HNTB’s winning concept for LA’s 6th Street Viaduct Replacement Project

winning proposal via Sixth Street Viaduct Replacement Project

In April, Mayor Villaraigosa and City Council Member Huizar announced an international design competition to redesign the historic, 80-year-old Sixth Street Bridge in Los Angeles. The decision to launch the competition came after engineers warned that the bridge was at risk of failing during a major earthquake due to a degenerative structural problem known as “concrete cancer”. After careful consideration and entertaining the idea of constructing a replica of the 1932 icon, the city committed to moving forward with a major redesign. In mid-October, the national infrastructure firm HNTB, along with team members and AC Martin Partners, were announced as winners of the international competition.

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HNTB winning proposal via Sixth Street Viaduct Replacement Project

“When I instructed the Bureau of Engineering to bring the best of the best to the City of Los Angeles to design the new Sixth Street bridge, they certainly delivered,” said Councilmember José Huizar. “This bridge by HNTB honors the history of the original while boldly looking towards the future with major river, pedestrian, multi-modal and community gathering features. Our new bridge will not only bring people from Point A to Point B, but to Point C – the bridge itself. It will be a shining-star destination spot worthy of the City of Angels.”

HNTB’s winning design of the 6th Street Viaduct Replacement Project recalls the form, scale and structural logic of Butler’s historic viaduct. It’s canted cable supported arches offer an efficient and cost effective solution that honors the existing bridge’s iconic structure that is embedded in the City’s memory.

HNTB winning proposal via Sixth Street Viaduct Replacement Project

It’s multimodal pathways engages the river, provides new opportunities of connection, and dissolves the dividing line between Los Angeles’ downtown and East side. What’s underneath the bridge is now treated as equally important as to what’s on top.

Beneath the viaduct, a new Arts Plaza blurs the line between infrastructure and urban fabric by integrating space for a market hall, restaurant, artist displays, film screenings, and more. The current existence of the static Sixth Street Bridge will be transformed into a cultural destination for all of Los Angeles. Patterned hardscape, landscape, furnishing and signage will create a new public identity that celebrates the vitality of the surrounding district.

HNTB winning proposal via Sixth Street Viaduct Replacement Project

HNTB also proposed that the new connectivity and growth catalyzed by the viaduct could include the extension of the City’s Clean Tech Corridor, allowing the project to have a significant economic impact. The neighborhood would no longer be a dividing line, but a new center for sustainable development accessible by foot, bicycle, and public transit.

The $400 million dollar redesign is supported largely by the Federal Highway Bridge Program. Construction is expected to begin in 2015, with completion scheduled for 2019.

For more, check out Los Angeles’ major plan to transform Union Station!

Also, review HNTB’s official design boards here.

Reference: Sixth Street Viaduct Replacement Project, The Los Angeles TimesArchitect Magazine 

Cite: Rosenfield, Karissa. "HNTB’s winning concept for LA’s 6th Street Viaduct Replacement Project" 05 Nov 2012. ArchDaily. Accessed 22 May 2015. <>
  • Alison

    For your sakes, I hope they don’t screw this up like they did the Wakota Bridge.