About the Bridges  • Frank Pictures Gallery Exhibition • Overview Booklet • Kids' Guide • Past Events
 

LOS ANGELES RIVER BRIDGES

Fourth Street Viaduct. Photo by Kevin Break

When is a bridge more than a bridge? When it's part of a unique collection of historic structures that help tell the story of L.A.'s explosive growth in the early twentieth century. Yet many of these historic spans are slated for alteration and, in some cases, demolition.

Read about the bridges below, and visit other pages for more information, including downloadable versions of our bilingual overview booklet and kids' guide:

Frank Pictures Gallery Exhibition
Spanning History Booklet, English-Spanish (PDF)
Spanning History Kids' Guide, English-Spanish (PDF)
Past Events, April 2008
Audio from April 2008 Panel Discussion (Getty website)

About the Bridges

Opening day, Fourth Street Viaduct, 1931. Photo courtesy Metro Library.

Twenty-seven bridges span the Los Angeles River between the San Fernando Valley and Long Beach. Within the City of Los Angeles, fourteen of these bridges were built between 1909 and 1938, as Los Angeles’ population exploded and the automobile emerged. The bridges were part of an ambitious bridge construction program to accommodate increasing numbers of cars and alleviate traffic snarls on surface streets.

Monumental in design and massive in scale, even by today’s standards, these early bridges reflected the nationwide City Beautiful Movement of the time, which sought to improve the character, morale, and civic virtues of residents through architecture and urban planning.

North Broadway (foreground) and North Spring Street bridges. Photo by Kevin Break

The styles of the bridges evolved over time, from an early preference for highly ornamental, classical designs (Macy Street/Cesar Chavez, Olympic Boulevard), to simpler, period revival styles (Fourth Street, First Street), and ultimately adopting clean and modern lines (Glendale-Hyperion, Sixth Street).

Together, these bridges tell an important part of the story of how Los Angeles came of age as a modern city. Yet they are threatened with alteration or demolition as part of the city’s long-term bridge “improvement” program.

Seventh Street Viaduct. Photo by Kevin Break

In recognition of the bridges’ collective significance, the city’s Cultural Heritage Commission took the unprecedented step in September 2007 of self-nominating thirteen bridges as city landmarks, known in Los Angeles as Historic-Cultural Monuments.

Sixth Street Viaduct. Photo by Kevin Break

In January 2008, the Los Angeles City Council voted unanimously to designate eleven of the thirteen bridges as Historic-Cultural Monuments. This designation ensures a role for the Cultural Heritage Commission in reviewing proposed bridge widening and replacement projects. Yet the commission can merely delay, not deny, demolition.

Why They're Threatened

The City of Los Angeles’ Bureau of Engineering (BOE) has an ongoing Bridge Improvement Program to overhaul city-owned bridges. Seven years after its inception, the program set its sights on the historic Los Angeles River spans.

First Street Viaduct. Photo by Kevin Break

With the First Street Viaduct widening project nearly complete as part of the Metro Gold Line expansion, environmental review is underway for “improvement” projects at the Riverside, North Spring Street, and Sixth Street crossings, posing major threats to historic resources up and down the river corridor.

Despite the historical and contextual links between them, until now there has been little consideration of the program’s cumulative impacts on this unique ensemble of monumental bridges.

Current Threat to Sixth Street Viaduct

Security Pacific Collection/ Los Angeles Public Library

Built in 1932, the two-thirds-mile-long Sixth Street Viaduct is the last and grandest of the monumental river bridges, with its graceful steel arches and clean lines evoking Streamline Moderne design.

The bridge stands as an iconic gateway to both sides of the Los Angeles River and was determined eligible for listing in the National Register of Historic Places in 1986. Featured in countless films, television shows, and commercials, it is the most widely recognized of the historic river bridges. It is also the most imperiled.

Photo by Kevin Break

According to a report released by the BOE, the bridge has been substantially weakened from a chemical process known as alkali-silica reaction (ASR), which BOE engineers have known about for decades. ASR is a process by which alkali and silica components in the concrete combine with moisture to form a gel that expands, causing cracking and weakening of the structure.

BOE representatives have predicted a seventy-percent risk of the Sixth Street Viaduct's "collapse" in the next major earthquake -- although city engineers have since clarified that "collapse" means that the viaduct would be rendered unusable, not actually fall down. Although a retrofit design was approved and partially implemented in the mid-1990s, the BOE is now pushing replacement as the only truly effective solution.

Photo by Kevin Break

The Conservancy acknowledges first and foremost the importance of ensuring public safety, but would also like to see a thorough evaluation of preservation alternatives and consultation with bridge engineers who have experience working with ASR before any replacement scenarios might be considered.

In September 2007, the Los Angeles Conservancy submitted detailed comments on the Notice of Preparation of the Draft Environmental Impact Report for the $200 million “Sixth Street Viaduct Seismic Improvement Project.” The initial study identifies only one retrofit alternative, compared to at least four alignments and myriad designs for replacement spans, revealing a bias in favor of demolition.

The Conservancy’s comments ask the BOE to consider at least two retrofit alternatives that meet current safety standards, using different technologies available for treating ASR.

Photo by Kevin Break

The Conservancy has also proposed a combined retrofit and partial replacement alternative that prioritizes retention of the iconic, arched section of the bridge over the river. Although the viaduct stretches over 3,500 feet, the arched section composes only a small portion of the total length at less than 400 feet.

Other Bridges at Risk

Major retrofit, widening, and realignment projects are also planned for the North Spring Street and Riverside Bridges, although neither project would increase traffic capacity. Both have been deemed “functionally obsolete” under current federal highway standards, based on limited curb-to-curb widths, lane widths, and the absence of shoulders, among other issues.

Riverside-Zoo Drive Bridge Photo by Kevin Break

Besides impacts to the bridges themselves, these projects also threaten historic buildings in the path of proposed realignments, such as the Raphael Junction building (1890) at 1635 N. Spring Street, which recently was designated a City of Los Angeles Historic-Cultural Monument. In both the North Spring Street and Riverside projects, the Conservancy is advocating alternatives that build stand-alone bicycle/pedestrian bridges in lieu of widening the existing bridges.