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"A catastrophic loss of function" is just the most hilarious and accurate engineer-speak for "the building collapses on you."

Building muscle gone

In jet engines, we say "Rapid Oxidation" instead of "Fire". There can be a real difference, but not usually

"at 12:34pm GMT the craft experienced a rapid unplanned disassembly"

The front fell off.

in the navy, reading the maintenance schedule....hitting something with a hammer was called "mechanical agitation."

Thanks for making this. Living in Seattle as a member of a family of civil engineers, I was pointing out the use of styrofoam in the construction around the viaduct southern entrance. My mechanical engineer colleagues refused to accept that the styrofoam was used for structure, insisting that it must be temporary packaging waste! I'll happily share this video with them.

As a service plumber I hate working at a house that is owned by a engineer! They are so egotistical and always think they know better

I live in Seattle! Where do I see this styrofoam?

It's used as a void form they also use cardboard boxes for this same effect. The structural attributes are minimal

@justjefff hah- the cement surfaces above the styro definitely iced over. I cant believe I made it to work that day. On the way out of the arena the plaza out side was nearly as much of an ice rink as the NHL one inside. That was one hell of a morning just to fix a cellphone antenna that no one was using that day 🤣

In Scandinavia it is common to use styrofoam as foundation material for buildings. The thermal disconnect is highly desirable when its -20 C outside, and it provides a very good stability when ground changes shape due to freezing water. Maybe an interesting subject for a video?

You may be thinking of insulated concrete forms. These are still concrete, but they use styrofoam to hold the concrete during cure. Once cured, the styrofoam acts as insulation.

@MadSwede87 Usually those blocks are coated with a thin layer of cement and/or a cement glue, to improve the adherence to the other building materials. In most cases rodents will not bite into those. I have not heard of any issues with EPS or XPS blocks in foundations because they are usually also surrounded by other impenetrable layers. However, if someone would come to me with that question as a genuine concern for their house, I would refer them to the EPS blocks that have metal meshing on the surface for even stronger adherence (p.e. needed in facade applications where plastering is mounted directly on the insulation).

Worst thing is that I was being sarcastic initially. Internet has thought me a lesson... Good luck, well-meaning people.

Can confirm, my dad is getting a shed built and Styrofoam was used before pouring the foundation

I wonder if it this is how the floating islands were made along Norway’s coast.

"Soil is heavy. They teach us that in college!" is the funniest thing I've heard today. Also, I learned that those "abandoned" highway construction sites that I have been complaining about for literally decades may not in fact be due to scheduling problems or lack of funding. They were probably just waiting out the settlement period. It's stuff like this that is why I love this channel.

Also bear in mind there may be other factors. We just accept that construction sites will "look abandoned" during summer because the heat here is literally deadly under those conditions, and we absolutely would have many more people complaining about workers being out in the heat than we would about them not working, to say nothing of the likely OSHA violations involved at certain temperatures. So if they work at all in summer it is in the middle of the night, so you never see them. Since someone got whiny in here earlier about "literally": about 12 years ago a construction worker in a parking lot (with regular access to water, sports drinks, food, and even air conditioning as well as supportive management and coworkers) got heat stroke and died in the bathroom at one of the businesses (that was providing such things to prevent that from happening), road construction doesn't have as many failsafes for preventing heatstroke and even with them it still happened. Literally as in this is an actual major concern for people's lives. Monsoon they often stop for a bit because otherwise they spend all their time dealing with high heat, high winds, and intense thunderstorms with flash flooding all fighting over which is the weather of the day. None of which are safe to be doing much construction in. But they work that into the schedule for the project and get the project to a usable state before seasons where they may have to stop for weather related concerns.

Bro's YouTube account is 16 years old

@E D the signs are generally the very first stage. Surveying and testing can be done overnight, either in the shoulders or under mobile closures so you might not actually see what's being done, but whenever there is *anything* different, the speed limit must be reduced by law.

What about when they put the construction barrels and signs along the highway, then don’t actually start for 2 or 3 years? I guess they’re seasoning the construction barrels, or the ticket books.

Your content just keeps getting better and better! Big fan of EPS and using it more and more in my industry too.

As a Lab Technician for ENGEO I would like to thank you for all your videos. They serve as training aides for our interns, and help us explain what we do and why we do certain testing in a simple and entertaining way. We can show them your videos and then what we use in our lab setting. Keep up the great work.

