Building Los Angeles’ Earthquake-Proof Bridge | The B1M

Los Angeles’ Sixth Street viaduct is one
of the most well-known bridges in the United States. Made famous by appearances in countless movies,
TV shows, commercials and music videos – the 1,066-metre-long structure was an engineering
marvel when first constructed in 1932. Making use of an on-site plant to produce
concrete during construction, it was later discovered that the concrete developed had
a high alkali content. This lead to alkali-silica reactions taking place and cracks forming throughout the structure. Though the bridge underwent numerous costly
restoration attempts over the years, no permanent solution to its problems was ever found. In 2004 a study of the structure revealed
that it was seismically unstable and had a 70% chance of collapse during an earthquake
in the next 50 years. With the bridge spanning the Los Angeles River,
the 101 freeway, the I-5, and numerous railyards and local streets, Los Angeles’ authorities
had no choice but to mark the historic structure for demolition and replace it with a bridge
that could stand for 100 years in the face of LAs strongest earthquakes. After an international design competition
in 2012, Michael Maltzan Architecture’s design dubbed the “Ribbon of Light” was
chosen to replace the Sixth Street viaduct structure. The new bridge features 10 pairs of illuminated
concrete arches that pay homage to the earlier structure, while enabling longer spans and
fewer ground supports. This reduces the number of points that can
be damaged in the event of an earthquake and opens-up development opportunities beneath
the bridge. Work to demolish the existing viaduct began
in February 2016 and an estimated 37,000 cubic metres of concrete and 4,200 tonnes of steel
were removed over the subsequent nine months. With the original structure removed, work
began on the new bridge and, in December 2017, erection of the falsework that will support
the new structure during its construction commenced. To support the arches and create the bridge’s
unique “Y Bents”, prefabricated falsework is being trucked-in from as far away as Indiana
and Toronto. As concrete gives off heat as it cures, liquid
nitrogen is poured into the concrete mixers during the summer months to control the temperature
of the mix and prevent it from curing too quickly in the Los Angeles heat which could
lead to cracks forming on the finished structure. With the arch structures complete, the new
road deck will be suspended by cables from these concrete structures. With Los Angeles located in an area of high
seismic activity, the city has developed some of the world’s most stringent building codes. To ensure that the new bridge remains standing
in the event of a severe earthquake, engineers have worked to exceed the latest seismic safety
codes. Along with its deep foundations and reinforced
concrete arch design, the columns of the bridge have been fitted with seismic isolation bearings
at their midpoints. The design of these bearings consists of three
main parts – with each element able to separate and break free from the other once certain
thresholds are reached. These bearings allow each of the columns of
the bridge to move up to 76cm (30 inches) during an earthquake event, with the bearings
– rather than the bridge – absorbing the majority of the quake’s energy. When the shaking stops, the internal concave
shape of the bearings allow them to re-centre themselves and return to the shallowest point
within the bearing. By fitting the bridge with 26 of these isolation
bearings – most of which have a diameter of over 2 metres (around 6.5 feet) – the
bridge should be able to provide a high level of protection during a seismic event. When complete in 2020, the new Sixth Street
viaduct will serve as a vital link in LA’s vast road network while opening-up a large
area beneath its structure to the wider community – where 12 acres of new parkland, art installations,
and other community facilities are planned to reinvigorate the space. At a cost of USD $428M – the largest bridge
project in the city’s history, and with its impressive architectural design that nods
to the past whilst insulating the structure against seismic threats in the future, the
new viaduct is firmly on its way to becoming an icon of Los Angeles. If you enjoyed this video and would like to
get more from the definitive video channel for construction, subscribe to The B1M.

100 thoughts on “Building Los Angeles’ Earthquake-Proof Bridge | The B1M

  1. The bridge here should have been bigger, better, w/ light rail train at the bottom, something similar to the new Long Beach Gerald Desmond Bridge….

  2. 4:45 Yes, I'm sure tons of millennial yuppies will be hanging out under the bridge in an industrial zone, next to a rail yard, next to a substation, next to a fetid concrete ditch, down the street from Skid Row.

  3. Los angeles is so ugly, only beverly hills is beautiful and santa monica. the rest of the city is very ugly, the building are ugly, the street, the quality of life… I prefer south of Europe : south of france, south of italia. San francisco was better more beautiful building and charming streets but colder than LA

  4. t i think the bridge would've looked better closer to little Tokyo. driving down 7th st is such an awful sight with all the homeless and drug addicts

  5. Great. Take the journey from the barrio to shitty downtown. Shitty on one side of the bridge and shitty on the other end. Great.

  6. I look forward to riding across The Ribbon of Light on my electric unicycle in 2020. Sorry the historical Sixth Street Viaduct had to be demolished, but the necessary replacement is impressive in this excellent presentation by The B1M. One question though, where is this "Los Angeleez" you speak of? Here in Los Angeles, we say "Los Angeles."

