SUMMER 2023 NEWSLETTER ︎ BRIDGE:
SIXTH STREET VIADUCT, 1932
Constructed in 1932, the Sixth Street Viaduct was, at 3500 feet, the longest of the 14 bridges that crossed the Los Angeles River. Built by city engineer Merrill Butler as a reinforced concrete bridge in the Art Deco style, the bridge was not only famous for its length, but also its two side-by-side arches, placed at the center, that gave it a monumental appearance. The aesthetic form was preferred to the economical and technical way of production that was common at the time. The Municipal Art Commission, which included some well-known architects of the time, such as Cecile B. DeMille and Donald B. Parkinson, was established and consulted for design approval. With the use of reinforced concrete that was poured on site, it was possible to customize all the steel arches and to integrate decorations in different eclectic styles, mostly imitating natural stone buildings. Ultimately, this was also the stumbling block for the life of the bridge. The composition of the concrete resulted in an alkali-silica chemical reaction which caused the concrete to deteriorate significantly, making it an impractical candidate for seismic retrofit. Already 20 years after the construction, the concrete started to decompose and cracked incessantly. Various methods had been attempted over the years to solve this problem.
In 2012, the City of Los Angeles’ Bureau of Engineering hosted an international competition to replace the bridge with a new construction. The idea was to work closely with the surrounding districts, Boyle Heights in the east and the Arts District in the west, to design a bridge in line with its historical predecessor. The focus, therefore, was on the form, colors, and surfaces. For this purpose, a Design Aesthetics Advisory Committee which included, amongst others, Hitoshi Abe, professor and chair at UCLA Architecture and Urban Design, and Eric Owen Moss, then director at Sci-Arc, was established. They participated in neighborhood events and provided feedback to contestants. After four months, the jury voted for HNTB Corporation as the Engineer of Record with local architect Michael Maltzan leading the design. In 2016, the old bridge was demolished, and after five years of construction, the new bridge opened last summer in 2022 to a neighborhood celebration with over 15,000 people, during which the bridge was closed to car traffic for a day. Hardly opened, however, it had to be closed again immediately for two weeks, because Angelinos used the bridge in all kinds of illegal ways, like racing cars and motorbikes, establishing a hairdressing salon in the middle of the lanes, climbing on the arches, and performing dangerous tricks.
RIBBON OF LIGHT, 2019-2022
“Part of the brief was to replace one icon with another,” says Maltzan, “but this was also a chance to create a real public space.”
The bridge is defined by ten pairs of arches ascending and descending along the edges of the entire structure. Each on-site, cast arch is fitted with a network of tensioned cables and extends below the pavement where it connects to the adjacent arch, forming a Y-shaped pillar resting on a seismic engineered base, the isolator. A total of 32 isolators with Triple Friction Pendulum Bearings at columns and abutments allow the bridge to move up to 30 inches in an earthquake. An additional second back-up safety system inside the columns comes into action and stiffens the structure if the isolators reach their capacity. The columns reach 165 feet below ground (which equals a 16-story high building).
The arches on the south side of the street mirror the arches of the same height on the north side. Following the 1932 design, the tallest arches rise 65 feet above the pavement, in the center, over the Los Angeles River, while a pair of 40-feet high arches crosses U.S. Highway 101 and forms a gateway to Boyle Heights at the east end. The remaining arches are 30 feet high. The series of arches also slope outward by nine degrees, creating a sense of movement and dynamism as it opens up to the sky. Resembling a graceful, dancing ribbon that moves gently in the wind, the lines of the bridge feel light and fluid. This is accentuated by the slight curvature of the bridge and the west-to-east incline by 63 feet.
In contrast to the 1932 Sixth Street Viaduct, the new carriageway is not only for cars, it also has wide, protected outer lanes on both sides for pedestrians (8 feet wide) and cyclists (10 feet wide). The new bridge is the same length as its predecessor, but its span measures 100 feet, 40 feet wider than the original. Five stairways and a 104-foot wide disabled and bicycle friendly central spiral ramp connect the bridge to the park below.
