Los Angeles Bureau of Engineering celebrates opening of HNTB-designed Sixth Street Viaduct Replacement Project

The new iconic viaduct celebrates opening since demolition of the original 1932 structure in 2016

LOS ANGELES (July 11, 2022) – 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 countless 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.”

“Los Angeles has invested in world-class infrastructure for now and for the future,” said Yoga Chandran, HNTB Los Angeles office leader who was involved as program manager during the project’s environmental phase and in securing funding for the bridge program. “The new Sixth Street Bridge will be on the world’s center stage as the Summer Olympics return to Los Angeles in 2028.”

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 seamlessly 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.

“We would like to congratulate the Los Angeles Bureau of Engineering and all Angelenos on the completion of this transformative bridge that pays homage to the original iconic structure and boldly looks to the future,” said Wayne Feuerborn, HNTB West Division president. “Downtown Los Angeles and the East side are seamlessly connected by the new viaduct that also serves as a destination with accessibility for pedestrian, multimodal and community gathering features.”

To celebrate the opening, the City of Los Angeles organized community celebrations on Saturday, July 9 and Sunday, July 10. The press event was held on Friday, July 8 for members of the media.   

“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.”

HNTB’s many signature bridge projects in the region include the recently opened 2,000-foot-long Gerald Desmond Bridge in Long Beach, the first vehicular cable-stayed bridge in the state and one of the widest cable-stayed bridges in the world; the I-405 Sepulveda Pass Widening Design-Build Project in Los Angeles, replacing and widening 23 bridges, including replacing the Mulholland Bridge with a 300-foot-long main span structure over the busiest highway in the U.S; and LA Metro’s Crenshaw Light Rail project, a design-build contract that integrates the Los Angeles International Airport with the regional rail network, among others.

Since its founding, HNTB has been nationally recognized for its bridge expertise. The firm has roots in Southern California dating back to 1914 with the landmark design of Pasadena’s historic Arroyo Seco Bridge. Spanning 1,486 feet and notable for its distinctive Beaux Arts arches, light standards and railings, the bridge is on the National Register of Historic Places and has been designated a National Historic Civil Engineering Landmark by the American Society of Civil Engineers.