Northern Pacific Bridge #9

Pratt Deck Truss Bridge over Mississippi River
Minneapolis, Hennepin County, Minnesota

Click the Photo Above to See All Photos of This Bridge!
Name Northern Pacific Bridge #9
Built By Northern Pacific Railroad
Contractor (Original Trusses) Edge Moor Bridge Works of Wilmington, Delaware
Contractor (Truss Rehabilitation) Minneapolis Steel & Machinery Company of Minneapolis
Contractor (New Truss Line/Approaches) American Bridge Company of New York
Currently Owned By City of Minneapolis
Length 949 Feet Total, 249 Foot Main Spans
Width 2 Tracks
Height Above Ground 90 Feet (Estimated)
Superstructure Type Pratt Deck Truss and Deck Girder
Substructure Type Concrete
Date Built 1922 using Rebuilt 1885 Trusses
Traffic Count 0 Trains/Day (Bridge is a Trail/Roadway)
Current Status Rails to Trail/Road
NP Bridge Number 9
Significance High Significance
One of several iconic crossings of the Mississippi River, Northern Pacific Bridge #9 also has an extremely unique history.
The first bridge here was built slightly downstream in 1885. This double track bridge featured a pair of pin connected Pratt Deck Trusses, which was the largest panel length of any truss in the country at the time of construction; several "triangular trusses", which were deck girders with added bracing; and several other standard deck girder spans on steel towers. The original bridge was designed by C.F. Loweth, and Onward Bates was in charge of erection. Both men would go on to work on projects for the Chicago, Milwaukee & St. Paul Railway.
Known as the Bohemian Flats Bridge, this bridge was reinforced in 1917. By the end of 1918, it was desired to move the NP "Line A" onto a new alignment to be less disruptive to the University of Minnesota campus. As a result, a solution was found to move the alignment north, and build a new stronger bridge.

Historic Photo
Original bridge; from the Journal of the Western Society of Engineers.

Work began in 1922, and the new bridge was completed in 1923. This new bridge was unique, as it was designed by famed bridge engineer F.W. Cappelan, but also because it reused the two large Pratt Deck Truss spans from the previous bridge.
It is reported that the original trusses were carefully disassembled, and sent to the South Minneapolis shops of the Minneapolis Steel & Machinery Company, which carefully rehabilitated the trusses. The new truss line was reportedly purchased from American Bridge Company. The addition and reuse of the deck trusses is highly unique and innovative, and considerably raises the level of significance of this bridge.
Further adding to the oddity of the structure is the slight "S" curve which it sits on, as both approaches are on 8-degree curves.
The new bridge would consist of:
3-90' Deck Plate Girders
2-247' 8-panel pin connected Pratt Deck Truss Spans
1-80', 1-85' Deck Plate Girder
As part of the new bridge, the two large Pratt Deck Trusses would be reinforced with a third, riveted truss line between them.
After NP merged with the Chicago, Burlington & Quincy and rival Great Northern in 1970 to form Burlington Northern, the bridge would see disuse, and was completely abandoned by 1981. The City of Minneapolis purchased the bridge in 1987, and would open the bridge to pedestrians in 1999.
As presently configured, the bridge has been largely unaltered since 1922-3. The most significant repair involved stabilizing, underpinning and encasing pier #4 in 2012-2013, followed by pier #5 between 2014 and 2016.
Further rehabilitations are planned for this bridge, particularly involving the maintenance of the piers and deck of the bridge.

The author hopes this bridge will be preserved indefinitely, particularly due to the unusual design of the bridge and notable features.
The photo above is an overview from the 10th Avenue Bridge upstream. The photo below is looking under the truss.

Mississippi River Railroad Bridges
Upstream Minneapolis Western Bridge
Downstream Washington Avenue Bridge

Detail Photos


Source Type


Build Date Northern Pacific Bridge Book, provided by Northern Pacific Railway Historical Association
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele

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