The INSANE Engineering of a Bridge That Never Touches the Ground
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- Опубліковано 7 лют 2025
- How do you build a bridge that never sits on solid ground? The Evergreen Point Floating Bridge, stretching nearly 8,000 feet (2,440 meters) across Lake Washington, is a feat of engineering brilliance and the longest floating bridge in the world.
We explore the challenges posed by Lake Washington’s deep waters and soft, muddy lakebed that made traditional construction impossible. You’ll learn how the new $4.65 billion bridge relies on principles of buoyancy and advanced anchoring systems to float while remaining stable against waves, winds, and even earthquakes.
What do you think about this engineering marvel? Let us know your thoughts in the comments below!
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#infrastructure #engineering #construction #usa
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What’s the most impressive thing you’ve learned about floating bridges? The Evergreen Point Floating Bridge is definitely a modern marvel!
If you’re into unique engineering stories, don’t miss our video on water bridges-bridges that literally carry rivers. Check it out: ua-cam.com/video/5fNR02_B7jw/v-deo.html
The other floating bridge south of there also made news prior: The I-90 floating bridge, also known as the Lacey V. Murrow Memorial Bridge, sank into Lake Washington on November 25, 1990, during a storm while it was being renovated . we have two crossing Lake Washington. Maybe make a separate video on it, I believe it is much larger , also... the I-90 has more lanes,
and also has light rail. Btw , the original sank on Thanksgiving day storm of 1990. and thankfully, there was no one injured. We also have the Hood Canal Bridge is the longest floating bridge over saltwater.
Both bridges do nothing with waste water or chemical spills on all 3 bridges. All surface runoff goes directly into the water ways. All 3 sets of pontoons do not address fish migration patterns, the bottoms sit below normal swimming patterns. Actually causing issues with salmon and Steelhead migrations.
Thank you! This whole video I was like, but this isn't even the cool one! Maybe it was just easier to put a _video_ together for this one because he has all this modern footage.
I would note that just the railing connection from the ground to the I-90 bridge is worth an entire video unto itself -- I personally sat through an entire hour long presentation _just_ about that one design element. No one had ever made a railroad that had to flex so many feet and still permit rail traffic at all times. It used a super unique support system that must maintain integrity all throughout any necessary movements (seasonal, winds, etc).
We Washingtonians have a love/ hate relationship with our floating bridges. Before replacement of each bridge we were 1 for 3. The I-90 bridge and the Hood Canal bridge had to be “upgraded” because they sunk, arguably because of mismanagement by Washington Department of Transportation. The one in this video is the only one that didn’t sink before replacement. One of the replacements had quality issues during construction due to lack of oversight by WDOT, the engineering office being exposed as slackers with beer in the office fridge. 😂
I think the cause was that some access doors or something like that were left open and the pontoons filled with water.
My grandmother was in a bridge club. I had no idea it was this fascinating.
I SEE WHAT YOU DID THERE.
That club would not be in the cards for me.
@@Geoffr524 did you just double?
That joke was over the top!
We have 4 floating bridges in Washington State. 3 on Lake Washington, one on SR 520 and two on I-90. The other bridge at the Hood Canal is tidal so it has additional challenges. A video about that bridge would be interesting.
When a renovation to the I-90 bridge caused damage to the bridge anchors they used tug boats to hold it stable until those got fixed.
Prior to the first bridge opening in 1940, and continuing for another 10 years, the lake had a ferry service from Kirkland to Madison Park. There have been discussions about adding passenger ferry service again but with light rail nearly complete on I-90, and sadly missing from SR 520, I don’t think ferries make much sense.
That’s a nice story. Good to hear of a difference for the greater good in engineering. Well done lake Washington bridge construction co.
I helped build this bridge. I invited a tool out of a couple 2x6s I called the "Doubler Troubler" which eliminated the need for a tugboat, barge, and 60' manlift. My foreman didn't seem impressed that I was accomplishing the same task, by myself as the entire crew working next to me.
That’s impressive! A ‘Doubler Troubler’ sounds like the kind of creative thinking every construction site needs. Eliminating the need for extra equipment must have been a game-changer - even if your foreman didn’t look impressed, I bet the efficiency spoke for itself!
