Bridges & Structures

Keosauqua bridge - Keosauqua

One of Van Buren County's celebrated "villages", the picturesque town of Keosauqua is located on the meandering Des Moines River. Iowa 1 crosses the river right at the city's doorstep, providing a vital link to the south and east. The recent replacement of an historic truss bridge at the site presented many challenges to bridge designers at the Iowa DOT, who recognized early in the project the cultural importance of the existing bridge and the important roles its successor would inherit. The site is scenic — off one end of the bridge is a small city park, a quiet green space between the bridge and the historic Hotel Manning. Off the other end is beautiful Lacey Keosauqua State Park, one of Iowa’s largest state parks and a year-round destination popular with many visitors.

Through informal public information meetings and personal contact with a local bridge committee, the Iowa DOT learned of the importance placed on the scenic riverfront area by the community. Over many years, the city had come to know and cherish its unique truss bridge, and the history of the crossing had created a tangible sense of place in the local mindset. Not just a functional access point, the bridge was also an important gateway to the community.

Keosauqua Bridge concept drawingThe new bridge's elegantly haunched steel girder shape was chosen by the designers to efficiently span the scenic crossing with more grace than a straight girder bridge could achieve. The use of weathering steel, too, was seen as a good choice for a natural appearance, not just because it reduces maintenance and avoids potential river contamination during re-painting.

Many river pier shapes currently used on modern bridges entirely ignore the flow direction of the waters in which they reside. The Iowa DOT’s designers wanted their pier to embrace and celebrate its waterborne setting. They borrowed lightly from the existing pier shape and enhanced its valued architectural characteristics. The pier design is an artistic blend of historical references to the existing piers while providing a fresh and unique appearance appropriate for a modern-day structure. The softened lines are suited to the natural context, as if the bridge has been shaped and weathered by the flow of time and of the river.

Towers on the piers soar upward to just above the railing of the bicycle path. The tower tops are constructed of dressed limestone blocks salvaged during removal of the existing stone piers, creating historical touchstones at the tops of each pier tower. It is through this poetic interface that all the power and strength of presence embodied in the pier could be said to be directly accessible to anyone on the bridge.

Keosauqua Bridge concept drawingThe chosen railing design takes a direct “quote” from the construction of the old bridge's trusses. The railing is made of steel bars woven together and bolted at most connections. This technique exhibits handmade qualities and recalls the honest connection details expressed in the previous bridge's trusses.

Along the 5-0 sidewalk there are small overlooks centered above each pier. At roughly four feet in diameter, these are intimate spaces designed to give one or two people a place to rest and contemplate the river, bridge, cityscape and shorelines. A commemorative bronze plate with images of the two previous bridges is installed on large limestone blocks rescued during the removal of the old bridge.

The new bridge retains the sense of place and history by creating a unique new vision while recalling its predecessors at the crossing. The design is worthy of the community’s identity as a city embracing its riverfront, and complements its scenic setting with sculptural form and grace. The design is unique to Keosauqua, and it is impossible to imagine its installation anywhere else in Iowa.

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