Bridging the Gap
how a city known for its bridges lost its luster
Twenty-five years ago, Eau Claire artist Michael Peterson snapped a photo of the Dewey Street Bridge from the bottom looking up. The idea for that particular angle came from his fondness of fishing underneath the bridge as a child, and he was inspired to capture the view as an adult years later while taking a photography course at UW-Eau Claire. Now the only remaining arch bridge in Eau Claire, the Dewey Street Bridge represents more than a memory from childhood – it’s a testament to the city’s history that Peterson hopes people will take time to appreciate as the city continues to change.
“Bridges have always been critical to Eau Claire. There’s a nostalgia, a history to them. … Now, I see those aesthetics coming back ...” – EC Public Works Director Brian Amundson
“You just think that stuff will last forever when you see it there – you don’t think about it being gone,” Peterson said of the picturesque arch bridges that crisscrossed the city until the 1970s. “The new ones are in better shape, so it’s clear why the old ones had to come down, but … this is our history. These bridges help the community stand out.” In fact, in our search for images of the city’s historic bridges we found that the vast majority of them at Chippewa Valley Museum are in fact postcards. Proof that these were the picturesque vistas of the city, the things that defined the area and compelled visitors to purchase an image of and proudly send it to loved ones elsewhere. Similarly, the Court’N House’s visual slideshow of our city’s history is inundated with bridge pictures in the 70s – the last moments of the bridges before being torn down, the process of them being torn down, and then the construction. Missing from the slideshow are images of the end result. We can only guess that those with cameras recognized the underwhelming result. So what happened? How did a city known for its bridges change over time?
Calling Eau Claire “a city of bridges,” Public Works Director Brian Amundson explained that although the past three decades have seen the remodeling of older bridges into stronger steel and cement ones, the aesthetics that were so often the first feature observers noticed about older bridges will continue to be considered when constructing new ones. However, the most important factors any city considers when remodeling or constructing a bridge has been (and always will be) cost – cost, and the carrying capacity of the river underneath. As Amundson explained, concrete and steel tolerate compression and tension a lot better than the wooden arch and truss bridges that were popular in the early 19th century. With the development of concrete and steel, particularly the I-Beam (a type of load-bearing beam whose cross section is shaped like the letter ‘I’), cities were suddenly able to produce stronger bridges that could span much farther distances than previously realized – and they could be produced at a lower cost.
Lookin' Good Ain't Cheap
Using rough estimates of costs per square foot provided by Ayres Associates bridge engineer Dave Pantzlaff, and the Engineering News Record Construction Index to calculate the current cost of building arch bridges, Amundson determined the current costs of constructing a concrete or steel beam bridge versus an arch bridge. It would cost $4.2 to $8 million to construct a concrete beam bridge with a deck area the size of the current Madison Street Bridge (41,481 square feet), depending on the condition of the foundations and whether they’d need to be replaced. Comparatively, it would cost $14.5 million to construct a concrete arch bridge with a deck area of that size, he estimated. Similarly, it would cost about $1.3 to $2.6 million to construct a concrete beam or steel beam bridge with a deck area the size of the current Dewey Street Bridge (12,984 square feet), while it would cost $4 to $4.5 million to construct a concrete arch bridge with a deck area of that size, he added. “The beams that we created starting from the 1920s and on allowed us to have a more efficient section that’s cheaper to build and can span a longer distance,” stated Amundson.