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Sixth Street Viaduct


Project of the Year


A true beauty and technological blockbuster, the new Sixth Street Viaduct is a groundbreaking structure. Replacing Los Angeles’ beloved steel double arch landmark with 10 pairs of sculptural arches, the new $588 million structure opened to traffic in July 2022.

It sets a new threshold for seismic safety and expands the utility of urban bridges. The largest, most complex bridge project in L.A. history, the structure advances the field of seismic bridge engineering and the engineering profession with a series of innovations. Designed to remain undamaged and operational after a seismic event with a 1,000-year return period, the viaduct is believed to be the world’s longest, seismically isolated concrete tied arch bridge. It features the first U.S. application of seismic isolators within the verticality of a bent, the world’s first next-generation triple-pendulum friction bearings modified to stiffen after a predetermined displacement and activate a secondary seismic resisting system, the first U.S. bridge to use DSI-manufactured multistrand post-tension couplers and Caltrans’ first use of grade 80-ksi concrete reinforcement.

The viaduct is designed to serve multiple purposes including safety, mobility, transportation equity, unity, longevity, and more.