Special to The Daily Reporter
In our dollars and sense world, where practicality can dictate form, and safety standards often dictate function, building a beautiful bridge might not be a priority.
But maybe it should.
“When a structure can provide both function and visual appeal, then you’ve really got the best of both worlds,” said Dave Pantzlaff, manager of Wisconsin structures for Ayres Associates Inc., Eau Claire.
When Pantzlaff gave a presentation on bridge aesthetics for the Wisconsin County Highway Association, he defined aesthetics two ways.
First: “Aesthetics is an emotion that relates to a sense of beauty based on visual appearance.” And second, Pantzlaff said, “Aesthetics can bring a structure into harmony with its environment.”
Those are objectives Jeff Polenske strives to keep in mind in his work as city engineer in Milwaukee.
“(Bridges) are major infrastructure improvements,” he said. “And while functionally you’re trying to get the motoring traffic and people over the valley or river, we also want to make it something that’s an improvement to the area.”
Sometimes that means making a statement.
The Sixth Street viaduct in Milwaukee stands out as a signature bridge. It not only provides access to Canal Street, but also was meant to create a “signature gateway” into the Menomonee Valley, Polenske said.
When the Harley-Davidson Museum settled in the valley, Polenske took it as a sign that the viaduct’s vision was realized.
“(The museum) is another monumental structure,” he said. “They set the bar higher because of the structure (the bridge) they built next to.”
While the white paint, cables and lighting of the Sixth Street viaduct create its unique character, the design elements of some bridges are more subtle — think tinted or textured concrete. It might mean using a decorative, but crash-tested, railing or incorporating scenery, as with the Humboldt Bridge in Milwaukee.
The bridge carries cars and pedestrians over the Milwaukee River. To incorporate bicycle and pedestrian traffic, designers included pedestrian alcoves, or “bump outs,” where passersby can stop safely to look over the water.
The design goes back to a key tenet of aesthetics: balancing environment and infrastructure. That is often achieved using shape, color, texture and lighting.
In the Marquette Interchange project, as well as with other Milwaukee-area bridges, Pantzlaff said, designers used a champagne glass-style or flared pier, which is narrower at the bottom than the top, as an alternative to the rectangular or cylindrical pillars often used to support bridges.
Concrete form liners can add texture to concrete. Paint or stain add color. Both can be used to enhance the look of a bridge and, during the last 10 years, have become costs covered with state and federal money; in the past, municipalities would have had to pay for such treatments.
Putting grooves, or rustications, in bridge concrete is another inexpensive way to improve the look of a structure. And, Pantzlaff said, it can deter vandals.
“Their artwork doesn’t stand out as well,” he said.
Flood lights can highlight signature structures, such as cabled or arched bridges, while smaller, decorative lights, called acorn lights for their acorn-like shape, often highlight smaller structures. Their shape, which mimics the gas lights of the 1920s and 1930s, are common in historic downtown centers or Main Street-type bridges.
And acorn lights are often accompanied by banner arms, which let municipalities display flower baskets or artwork.
With so many options, aesthetics can subtly give a bridge character, as with Milwaukee’s Highland Avenue Bridge, which is under construction.
From underneath, the bridge will look like a traditional two-pier and abutment bridge spanning a set of railroad tracks, said Craig Liberto, structural design manager for the Milwaukee Department of Public Works.
But on top of the bridge, along the new metal railing, the concrete will be textured and stained to resemble brick and reflect the buildings of nearby Miller Brewing Co. and Harley-Davidson Inc.
With the Prospect Avenue Bridge, also in Milwaukee, Liberto said designers were limited in changing aesthetics when they replaced the metal grading and concrete decking.
But color was used to transform the “drab, battleship gray” of the old bridge into a natural brown to reflect the bridge’s connection to the nearby Oak Leaf Trail. Yellow lettering also was used to denote the street name as a nod to the colors used in county park signs.
“Again, it’s subtle,” Liberto said, “But it gives a point of reference.”
It’s also relatively inexpensive.
“We have a greater need out there than we have dollars, so we definitely need to be more conscious of how we apply the money we have,” Polenske said.
But the recession has not derailed any bridge projects in Milwaukee, said Cecilia Gilbert, communications manager for Milwaukee’s Department of Public Works.
“We’re not building any new bridges; we’re going to be rehabbing several,” Gilbert said.
Liberto said money spent on aesthetics is well worth the result.
“We have these assets,” he said, “Let’s make them look nice.”