By Dan Sydow, PE
Sustainability thought leaders around the world are changing the way we perceive infrastructure – the service mechanisms and underlying hardware that serve our communities every day. These systems supply clean water, power up our homes and businesses, enable safe travel, remove waste, facilitate communication, connect us to the internet, and much more. In short, they drastically improve our quality of life.
About the Expert:
Dan Sydow, PE, is Structural Engineering Group Manager of Ayres’ Midwest Transportation division. He has designed hundreds of bridge replacements and rehabilitations in nearly all Wisconsin counties and in 10 states, including project management of the 2018 Grand Avenue pedestrian bridge rehabilitation.
What to do, however, with aging or obsolete infrastructure? That question is the focus of resourceful engineers, civic leaders, and urban planners who are opening eyes to new possibilities. Telephone booths, scaffolding, billboards, parking meters, light fixtures, and more are being repurposed to better serve current wants and needs, as reported by Smart Cities Dive.
Thinking well beyond the infrastructure’s original purpose, these visionaries bring hefty doses of creativity and innovation to their work, pondering open-ended considerations like, “What could this surface become?” or “How might this structure be used?”
In the case of a 100-year-old pedestrian bridge in Eau Claire, WI, city officials could see the structure’s potential to serve an enhanced role as an outdoor community space, a downtown destination in and of itself. They pictured the bridge as a place where commuters could pause for exceptional views, a welcoming venue for guests to participate in special events, festivals, and other public gatherings.
To achieve these functional and aesthetic goals while preserving an irreplaceable historic landmark, in 2018 Ayres conducted detailed evaluations to ensure that existing features, including massive limestone piers and steel girders, could be safely incorporated into the rehabilitated bridge. Their findings confirmed these elements were sound, requiring only minor maintenance to continue providing the structure with reliable support and save costs for the City.
The design team also performed specialized analysis of strength and vibration dampening contributions from the steel girders, concrete deck, and concrete parapets. The City reviewed detailed comparisons of bridge capacity and user comfort at various width and railing configurations, and collaboratively chose the new design which replaces and widens the deck by 20 percent.
New overhead and underdeck lighting now lend color and motion while improving security. Painted steel railings convey distinct downtown style and provide a seamless transition into Eau Claire’s downtown business area. Six overlooks invite pedestrians to enjoy the Chippewa River from a unique vantage point that also frames Phoenix Park, Haymarket Landing, and the regional arts center – Pablo Center at the Confluence.
In addition, the bridge has been successfully transformed into an ideal spot for community gatherings, including “A Grand Evening on the Bridge,” an elegant local fundraiser with music, drinks, and dining that supports continuation of free downtown entertainment throughout the year.
Honored with a 2020 Engineering Excellence Best of State Award from the American Council of Engineering Companies of Wisconsin, the rehabilitated Grand Avenue pedestrian bridge is an outstanding balance of performance, practicality, aesthetics, and historic preservation. With old and new features blended into a cohesive design, the bridge is not only a steadfast means to cross the river, but also a beautiful outdoor space that invites commuters to stay awhile, to appreciate the good things downtown has to offer, and to build community on the bridge.