ORAL+PRESENTATION





**Oral Presentation. Tower Bridge**
This bridge is located in Greater London, England, crossing the River Thames. Its construction was finished in 1894 and the designer was Horace Jones with the collaboration of Wolfe Barry, but the responsibility of its construction fell on George Daniel Stevenson.

All bridges of London were built at the west of London Bridge, the first to be built, because the east part was a busy port. But in the 19th century when the population of east London grew, a new bridge was needed to decrease the traffic congestion. So the tower bridge was constructed.
 * __Purpose__**

The Tower Bridge is the most famous example of the bascule bridge, but it is also a suspension bridge. The bascule consists on two arms that can be raised to allow ships pass up and down the river and it works with a moving hydraulic system. The platform at both ends of the bridge are supported by steel rods that hang up from a main steel chain which hang down from the towers, pass over the abutments and are anchored at the shore.
 * __Type of bridge__**

Concrete was used for the foundations of the towers. And the structure and upper walkway were made of steel. While granite and stone were use to protect the framework and made the facades of the towers.
 * __Materials__**

The construction of the bridge began on 1886, and took eight years (until 1894). Twelve iron boxes, called caissons were used to construct each pier of the bridge. The group of caissons, joined forming almost the same shape of the piers, consists on two parts; the one deeper into the water is permanent, the upper part was removed when the foundations were finished. The procedure was to construct the caissons, to excavate for placing them into the riverbed, and then water was pump out to excavate again, but this time for constructing the foundations.
 * __Construction__**

Above the piers were built the steel structures of each tower, consisting on four octagonal columns joined by girders at each one of the three levels that have the towers. And at the end the structure was clad in granite and stone.

This bridge has many advantages first of all • It is a connection between the two shores of the Thames • It reduces the traffic congestion • It does not interrupt the maritime traffic • It is a vehicular, but also pedestrian bridge • And besides been used for circulation, it has spaces (in the towers) where cultural activities can be done
 * __Advantages and Disadvantages__**

• Any bridge has advantages and disadvantages. While talking about Tower Bridge a disadvantage can be that the circulation of the bridge has to be stopped when arms are lifted to allow the pass of the boats. Though the tower bridge is a great example of a bridge, because the benefits that it provides to the surrounding community are more significant than the disadvantages.

Check out this video.

Peter Pan and the Tower Bridge

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