Before the real work can begin on a replacement for New York State's Tappan Zee Bridge, crews need to construct a jobsite. The $3.9-billion design-build project has limited access on both sides of the river, so workers are erecting massive steel trestles that will serve as staging areas.
By the time permanent foundation piles are driven in October, this three-mile-wide stretch of the Hudson River, about 20 miles upstream from New York City, will be a bustling jobsite. Two steel trestles—1,300 ft long and 1,040 ft long, respectively—will line its shores, and up to 100 barges with as many as 30 cranes will be working concurrently in the river.