The 25 de Abril Bridge (Ponte 25 de Abril "25th of April Bridge", Portuguese pronunciation: [ˈpõt(ɨ) ˈvĩt(ɨ) ˈsĩku dɨ ɐˈbɾiɫ]) is a suspension bridge connecting the city of Lisbon, capital of Portugal, to the municipality of Almada on the left (south) bank of the Tejo river. It was inaugurated on August 6, 1966 and a train platform was added in 1999. Because it is a suspension bridge and has similar coloring, it is often compared to the Golden Gate Bridge in San Francisco, USA. In fact, it was built by the same company (American Bridge Company) that constructed the San Francisco-Oakland Bay Bridge and not the Golden Gate, also explaining its similarity in design. With a total length of 2,277 m, it is the 23rd largest suspension bridge in the world. The upper deck carries six car lanes, while the lower deck carries two train tracks. Until 1974, the bridge was named Salazar Bridge (Ponte Salazar). The name "25 de Abril" commemorates the Carnation Revolution.

Construction

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From the late 19th century there had been proposals to build a bridge for Lisbon. In 1929 the idea advanced as a Portuguese engineer and entrepreneur, António Bello requested a Government concession for a railway crossing between Lisbon and Montijo (where the Vasco da Gama Bridge, the second bridge serving Lisbon, was later built in 1998). As a result, the Minister of Public Works, Duarte Pacheco, created a commission in 1933 to analyse the request. The commission reported in 1934, and proposed building a road and rail bridge. Bids were obtained. However, this proposal was subsequently put aside in favour of a bridge crossing the river at Vila Franca de Xira, 35 km north of Lisbon.

In 1953 a new Government commission started working and recommended building the bridge in 1958, choosing the southern anchor point adjacent to the recently built monument to Christ the King (Cristo-Rei). In 1959 the international invitation to tender for the project received four bids. In 1960 the winner was announced as a consortium headed by the United States Steel Export Company, which had submitted a bid in 1935.

Construction began on 5 November 1962. Forty-five months later (six months ahead of schedule) the bridge was inaugurated on 6 August 1966. Presiding at the ceremony was the President of Portugal, Admiral Américo Thomaz. Also present were the Prime-Minister, António de Oliveira Salazar, and the Patriarch of Lisbon, Cardinal Manuel Gonçalves Cerejeira. The bridge was named Salazar Bridge (Ponte Salazar), in honour of the Prime Minister.^{[citation needed]}

United States Steel International, Inc. based in New York, was prime contractor for the bridge. Morrison-Knudsen of Portugal, Ltd., an American firm based in Boise, Idaho was U.S. Steel's principle associate. Morrison-Knudsen had previously worked on the San Francisco Bay Bridge. Steinman, Boynton, Gronquist and London of New York, and Tudor Engineering Company of San Francisco designed the bridge.^[1] The steel was imported from the USA. Four workers lost their lives, out of a total of 3,000 who worked on the site. Construction took a total of 2,185,000 man-hours of work. The total cost of the bridge came to 2,200,000,000 Portuguese escudos, or US$ 32 million (US $225 million in 2011 adjusted for inflation).

Soon after the Carnation Revolution in 1974, the bridge was renamed the 25 de Abril Bridge, the day the revolution had occurred. A symbol of those times was captured on film, with citizens removing the big "Salazar" brass sign from one of the main pillars of the bridge and painting a provisional "25 de Abril" in its place.

Expansion

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The upper platform, running 70 m above water, started carrying 4 car lanes, two in each direction, with a dividing guardrail. On 23 July 1990, this guardrail was removed and a fifth, reversible lane was created. On 6 November 1998 the side walls were extended and reinforced to make space for the present six lanes. Cars crossing the bridge make a peculiar hum - listen (59s) - as two of the lanes are metallic platforms instead of asphalt.^{[citation needed]}

Since 30 June 1999, the lower platform has carried two railroad tracks. To accommodate this, the bridge underwent extensive structural reinforcements, including a second set of main cables, placed above the original set, and the main towers were increased in height. The rail line had been part of the initial design, but was eliminated for economy, and the initial structure had been lightened. Original builder American Bridge Company was called again for the job, performing the first aerial spinning of additional main cables on a loaded, fully operational suspension bridge.^{[citation needed]}

Traffic soon increased well beyond predictions, and has remained at maximum capacity despite the enlargement from four to six lanes, the addition of the rail line, and the building of a second bridge serving Lisbon, the Vasco da Gama Bridge. A third bridge has been on and off Government plans for some time, presently the plan has been dropped due to Portugal's budget constraints.

Several movies have been filmed on the bridge, including some scenes in the 1969 James Bond film On Her Majesty's Secret Service when James Bond is in a car with Marc Ange Draco's henchmen and they drive across a bridge, and the bridge is featured near the end of the movie when Bond marries Tracy and drives with her in Bond's Aston Martin across the bridge again.

Tolls

The bridge was projected to have paid all debt in 20 years, and to become toll-free (or reduced toll) after that period. However the Government kept charging tolls well beyond the 20 year period, until it gave the concession to Lusoponte, creating a monopoly of the Tagus crossing in Lisbon. As such, the bridge has always required a toll, first in both directions and from 1993 northbound only, with the toll plaza situated on the south bank of the Tagus river. The tolls have become a source of political dispute in recent years.

When opened, one had to park their car and walk to buy the toll ticket costing 20 escudos. On 14 June 1994, the Government, which ran the bridge at the time, raised the toll by 50% (100 to 150 escudos), to prepare to give the bridge into private concession for 40 years from 1 January 1996. The concessionaire was Lusoponte, a private consortium formed to build the Vasco da Gama Bridge at zero-cost to the public finances in exchange for tolls from both bridges. As a result, a popular uprising led to road blockades of the bridge and consequent police charges, an event which made the then right-wing Government highly unpopular and which many believe led to a centre-left win in the 1995 general elections. The toll is set at €1.60 for passenger cars, northbound (into Lisbon). There is no toll southbound and, until 2010, no tolls were collected during the month of August. From 2011 on, the Portuguese Government abolished this exception and ordered tolls to be charged also during this month, in order to help the efforts to reduce the budget deficit.

Design

The 25 de Abril Bridge at night.

The 25 de Abril Bridge is based on the San Francisco – Oakland Bay Bridge [SFOBB] near the Golden Gate Bridge in San Francisco, USA. Both SFOBB and the 25 de Abril Bridge were built by the same company. The American Society of Civil Engineers says that "Like its sister bridge, the SFOBB in San Francisco, the Tagus River Bridge is located in an area with a long history of earthquakes" and seismic data had to be taken into account in its construction. Another sister bridge is the Forth Road Bridge in Edinburgh.

Upon completion the bridge had the longest suspended span and the longest main span in Continental Europe, the world's longest continuous truss, and the world's deepest bridge foundation. It was the fifth largest suspension bridge in the world, the largest outside the USA. Today it is the 25th largest suspension bridge in the world.