@TungstenCarbideProjectile There are exceptions of course

@TungstenCarbideProjectile YT offers no shortcuts. Entertainment/academic busywork. Only appearance of Knowledge, like one's accomplishments in video games

@Tara Li Introduction/overview of course. That is it. As with many topics on YouTube. Be it history, cosmology or quantum mechanics-sounds interesting and profound for general audience. Not so after 10y actually in the field like in my case.

@Madis Tamela You do realize getting students past the first two pages of the book is often the hardest part? Besides, you're wrong - this is an overview of a section. Combined with other videos from this channel, they form a fairly comprehensive overview of the field. Then you have the students digging in, often with stills captured to point out specific things. And then there's the additional bits of non-textbook knowledge from experience that pops up - you do realize Grady is actually a working engineer, right?

I worked for an EPS manufacturer many years ago and one of their contracted projects was scrap EPS blocks to go into the middle wall and other sections of a dual tunnel roadway. The grade was usually a SL or L grade (Super Light or Light) EPS block, up to 5 metres long, by 600mm by 1.2m. For its size, they're very light. Saved the joint venture construction partners millions in fill and related costs, plus gave the EPS company plenty of work besides making sheets insulation and lobster boxes.

As a native Mainer I thank you on behalf of our lobster industry

I didn't know standard block forming machines could do 5m blocks, I thought they were standardized at 2.5m industry wide. Obviously making a double size machine is technically trivial, just not what can be easily ordered and shipped from a major supplier of EPS equipment.

Thanks for making this video. I live in the Netherlands, where large parts of the western part of the country are basically glorified swamp. In my new neighbourhood, the decline is 2.5 to 4 centimeters a years, and have been declining at this rate for about 30 years now. The locals often refer to the peat ground as "thick water". All houses are build on poles, that reach a layer of sand 7-10 meter deep, and are stable. However, gardens and roads are not. Over time, in particular the roads have subsided (not really settled, as it is still declining) and the common solution was just to add another layer of asphalt on top of the parts that settled too much. Of course, that added a lot to the weight, so it settled even further. They found that by now some parts of the asphalt were 1.5 meter thick. After some heavy rain they decided to tackle this and for the whole village, street-by-street, and replace the heavy roads with low-weight material that basically floats on top of the thick water (also known as "ground"). It's a 10-year project, and interesting to see. Other solutions were tried as well, like excavating the borders of a neighbourhoud up till the sand-layer 7 meter deep, and replacing it with clay. This basically turned the watery ground into a bath tub: all the peat (thick water) in the middle would be contained by sand underneath and impermeable clay on the sides. In theory, this should stop the decline of the ground. In practice, it failed. It just keeps declining about 3 centimeters every year.

A better solution is to treat the large roads the same way as the houses, by building them on concrete plates supported by poles, with an asphalt top layer.

Can confirm: I worked as an Operating Engineer and placed many thousands of yards of cellular concrete all over the country and our primary work was on bridge embankments and abutments, especially in the Bay Area of California. We also did many abandoned pipe fills using it for pressure grouting and some interesting annular fill projects too.

Grady, I just finished reading your book and it was such a pleasure! It was fun to learn so much about the "boring" world, and you've imparted your curiosity on me as well. The illustrations are awesome.

ok

Does the book include a coupon code for Hello Fresh?

Two really great lines in this: “catastrophic loss of function”, and “soil is heavy, they teach us that in college”

I was once an engineer this is how I became successful in life .I know that you all know about digital currency exchange 💱💱💱💱 where you can invest and make more profitable gain 🖕🖕🖕🖕 thanks

About 25 years ago, I was part of a geotech team tendering for a second bridge across the Swan River in Perth, Western Australia. The ground was very soft alluvium, and the embankment needed to be quite high. We proposed a stabilised soil fill over foam-core solution, but were unsuccessful - the Main Roads Department were very conservative (and still are), and went for a conventional (and much more expensive) pile-supported solution. Nice vid, thanks.

@B100 The Netherlands virtually invented wick drains and preloading! I had no idea you used EPS, but it makes perfect sense.

Here in the Netherlands we need a combination of eps backfill and pile supported retaining walls after the ground was compacted by adding 3 meters sand on top(with vertical drains to 15m below surface) and let it settle for a year.

