25 de Abril Bridge

Infobox_Bridge
bridge_name= 25 de Abril Bridge


View from Cristo-Rei (south bank)
official_name= "Ponte 25 de Abril"
carries= Six road lanes
Two train tracks
crosses= Tagus river
locale= Lisbon, Portugal (right bank)
Municipality of Almada (left bank)
maint= Lusoponte [http://www.lusoponte.pt/]
id=
design= Suspension
mainspan= 1,012.88 m
length= 2,277.64 m
width=
clearance=
below= 70 m at mean higher high water
traffic= 150,000 cars
157 trains
open= August 6, 1966
closed=
toll= 1.30 euro (northbound)
map_cue=
map_

map_text=
map_width=
lat= 38.690066
long= -9.177017

The 25 de Abril Bridge (translation: 25th of April Bridge, in Portuguese: "Ponte 25 de Abril", pron. IPA2|'põt(ɨ) 'vĩt(ɨ) 'sĩku dɨ ɐ'bɾiɫ) is a suspension bridge connecting the city of Lisbon, capital of Portugal, to the municipality of Almada on the left bank of the Tagus river. It was inaugurated on August 6 1966 and a train platform was added in 1999. It is often compared to the Golden Gate Bridge in San Francisco, USA, due to their similarities and same construction company. With a total length of 2,277 m, it is the 19th largest suspension bridge in the world. The upper platform carries six car lanes, the lower platform two train tracks. Until 1974 the bridge was named Salazar Bridge.

History

Construction

Since the late 19th century there had been proposals to build a bridge for Lisbon. In 1929 the idea advanced as Portuguese engineer and entrepreneur António Belo requested a Government concession for a rail crossing between Lisbon and Montijo (where the Vasco da Gama Bridge, the second bridge serving Lisbon, was built in 1998). This forced the Minister of Public Works Duarte Pacheco to form a commission in 1933 to analyze the request. In 1934, the result was a proposal to build a road and rail bridge, and bids were obtained. This proposal was put aside in favor of a bridge which was built in Vila Franca de Xira, 35 km north of Lisbon.

In 1953 a new Government commission started working and recommended in 1958 building the bridge, choosing the south anchor point adjacent to the recently built monument to Christ the King ("Cristo-Rei"). In 1959 the international open bid 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.

On November 5 1962 construction began. 45 months later the bridge was inaugurated on August 6 1966, six months ahead of schedule. Presiding at the ceremony was the President of Portugal, Admiral Américo Thomaz. Also present were the Prime-Minister, dictator António de Oliveira Salazar, and the Patriarch of Lisbon, Cardinal Manuel Gonçalves Cerejeira. The bridge was christened Salazar Bridge ("Ponte Salazar"), in honor of the Prime-Minister.

The bridge was built by the American Bridge Company, part of the winning consortium, assisted by eleven local companies. The steel was imported from the USA. Four workers lost their lives, out of 3,000 that worked on the site, for 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 $201 million in 2006 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

The upper platform, running 70 m above water, started carrying 4 car lanes, two in each direction, with a dividing rail. On July 23 1990, this rail was removed and a fifth reversible lane was created. On November 6 1998 the side walls were extended and reinforced to make space for the present six lanes.

Cars crossing the bridge make a peculiar hum - - as two of the lanes are metallic platforms instead of asphalt.

Since June 30 1999, the lower platform carries 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.

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.

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.

When opened one had to park their car and walk to buy the toll ticket costing 20 escudos. In June 14 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 in concession for 40 years from January 1 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, weakening the Government. As of 2008, the toll is set at € 1.30 for passenger cars, northbound (into Lisbon). There is no toll southbound and no toll either way during August.

Design

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 17th largest suspension bridge in the world.

Numbers

In 2006 a daily average of 150,000 cars cross the bridge, including 7,000 on the peak hour. Rail traffic is also heavy, with a daily average of 157 trains. In all, around 380,000 people cross the bridge daily (190,000 if considering return trips).

Other numbers:
*1012,88 m - length of main span
*2277,64 m - length of truss
*70 m - height from water to upper platform
*190,47 m - height of main towers (second tallest structure in Portugal)
*58,6 cm - diameter of each of the two sets of main cables
*11,248 - number of steel wire strand cables, each 4,87 mm in diameter, in each set of main cables
*54,196 km - length of steel wire strand cables making up the two sets of main cables
*79,3 m - depth (below water-level) of the foundation of the south pillar
*30 km - length of access roads
*32 - viaducts in the access roads

Partial source: TV documentary aired on August 6 2006 on Portuguese station RTP1.

See also

* Vasco da Gama Bridge - the other bridge serving Lisbon.

External links

*
* [http://www.personal.u-net.com/~luso/bridges.htm Bridges of Lisbon]
* [http://www.bridgemeister.com/list.php?type=country&country=Portugal Bridges of Portugal at Bridgemeister.com]