system from the Algarve in the south to the province of Minho in the north, with no need to fight Lisbon’s chaotic traffic!
In the building of this bridge, special attention was given to safety measures. A simple car breakdown could cause a major traffic jam. However, with 87 video cameras strategically placed on the bridge and its accesses, all irregularities in traffic are transmitted to monitors located at the police station and traffic control center. If a vehicle stops, an alarm goes off in the control room.
Additionally, a total of 36 pairs of SOS telephones have been placed every 1,300 feet [400 m] on the ten-mile [17-km] length. How does the emergency system work? Special vehicles regularly travel the bridge to care for needs that might arise, including combating fires and towing.
What about drastic changes in weather? Two meteorologic stations measure the speed, intensity, and direction of the winds and monitor weather and road conditions, adjusting speed limits according to atmospheric conditions.
The beauty of the symmetrical lines is intensified by nighttime illumination, consisting of 1,200 highway lights.
Deciding on the final location of the new bridge was no easy task. What factors were involved?
Ecologically the site presented a great challenge. This was because the bridge crosses a natural reserve for birds, located at one of the largest estuaries in Western Europe. Extensive studies had to be made for the protection of flora, fish, birds, archaeological findings, water and air quality, and hundreds of acres of salt pans. Why does the Tagus estuary attract wildlife? It is one of the most important humid zones of Portugal and Europe, making it an ideal breeding ground for internationally protected migrating birds, such as the black-winged stilt, the Kentish plover, and the little tern. During the autumn and winter periods, thousands of birds use this salt marsh as a high-tide refuge.
Long-standing fish nurseries had to be taken into account. This meant further care had to be exercised in order to disturb the fish as little as possible. Three thousand fish, basically sole and sea bass, were tagged so as to monitor the nurseries.
Suddenly, this quiet, natural habitat has been brought close to the city. To what point will the natural environment be affected? It is hoped that the measures taken to preserve the precious southern shore will protect the reserve’s natural resources as much as possible.
The Vasco da Gama Bridge is truly a great accomplishment in engineering progress, architectural beauty, and symmetry. Portugal can justly be proud of the bridge that bears Vasco da Gama’s name!
[Maps/Picture on page 15]
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Vasco da Gama Bridge
Courtesy of Lusoponte/Sonomage