I think a major takeaway that transcends industries and disciplines, is the fact that the least expensive suitable material does not always result in the net least expensive finished product.

@macmedic892 Cheap, fast, good. Pick any two.

@MarcBerm And then they wonder why their maintenance programmers and network guys can't seem to figure out the weird, sporadic, and downright intractable errors that keep unreliably popping up in the logs causing random users intermittent grief.

ok

@Kain Yusanagi Thank you, Dr. YouTube.

@Brian Mueller It's the Sam Vimes "Boots" theory of socioeconomic unfairness applied beyond socioeconomic status; pay for cheap, you get cheap, and it wears out quick and performs worse. Pay for good quality, get good quality, it wears out slower and performs better. That isn't to say EPS is low quality, mind; it could truly be the best option in a given scenario, and allows recycled EPS to have a stable landfill function while performing support, too. Just was noting it as a generalism.

Oh man I still remember when sand compaction video came out and introduced us to your channel., time really flies. Your content has been consistently amazing,, always looking forward to what you got for us. I'm not a civil engineer, but I just love learning from your channel.

Chemical engineer here, but fascinated by the topics you cover here! Thank you for letting us into this mysterious world around us and making it simple to understand

That is what I live for--an easy-to-understand explanation of something I was only vaguely aware of. Grady, this is, hands down, one of my favorite youtube channels, and one that I share often with other people.

I'm always impressed with the quality of content you and your team makes Grady! Keep up the great work

You inspire me. You make me feel at home for wanting to be an engineer who wants to help people. Thank you so much, Grady. For lifting my spirits. For showing me there are other people who care about the weird nerdy stuff that I like and won't make fun of me for just trying to help.

Here in Canada when a section of the trans canada highway was being upgraded from two lanes to four lanes there was a section of about 2 km crossing a swamp, the swamp had muskegs that were over 90 feet deep, and the engineers used drills and bored into the swamp using tubes to collect the water, and diverting it into pumping stations, then the whole thing was built up with geofoam. All of the drilling and piping techniques are covered on this channel. Thanks for the great content:)

@Kain Yusanagi LA is a perfect example of what not to do. People are leaving LA in droves. Why? Because continually forcing good folks to cater to the drugged-out homeless people and gangs doesn't work. Trains work in societies that don't have the disparities (or freedoms, in that our people are allowed to not work, allowed to be drugged out of their minds, allowed to steal, rob, etc.) of the USA. You just won't get the common folk behind trains where we would be trapped with the dangerous segments of society. We had a choice - become lenient on crime, or have a functioning society where you would have widespread support for trains. We chose to be lenient and forgiving. On top of that, California chose to de-arm its law-abiding citizens.

@Dakota Reid I don't live there I just know about the project, lol. Definitely want to visit though!

@The Iron Rhinolol I live in parry sound, small world

@Namm0x it its great place, fishing on bernard is great also. Remember its the largest fresh water lake in the world without an island.

@NFG Today please see the comment above from charles.

This is literally one of the best channels on YouTube. You’re such an amazing teacher, Grady. The way you clearly and concisely lay out the information in a very easy to understand manner is one of your biggest strengths, next to your knowledgeability. You make me look at the world differently and wonder what things are for, and why they’re designed that way. This leads me down many internet rabbit holes of information gathering, but they’re not as fun as your videos lol

This video made me think about arrestor beds installed at the end of some runways. I'd love to see a video on those and it was interesting to read how some of these same materials are used.

Thank you for another wonderful video! Speaking of using styrofoam for thermal insulation, I work for a small mountain railway where we sometimes battle with frostheave (also a video idea? ;) ) We experimented with using styrofoam in the subgrade to prevent the ground from freezing. It worked well as insulation, but unfortunately the ballast stones have a knack of punch through the sheets under load!

They also use it to protect the permafrost up in Alaska on the Dalton Highway for the same reason (and dang that road can create some epic frost heaves!). From what we could see they used some sort of fabric membrane between the aggregate and the foam to avoid the same problem.

I'm so glad I found your channel, I never knew how much I loved civil engineering. It really is fascinating how the world we use works

I have been watching your channel since you were doing wood turning and Arduino projects. I got your book at Christmas and am enjoying it very much. Thanks for all the work you put into your videos. It is worthy of praise and recognition.

