The Historic Alsea Bay Bridge Interpretive Center in Waldport is like a museum dedicated to the bridges of the Oregon coast and their designer Conde B. McCullough. I’ve mentioned this Interpretive Center before, but today I’ll devote more space to it.
The blue-roofed building sits just south of the (new) Alsea Bay Bridge, and on its north-facing wall is a large round window, where a great view of the new bridge is visible. An even better view is possible from the viewing area outside. Actually, the new bridge is no longer new; it turns 22 this year. And it’s become much admired and the pride of Waldport. But the historic bridge it replaced was an icon of the Oregon coast and a hard act to follow.
The original Alsea Bay Bridge was part of the Coast Bridges Project of 1934–1936 where five bridges all designed by McCullough, one of the world’s greatest bridge designers, were built during the height of the Great Depression. Those five turned out to be five cutting-edge masterpieces that represented the pinnacle of McCullough’s career.
The historic Alsea Bay Bridge was a favorite with its symmetrical design of three tied arches in the center flanked by three deck arches. It was constructed totally of reinforced concrete—the largest reinforced-concrete bridge ever designed by McCullough. And it was one of his longest bridges, just slightly shorter than Newport’s Yaquina Bay Bridge.
When it was built, the engineers hoped it would last for 100 years, but only promised 50. It fulfilled their promise, plus five. Then it was replaced.
People often ask why, and there were many reasons. The main culprit was salt. Because the bridge was located so close to the waves, it was always surrounded by salt air and often salt spray. This moist salt air worked its way insidiously into any tiny little crack in the concrete, eventually getting to the rebar within and corroding it. As the rebar corroded, it expanded, which hastened the cracking of the concrete. This process is called spalling. By the time it was detected in the early 1980s, it was too late to save the bridge and ODOT didn’t have a process in place to halt the corrosion. The loss of the Alsea Bay Bridge was a wake-up call, and ODOT has since implemented a program involving concrete restoration and cathodic protection that is saving the other historic reinforced concrete coastal bridges.
The old bridge was in such bad shape, that fishermen in Alsea Bay would make a mad dash crossing under it, trying to avoid getting hit by falling concrete. Spalling was the worst problem, but not the only one. The bridge was settling unevenly. It had not been built on bedrock at any point, although the wooden foundation piling had extended about 40 feet below the river bottom. And those piling had become riddled with marine worms. If that wasn’t enough, this bridge also received more scouring around the base of its supports than any of the other bridges along the coast. Scouring, which undermines the supports, is a major cause of bridge failure in the United States today. Any one of these problems was major; together the bridge didn’t have a chance.
For those who never saw the old bridge, The Interpretive Center showcases a detailed model of the entire bridge giving a great representation of how it looked. There are also historic photos of its construction on display along with a concrete railing section from the actual bridge.
The old bridge was pleasing to the eye and so is the new one. And everyone appreciates the four lanes that should be able to handle traffic increases far into the future. The new bridge was built with cutting edge sealants coating the steel rebar, much more concrete around the rebar (an average of four inches instead of one inch), and the piling foundations below the Y-shaped piers are made of stainless steel and concrete and extend to bedrock up to 100 feet below the river bottom. This bridge was built to last at least 100 years.
In the Interpretive Center’s tiny theater, a video shows the building of the new bridge from beginning to end as well as the destruction of the old one.
On the wall is a sketch of both bridges side by side, making it easy to see the differences.
Throughout the center, the walls are adorned with bridge photos, paintings, and sketches, of many of the coastal bridges designed by McCullough. At the entrance, a whole section of wall is devoted to the coast’s most important bridges with a photo and description of each along with a couple of maps showing where all the bridges are located and which were designed by McCullough.
There’s even a replica of McCullough’s office replete with furnishings and memorabilia from his actual office.
The Historic Alsea Bay Bridge Interpretive Center was built in 1991 after the completion of the new bridge. For bridge aficionados, it’s a must stop. For everyone else, it’s a chance to learn about Oregon’s beloved and iconic coastal bridges. And for me, it’s the perfect spot for both of my books.
Note: In Waldport, turn west at the signal at the southern end of the bridge. Then turn right and go approximately half a block to the parking area behind the Historic Alsea Bay Bridge Interpretive Center.