BridgesPresentations

=** The Golden Gate Bridge **= Before the bridge was built, the only practical short route between San Francisco and what is now Marin County was by boat across a section of San Francisco Bay. Ferry service began as early as 1820, with regularly scheduled service beginning in the 1840s for purposes of transporting water to San Francisco. The Sausalito Land and Ferry Company service, launched in 1867, eventually became the Golden Gate Ferry Company, a Southern Pacific Railroad subsidiary, the largest ferry operation in the world by the late 1920s. Once for railroad passengers and customers only, Southern Pacific's automobile ferries became very profitable and important to the regional economy. The ferry crossing between the Hyde Street Pier in San Francisco and Sausalito in Marin County took approximately 20 minutes and cost US$1.00 per vehicle, a price later reduced to compete with the new bridge. The trip from the San Francisco Ferry Building took 27 minutes. Many wanted to build a bridge to connect San Francisco to Marin County. San Francisco was the largest American city still served primarily by ferry boats. Because it did not have a permanent link with communities around the bay, the city’s growth rate was below the national average. Many experts said that a bridge couldn’t be built across the 6,700 ft (2,042 m) strait. It had strong, swirling tides and currents, with water 500 ft (150 m) in depth at the center of the channel, and frequent strong winds. Experts said that ferocious winds and blinding fogs would prevent construction and operation.


 * Tower Bridge **

Many wanted to build a bridge to connect San Francisco to Marin County. San Francisco was the largest American city still served primarily by ferry boats. Because it did not have a permanent link with communities around the bay, the city’s growth rate was below the national average. Many experts said that a bridge couldn’t be built across the 6,700 ft (2,042 m) strait. It had strong, swirling tides and currents, with water 500 ft (150 m) in depth at the center of the channel, and frequent strong winds. Experts said that ferocious winds and blinding fogs would prevent construction and operation.


 * The Millennium Bridge **

The **London Millennium Footbridge** is a pedestrian-only steel suspension bridge crossing the River Thames in London, England, linking Bankside with the City. It is located between Southwark Bridge (downstream) and Blackfriars Railway Bridge (upstream). The bridge is owned and maintained by the Bridge House Estates, a charitable trust overseen by the City of London Corporation. Construction of the bridge began in 1998, with the opening in June 2000. Londoners nicknamed the bridge the **Wobbly Bridge** after crowds of pedestrians felt an unexpected swaying motion on the first two days after the bridge opened. The bridge was closed, and modifications eliminated the wobble entirely. It was reopened in 2002. The southern end of the bridge is near Globe Theatre, the Bankside Gallery and Tate Modern, the north end next to the City of London School below St Paul's Cathedral. The bridge alignment is such that a clear view of St Paul's south facade is presented from across the river, framed by the bridge supports. The nearest London Underground station is Mansion House. **Woman's Bridge**

The Puente de la Mujer (Spanish for "Woman's Bridge") is a footbridge in the Puerto Madero district of Buenos Aires, Argentina that spans dock 3 (//dique 3//). It is of the Cantilever spar cable-stayed bridge type and is also a swing bridge, but somewhat unique in is asymmetrical arrangement. It has a single mast with cables suspending a portion of the bridge which rotates 90 degrees in order to allow water traffic to pass. When it swings to allow watercraft passage the far end comes to a resting point on a stabilizing pylon. It was designed by Santiago Calatrava and is similar to his Puente del Alamillo and Sundial Bridge at Turtle Bay, but with a forward, rather than a reverse angled cantilever, as is seen in those bridges. The footbridge was donated by Alberto L. González to the City of Buenos Aires in gratitude for 60 years of work in the country. Started in 1998, it was completed on December 20, 2001.

**Juscelino Kubitschek Bridge or JK Bridge** The Juscelino Kubitschek Bridge (Portuguese: //Ponte Juscelino Kubitschek//), also known as the President JK Bridge or just the JK Bridge, crosses Lake ParanoáBrasília, D.F. It is named for Juscelino Kubitschek de Oliveira, former president of Brazil, who in the late 1950s decided to build Brasília as the new capital of the country. It was designed by architect Alexandre Chan and structural engineer Mário Vila Verde. The main span structure has four supporting pillars submerged under Lake Paranoá, and the deck weight is supported by three 200-foot tall asymmetrical steel arches that crisscross diagonally. The decks are suspended by steel cables alternating at each side of the deck, interlacing in some kind of twisted plane (parabolic like). The entire structure has a total length of 1,200 m, and it was completed at a cost of US$56.8 million (R$160 million - Brazilian //Reais//, current 2003).[3] The bridge has a pedestrian walkway and is accessible to bicyclists and skaters.