I come from Australia. The old bridge had no provision for cyclists which involved a very long detour via I 90 or by Kirkland. The new bridge is a marvellous change to getting around the city.
As far as the rail connection between Seattle and eastside cities such as Bellevue, Redmond, Kirkland, I think Sound Transit had already decided on the other floater, the I-90 bridge for that. That project's functionally completed but currently only with test trains on the I-90 bridge till 2025.
The thing I like most about it is that pedestrians and cyclists are allowed use of the bridge and it was planned that way.
I live in NYC and most of the bridges to the various outer boroughs are off-limits to pedestrians and cyclists and the MTA is proud of this lousy decision. They only want cars to be the main transportation on bridges. These people's heads are messed up and they're downright inconsiderate.
Much respect to the leaders in Washington State for having foresight and consideration for everyone that might use this magnificent bridge. I would sure like to bike over that bridge for a nice smooth ride across the lake.
A big thumbs down for the narrow-minded leaders in NYC and their selfish love only for car traffic.
Washington State is the #1 ranked state for bicycle infrastructure in the US. It's not quite Europe, but at least they are trying.
If you ride over the I-90 bridge then you'll also be riding under a park on the Mercer Island side and then through the mt. Baker tunnel on the Seattle side !
Do pedestrians and bikers have to pay the toll? Or is the toll only for cars and trucks?
Incredible!
I've been over this bridge quite a few times from Spokane to Seattle
The video starts at 5:50
nice👍
7.04. It does touch the ground, via the anchors.
Copying another comment: I see what you did there. 🤣
@@MegaBuilds5280lol 😂
love ur content
Thank you! We aprreciate it!
Been across both the original and the current modern generation hundreds of times.. It's completely straight and flat so the biggest temptation, especially early in the morning when nobody else is around, is to slightly exceed the posted speed limit.
I've been over this bridge a lot, visiting Seattle from Spokane.
Innovative.
I think the bridge is a technological marvel. What concerns me, however, is the slope at both ends. What would happen during an ice storm that could coat the roadway with such affecting vehicles attempting to maintain traction climbing it and those attempting to maintain control during braking going down?
It's like a hill, drive carefully or stay home.
Good question! The bridge doesn’t have any special built-in features like heating cables or automatic de-icing systems to handle icy conditions. Instead, the WSDOT manages safety during severe winter weather by implementing practical measures such as reducing speed limits, restricting lanes, or even closing the bridge entirely if conditions become too hazardous.
I think I'll use it this summer when I go to my sister's in Issaquah.
Where are the anchor points bolted? Isn't the whole reason they built it as a floating bridge is that they couldn't bolt down the pylons to anything solid.?
Amazing feat of engineering!
Do a video on the Blue Ridge Parkway in NC on how that was constructed without modern heavy equipment.
Don't underestimate the power of steam.
@Stacy_Smith Exactly, moving all that coal by horse.
@@ginog5037 Actually, a lot of steam equipment ran on kerosene because of energy density.
Did you know Caterpillar came up with their name from a comment made by a publicist?
@Stacy_Smith Yes, that is exactly what I want know the lingistics of moving everything up the mountains. And yes how CAT gots it's name.
Thanks for the suggestion! The Blue Ridge Parkway is an amazing feat, especially since much of it was built in the 1930s without the modern equipment we have today. A lot of the work was done by hand or with early machinery, with help from programs like the Civilian Conservation Corps.
We don’t have a video on the Parkway yet, but we do have one on water bridges, which highlights some incredible structures built around the same time. Check it out and let us know what you think! ua-cam.com/video/5fNR02_B7jw/v-deo.html
Why the heck did you used the Rio-Niteroi bridge as a thumb?
nail?
So you would comment
Because the photo looks great :)
I used to drive the old span. The lanes were extremely narrow and I would drive box trucks across, sometimes it was scarry due to the wind blowing me around the lane.
When you cross the bridge it feels as stable as a grounded bridge.
I sailed a 37 foot boat with a 52 foot mast under the east end of the old bridge in 2005. Never saw a draw span.
The cost is just crazy, why is it so high?
It basically was built twice. The initial contractor use substandard materials and they basically had to rebuild like 3/4 of the bridge
Real reason... Blue, deeep blue state.
