Northtown and the St. Anthony Parkway Bridge

Northtown and the St. Anthony Parkway Bridge. . , The first bridge at 33rd Avenue N.E. (1911) before dismantling, June 1925 (NP Archives, MHS), Crossing Northtown Yard: The St. Anthony Parkway Bridge, Three bridges have spanned the wide expanse of the Northtown Yards below St. Anthony Parkway. The first was completed in 1911 by the Northern Pacific Railway to carry what was then 33rd Avenue N.E. over its new Northtown rail yard. Grade separation was desired by Minneapolis residents, because the city's many railroad grade crossings were the scene of bad accidents, first involving pedestrians and horse-drawn vehicles, and then automobiles and trucks., The four Howe through truss spans rested on timber piers and carried an 18'-wide roadway. This bridge was considered temporary, and was initially planned for replacement in five years., This 1914 map shows the Northern Pacific Railway's new brick roundhouse, yards, and shops. Brickyards lined the east side of the river, some were served by rail spurs., Northern Pacific Railway. "Overhead Bridge 33rd Avenue N.E." General Plan and Location Plat, March 13, 1925. (NP Archives, MHS), Northern Pacific turntable at Northtown, 1948. (Ron V. Nixon Collection, Museum of the Rockies), The 1925-26 Bridge, The Northern Pacific built a replacement bridge in 1925-26. The new structure was designed to carry increased St. Anthony Parkway traffic, and heavier loads. New construction standards required by the State of Minnesota required that through truss roadway bridges in the state use riveted connections., The bridge was a five-span structure, with a length of 533'-6". Each span was a Warren through truss with verticals assembled with riveted connections. The trusses were placed 37' apart, center to center, with roadway traffic carried between the trusses, and a sidewalk cantilevered on the south. The bridge was skewed 27 degrees to minimize impact to the rail operations below., Bridge under construction, March 10, 1926, looking west., NP Engine 1534 leaving Northtown, St. Anthony Parkway Bridge at rear, ca. 1927. (Ron V. Nixon Collection, Museum of the Rockies), The Northern Pacific Railway Engineering Department designed the bridge, with M.F. Clements as Bridge Engineer. Fort Pitt Bridge Works in Pittsburgh supplied the steel, and local contractor N.W. and W.A. Nelson Company erected it., More than 75 years later, the Burlington Northern Santa Fe Railway (BNSF) owned the bridge when the structure required replacement due to its age and condition. At this time it was eligible for the National Register of Historic Places for its engineering significance and its relationship to the Minneapolis Grand Rounds and Great Northern and Northern Pacific railroad corridor historic districts. This historical significance was considered in planning the new structure., Riveting Span #1, March 10, 1926, looking north., St. Anthony Parkway Bridge, August 23, 1926, looking east., The bridge in 2014., The Warren Truss ,

"The rigid-connected Warren through truss was popular among American railroad engineers for the economy of its detailing and the stillness of its webs."

Bridge No. 90664, Minnesota Historic Bridge Inventory forms, 1997, Diagram of a Truss Bridge, By 1900, the Warren truss, a truss bridge type patented in England in 1848, was frequently used for steel highway bridges in Minnesota, especially for long spans., A metal truss bridge uses many small pieces, or members, to make a beam long and strong enough to span distances. The individual components are connected in a series of triangles. Each truss member is either in compression or tension, and connections at the panel points can either be bolted or riveted.