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Omaha Bridge #15

Bobtail Through Truss Swing Bridge over Mississippi River
St. Paul, Ramsey County, Minnesota

Click the Photo Above to See All Photos of This Bridge!
Name Omaha Bridge #15
Built By Chicago, St. Paul, Minneapolis & Omaha Railway
Built By Chicago, Milwaukee & St. Paul Railway
Chief Engineers C.F. Loweth and H. Rettinghouse
Contractor (Swing Span) Milwaukee Bridge Company of Milwaukee
Contractor (Swing Span Erection) Strobel Steel Construction Company of Chicago
Contractor (Girders) Chicago Bridge & Iron Works of Chicago
Currently Owned By Union Pacific Railroad
Length 1035 Feet Total, 260 Foot Swing Span
Width 1 Track
Height Above Ground 20 Feet (Estimated)
Superstructure Type Bobtail Swing Bridge and Deck Girder
Substructure Type Concrete
Date Built 1915
Traffic Count 15 Trains/Day (Estimated)
Current Status In Use
UP Bridge Number 2.46
Significance Regional Significance
In 1865, the Minnesota Valley Railroad Company built a line from St. Paul to Mankato. This line quickly became part of the Chicago, Minneapolis St. Paul & Omaha Railroad, known as the Omaha Road.
The Omaha Road was primarily purchased by the Chicago & Northwestern Railway in 1882, although the Omaha name stuck and independent operations ensued until 1957.
Due to the heavy traffic this line was projected to see, the line was significantly rebuilt between Shakopee and Mankato between 1890 and 1910, including revised slopes and grades, new bridges and new rails.
Mankato was a significant stop for the railroad, as the Minnesota Valley was the most important feature in central Minnesota. At Mankato, the line would interchange with other railroads that connected to other stops.
The railroad also went through major industrial hubs, such as Le Sueur, Shakopee and Savage.

The C&NW continued to operate this as a mainline until 1995, when they were purchased by Union Pacific Railroad.
Union Pacific still operates this as a mainline called the Mankato Subdivision. It sees significant traffic heading between Sioux City and Chicago, bypassing the more congested lines through Iowa.
11/12/21


View an article detailing the construction of this bridge.

Likely the most unique railroad bridge in Saint Paul, this bobtailed swing bridge features a massive concrete counterweight.
Named for being the fifteenth bridge on the Chicago, St. Paul Minneapolis & Omaha Western District, this bridge is the only bobtail swing span to cross the Mississippi River, and one of only a few such spans ever built.
The site of the first railroad crossing of the Mississippi River in St. Paul, the original wooden swing bridge was completed in 1869, and replaced by 1877. In 1885, the original swing bridge was replaced with an iron lattice through truss, built by Lassig Bridge & Iron Works. Lassig did further work in 1887, replacing the original west approach with a 150' Quadrangular Through Truss. Additional work was contracted by the Milwaukee Road the following year, when Keystone Bridge Company replaced the six 150-foot east approach with pin connected Pratt Through Trusses.

Historic Photo
Previous bridge, looking west; from the Journal of the Western Society of Engineers. A view of the swing span and west approach can be seen here.

In 1915, that bridge was replaced with the current bridge, which was jointly designed by C.F. Loweth of the Milwaukee Road and H. Rettinghouse of the Omaha Road. A massive riveted warren Through Truss has a large counterweight on one end was constructed, and several spans of deck plate girder to approach. The entire bridge was set on concrete substructures, which did not reuse the original stone piers. It is unknown for sure what happened to the old spans, but it is believed that the stationary spans may have been reused.
The construction of the current bridge was a complicated affair, involving numerous contractors, two chief engineers and the requirement to keep traffic moving at all times. The link above details the construction process in a very excellent manner. As part of the construction, 48,000 cubic yards of earth were moved from the river bed, with LaCrosse Dredging Company of Minneapolis completing the work. The bridge was completed under J.D. Moen, with I.F. Stern used as a consulting engineer and T.E. Van Meter as the assistant engineer.

Historic Photo
Blueprint showing the current bridge and old bridge

Today, this bridge has had very little alteration and retains a great historical integrity. It is believed that the Milwaukee Road, who jointly owned this bridge, supplied the engineering for this structure. Of the few railroad bridges utilizing a bobtail swing design, almost all of them were along the Milwaukee Road system.
Overall, the bridge appears to remain in fair to good condition.

The author has ranked this span as being regionally significant, due to the bobtail design.
The photo above is an overview.

Mississippi River Railroad Bridges
Upstream Short Line Bridge
Downstream Robert Street Lift Bridge

Citations

Source Type

Source

Build Date Concrete Inscription
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele



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