I saw the EPS used for an overpass in my area. The road needed to go over a train track, and was in a developed area so the embankment had to be as thin as the road. As well, the area was partial wetlands so settling was likely a substantial concern. I had always thought it looked like styrofoam, interesting to find out that it was exactly what it looked like!

Styrofoam can have 50-100 psi compression strengths, in inherently spreadsouts out load well if it ever is overloaded, which seems unlikely given that most tires are more in the 30-50 psi range.

Would you happen to live in SLC, Utah?

I love how you demonstrated EPS' weakness to fuel spills by essentially making Napalm.

I’m a 3rd year Civil undergrad and man. I love these videos so much! Winding down my day after dynamics and mechanics of materials to see the application and connections from the learning is awesome! Much love from Florida 🤘🏼🤘🏼📐🔩

I love your videos so much, and they’re one of the reasons I fell in love with civil engineering and why I’m studying it in college. Thank you for your hard work and incredible videos!

I'm much more intrigued by the floating concrete than the styrofoam, to be honest. It's in that category of "ordinary thing given counterintuitive properties," like making clear wood or boiling water at below-freezing temperatures in a vacuum. Weird materials are fun in general. Carbon nanotubes! Aerogel! The mysterious sticky stuff my nieces leave on surfaces they should have no reason to touch!

It's really inspiring to see your family (and cooking confidence lol) grow as your channel does! Keep up the great work, Grady!

One of our local bridges has an approach underpinned with Styrofoam, it wasn't protected properly and rats got in there and made enough tunnels that the surface of the approach started to subside.

Hi Grady, thanks for nice video. I can confirm based on my own experience that this is working. I did time ago (as young engineer) the design of retaining wall (embedded structure, wall supported by laterally loaded piles). Because of mess in the project it turned out that wall has to be locally extended from 2m to 3.3m height (6.6ft - 10.8ft) during construction. To challenge that I thought that lateral force depend on backfill weight, so it needs to be replaced with lighter material. That was idea to use EPS blocks as most available light material. Then I did small research and discovered that similar solution was used in my country. That ensure me it is good idea and I implemented this into design. Despite structure is not impressive I am still very proud of that design. Greetings from Poland.

ive seen big cubes of styrofoam under a road during construction and thought it had to do with frost management, but now that ive seen your video i remember that it was on some part of an embankment for a highway overpass... gotta learn something every day!

I tend to consider a larger environmental impact of highly processed substances such as plastics compared to naturally occurring backfill soil. However EPS has inconceivably low density around 20-30 kg/m^3. In EPDs I reviewed, both Global Warming Potential and Energy Use during manufacturing are lower than even wood products for unit 1m^3 of element. Maybe one also needs to check its interaction with its environment, impact to local ecology etc. Great video btw, Grady!

I remember watching the Apple Park construction timelapses years ago and seeing them build the hills out of what looked like blocks of foam - it’s good to finally understand why that was!

My grandfather started an EPS company back in the 70s (Plymouth Foam). I was so surprised to hear they had a contract with a major local construction project to fill in under the new roadways and embankments. This was so cool to see on here. Thanks as always for putting out the entertaining and educational content you do.

As a person who is not an engineer, civil or otherwise, thank you for this video. I had a feeling that, this is why many projects around town take forever. I know this is just a primer, but still valuable information none the less.

Then what would make public reviews simultaneously more popular and also not prone to trolling or the twisting of results to support a group? Because having accurate opinion and having lots of people act on it are unfortunately exact opposites.

@John DoDo Doe They do this very, very frequently. Public review of projects is mandated by a lot of places, people just overwhelmingly don't participate.

A huge demand to speed things up.

If only they would put up accurate signs of what we are waiting for as we are stuck staring at an abandoned work site blocking our daily commute. This would create a clear distinction between necessary inconvenience and incompetent mismanagement. For example, my commute has been seriously disrupted for years by a never explained decision to relocate every pipe and cable under a major road allegedly to prepare for an already controversial project on the surface. As a commuter I always felt that was an unnecessary step as they could probably have used pillars or horizontal load spreading to support the surface project while leaving most of the substructures unchanged.

well 90% of the work is just waiting ... just like in military... sometimes you are just waiting for that BRTTTTttt~~

I'm a Geotech Engineer who mostly works on PennDOT and PA Turnpike projects, and I approve of the definition of "a heavy pile of dirt" haha. We geotechs are often pretty chill because we spend lots of time playing in the dirt and working with that understanding that so much of what we do is working with nonhomogeneous materials, interpolating between borings limited by funding, and factoring for safety. I'm fairly young, so I haven't had the chance to work with lightweight fill material yet.

