Old US-41 Backwater Creek Bridge

Information and Findings From Michigan Historic Sites Online

Architects/Builders

Northwestern Bridge and Iron Company
Smith-Sparks Construction Company
State Highway Department

Narrative Description

main span number:1
main span length: 80.0
structure length: 81.0
 roadway width: 18.0
 structure width 21.0

Included among the six Baraga County spans in the Survey Sample is this long-span pony truss in Baraga Township. The Backwater Creek Bridge carries an abandoned segment of US-41 (now a privately owned road) immediately above the creek's mouth at L'Anse Bay. Fabricated from a standard plan by the Michigan State Highway Department, the bridge is an 80-foot, rigid-connected Warren truss with an 18-foot roadway width. The web members are comprised as follows: upper chord and inclined end post - two channels with cover and batten plates. I-beam floor beams are field-bolted to the verticals and support steel stingers, which in turn carry a concrete deck. These floor beams are braced laterally by steel angles. The guardrails are latticed. The truss is supported on its four corners by built-up steel bearing shoes, which rest on concrete full-height abutments with angled wingwalls. Apparently unaltered, the Backwater Creek Bridge is in good structural condition.

Statement of Significance

Soon after the legislature passed the State Trunk Line Act in 1913, authorizing the formation of a trunk line system of roads, a mainline route across Baraga County was designated. The route extended from Michigamme, at the county's east line, northwest to Chassell, at the Houghton County Line. By 1915, the road had been completed along its entire length through the county, including the segment through a bayou at the southern edge of L'Anse Bay. Using trunk line rewards from the state, the Baraga County Road Commission improved the route incrementally through the late 1910s, regrading and rebuilding segments and constructing new bridges.

One of these improvements involved construction of abridge across the L'Anse Bay backwater, about two miles south of the town of Baraga. For the crossing, engineers for the state highway department delineated this long-span pony truss, supported by concrete abutments. Designating the structure State Trunk Line Bridge No. 86, MSHD in 1917 awarded a contract to build the concrete substructure to the Smith-Sparks Construction Company for $5,414.20. Using steel members rolled by the Illinois Steel Company, the Northwestern Bridge and Iron Company fabricated the truss, completing its erection in 1918 for $4, 536.00. In the 1920s, the trunk line road and this bridge were incorporated into US-41. The bridge carried increasingly heavy traffic until its replacement by another structure immediately downstream. It remains in place today, in essentially unaltered condition.

US-41 has historically formed one of two backbones for overland traffic in the Upper Peninsula, providing both tourist access and local travel in the region. The Backwater Creek Bridge is an unaltered part of this route, built as the road was first developing as a state trunk line in the 1910s. For this reason, the bridge is historically significant as a formative part of regional transportation. The Backwater Creek Bridge is technologically noteworthy as one of the oldest intact examples of MSHD standard pony truss design. Although the highway department first delineated its Warren truss standard as early as the 1907-1908 biennium and had erected 19 such trusses at trunk line crossings by mid-1918, attrition has since taken most of these earliest spans. The Backwater Creek Bridge is technologically significant as a well-preserved and well-documented example of this important highway department structural type.