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July 2005: Superstructure Erection, Piers 37 & 38; Footing Preparation, Pier 39 |
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July 2005: View from the 1940 bridge. Towers at Piers 37 and 38 are close to full height. |
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The first pier table component in place at Pier 38 (left); the superstructure begins to reach out from Pier 37 (right). |
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View of the access stairs and walkway atop the tower at Pier 37. |
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View of the access stairs and walkway atop the tower at Pier 37. |
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View from atop Pier 37. The black crane tower, mounted on the pier at roadway level, is some 300 feet (91.4m) tall. |
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Field sections are preassembled steel structures consisting of edge girders and floor beams. Each field section is 95 feet (28.9m) wide and 48 feet (14.6m) long. In this photo, a field section is lifted into place by crane. |
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A field section is lifted into place by crane. |
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Field sections are held in place by crane and their position is checked by surveyors on shore. Ironworkers then install and tighten hundreds of bolts to connect the new field section to the superstructure. |
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Once a new field section is bolted into place, steel grate platforms are installed in the open bays to create an accessible work area. The grates are eventually replaced by precast concrete slabs. |
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Precast, steel-reinforced concrete slabs are brought to the site for installation. The deck slabs serve as a base for the roadway. Each slab is 15 feet, 9 inches (4.8m) wide, 47 feet (14.3m) long and weighs 40 tons (36.28 metric tons). |
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A precast deck slab is hoisted into place on the field section. |
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The 47-foot (14.3m) wide deck panels are laid atop the field sections in rows of two and stitched together with reinforcing steel. Gaps between the slabs are filled with concrete to form a continuous surface. A two-inch (5cm) layer of a dense concrete called silica fume, will be laid over the panels to create the roadway surface. |
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Field sections are supported from the bridge towers by bundles of cable. Depending on their location, cable bundles may contain anywhere from 27 to 68 individual steel strands. As stay cables are installed, a worker helps to guide the individual stands into the stay pipe extending from the tower face. |
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As stay cables are installed, a worker helps to guide the individual stands into the stay pipe extending from the tower face. |
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Individual cables within each bundle are strung between anchorages on the edge girders (left) and tower legs (right), then pulled to predetermined tensions. |
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Pier 39: The land piers or ?anchor piers? are supported by a foundation made up of 15 drilled shafts. Each 6.5 foot diameter drilled shaft contains approximately 150 cubic yards of concrete and 6 tons of reinforcing steel. Each shaft projects 125 feet into the ground below the pier. |
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View of Pier 39 through the support framework of the sheet pile cofferdam |
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View of Pier 39 through the support framework of the sheet pile cofferdam |
