High Quality Content by WIKIPEDIA articles! The Chicago and North Western Railway`s Kinzie Street railroad bridge (also known as the Carroll Avenue bridge) is a single leaf bascule bridge across the north branch of the Chicago River in downtown Chicago, Illinois. At the time of its opening in 1908 it was the world`s longest and heaviest bascule bridge. Previous bridges on the same site included the first bridge to cross the Chicago River, Chicago`s first railroad bridge, and one of first all-steel bridges in the United States.