Northern Avenue Swing Bridge, Spanning Fort Point Channel at boundary between Boston & South Boston, Boston, Suffolk County, MA

Significance: The Northern Avenue Swing Bridge, built in 1908, is one of only three surviving swing bridges built by the city of Boston in the late 19th and early 20th century. Today, still operated infrequently on its original compressed-air system, it is the only operable bridge in Boston of its type. The bridge is 80 feet in width, encompassing between four sets of pin connected trusses, two sidewalks, two roadways and a center lane reserved for a double-track freight railroad. The swing span is 283 feet in length. The rim bearing swing span is carried by a 40 foot diameter drum, in turn supported by 56 steel wheels running on a track along the rim of the granite island pier.
Unprocessed Field note material exists for this structure: N1370
Survey number: HAER MA-37
Building/structure dates: 1908 Initial Construction