Why the difference in pile heights?

Why the difference in pile heights?

An increasing number of concrete piles, many of varying heights, adorn the west side of the Pensacola Bay Bridge. These piles will eventually form the foundation for the new bridge.

Piles are driven to depths that allow them to reach the desired load-bearing capacity. For this to occur, each pile is driven to the minimum depth stipulated in the design documents. From there, the piles must exhibit sufficient resistance. This is determined by the number of strikes needed from the 22,000-pound hammer to drive the pile one-foot. Piles reach the needed load-bearing capacity at different depths due to the irregular layers beneath the bay bottom. This results in piles of different heights, and the need to cut them to the same elevation near the water line.

After they’re cut, the piles will be topped by a “trophy piece” that consists of a concrete footer, column, and cap. A total of 416 trophy pieces will be placed, some weighing as much as 265,000-pounds.

After they’re in place, the trophy pieces will be connected horizontally using concrete beams. The bridge deck, which includes the riding surface, will be constructed atop the deck.

Click here for an animated sequence that illustrates the setting of the trophy pieces.