the towers at their base. The arches are four and one-half feet wide. The bridge was designed to support more than six times its intended load. The two large, vertical buttresses or supporting pillars on either side of the arch, while aesthetically pleasing, are functionally unnecessary. Engineers of later arch bridges such as the Frederick W. Panhorst Bridge omitted them from the design. The Rocky Creek Bridge and the Malpaso Creek Bridge to the north are also open-spandrel arch bridges built of reinforced concrete. Construction The state first began building Route 56, or the Carmel–San Simeon Highway, in 1919. A number of bridges needed to be constructed, the largest among them across Bixby Creek. Bridge design State engineers considered two alternatives to crossing the creek, an inland route and a smaller bridge, or a coastal location and a larger bridge. The inland route would have needed an 890-foot (270 m) tunnel cut through the Santa Lucia Mountains to a 250-foot (76 m) bridge upstream. The engineers selected the coastal route because it was safer, more scenic, and least affected the environment. California state highway engineer C. H. Purcell and bridge engineer and designer F. W. Panhorst considered whether to build a steel or concrete span. A steel bridge would cost more to build and maintain, as the sea air would require expensive ongoing maintenance and painting. A steel bridge was also less in keeping with the natural environment. Using concrete reduced material costs and allowed more of the total cost to be paid to workers, which was a positive aspect of the design during the Depression. They chose concrete in part because it would not only reduce both construction and maintenance costs but would also echo the color and composition of the natural rock cliff formations in the area. The state awarded a contract for $203,334 to the lower bidder, Ward Engineering Company of San Francisco, on August 13, 1931. Construction began on August 24, 1931. Design and materials Over 300,000 board feet (700 m3) of Douglas fir timber, used to build a 250-foot (76 m) high falsework to support the arch during construction, was transported from the railroad terminal in Monterey over the narrow, one-way road to the bridge site. The falsework, built by crews led by E. C. Panton, the general superintendent, and I. O. Jahlstrom, resident engineer of Ward Engineering Co., was difficult to raise, because it