Los Angeles County Opens and Closes Iconic Bridges

July 11, 2022

Two bridges in Los Angeles County saw some big milestones this weekend, but for opposing reasons.

At the Port of Long Beach, the Gerald Desmond Bridge, a 53-year-old structure was slated to come down over the weekend. Its replacement was opened in October of 2020.

On the eastern edge of downtown, the replacement for the Sixth Street Viaduct was open on July 9th. This structure was the largest construction bridge construction project in the history of Los Angeles, coming in at $588 million.

Opening in 1932, the original viaduct was the connection between the Arts District on the west side of the Los Angeles River and Boyle Heights on the east side. The structure spanned roughly 3,500 ft. across the river. Over time, it degraded, and because it also needed to be seismically upgraded, the city’s Bureau of Engineering set to work creating a replacement crossing.

The main unique feature from the design team for the new bridge, consisting of Kansas City, Missouri-based HNTB Corp. and Los Feliz-based Michael Maltzan Architecture Inc., was a series of 10 sweeping arches on each side of the bridge, creating a nighttime effect called the “ribbon of light.”

While Maltzan Architecture was busy creating the arches, HNTB was tasked with making sure the bridge had all the latest seismic mitigation equipment. According to HNTB’s project manager and principal engineer Michael Jones, the arches posed a significant obstacle to traditional seismic isolators because they extend below where the isolation bearings would typically be placed.

HNTB turned to Vallejo-based Earthquake Protection Systems Inc. to come up with the new design.

Once the design was developed, the new seismic isolation devices were installed by the project’s construction team, led by a joint venture of Skanska USA Inc., a unit of Stockholm, Sweden-based Skanska, and Stacy and Witbeck Inc. of Alameda.

Meanwhile, at the Port of Long Beach, the back channel was slated to be closed July 9-10 to accommodate the removal of the main 410-foot span of the old Gerald Desmond Bridge over that channel. This is the first step of the $59.9 million demolition contract that the port awarded last July to Kiewit West Inc. (a unit of Omaha, Nebraska-based Kiewit Corp.), to dismantle and remove main truss spans, steel plate girder approaches, abutments, foundations and other pieces of the old bridge.

“The Gerald Desmond Bridge served Southern California’s regional transportation network for over 50 years, carrying more than 60,000 Southern California commuters and cargo-hauling trucks every day by the time construction started on the new bridge,” Steven Neal, president of the Long Beach Board of Harbor Commissioners, said in the announcement of the back-channel closure.

The replacement bridge, which crosses the channel at a level 50 feet higher, can now serve all elements of its purpose, nearly two years after it opened to vehicular traffic. With the old crossing gone, larger cargo ships now have enough clearance to pass under the replacement bridge. Until now, those ships have been blocked from accessing the port’s inner harbor.


Source: LAist.com

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