@@thewombat4377 yea, that's the reason lol.
@@robertmcnearny9222 Corruption, yet, Americans have the audacity to talk about corruption in other nations and lecture people about it...
When you're breaking ground with a lot of unknowns and leading the way in a new direction, it's going to cost more. Also, as Robert said, a number of issues came up. Now, how exactly it got all the way up into the billions, I'm not sure. Probably some corruption for sure, as with ALL States (why you gotta bring politics into this?).
You can look at the original bridge and it only cost 24m, about a quarter a billion after inflation. So the new bridge cost about 18x more, which is kind of crazy, but honestly, that's modern construction. We actually, finally, are starting to truly understand the costs associated with building a mega project.
I feel really bouyed up by this explanation
Any kind of protections for those under water wires?
Great question! The underwater cables anchoring the bridge are super tough-they’re made of thick, woven steel (over 3 inches) and are built to resist corrosion and wear. To protect them even further, the bridge has a system that actively prevents rust, called cathodic protection.
On top of that, there’s a monitoring system that keeps an eye on the cables 24/7, and WSDOT regularly inspects and replaces them when needed. In fact, they replaced 15 cables just this year to make sure everything stays secure. Pretty impressive, right?
@@MegaBuilds5280 Awesome thanks for the info! Was wondering how they handle anchors etc but makes sense they are heavily monitored and upkept. Def one of those bridges that cannot just "patina"
They should build this type of bridge across straight of gilbraltar
yea there is a video as to why
ever thought of the third of ocean cargo goes thru there
also how high would it have to be to get pano max tankers under it
yea clever clogs you are
go learn a bit on bridge building
also do you know how high they are
How does the deck stand for water height variations (tides)? Does it flex?
No tides in the lake but the water is lowered during the winter months there are slip joints on both ends to compensate for this.
@martypeterson9214
Thanks for your early reply. Where can I find more details on these slip joints?
@@albertoazcue6417 I can't direct you to a site that covers them but they are a set of steel fingers one on either side of the expantion joint that slide between each other like fitting the fingers on each hand together flat, if that makes sense.
@@albertoazcue6417 Google "sr520 expansion joints" I didn't click anything, but a number of likely articles/resources popped up.
Gibraltar is much deeper, this means much longer cables. The longer the cable, the bigger they have to be for a given allowed expansion. To compensate for water rise, the cables have to be at angle, the greater the rise, the greater the angle so that the cable does not need to stretch too much to compensate. To provide lateral stability, the cables must be under load at the lower level, as the water rise the load will increase. If the cable are vertical, the load come from the buoyancy of the pontoons only but then there is no lateral stability. With an angle the load come from the buoyancy of the pontoon plus the opposite cable. If the cable were at 180 degrees, a small water rise would lead to an infinite load in the cable. It is a similar calculation has lifting an object with an overhead crane. I am not saying it is impossible, I did not do the calculations, but it is not as simple as ordering a longer cable. Then there is the issue of whale migration and submarine. There is a video on UA-cam about a bridge across Gibraltar and I am pretty sure they thought about a floating bridge but I do not remember the conclusion, impossible or too expensive.
At 7:00 on the graphic, my question is, "What is a Stomwater Lagoon?" I think your graphic artist needs re-education or a new job. I suggest it should be Stormwater..... you know, stormy.😊
Great engineering!!! ~ How much were e engineers pay again ?
Ships slicing the cables?
There's no shipping in lake Washington !
5:50.
I enjoyed the video overall, but one niggling point: at 0:16 Ummmm Why do Americans measure long distances in feet?
What you called almost 8000' is "around a mile and a half". If you're going to use imperial, please use the unit from that system that makes an easy to understand number. Humans are not good at imagining thousands of anything.
I'm not making a point here about metric, but rather the insane use of a very small unit (the foot) rather than a seemingly appropriate sized one (like a mile, if you don't like kilometers).
I can imagine a foot or a centimetre or a yard or a metre or a mile or a kilometre; but right thousand of them bundled together, no thanks!
Kind of makes nonsense of all the videos saying how human scaled the imperial units are, when you don't use the one that's appropriate to the measurement in question.
