The Manhattan Bridge connects Brooklyn and Manhattan, with vehicular lanes, transit tracks, and pedestrian-bicycle paths, over the East River. It consists of a 2,920 ft long suspension bridge and 3,935 ft of approach spans, for a total length of 6,855 ft. Its design and construction oversight are credited to the New York City Department of Bridges and engineers Othniel Nichols, Leon Moisseiff, and Rudolph Modjeski. It was originally opened to traffic on December 31, 1909.

Heavy eccentric loads due to rail traffic have caused considerable twisting of the relatively flexible suspension bridge spans. Maintenance issues including bracing failures, cable-band slippage, and fatigue cracking have been attributed to the twisting under eccentric rail loads. A comprehensive rehabilitation program to minimize the twisting, address other condition and maintenance issues, and bring the bridge into compliance with New York City seismic codes is currently in progress.

As a component of the rehabilitation program, Weidlinger Associates prepared a seismic assessment and retrofit recommendations in accordance with New York City DOT Guidelines for Critical Bridges. The evaluation considered both 2500-year and 500-year return period earthquakes. OPAC performed an peer review of Weidlinger's evaluation and retrofit recommendations.