The 33rd Street Railroad Bridge is a truss bridge that carries the Allegheny Valley Railroad on the P&W Subdivision over the Allegheny River that connects downtown Pittsburgh, Pennsylvania to Herrs Island, Pittsburgh, United States.

The Allegheny River was first crossed at this point by a railroad bridge built in 1884[1] by the Iron City Bridge Works, which moved to Pittsburgh from Cincinnati in 1856.

[2] This was replaced by the B&O bridge in 1921.

[3] List of crossings of the Allegheny River