A cool application of lightweight concrete is the concrete canoe competition a lot of civil engineering students compete in. As a mechanical engineer, it's really neat to see floating concrete!

Seasteading too

Yeah

Years ago I was watching a new construction project in progress near my home and was amazed to see them using the foam blocks. I wondered to myself how long it would take for ground digging animals to discover these and make a nice warm home out of them.

Thank you for this amazing explanation. I saw blocks being used for some roadwork (embankments) and I assumed they wouldn't be strong enough to handle the compression of vehicles going over, but you've proven me wrong. Also, I use that highway overpass many times a week and it has yet to fail. Also, I agree with your wife, waiting that long to get to dinner is a *huge* "I'M HANGRY!" problem.

I wish you had discussed the environmental downsides of Styrofoam. It's probably the worst of all plastics. I am curious if roadway engineers have mitigated any of those issues or if they just ignore them for the short term benefit of "completing the project quickly".

I fully agree!

Haha, awesome! I have seen those gigantic styrofoam blocks used as floating devices and have even lifted one (it feels unreal how lightweight it is, given how huge volume it has) and also seen them being used during construction of pipelines for district heating (in that case for heat insulation). But I could never think they would be strong enough to use for whole road embankments, haha. That's cool. The foamy structure and light weight also means very little material can be used to fill up a huge volume - which cuts down cost and environmental impact during manufacturing.

The second half of your comment just repeated the video :P

I have only heard of their use in construction, but I have seen and handled slicing them into panels by pushing entire blocks through a frame of hot wires spaced according to desired plate thickness. This was between 1970 and 1990.

Those blocks, with a concrete top, and a mesh and gunite covering, are doing sterling service in the harbour as walk on moorings for the yacht mole, where they form the spine and walkways used to tie up the boats. there is a steel rim on the top used to provide the hard points to fix them together, and to carry the piping used to provide power and fresh water to the boats along it. easy to expand as needed, and as they float, they only need a chain to a bottom concrete block anchor, with slack to handle the tidal difference, to keep them in position, and a rolling gangplank to allow access at all tide heights. Been there for decades, and still going strong.

In theory, one could argue that using styrofoam as backfill could count as carbon sequestration, reducing the environmental impact even more compared to using a similar volume of styrofoam for disposable cups and the like.

We had a section of a 4 lane divided highway near us that just kept sliding down the mountain. After decades of lane closures and repairs, they finally just removed the soil/clay in that section and replaced it with Styrofoam blocks. One would never know that you are driving over thousands of giant Styrofoam blocks. I marvel at how stable the area is now, while wondering how often I am driving over Styrofoam on other roads.

Your channel is just the most amazing thing! Stuff that seems incomprehensible is suddenly made clear, even to me! I cannot tell you how much I appreciate this. Too many engineers are so entranced by the science that they forget to explain the form, function and desired outcome. Thank you for being different! 🇨🇦💕

As a retired mechanical engineer I absolutely LOVE following your channel. VERY interesting info presented in a fun way. Keep up the good work Grady

I love your videos, always so informative. You make learning about roads fun!

I enjoyed this a lot and I hope we use styrofoam more in the future because that's super cool!

"Soil is heavy! They teach us that in college." -- This is the type of engineering humor I expect here 😆

A few years ago my exit on the Denver Boulder turnpike had a partial collapse due to soil settling/movement (soil expansion and contraction is common here because of high clay content). They ended up using styrofoam blocks as the fill material which probably wasn't an option back when the highway was first built.

Thanks for the informative video. Driving past the viaduct project I always wanted to know more. Please consider doing more videos on Seattle’s unique projects like the viaduct tunnel, West Seattle Bridge, or our many drawbridges!

I used to work near and frequently see work on the project depicted at 12:09 (this is at the southern end of the SR99 tunnel in Seattle that replaced the Alaskan Way Viaduct), and was always curious abut all the styrofoam they were using there. To put it mildly, the soil a lot of Seattle is built on, especially near the waterfront, is seismically questionable (one of the main reasons to get rid of the Viaduct in the first place) so it makes sense to make things as lightweight as possible in that area.

