In the spring of 2014, the Tama County Engineer's Office will remove the Historic Chamber's Ford Bridge over the Iowa River, along 380th Street near Chelsea. The bridge was listed on the National Register of Historic Places in 1998 because it was one of the few remaining pinned Pratt through truss bridges left in the state that was unmodified since its construction. Plans are being made to construct a new bridge at this location, once again allowing vehicular access across the Iowa River along 380th Street.
Designed in 1842 by Thomas Pratt, the Pratt truss type was essentially a streamlined version of the Howe Truss patented in 1840. Pratt through truss bridges, a distinctive form of the Pratt truss type, include vertical, horizontal and diagonal beams that form a series of triangular shapes that handle the loads and stress of the bridge as it carries traffic. Although the Pratt Truss was initially unpopular due to the high cost in metal, it was later favored over the Howe Truss for its greater strength, stability, and simplicity, ultimately making it more economical and versatile.
Originally constructed by the Clinton Bridge and Iron Works Company in 1890, the Chamber's Ford Bridge was initially a timber-trestle bridge. Within 10 years, however, the wooden trestles began to deteriorate beyond repair. In September 1902, the Tama County Board of Supervisors chose the Jones and Laughlin Company of Lackawanna, New York, to produce the steel to repair the bridge and the George E. King Bridge Company of Des Moines to replace the timbers with steel and to construct a second span to accommodate the ever-changing river channel. These spans, finished in 1903, still cross the Iowa River today.
The bridge was listed on the National Register of Historic Places because it showcased the evolution of bridge construction materials and techniques?from wood, to cast and wrought iron, to steel?across the 19th and 20th centuries. The Historic Chamber's Ford Bridge, measuring 15.1 feet wide and 345 feet long, exhibits all of the physical features of the Pratt through truss but has deteriorated beyond feasible repair. Although the bridge is one of the few remaining examples of its type in Iowa, due to its age and lack of structural sufficiency it cannot accommodate modern traffic needs and must be replaced. It has been deemed unsafe to carry traffic and has been closed since 2007. The bridge is warped, is missing many of its pins and bolts, and has several large holes in the wooden deck.
The Tama County Engineer's office has received federal funding to replace the old structure with a precast concrete beam bridge. The new concrete bridge will be able to carry heavier loads, allowing E911 services and modern farm traffic to once again cross the river at this location. The county hopes a new crossing will also reduce illegal activities in the area.
The Tama County Engineer's Office is working with cultural resources services firm Wapsi Valley Archaeology, Inc. to document the old bridge and record its history before the structure is removed. Wapsi Valley Archaeology, Inc. will prepare a general interest booklet that details the history of the bridge. The booklet will be available at Tama County libraries, the State Historical Society Library in Des Moines, and other locations across the state.
Wapsi Valley Archaeology, Inc. wishes to learn more about how the bridge served local community members and their families over the years. If you have information about the old bridge's history or photographs to share to include in the bridge history booklet, please contact Historian Kristy Medanic of Wapsi Valley Archaeology, Inc. at 515-233-1146.
Tama County would like to sell the historic Chamber's Ford Bridge so that it can be moved to a different site where it can be preserved for future generations. If your organization is interested in purchasing the historic bridge for relocation, or if you have questions, comments or concerns about the project, please contact Lyle Brehm, Tama County Engineer, at 641-484-3341.