IAIS 8th Street Bridge


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Name IAIS 8th Street Bridge
Chicago, Rock Island & Pacific Railroad Bridge #3476
Built By Chicago, Rock Island & Pacific Railroad
Currently Owned By Iowa Interstate Railroad
Superstructure Contractor Unknown
Substructure Contractor Iowa Bridge Company of Des Moines, Iowa
Length 273 Feet Total, 64 Foot Main Spans
Width 1 Track
Height Above Ground 15 Feet (Estimated)
Superstructure Design Through Plate Girder and Steel Stringer
Substructure Design Concrete
Date Built 1955
Traffic Count 5 Trains/Day (Estimated)
Current Status In Use
Chicago, Rock Island & Pacific Railroad Bridge Number 3476
Iowa Interstate Railroad Bridge Number 347.80
Significance Minimal Significance
Documentation Date 2/22/2020

In 1856, the Mississippi and Missouri Rail Road Company (M&M) constructed 55 miles of new railroad, extending from Davenport, Iowa to Iowa City, Iowa.  As part of the work, a wooden bridge was constructed across the Mississippi River, connecting Rock Island, Illinois and Davenport.  In 1862, the line was extended an additional 31 miles to Marengo, Iowa; followed by an additional 20 miles to Brooklyn, Iowa in 1863 and 26 miles to Kellogg, Iowa in 1864.  In 1866, the M&M and the Chicago and Rock Island Rail Road Company (C&RI) merged to form the Chicago, Rock Island & Pacific Railroad (Rock Island), which constructed an additional 44 miles to Des Moines, Iowa in 1867.  In 1869, the line would continue to be extended west towards the Missouri River.  At Davenport, this line connected to an existing Rock Island line, which extended east to Chicago, Illinois.  In 1880, the Rock Island was reorganized as the Chicago, Rock Island & Pacific Railway.  The Rock Island constructed and acquired a large network of railroads, primarily in Iowa during the late 1880s.  This line became part of the principal mainline of the Rock Island, and allowed for further development of branch lines throughout central Iowa and eventual expansion west of the Missouri River.

In the late 19th Century, several improvements were made to the line, including revising grades, curves and replacing wooden bridges with stone and iron structures.  Due to heavy traffic over this line, portions of the line between Davenport and West Liberty was double tracked in the late 1890s.  The Rock Island struggled financially throughout much of its history, experiencing repeated bankruptcies and chronic instability.  After World War II, the Rock Island struggled to survive, proposing mergers and deferring maintenance on their routes. The railroad reorganized as the Chicago, Rock Island & Pacific Railroad in 1948. By the mid-1970s, the railroad was in serious decline.  The railroad secured loans to eliminate slow orders, acquired new equipment, and attempted to restore profitability.  Several sections of this line had fallen into serious disrepair, hampering the Rock Islands ability to maintain efficient operations.  In 1978, the railroad came close to profit, but creditors were lobbying for a complete shutdown of the Rock Island.  During the fall of 1979, a strike crippled the railroad, and by January of 1980, the entire system was ordered to be shut down and liquidated.  Many of the lines and equipment were scrapped.  Profitable sections of railroad were prepared for sale.  

In November 1981, the Iowa Railroad Company (IARR) began operations over the former Rock Island mainline in western Iowa.  In June 1982, the IARR entered into a two-year lease for the entire Rock Island mainline between Bureau, Illinois and Council Bluffs, Iowa; including the Davenport to Des Moines section.  In 1983, concerns had grown over the ability of the IARR to provide reliable service to shippers along the line, and several industries came together to form Heartland Rail Corporation, which purchased the line between Bureau and Council Bluffs from the Rock Island trustees.  Iowa Interstate Railroad (IAIS) was chosen to operate the line, and began operations in late 1984.  After years of thin profit margins, IAIS began making significant financial strides in the 1990s and early 2000s, eventually becoming a major railroad in central Iowa.  Increased profit margins and large grants meant IAIS could rebuild deteriorated track, improve bridges and expand operations.  Today, IAIS continues to operate the Iowa City Subdivision between Davenport and South Amana, as well as the Newton Subdivision between South Amana and Des Moines.


Located in Altoona, this through plate girder bridge carries a former Chicago, Rock Island & Pacific Railroad (Rock Island) mainline over 8th Street (former US Highway 6). Originally, the Rock Island had two separate lines at this location, including the present mainline and a secondary line known as the "KDM Line". In 1928, a pair of underpasses were constructed at this location. These underpasses each consisted of a 54-foot skewed deck plate girder span, set onto timber pile substructures and approached by timber pile trestle spans on either end. It is likely that the center spans were reused from another location. By the mid-20th Century, this configuration had become a major bottleneck for traffic underneath, and it was decided to replace the bridges with two new bridges to span four lanes of traffic. Work on the project began in 1954, and was completed in late 1955. The eastern bridge was removed in the late 1980s after the KDM line was abandoned and operations were consolidated onto one line. Currently, the bridge consists of two 64-foot through plate girder spans, approached by two 35-foot steel stringer spans at either end. The entire bridge is set onto concrete substructures and runs at a heavy skew.

The main spans follow a standard design for the era, with two heavy plate girders, a solid floor and rounded and tapered ends. The approach spans also follow a standard design, with six beams per span and a ballast channel on top of the span. All five of the piers use a standard rounded rectangular design, and the abutments use a standard design with short sloped wing walls. An unknown contractor fabricated the superstructure, and the substructure was constructed by the Iowa Bridge Company. Through plate girder spans were popular for railroad use, as they were durable and easy to construct. Unlike some grade separations constructed during this era, this bridge does not use any significant decorative features. Since the initial construction, the bridge has seen no significant alterations. Today, it remains in regular use as part of an Iowa Interstate Railroad mainline. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being minimally significant, due to the newer age and common design.


Citations

Build date and builder (substructure) The Des Moines Register; September 13, 1955
Railroad History Citation ICC Valuation Information, Compiled by Richard S. Steele

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