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

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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 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 exceeded 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:

● 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.

About HNTB
HNTB Corporation is an employee-owned infrastructure solutions firm serving public and
private owners and construction contractors. With 108 years of service, HNTB understands the life cycle of infrastructure and addresses clients’ most complex technical, financial and
operational challenges. Professionals nationwide deliver a full range of infrastructure-related services, including award-winning planning, design, and program and construction management.

For more information, visit www.hntb.com, or follow HNTB on LinkedIn, Twitter, Facebook or Instagram.

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