This is a rare example of a high level style pin-connected Baltimore deck
Information and Findings From Iowa's Historic Bridge
Discussion of Bridge
Located in Burlington in southeastern Des Moines
County, the four-span deck truss Cascade Bridge carries South Main
Street across the Cascade Ravine. The bridge is comprised of a Baltimore
deck truss, with Pratt deck trusses at both the north and south ends.
The structure is supported by stone and concrete abutments along with
concrete pedestals and a single concrete-filled steel cylinder pier.
In April of 1896, the Burlington City Council directed the city
engineer to advertise for plans and estimates for a "high bridge on
lower Main Street across the Cascade." The bridge was originally not to
be more than 400 feet long and not less than 240 feet long and "built in
such a manner as to permit vehicles of all kinds to travel in opposite
directions on said street car tracks and to have sidewalks on either
side of not less than 6 feet in width for foot passengers." A petition
was received by the court in support of the proposed bridge's
construction from Cascade Lumber Company, who would apparently benefit
economically from the new crossing.
Estimated to cost $16,000,
the county engineer, S.D. Eaton, advertised separately for the bridge's
construction, eventually receiving six bids for the entire project.
After much discussion and debate over the eminent contract award, the
city council determined that it would be in their best interest if they
would contract with the Milwaukee Bridge and Iron Works for the
superstructures and have the city build the concrete substructure. The
Milwaukee, Wisconsin, firm contracted with the city for the aggregate
sum of $13,900 for the fabrication and erection of the massive trusses.
Using steel components rolled by Carnegie Steel Company and
fabricating the truss according to design plans drawn up by the Cedar
Rapids-based firm of Boynton and Warriner, the bridge was completed in
the fall of 1896. The original deck has been replaced with a steel grid
deck and concrete has been added to the face of the stone abutments, but
the bridge remains otherwise unaltered. Continuing to function in place
in its urban setting, the Cascade Bridge retains an unusually high
degree of structural and historical integrity. With its pin-connected
Baltimore trusses supported dramatically above the ravine, it is one of
Iowa's most significant and unusual urban bridges [adapted from
Crow-Dolby and Fraser 1992].