Ball Rd/ Little Salt CreekCounty: Midland
Location: Ball Rd/ Little Salt Creek
Year Built: 1901 About this Bridge: This single-span, steel bridge crosses Little Salt Creek on Ball Road in rural Jasper Township. Spanning 40 feet, the Ball Road Bridge is a pin-connected, Pratt bedstead truss, with web members built up form rolled components comprised as follows: upper chord - two channels with cover and batten plates; upright end posts - two channels with lacing; lower chord - two angles with batten plates; vertical - four angles with double lacing; and diagonal - two punched rectangular eyebars. I-beam floor beams are hung from the lower chord pins by U-bolts and support steel stringers, which carry a timber deck. The truss is supported on its four corners by steel truss legs, with concrete back- and wingwalls. The bridge today is closed to vehicular traffic, in structurally fair condition. Though never as popular as the pony truss, the truss-leg bedstead was a standard bridge type marketed in the late 19th and early 20th centuries by bridge fabricators nationwide. The structure acts as a rigid frame, with its endposts extended below the truss itself to form the supports. This was both the strength and the weakness of the bedstead. The combined super- and substructure reduced costs somewhat, but bedsteads were prey to flood and collision damage and suffered from inherent structural weakness relating to compression stress in the lower chords. Between about 1880 and the first decade of the 20th century, a number of bedsteads were built in Michigan. Through attrition, however, all but a handful have since been demolished. The Ball Road Bridge, built around the turn of the century, typifies this construction trend.