North Spring Street Viaduct Over Los Angeles River & Metrolink Tracks

Owner: City of Los Angeles
Location: Los Angeles, CA
Date of Performance: 2010-2018
Project Cost (Est.): $50 million / $500,000

Project Overview: Structural bridge design; preliminary, PA/ED, and final PS&E; Bridge widening and rehabilitation; Caltrans project management and coordination; Caltrans Project Development Process; Design check; Permitting; Local agency coordination; Construction staging and support; Railroad coordination; Seismic analysis; HBP project

Summary: As a sub-consultant to Psomas, IDC provided preliminary and final design services, and construction design support for the widening and seismic upgrade of the historical arch bridge over the Los Angeles River. The City of Los Angeles aimed to widen and rehabilitate the bridge to meet future traffic demand, improve pedestrian and cyclist safety, and maintain its historic integrity.

IDC's responsibilities included developing a 3-D computer model of the original and proposed structures to study structural behavior, devising a precast pier system to accommodate limited construction windows, and ensuring historic preservation in the structural design. The project widened the viaduct by approximately 25 feet on the south side, reconfigured adjacent roadways, and corrected seismic vulnerabilities.

IDC's innovative design solutions saved over $1 million and shortened the construction period, reducing commuter impact. The final design featured a modern-looking deck arch on the south side, preserving the historic appearance on the north side. IDC also worked with the State Historic Preservation Office to restore original architectural details and presented design plans to stakeholders, including at City Council meetings.