Historic Bridges

Year constructed: 1920
Alternate name: Yellow River Bridge; Oelberg Bridge
Bridge type: Timber/Iron Pratt Through Truss
National Register of Historic Places status: Listed
Length: 128.0 feet
Width: 13.9 feet
Spans: 1
FHWA: 061360
Jurisdiction: Allamakee County
Location: Fuel Hollow Road over the Yellow River, 7.3 miles northeast of Postville, Section 15, T96N-R5W (Franklin Township)

Details

Now abandoned with its stringers and deck removed, the Red Bridge spans the Yellow River northeast of Postville, in Franklin Township. The structure dates to 1920. That year the Allamakee County Engineer designed this 98-foot timber truss--the first bridge at this crossing--estimated its cost at $2,500, and let a series of private contracts for its fabrication and erection. The Worden-Allen Company of Milwaukee provided the structural steel, City Lumber provided the timbers, a man named Ryerson provided the hardware, and local contractor A.L. Powell built the truss. Total cost of the bridge was $2,304.74. Called the Red Bridge, the Yellow River Bridge or Oelberg Bridge locally, this timber truss featured a Pratt configuration, with timber compression members and forged iron tension members. The upper-chord timbers are bolted to the timber verticals using iron plates; the iron eye-rod lower chords are pinned to the verticals. From these pins the floor beams are hung using U-bolts. The Red Bridge carried traffic until its later closure (at an unknown date). The timber deck and stringers were subsequently removed, and the bridge now stands abandoned in deteriorating condition.

In the 1850s and 1860s, Iowa's counties were in their formative stages, and for the most part they could ill-afford the expense of substantial iron or masonry bridges for their developing road systems. Instead they opted for wood construction--either in timber pile or timber truss configurations--willingly sacrificing longevity for economy. Without the protective sheathing of covered bridges, timber spans rarely lasted more than twenty years in service, and the worst of the early wood bridges required maintenance after virtually every flood. Although some counties continued to work with wood bridge construction after the turn of the century, most eschewed timber stringer or truss spans. As a result, only a handful of timber covered bridges remains in place today, and all of the timber pile bridges built during the 19th century are gone. The Red Bridge in Allamakee County is distinguished as the last uncovered timber truss remaining in the state. It is unclear whether the existing timbers on the Red Bridge are original or whether some or all have been replaced, but they do appear original. The Red Bridge is today an important resource from what was once a large group of early timber roadway bridges in the state [adapted from Fraser and McWilliams 1992].