Red Bridge

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 $2500.00, 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: $2304.74. Called the Red 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.

As Iowa's counties were in their formative stages between the 1850s and 1890s, 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 the 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, most eschewed timber stringer or truss spans in large part after the turn of the century. As a result, only a handful of timber-covered bridges remain in place today, and no 19th-century timber pile bridges have been documented by the statewide bridge inventory. Although not truly "old" by Iowa bridge standards, 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 - given the notoriously short-lived nature of timber structures in Iowa - but they do appear original. Nevertheless, the Red Bridge is today an important resource from what was once a large group of early timber roadway bridges in the state.