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TNB Tower Construction to Begin Reaching for the Skies
TACOMA - This week, two noteworthy changes will occur on the Tacoma Narrows Bridge project, both associated with the beginning of tower construction.
On Wednesday, August 4, crews will begin erecting a large yellow tower crane on the new Tacoma caisson, similar to the crane now located on the new Gig Harbor caisson. The crane will reach roadway height by Friday, August 6, and will sit immediately south of the existing bridge just like its cousin to the west. Both tower cranes will be used to hoist construction materials into place during tower construction over the next year. Both will expand in height as the towers rise. Eventually the tower cranes will reach 650 feet high, a height needed to place materials on the towers as they approach their ultimate 510-foot elevation height.
Also on Wednesday and Thursday of this week, crews will set two “birdcages,” or warehouse-type structures, over the north and south tower pedestals on the Gig Harbor caisson. Each birdcage measures 26 feet wide, 39 feet long and 46 feet high, and weighs 105,000 pounds. Its purpose is to enclose the concrete forms that will be used to contain, and then advance, the tower concrete as it is poured into place. It also protects tower crews from environmental elements as they build the towers.
The best vantage point from which to watch the birdcages and tower construction is at the “official bridge viewing site,” Pierce County’s Narrows Park. The park, open from dawn to dusk, is located on the shores of the Narrows. A highlight of the park is two telescopes, donated by design-builder Tacoma Narrows Constructors, that were installed specifically to help bridge buffs watch bridge construction activities. Directions to the park can be found at .