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Hopelessly devoted: Cowi celebrates milestone on ‘Grease’-famed bridge replacement

The new viaduct replaces the 1932 bridge made famous outside LA for its appearance in the hit film Grease (Image courtesy of Cowi)
Denmark-founded international engineering consultant Cowi is celebrating an engineering milestone on the new 6th Street Viaduct replacement project in Los Angeles (LA) following the successful hanger installation of the first span out of 10.

Famous outside LA for its appearance in the hit film Grease, the original viaduct was built in 1932 and now spans Freeway 101, several rail lines and the LA river to link Boyle Heights and Downtown LA’s Art District.

In 2016, the original bridge was demolished owing to its seismic vulnerability.

At 933m in length and 30.5m wide, the new bridge was designed by architect Michael Maltzan and structural engineer HNTB.

It has 10 network arch spans, with a total of 388 hangers supporting the bridge deck.

Appointed as the erection engineer, Cowi worked with Skanska Stacy and Witbeck (SSW) to develop an erection sequence that includes step-by-step camber and stress analyses, hanger installation and stressing procedures.

They have now finished installing the the hanger of the first span and removing the falsework underneath, a tricky operation given the highway below stayed open.

To do that, SSW and Cowi monitored the falsework supporting the deck and the hanger forces during installation to ensure everything went to plan.

“If you consider each arch span as an individual bridge, then this essentially marks the completion of the first of ten bridges, making this such an exciting milestone for the project,” said Tobias Petschke, senior project manager at Cowi North America.

Safety precautions include the design of customised lock-up devices to stabilise the seismic pendulum bearings of the bridge during construction.

The next step of the project is the closure of the superstructure continuity followed by the hanger installation in the second span, with completion of the bridge planned for mid-2022.

“This is a really exciting time to be an engineer,” Petschke said in a press note. “Having the opportunity to apply our expertise to projects of this kind reminds you just how important our work is. By exploiting some of the most advanced techniques we can ensure the safe and sound erection of complex infrastructure projects. We are proud to be working with an amazing construction joint venture such as Skanska Stacy and Witbeck, who are providing exceptional services and are going above and beyond to build this viaduct.”

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