Swing Span

Center Pier

Operator’s House

Machinery House

Fender

Former Willis Avenue with swing span opening for navigation.

A swing bridge is a movable bridge that opens for navigation In the early 20th century, there were 11 swing over by rotating horizontally about a center pivot pier located in the middle the . Seven of these bridges were center pier swing bridges, probably the world’s largest collection at that time. Th e A typical swing of the waterway. Th e top section, known as the superstructure, is bridge center pier usually locked in position so that traffi c and pedestrians can cross. original Willis Avenue swing bridge was unique in that its center pier operating mechanism. TOP: Looking northeast from Manhattan toward When a tall ship or boat needs to pass beneath, traffi c is stopped was not positioned exactly at the center over the Harlem River. Its This design is known the swing span and center pier. A pair of as rim-bearing, navigation channels was kept clear beneath this (usually by traffi c signals and barriers) and electric motors then rotate swing span was placed off center over the western part of the river to meaning the weight part of the bridge. of the swing span, the swing span of the bridge, turning it approximately 90 degrees accommodate the rail operations in the Mott Haven Rail Yard. CENTER: Looking northwest at the swing span’s as it moves, is center pier, the swing span superstructure, and horizontally around this central pier. supported by the the operator’s house. The protective wooden outside rim of a large Th e former over the Harlem River was a swing Swing and Fixed spans over the Harlem River circular drum and fender is shown in the foreground. girder, or horizontal bridge that linked Manhattan and the Bronx. Th e lattice river Operator’s House BOTTOM: One of the two machinery sets from spans included both a fi xed span that did not move and the swing ironwork. Swing the 1950s which opened the old Willis Avenue bridges were the Bridge. They were an upgrade to the original span that opened to allow ships and boats on the Harlem River to most common steam powered machinery located in the pass. Th ese spans carried four lanes of traffi c and two walkways. movable spans in machinery house. use in the 19th and Originally steam engines and later electric motors turned early 20th centuries. Machinery House (From MTA Archives and Robert Stewart, the swing span. Historic American Engineering Record, 2004) (Adapted from Historic American Engineering Record, 2004)

B2_SwingBridges5.indd 1 7/1/11 1:50 PM