Queensboro Bridge, over welfare Island, East River, New York. The queensboro Bridge extends over the East river fro E. 59the Street and 2nd Ave., Manhattan, to Jane and Academy Streets, Long Island city. It is a great cantilever structure, costing $25, 000,000. and rests on six masonry piers. It is 7636 feet long, west span 1182 feet, clear height over channels 135 feet height of island toward 324 feet width 86 feet, two decks with 53 - foot road. Welfare Island was formerly known as Blackwell's Island.