  7. I want that bridge in my city! I love that those arches double as staircases.
    they are probably going to make for great suicide spots though. 😛

  8. I drived from Boyle Heights to Downtown all the time. I was heartbroken when it was gone, but can't wait for the new bridge.

  9. zero preservation…..We are always out to erase the past. I’m all for a new bridge but, keep the old one as well.

  10. I don't like Los Angeles. It is the epitome of everything that is wrong with American infrastructure — unending urban sprawl, congestion because of total dependency on the automobile, lack of public transport such as underground metro & street-level light rail.

    I mean, no American city performs remotely well for a "first-world" country, but LA is the worst of the lot.

  11. It's sad they got rid of such an iconic bridge.

    Those concept images of the new bridge are wishful thinking. In that neighborhood that bridge will look as worn down as the old one in a few years.

  12. Hi all, does anyone know what program was used to create the representation at 3:31? Looks like sketchup but can't be sure. Thanks.

  13. 70% chance of collapse in the lifetime of most Angelenos (spell check doesn't recognize "Angelenos". I'm surrounded by philistines) alive! =:-O

  14. What a fantastic new bridge; definitely one to visit on my next trip to LA. Congrats to designers and builders and LA authorities for going ahead with this bridge.

  15. Hate to say it but it will take an earthquake to bring this new structure down… Here's to this happening. Earthquakes didn't take her… Rot of concrete did.
    Still would love to see an earthquake destroy California anyhow. Quicker the better.

  16. It's refreshing to learn about a structure in the US that is also described by the metric system :'))

  17. Had no idea that cement covered looking gutter was once a river, so sad that such a beautiful natural feature of city has been lost

  18. While other cities are building cool and innovative sky scrapers…were building bridges….😑 yay. 😐

  19. I love the music for this one. It reminds me of the Soarin’ over California music from Disney California Adventure. Los Angeleese makes me smile 🙂

  20. My "two-bits." Don't like the swoops and loops style in it's desgn. The previous bridge design, art Deco style was best.

  21. Sweet! Another bridge for homeless people to live under, while elite liberals lobby against funds for shelters in their neighborhoods!

  22. Hi B1M please check out the massive build build build program of the Philippines government with masive infrastructure projects through out the whole country.

    Thanks and more power to B1M.

  23. I love almost all of your videos and appreciate their complexity as you explain construction to many lay folks. BUT, please, LEARN to pronounce MY city name correctly. It is NOT "LOS ANGELEEEEEEES" (as some old-fashioned out-of-touch Brits call it), BUT LOS ANGE-LUS. Can you please incorporate this new pronunciation into your next Los Angeles-themed video. Los Angeles is a Spanish name meaning 'City of Angels' that is meant to be pronounced as we Angelenos pronounce it.

  24. there are thousands of bridges in la but decided to make one bridge thats earthquake proof? what a waste of money. pretty soon all the homeless will find shelter under the bridge and graffiti all over the beams. la cant have nice things.

  25. I hope development takes off when the bridge is done. There is a lot of construction for residential /commercial use on the west side of the LA river called the Arts District (mainly industrial/warehouse area where cheap rents and huge spaces enticed struggling artists). Warner Music and Spotify are now moving into a couple of new buildings. Lots of cool architecture for residential is also proposed. Also lots of trendy restaurants, cafes, too. But it is still 70+% industrial/warehouse. This should help bring more attention to the bridge on the west end. Also a proposal for a Metro station around this area since the rail yards for metro trains is here but the first station is currently Union Station just north of there. This would make this bridge more accessible and the area called the southern part of the Arts District, too. The other side of the river is industrial/warehouse as you can see in the video aerials. SO if development was built, park and other things like restaurants and cafes would bring in more people. Beyond the highways is a very poor residential area. Part of a good bridge use is having reasons for people to come. Brooklyn Bridge and Golden Gate Bridge are very popular bridges for pedestrians/cyclists/cars for different reasons. Hopefully this bridge can bring in people, too

  26. Born and raised in LA. i love how in the render they made it look like a luscious green landscape when in reality there is A LOOOOOOOOOOOOOOOOOOOOT of homeless people around. The river that runs underneath is full of graffiti. Come on now guys. You guys really think its going to look like this. Maybe in a perfect world where there is no homeless, drugs, crime and graffiti. I give it 2 months before the bridge gets tagged with graffiti and homeless people camp in and around the area.. Maybe all those HIPSTERS that moved in the area in the past 4 years, will keep it clean.
    But hey….!!! this is the way architects sell there stuff, by making it look neighborhood friendly.

  27. This beautiful new bridge will be covered in graffiti within ten minutes of its grand opening. It will also be a lovely place for crackheads to erect their Garcetti camps (tent cities).

  28. The US needs to gets its competitiveness back and open up to the world. China might not have the technical skills and standards of the US and Europe yet but in recent years they have had more positive impact in the developing world than the US and Europe combined. Roads and bridges construction projects have been at the forefront of Chinese diplomacy while the US has focused on wars and threats in the middle east.

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