From the Queens Gazette:
The original Hunters Point Avenue Bridge dates back to 1874 when the bridge was constructed of wood. Then, from 1874 to 1907, an iron bridge was built before it too was replaced in 1910 by a doubleleaf bascule bridge, designed by the Scherzer Rolling Lift Bridge Company under the supervision of Edward Byrne of the Department of Bridges. It was modified in the early 1980s as a single-leaf bascule bridge. Bascule bridges are designed with a counterweight that balances the span as it swings upward while a single leaf lifts up from one end and a double leaf lifts up from both sides in the middle of the span.