Extended Life Span

The Harlem River Lift Span—part of New York City's Triborough Bridge System—was the largest vertical span in the country at the time of its construction in 1936. The lift span is 310 ft (94 m) long and when closed, it provides a 55-ft (16.8 m) clearance above the river. The bridge also includes two through-truss spans and two tower spans, for a total length of 770 ft (235 m), bringing the Harlem River Lift Span into compliance with current standards required, increasing its live-load capacity, replacing its deck, protecting its piers from vessel collisions, and adding seismic isolation bearings. The designers recommended a new steel battle deck for the entire bridge and the approach spans, in conjunction with the strengthening of four substandard floor beams, to improve the bridge's load rating without increasing the weight of the deck. Along with the deck replacement, the overall roadway geometry is to be improved, with the six existing 10 ft 2 in. (3.1 m) wide lanes widened to 10 ft 6 in. (3.2 m) by decreasing the shoulder width from 1 ft 6 in. (0.46 m) to 1 ft (0.30 m). Additionally, a reinforced-concrete pier protection system will be installed in the form of a continuous concrete rim beam supported on concrete piles that will be embedded in rock below the river bottom.