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Bentonsport Bridge

   


Bentonsport Bridge

Primary Photographer(s): Nathan Holth and Rick McOmber

Bridge Documented: July 2, 2009
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Key Facts

Facility Carried / Feature Intersected
CR-J40 (Old Alignment) Over Des Moines River
Location
Bentonsport and Vernon: Van Buren County, Iowa
Construction Date and Builder / Engineer
1882 By Builder/Contractor: King Bridge Company of Cleveland, Ohio

Technical Facts

Rehabilitation Date
1903
Main Span Length
146 Feet (44.5 Meters)
Structure Length
730 Feet (222.5 Meters)
Roadway Width
Not Available
Spans
5 Main Span(s)
NBI Number
Not Applicable

Historic Significance Rating (HSR)

Bridge Documentation

There are several extremely rare and significant pin-connected truss bridges on the lower section of the Des Moines River. Each are distinguished as rare surviving examples of large, multi-span examples of their type. Among them, the Bentonsport Bridge stands out as a large, relatively complete, and early example. The bridge is a long, five-span truss bridge. Each span contains eight panels. One of the central spans was replaced after it was damaged in a flood in 1903. The span was replaced by the George E. King Bridge Company of Des Moines, Iowa, which was a spinoff of the King Bridge Company who built the original bridge.

All spans on the bridge are traditionally composed, but the original spans do contain a few unusual details. Most noteworthy, a number of the pin bolts on the bridge are square bolts. Square bolts were common during the period this bridge was built, but not as pin bolts, where hexagonal bolts were far more common. There are also cast iron intersection assemblies for the diagonal member intersections with the counters, and also where the lateral bracing intersects. Finally, the original truss spans also contain fishtail style built-up floor beams.

The Bentonsport Bridge was also refitted to allow pedestrian usage. The preservation work was limited to the installation of a narrow deck with no work done to the bridge itself.. What was left of the former deck was allowed to remain in place. Original railings were left in place on the bridge, The structural condition of the bridge appears to be fair, and with its use being limited to non-motorized traffic, and the material of the bridge being corrosion-resistant wrought iron, the rate of deterioration on this bridge is low, even in its un-restored condition. There is interpretive signage posted for the bridge. However it is worth noting that although this 1882 bridge is the oldest intact bridge in Van Buren County, it is not the oldest Des Moines River Bridge as the sign claims, since the Eveland Bridge in Mahaska County was dated to 1877.

Most of the surviving Des Moines River pin-connected truss bridges in this region remain inaccessible due to flooding and deck damage. As such, the placement of a deck on the Bentonsport Bridge is significant because this makes the Bentonsport Bridges one of the few of these amazing Des Moines River bridges that can be more completely experienced. The bridge is a centerpiece that unifies the tiny communities of Vernon and Bentonsport, and the bridge provides a noteworthy attraction for two tiny communities that might otherwise pass unnoticed.

Information and Findings From Iowa's Historic Bridge Inventory

Discussion of Bridge

Van Buren County built the Keosauqua Bridge, its first major bridge over the Des Moines River, in 1873. Soon thereafter other communities along the river began clamoring for bridges of their own, prompting the county board of supervisors to pass a resolution in January 1877 regarding bridge construction.
In April 1882 the supervisors received petitions for three Des Moines River bridges-- Pittsburgh, Farmington and Bentonsport--along with pledges from the petitioners to help pay for the construction. The board approved all three, appropriating $25,000, "or so much thereof as may be necessary," to build the structures. The county hired local masons Snyder and Kramer for the stonework on the Bentonsport Bridge. The King Iron Bridge and Manufacturing Company would fabricate and erect the wrought iron trusses for $31 per lineal foot. Comprised of five 146-foot, pinned Pratt trusses, the Bentonsport Bridge was completed at a total cost of $33,309.39. In June 1888 the county hired Fair Williams and Company of Ottumwa, Iowa, to install iron ice-breaker plates on the upstream side of the piers. But the ice-breakers could only do so much to protect the bridge. In 1903 a major flood on the Des Moines River inundated the town of Bentonsport and washed away the bridge's middle span. The county contracted with the George E. King Bridge Company of Des Moines to provide a replacement span. Local lore states that the replacement was erected on the frozen river that winter and hoisted into place with derricks. Motive power was provided by elephants from a circus troupe that was wintering nearby in northern Missouri. In 1972 parts of Bentonsport and Vernon--and the bridge--were designated a National Register Historic District. The Bentonsport Bridge carried traffic until 1985. It now functions as a pedestrian bridge to link the two towns.

Before the formation of the state highway commission, the individual counties of Iowa built wagon bridges themselves, typically contracting with bridge companies to design, fabricate and erect the all-metal spans. Numerous multiple-span bridges were built in this manner throughout Iowa in the late 19th century, many of the more spectacular examples spanning the Des Moines River in the southeast part of the state. Van Buren County eventually built eight large-scale bridges over the Des Moines River--at Selma, Douds, Keosauqua, Bentonsport, Bonaparte and Farmington. Although not the first such structures built, the Bentonsport Bridge is noteworthy as the oldest remaining intact bridge in the county. In well-preserved condition, the Bentonsport Bridge is an outstanding early wagon truss - one of the last multiple-span bridges from this formative period in Iowa transportation [adapted from Fraser 1991].

Bridge Considered Historic By Survey: Yes

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Photos and Videos: Bentonsport Bridge

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A collection of detail photos that document the parts, construction, and condition of the bridge. For the best visual immersion and full detail, or for use as a desktop background, this gallery presents the photos for this bridge in the original digital camera resolution.
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Structure Overview
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A collection of overview photos that show the bridge as a whole and general areas of the bridge. View the photos for this bridge in a reduced size which is useful for mobile/smartphone users, modem (dial-up) users, or those who do not wish to wait for the longer download times of the full-size photos. Alternatively, view this photo gallery using a popup slideshow viewer (great for mobile users) by clicking the link below.
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View Photo Gallery
Structure Details
Mobile Optimized Gallery
A collection of detail photos that document the parts, construction, and condition of the bridge. View the photos for this bridge in a reduced size which is useful for mobile/smartphone users, modem (dial-up) users, or those who do not wish to wait for the longer download times of the full-size photos. Alternatively, view this photo gallery using a popup slideshow viewer (great for mobile users) by clicking the link below.
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