This is arguably the most famous bridge never built. It is a 50-foot wide two-lane highway bridge designed to cross the middle fork of the American River at a point 10 miles upstream of the planned Auburn Dam. The river is 450 feet deep and 1,200 feet wide at the site. To avoid the need for any piers, a "hanging arc" design was developed. It curves 50 degrees along a 1,500-foot radius in a length of 1,300 feet. The deck edges are supported by cables that are anchored on the slopes of the river valley. The cables are arranged in a position that produces an axial line of pressure in the curved girder. They are post-tensioned to control stresses and strains and achieve an ideal condition of almost no bending or torsional moment in the girder. T.Y. Lin International (TYLI) was the engineer of record.

• Mark Ketchum, current OPAC principal, served as Design Engineer while at TYLI, and performed all dynamic analyses for both the steel and concrete design alternatives.