While bridges are part of a fleeting culture for motorists, who zoom by sometimes unaware they’re crossing one, they can be a significant part of the visual environment for the locals who use them every day. Concrete enhancements give project teams and residents a way to personalize these infrastructure essentials so they become memorable landmarks.
Since 2003, the Oregon Department of Transportation (ODOT) has repaired or replaced 271 highway bridges through its OTIA III State Bridge Delivery Program, part of the Oregon Transportation Investment Act. Eighty-five percent of those bridges were replaced with concrete superstructures and, of those, 60% contained precast, prestressed concrete elements, so concrete was essential to upgrading the highway infrastructure.
The transportation department also incorporated decorative concrete techniques to enhance some of those bridges’ appearances while tying them to the communities they serve. These efforts were undertaken to meet the bridge program’s goal of building projects sensitive to their communities and landscape. Applications include using vertical forms to create “stone” façades, carving emblems and designs into vertical concrete, and installing decorative soundwalls. Following are a few examples.
Blending with the scenery
The dramatic landscape of the Columbia River Gorge—a wide river basin flanked on the north by golden grasslands and on the south by columns of basalt pierced by waterfalls—was formed millions of years ago by two repeated geologic actions: volcanic eruptions of lava and a series of rapid inundations known as the Missoula Floods. In essence, 6,000 feet of lava accumulated and hardened, and periodic flooding carved away at it. Today, the visually stunning environment is protected as the Columbia River Gorge National Scenic Area.
During the bridge program, ODOT replaced eight Interstate 84 bridges along this corridor, which brings commerce as well as travelers east and west through Oregon. The agency coordinated its construction in the Gorge to include input from all stakeholders.
Representatives of federal and state agencies—including ODOT—and adjacent counties, in partnership with local citizens, developed design guidelines for the new bridges that would meet public safety and transportation needs while also meeting National Scenic Area provisions that protect federally designated areas of outstanding natural and scenic value. The resulting Cascadian bridge design specified a rocklike façade in shades of tan and brown typical of the surrounding landscape. Crews used (and reused) plastic forms incised with irregular rock shapes, like those in a hand-stacked wall, to create the surface area of the concrete abutments, piers, pylons, and a 1,200-foot-long retaining wall that will support a bicycle and pedestrian path. Denver-based formliner manufacturer Scott Systems Inc. used pattern #189 Teton Dry Stack to complete the enhancements.
Specialty contractor Livingston Construction Inc., located in Doty, Wash., created the perfect coloration for the new Gorge bridges. The primary method the company used was a water-based and environmentally safe concrete “rock” stain. With the surrounding area for inspiration, owner Jill Livingston blended her stains onsite, mixing colors in natural light to ensure that the result worked well with the projects’ settings. The stains were applied with a low-volume, low- pressure sprayer and by hand. Using the proper layering technique with both methods was a crucial element to ensure that the structure blended with the surrounding environment and added to the natural beauty of the area.