Eight 419-ft-high concrete towers, which will support the 2,230-ft-long, cable-stayed main spans of the Tappan Zee Bridge replacement over the Hudson River in New York, topped out in early December. The 61-year-old existing span carries the New York State Thruway and serves an average of 140,000 vehicles a day. The new $3.9-billion bridge, being built by a joint venture of Fluor, Granite Construction, American Bridge and Traylor Bros., is set for completion in 2018.