Rare in any state, this truly unique bridge in Wisconsin's small surviving population of historic highway bridges was nevertheless sentenced to the dumpster. Demolition is scheduled for 2022. These are the only known Pennsylvania truss highway spans in Wisconsin. It was moved to this location from another location 15 miles downstream in 1918-1919 when its previous location was going to be innundated by a new dam.
Information and Findings From Wisconsin Historic Bridge Inventory
Discussion of Bridge
Significance of the Cobban Bridge By Diane Kromm, Wisconsin Historic Bridges Recording Project, Summmer 1987
The Modern Steel Structures Company of Waukesha
constructed the Yellow River Bridge across the Chippewa River in 1908.
The firm, incorporated in 1900, developed the most modern and complete
steel structural plant in the West. Between 1916 and 1918, the
Wisconsin-Minnesota Power & Light Company built a hydroelectric dam four
miles downstream from the bridge, putting the site under water. The
townships of Eagle Point and Arthur arranged to have the 486-foot span
dismantled and re-erected 15 miles upstream near the village of Cobban.
The Cast Stone Construction Company, in Eau Claire, installed the new
concrete substructure. Crombley and Thailacker, a Milwaukee
bridge-building firm, apparently erected the steel work. The Yellow
River Bridge is the oldest of four Pennsylvania truss bridges remaining
Measuring over 480 feet in length, the Cobban Bridge
crosses the Chippewa River in an east-west direction on County TT about
5 miles southwest of the city of Cornell. The structure is a
pin-connected overhead truss with two identical Pennsylvania spans
bordered by channel and angle-iron railings. It rests on concrete
abutments and a single concrete pier. In addition to portal, top-lateral
and sway bracing, the bridge's webbing is stiffened with sub-diagonals,
extended sub-verticals, and intermediate, horizontal struts. The wood
decking is protected by metal runners.
Fabricated in 1908, the Cobban Bridge was the oldest
of four Pennsylvania truss bridges surviving on Wisconsin highways in
1986. It is an excellent early Twentieth Century example of the type,
which is basically and overhead, sub-divided Pratt truss with a
polygonal upper chord.. Developed specifically for long spans in 1875 by
the Pennsylvania Railroad (hence the name) the Pennsylvania truss was
modified a decade later by the Chesapeake & Ohio Railway, which
introduced intermediate horizontal struts to increase rigidity of the
web. Another characteristic feature, also seen on the Cobban Bridge, is
the upward extension of sub-verticals for the purpose od stiffening the
long upper chord members. As is customary on highway bridges of the
1890s and 1900s, the Cobban Bridge displays built-up sections for its
structural members -- a practice that was later replaced by the use of
rolled sections, as can be seen on two previously extant Pennsylvania
trusses of the 1930s.
Bridge Considered Historic By Survey: Yes
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