Grand Coulee Bridge by two concrete piers, about 150 ft high. During construction, one of the piers began to tilt, probably due to fine glacial material under the gravel. Additional supports were added as a temporary measure. The piers were later taken down to the bedrock using pneumatic caissons. Grand Coulee Bridge The Grand Coulee Bridge, or Columbia River Bridge at Grand Coulee Dam, is a steel thru cantilever truss bridge built in 1934-1935. It carries Washington State Route 155 across the Columbia River immediately below Grand Coulee Dam, near the city of Grand Coulee, Washington. It was added to the National Register
Grand Coulee wide as Niagara Falls and three times as high. Steamboat Rock high and a in area, now stands as an isolated rise, but for a time it created two cataract. When the falls passed north of Steamboat Rock, it found a granite base beneath the basal flows. Granite lacks the close vertical joints of basalt, was resisted the erosion from the cataract's plunge. It remains as hills on the broad floor of the Coulee. Some gravel-bar deposits are visible along the Route 155. They provide evidence of eddies in the lee of rock shoulders. Dry Falls is at the head