LOS ANGELES, CA — The City of Los Angeles Bureau of Engineering officially opened the new Sixth Street Viaduct Replacement Project in downtown Los Angeles with several celebrations. It is the largest bridge project in the history of Los Angeles and replaces the original, seismically deficient structure that was built in 1932.

The new bridge, dubbed “the Ribbon of Light”, was created by HNTB Corp. in collaboration with Los Angeles architect Michael Maltzan Associates and Danish bridge architect Dissing+Weitling. The design was selected by the Bureau of Engineering through an international design competition. Construction was led by contractors Skanska and Stacy and Witbeck, a joint venture.

Serving as both architect-of-record and engineer-of-record for the decade-long project, HNTB was responsible for the design of the 3,500-foot-long viaduct, connecting the historic Boyle Heights neighborhood to the downtown Arts District. The original bridge was often used in movies, music videos, and TV commercials, including riverbed car chases.

“After so many years of work and anticipation, it was a great feeling this past year to see the viaduct as forms and falsework were finally stripped to reveal the actual concrete structure,” said Michael H. Jones, PE, SE, HNTB Project Manager, Engineer-of-Record, and HNTB Fellow. “It was truly rewarding to see the completed structure exceed our expectation of delivering an extremely elegant, well-proportioned, and iconic viaduct that all Angelenos can be proud of as it connects our communities and improves mobility for everyone.”

The replacement viaduct pays tribute to the original bridge with innovative safety, durability, and architectural elements recognized for enduring design excellence. Highlights of HNTB engineering design features include:

• Earned an Envision Platinum award from the Institute for Sustainable Infrastructure.
• Columns and abutments fitted with triple pendulum friction bearings allow for a 30-inch sway in any lateral direction, able to withstand a magnitude 9.0 seismic event.
• The substructure features concrete “Y-Bents” that flow into the arches and uses grade 80 reinforcement instead of grade 60, which is a first for a California bridge.
• A 100-year service life, making it the first HNTB design to use the Envision Infrastructure Rating System for sustainability and resource efficiency.
• Viaduct pilings extend up to 165 feet underground, equivalent to a 16-story building.
• An additional 40 feet was added, widening the span to 100 feet to enable safe multimodal transportation using dedicated lanes for foot, bicycle, as well as vehicle transit.

“I am proud to have been involved with this project from the beginning and excited to witness the completion of the Sixth Street Viaduct,” said Yung-Nien Wang, PE, HNTB Director of Structures. “The collaborative efforts by the City of LA, Bureau of Engineering, designers, engineers, and contractors, with support from Angelenos, has culminated in a ‘bridge to future opportunities’ as we continue to connect our communities together.”