This "hanging arc" bridge is designed to cross the American River in California, and its arc shape is to avoid costly extensive cuttings and intermediate supporting piers. The bridge is supported by cables, spread and anchored on the slopes, and post-tensioned to control vertical and horizontal stresses and strains in the girder. Details are given of cable layout and design bases on computer analysis of various formations. Alternative steel and concrete designs are included for the box girder which will be constructed outwards from each abutment. Calculations are made for possible seismic risk, and the results of model tests and wind tunnel studies are presented. Construction techniques are discussed and the steel and concrete designs are compared. (TRRL) international, 1979, vol 1, no 7 pp 31-7.