The dramatic nighttime illumination of the roadway with LEDs deeply embedded in concrete barriers and with upward-facing lights under the arches, makes the bridge a “strip of light” that flies past as you drive over the bridge in a car; it also provides a foreground for the high-rise landscape of downtown behind it. During the day, the calligraphic arches play with the downtown skyline and, through their slightly curved span, offer changing vantage points over the broad thoroughfares and the snow-capped San Bernardino Mountains in winter.
Boyle Heights, the neighborhood directly to the east of the bridge, is a historically significant and urban-dense area sandwiched between two freeways, Interstate 5 and U.S. Highway 101. Throughout the 20th Century, the neighborhood proved to be a beacon of diversity. It was one of the few areas that did not discriminate against Japanese immigrants in the 1910s. In the 1920s and 30s, a politically active Jewish community made up 40% of the population, the largest concentration west of Chicago. It was also home to significant Russian, Italian, African American, Armenian, and Mexican communities. In the late 60s, students walked out of their schools to march against racial discrimination, contributing to the Chicano Movement. By 1961 around 15,000 residents were displaced because of the construction of the East LA Interchange. In the last 10 years, the now mostly Spanish speaking community have successfully defended themselves against the gentrification of their industrial buildings by art galleries and the rising price of living space by young, affluent tech people. With the same importance given to the bridge’s significant architectural form, the planning committee attempted to include the community of Boyle Heights into the planning process and the park design so as to not repeat the former mistakes in urban planning decisions.
The bridge crosses 17 railroad tracks operated by five different companies, Interstate 5 and U.S. Highway 101, the L.A. River, and various streets in the neighborhood (Mission Rd., Anderson St., Clarence St., Santa Fe Ave). The new 12 hectares of public park under the bridge will connect with Boyle Heights by 2024 (also called PARC, Parks, Arts, River, and Connectivity Improvements). As of today, the area is still a vast and empty dirt field. The works could not start until the construction of the viaduct was completed and the money for its realization was found. 58.7 million dollars are now available (out of a total of 82 million budgeted for this park). Green areas, picnic areas, an event room, and sports facilities for football, basketball, and volleyball are planned on the east side, while a performance stage, dog park, and fitness circuit are planned on the west side. This area underneath the bridge seems to be the leftover area in the shadow of the bridge, but with this plan, the hope is that it will become a big open shaded public space available to Angelinos in the daytime with the glaring sun above. In the evening, the underside of the structure is illuminated, and its concrete ribs shows the structural form like the crossbeams of a basilica.
LOS ANGELES LANDMARK
The new replacement bridge pays homage to its Art Deco predecessor, which was already a landmark for the city and was used as a backdrop for car races in many movies, like Grease and Terminator 2. It seems logical that this new spectacular architecture turned the film stories into a dangerous reality, which almost eliminated the purpose of the bridge as a motorway and led to its temporary shutdown. Voices emerged to turn the whole bridge into a public space, probably also because of the lack of the promised park underneath. The appropriation of the bridge by the community and the integration into the daily life of every Angelino as well as into the commercial world of Hollywood (first car adds with the bridge in the background are airing right now) could be the actual success of the new connection.
Michael Maltzan Architecture
Architect/Engineer of Record:
Skanska-Stacy and Witbeck
Hargreaves/Jones Associates (landscape), AC Martin (urban planning)
City of Los Angeles, Bureau of Engineering
3,500 feet long
Roadway and accent Lighting:
Earthquake Protection Systems
This project is made possible in part by a grant from the City of Los Angeles Department of Cultural Affairs.
Photographs: CONTENT PRODUCTION
Text: Lilian Pfaff
Editor: Quynh Nguyen
Graphic Design Credit: Still Room