Why wasn't a tunnel an option?
Did you have to use the click bait photo as the video thumbnail?
The bridge is floating on water
As a Civil Structural Engineer
Yup I only have a BSc Eng
But come on this doesn’t not fit into everything my Professors taught 😂😂
I prefer another floothing cable with spring protecting the wave.
DERVARSNERVOURZERHERZHARLEY?
What about ships?
It looks as though there's a high part for them to sail under.
Just like floating blocks in the bathtub
Seems like an accident waiting to happen. Imagine if just one cable snaps…
5.56 min in to 8.16 min into video we get to the point lol
And it costs $4 to cross by car.
"A new bridge was the only option" WTF?
The old one was inadequate in its fundamental design. No repair or upgrade on it would have sufficed. I guess there's always the option to shrink civilization and the human population, but the system doesn't reward politicians who don't support growth.
But can it handle tsunami's? Remember the "Big One" is due!
No apostrophe.
Explaining buoyancy like we’re a bunch of halfwits
Some of us is.
stay down the pub
you are all the same there
Kirk LAND. HOW ton. Lol. Kirkland pronounced like Ireland. Houghton like Hoeten.
Much ado about explaining floating phenomenon...
do one on the Gibraltar Strait
That's part of an ocean, not a lake and this one is merely 6m above the water. No room for ships of any kind 😅.
@@borstenpinsel also tidal 40 ft
600 ft deep
also to be 150-200 above the waves
do you have a drawing board
i use feet those things you walk on
All it took to sink it was 1 person to leave the hatch open, done on purpose so the construction co could make more money. Most major construction in the Seattle area has had issues, it's all a scam with all the errors that have shut down our traffic so they could do it right
No there were large cut outs on the south side of the bridge cut during the rebuilding. In western Washington the fall/winter storms come from the south a fact the engineers for the Washington department of transportation (known in state as the department of incompetence) failed to recognize so the bridge was a goner. On purpose or not that is the question.
The previous 520 bridge didn't sink. It was dismantled and its components are in the process of being renovated and reused for a new bridge (I believe in Canada) that has lower traffic volume.
@@borisgalos6967 Yes it was the I90 bridge that sank in the vid they kinda blurred the lines between the two.
The correct title is: 'The INSANE Engineering of a Bridge That Floats But Is Still Supported by the Ground.' No floating bridge exists without some form of support from the ground. Stop embarrassing yourself with clickbait and get your facts straight before you make a fool out of yourself.
Stop embarrassing YOURself with your inane pedantry. It's perfectly obvs what was meant here.
No railway!
The light rail connection is built and being tested on the other floating bridge across Lake Washington.
yea 5000 tons all in one place
it would have to travel down the middle
Man engineering in the US never fails to amuse
from the other side of the pond
would it be impress
Misleading clickbait thumbnail. Unsubbed
It needs light rail. Accommodating cars is no major feat.
That is happening right now on the I-90 bridge across that lake. Also having rails on a moving bed is another engineering challenge.
That is nothing special either🤷
@@TylerTheBassCreator Actually, running rail tracks on a floating bridge which drifts both in horizontal location with wind and water currents and in elevation with tides is a massive challenge that has never been accomplished before.
@borisgalos6967 false. It's been done
@@borisgalos6967 Homer M. Hadley Memorial Bridge
Shouda oughta put a rail on it. But West Coast thinking would never think of mass transit. That said the video is spot on. Well done
Rail is going over the other floating bridge on that lake. They are now testing the trains between downtown Seattle and Bellevue.
@@cnhaynes57 Which is worth an entire video unto itself.
@@kindlin True! Especially since the 1-90 bridge is the first time rail has been done on a floating bridge. Because floating things move up and down and side to side. Train rails... not so much.
@@cnhaynes57 I sat in a lecturer (lunch and learn) from the students working through much the analysis and design. It was super interesting. That was also about 6 years ago at this point lol.
@@kindlin This engineer is jealous!
would have been cheaper to drain the lake
AI sucks.
It won't matter how they're built, they won't be maintained properly.
Why wasn't a tunnel an option?
The lake is over 200 feet deep and so is the muddy bottom ! There is a tunnel at the end of the bridge , Mt. Baker tunnel !