Vasco da Gama Bridge
From Wikipedia, the free encyclopedia
| Vasco da Gama Bridge | |
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| Official name | Ponte Vasco da Gama |
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| Carries | Six road lanes |
| Crosses | Tagus River |
| Locale | Sacavém, north of Lisbon (right bank) Municipality of Montijo (left bank) |
| Maintained by | Lusoponte [1] |
| Design | cable-stayed, viaducts |
| Longest span | 420 m (1,378 ft) |
| Total length | 17.2 km (10.7 mi) |
| Width | 30 m (98 ft) |
| Opening date | March 29, 1998 |
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The Vasco da Gama Bridge (Portuguese: Ponte Vasco da Gama, pron. IPA: ['põt(ɨ) 'vaʃku dɐ 'gɐmɐ]) is a cable-stayed bridge flanked by viaducts and roads that spans the Tagus River near Lisbon, capital of Portugal. It is the longest bridge in Europe, with a total length of 17.2 km (10.7 mi), including 0.829 km (0.5 mi) for the main bridge, 11.5 km (7.1 mi) in viaducts, and 4.8 km (3.0 mi) in extension roads. Its purpose is to alleviate the congestion on Lisbon's other bridge (25 de Abril Bridge), and to join previously unconnected motorways radiating from Lisbon.
The bridge was opened to traffic on March 29, 1998, in time for Expo 98, the World's Fair that celebrated the 500th anniversary of the discovery by Vasco da Gama of the sea route from Europe to India.
[edit] Description
The bridge carries six road lanes, with a speed limit of 120 km/h, the same as motorways, except on one section which is limited to 100 km/h. On windy, rainy and foggy days, the speed limit is reduced to 90 km/h. The number of road lanes will be enlarged to eight when traffic reaches a daily average of 52,000.
- Bridge sections
- North accesses - 945 m
- North viaduct - 488 m; 11 sections
- Expo viaduct - 672 m; 12 sections
- Main bridge - main span: 420 m; side spans: 203 m each (total length: 829 m); cement pillars: 150 m-high; free height for navigation in high tides: 45 m;
- Central viaduct - 6.351 m; 80 pre-fabricated sections 78 m-long; 81 pillars up to 95 m-deep; height from 14 m to 30 m
- South viaduct - 3.825 m; 45-m sections; 84 sections; 85 pillars
- South accesses - 3.895 m; includes the toll plaza (18 gates) and two service areas
[edit] Construction and cost
The project was split in four parts, each one built by a different company, and supervised by an independent consortium. There were up to 3,300 workers simultaneously in the project, which took 18 months of preparation and another 18 months of construction.
The bridge has a life expectancy of 120 years, having been designed to withstand wind speeds of 250 km/h and hold up to an earthquake 4.5 times stronger than the historical 1755 Lisbon earthquake (estimated at 8.7 on the Richter scale). The deepest foundation piles, up to 2.2 m in diameter, were driven down to 95 m under mean water level. Due to the bridge's length, it was necessary to take the Earth's curvature into account to site the piers correctly, otherwise a mistake of 80 cm would have appeared at either bridge's end. Environmental pressure was a constant throughout the project, resulting in the left-bank viaducts being extended inland to preserve the marshes underneath, as well as the lamp posts throughout the bridge being tilted inwards so as not to cast light on the river below.
The cost of the bridge came at zero to the State, as it was built in the BOT (build-operate-transfer) system by Lusoponte, a private consortium which got a 40-year concession on the tolls of both Lisbon bridges. Lusoponte's capital is 50,4% from Portuguese companies, 24.8% French and 24.8% British.
In 2006, the toll is €2.15 per passenger car for northbound traffic. There is no toll for southbound traffic.
[edit] Source
- (Portuguese) www.civilium.net
[edit] External links