Man I just love how passionate and informed you are on engineering processes and challenges.

there was a critical failure of the embankment under a highway near my home, and when they replaced it, they used geofoam instead of traditional backfill, it was surprising to see, but made perfect sense, cause they were building next to a reservoir, so the soil had compacted under the traffic load so much that the roadbed actually fell away in a small landslide across most of the southbound lanes, emphasizing the need for a lightweight backfill material.

No there wasn't. Quit lying. Buy Hello Fresh.

love this channel. VERY educative and makes us think more about the vital infrastructure important to us all

@Marty McFly what?

From your lapse in grammar, it sounds like you could use some Hello Fresh food. Order today!

Educational?

Yes! There's annoying bumps on each end of bridge going over the freeway. I believe problem could be fixed by filling the transition points with a smooth material, or by covering with rubber mats.

I used to make geofoam, actually did for that exact seattle project. We used something we dubbed 2 pound it is about 10 to 15 times as dense as what you get as packing peanuts, but each 4 ft by 4 ft by 8 ft block was only about 300 lbs. Light enough to be moved very easily. Some of these blocks were even cut to order at the plant before being sent to the project. They would then only need to make minor tweaks to the foam to ready it for the roadway.

Interesting video! It seems to me as best used in special conditions over settlement prone areas. I can’t imagine the cost of making embankments out of manufactured material to be cheaper than re-paving due to settlement 🤷‍♂️. I do get excited to see new tech in the earthworks world though!

In model trains and other scale miniature dioramas, styrofoam or other foams are often used to create and shape terrain - really funny to see it happen in full size to make roadways as well

I know those huge Styrofoam blocks real well. In Nov 2012, I worked with Superior Construction delivering precast concrete wall panels to a new bridge over railroad tracks on Industrial Highway (now renamed Airport Road) in Gary Indiana. The bridge deck was steel/concrete, the approaches were done with six levels of these huge foam blocks topped with sand/asphalt. The wall panels we delivered contains the sidewalls to keep the foam blocks from shifting and to keep them from rising and/or floating away during periods of flooding. Important since this location is only 3/4 mile away from Lake Michigan. This project coincided with the expansion of the Gary Chicago Intl Airport. The local rail line that used to cross the north end of the airport property where the expansion occurred was moved further north to join the railroad east/west mainline, which also utilizes the new bridge, East Chicago Ave between Cline Ave and Industrial Hwy was removed. It was an impressive project which is highlighted on the airports north end on Google Earth. I took a few photos on the project and now 11-years later, it still stands. That was the first time in my 39 years in construction transportation being involved with a project that used Styrofoam as a base material. Besides the airport, the area is heavy industrial with heavy truck use and it has held up very well.

Thank you, I have often wondered why. I see a lot of styrofoam used at the on and off ramps of bridges. There is a particular place where I live where it's used in the road construction, going over a marshy area, two places in particular, and it's a noticeable drop after only a few years. They have replaced one of both sides of the short stretch a few times, since I have lived in the area, the most recent being last year after a once in 100 year flood eroded the sections of the highway significantly. I am curious as to why they would continue to replace these two sections the same way every few to several years, knowing that, in my opinion, it is not a permanent fix?

Could also be budgetary--for example, the permanent fix might be $1mm, while it's only $100k for the temporary fix. If you will never receive a $1mm appropriation for that road fix, well, you can't do the "correct" fix, so you just do the repairs you can afford. Especially if you can get sued if somebody gets hurt, so you can't wait to get the alignment back up to standards. Same way that somebody might be driving a beater car that eats repair dollars. They know full well that it would be cheaper overall to buy a good used car, but they also know they'll never have all the cash required to pay for the newer car in one place at one time, and they can't not go to work for a couple years to build up the bank account. So you spend the smaller repair money you actually have on hand. One other thing that can't be forgotten: it might be cheaper overall to just do the cheapo repairs. If the "permanent" fix is gobsmackingly expensive enough, you might want to just eat the ongoing costs as that will be less money. To continue with my toy example from the first paragraph: if the permanent fix is $10mm, you could do that "temporary" fix *100 times* before you add up to that permanent repair cost. If you will only be doing it every 5 years, it is better value for the taxpayer to just do the temporary fixes. (This assumes that you're not having the road closed unduly long--as Grady points out, that has a cost of its own.) The first rule of civil engineering is "Every Hole Is An Adventure." You don't *really* know what's involved in something until you actually start construction. In my own field (structural) you might have as-builts that purport to show where the reinforcement is in concrete, but prepare to be surprised once workers start drilling in anchors. When digging a foundation, most of the information comes from boreholes on fairly wide spacing, and they can miss entire geologic features between the holes that then impacts your design. You start digging in a marshy area, you don't really know what's down there, and a "permanent" fix in those conditions might be very, very expensive.

