Congratulations to our Los Angeles based Engineering team for receiving a 2022 Engineering Excellence Honor Award from the American Council of Engineering Companies, California (ACEC California).
Psomas received the prestigious award for our work on the North Spring Street Viaduct Widening and Rehabilitation. The project was one of sixteen selected for an honor designation, winning in the Structural Systems Category.
Built in 1928, the North Spring Street (NSS) Viaduct is one of over two dozen historic bridges spanning the Los Angeles River between Long Beach and the San Fernando Valley. Designed by architect John C. Shaw, the bridge has provided a vital connection between the Lincoln Heights and Chinatown neighborhoods northeast of downtown for nearly a century.
In 1939 the bridge was widened by removing the southern sidewalk, and in 1992 the city commissioned a retrofit and comprehensive rehabilitation, repairing and replacing the damaged railings, electroliers and historic lanterns. However, despite these structural and cosmetic interventions, the NSS Viaduct was deemed in need of a more dynamic upgrade, and in 2006 the City of LA Bureau of Engineering (BOE) proposed a new retrofit and widening project. This plan, intended to bring the bridge up to a “major highway standard”, called for significant widening but also a full demolition, prompting strong opposition from LA historical preservation groups.
In 2008 the bridge was designated a Los Angeles Historic-Cultural Monument, and in 2011 new plans providing the necessary upgrades while maintaining the Viaduct’s historic designation and appearance were presented and accepted by all stakeholders.
Psomas was selected by the BOE to provide project management, value analysis, civil design services and design support during construction on the NSS Viaduct Widening and Rehabilitation project. This high-profile upgrade provided the City of LA the opportunity to reduce the seismic vulnerability of the NSS Bridge, mitigate traffic congestion, increase pedestrian and cyclist safety, ensure Americans with Disabilities Act (ADA) compliant paths of travel, and restore and protect the bridge’s historic design elements.
The new North Spring Street Viaduct successfully met the seismic and widening goals set by the BOE. The completed 23-foot roadway widening includes the addition of bike lanes, a sidewalk and striped median. A new, yet compatible, design featuring a more modern, articulated double-arch span complements the original north side, maintaining the bridge’s original classical style and ensuring the structure’s historical integrity for the next generation.
The project was completed in June 2021. Congratulations to Andrew Nickerson and the Southern California Transportation team on this honorable win.
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OWNER: City of LA Bureau of Engineering
DESIGN PRIME CONSULTANT: Psomas
DESIGN STRUCTURAL ENGINEER: IDC Consulting Engineers
RETROFIT: CNS Engineers
HISTORIC PRESERVATION: JRP Historical Consulting
UTILITY ENGINEER: Sukow Engineering
CONTRACTOR: Griffith Company
CONSTRUCTION SUPPORT – PRIME: Kimley-Horn
CONSTRUCTION SUPPORT – STRUCTURAL: Biggs Cardosa
GEOTECHNICAL: Hushmand Associates
