|Facts & Figures|
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The pilings are driven using a diesel pile-driving hammer. Depending on the height that the hammer drops on a given setting, it transfers a large amount of energy into the pile to force it into the ground.
There is no bedrock in the area. The pilings are driven down to a hard sand layer or to a deeper hard clay layer to achieve the required strength to support the bridge.
The design plans include a minimum depth that the pilings must be driven in order to make sure the bridge supports are not affected by the current and wave action (referred to as "scouring''). The design calculates the anticipated worst scour that would occur during a 100-year storm event and the minimum depth is much deeper than that worst-case scenario. So, say we are hit by a storm on the scale of the epic 1921 hurricane that pummeled Pinellas County with 100-mile winds. The new bridge should still be standing.
Depending on the location, the piles are driven into the ground to depths varying between 75 to 115 feet below the water elevation. Once all of the pilings are driven for each pier location, they are cut off at the required top elevation and a reinforced concrete footing is built on top of the 16 piles. Each footing measures is 22 feet by 22 feet and 6 feet deep.
Once the piling is driven to the specified depth, a steel-reinforced concrete footer is constructed on top of the piling. The footers contain approximately 100 cubic yards of concrete. On top of the footers are the columns and pier cap. Since these vary in height between 17 to 65 feet for the new bridge, the overall concrete varies between 110 cubic yards to 230 cubic yards. So, for each pier in the water, the overall concrete quantities vary between 210 and 330 cubic yards.
In total, more than 23,500 cubic yards of concrete and 2,300 tons of reinforcing steel will be placed on site to build the new bridge. This total doesn't include the concrete and steel used to construct the pre-cast pilings and spans. To put that in perspective, that is about enough concrete to fill 280 residential swimming pools. Nearly 6,700 tons of asphalt will be used to build the new lanes and resurface the existing travel lanes. More than 100 palm trees and other landscaping will be planted along the bridge and its new wider approaches.
Approximately 60 people are working on the project on a given day, including the prime contractor, Orion Marine, and various sub-contractors and DOT staff.
|Facts & Figures published courtesy of Tampa Bay Times|
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