BergerWorld: 2nd Quarter 2008

The Bronx-Whitestone, a long-span suspension bridge with a main span of 701 meters and side spans of 224 meters, crosses the East River, connecting the boroughs of Queens and the Bronx via Interstate 678. Designed by Othmar Ammann, the four-lane bridge opened to traffic in 1939.

A&W was recently retained to develop conceptual designs for the strengthening/replacement of the main cables. A&W first inspected the existing cables to determine their remaining service life expectancy. Alternatives for cable replacement and/or strengthening were then developed, including the addition of auxiliary cables to supplement the existing cables and the complete replacement of the main cables. One of the cable replacement alternatives provided for increasing the traffic capacity of the bridge by adding a second level. A&W also evaluated the existing vertical suspender ropes and developed designs for their replacements. Following the Team's evaluations, global non-linear modeling was developed for the structure, and seismic and aerodynamic analyses were undertaken to determine the effects of the additions of the recommended new cables to the towers, tower foundations and anchorage structures.