Hard to say for sure, but it could be that the permanent fix would take the road out of service for too long during construction.

This has opened my eyes on why I see so many construction sites that looked abandoned. I just hope half of them are really waiting for the soil to settle!

Before I began following this channel I thought of infrastructure as marginally boring and something that, well, could be given for granted a little bit. Got slightly pissed off at some irregular sections of highway, found bridges nice or ugly and that was about it. Now, after being a subscriber and having watched a lot of these videos (many a lot of times) I find it extremely interesting, a real engineering product and something to get excited about --this video in particular reminded me of a huge shopping center that has been built close to my home, and how they were making the structure lighter by adding EPS to the reinforced concrete where it was possible. Also, next Friday I will probably obsessively looking for bumps before driving over bridges, although I must say that I hardly remember any. But I will probably pass a construction site where they are widening a highway that needs to go over a bridge: maybe I will get a glimpse of how they are constructing the embankment and let you know if they are using something interesting to fill it.

You make engineering look so easy. Just the way it is.

I remember in elementary school in the '60s in the San Fernando Valley learning about all the ways the state was thinking of to fix the San Diego Freeway (I405). And there have been multiple times and ways the SoCal freeways have been "fixed"... 😃 Thanks for the very entertaining education. 👍

I travel across a bridge that had a rough and jarring bump. The DOT repaired the entrance by drilling holes and pumping some material under the existing slab on the embankment. It was interesting that it took maybe an hour to complete the entire process, and the bridge entrance feels almost level as a result.

I drove across northern Scotland last summer on the North Coast 500 route and stopped at a place called Moine house up on remote boggy moorland. There was a sign there which said that the original road crossing the moor which had only recently been replaced was built on top of bales of heather to stop it sinking into the peat. This road was hundreds of years old.

@mrgreatauk George Stephenson was responsible for this work in 1829 and his locomotive Rocket would be chosen to operate on this Manchester to Liverpool line.

There's a section of railway not far from me, near Manchester, crossing 'Chat Moss' which used a similar method, essentially building a big raft of Heather and branches, then covering it in rubble and building the railway on that. When they electrified the line a few years back I hear it was particularly 'interesting' designing the mast foundations and there was a lot of work monitoring relative movement between the masts and the railway!

I watched a road crew use the styrofoam bricks to build up an embankment for I-44 a while back. they were building an entire new interchange with 44 that used fancy J turns. it completely relieved all traffic that was waiting to get on or off 44. pretty sweet!

I had a summer work on a road construction a few years back. The site was on a former seabed and wasn’t hard as rock. We used expanded clay as filler on embankments. There was a huge pool of it after the bridge. We used also tons of expanded clay concrete under the roads.

I saw a road being built in the late 90’s with big blocks of styrofoam. Now that I think about it, it was right next to a bridge. Thanks for explaining why they used styrofoam.

In the netherlands we always use a concrete slab that rests one side on the structure, the other side on the ground. This way, the "bump"' created by settlement, is also distributed more evenly. We still use lightweight materials a lot too though

I saw this process being put to use recently on the I75 rebuild through Metro Detroit, watching this jogged my memory of driving the the office and on the northbound lanes seeing giant blocks of foam being used to build an on ramp between 2 large concrete retaining walls going from the service drive at ground level to the subgrade roadway below.

Here in Pennsylvania most road construction drags on long enough that everything has fully settled by the time paving takes place lol. Love the videos! Thank you.

@Jehty well they just started work on a section of Rt 23 that was originally planned and graded in the 70s. It's affectionately known as the goat path because grazing livestock is the only traffic it has ever seen. I'm leaning towards dysfunction more than planned settling.

Maybe they do that deliberately?

@John Smith Hey now, Pittsburgh and Philly may be the two most famous shithole cities in PA, but you can't forget the capital, Harrisburg. As someone who lives very close to Harrisburg, it is continuously funny to hear this quite urban area referred to as "Pennsyltucky".

81 is never done....

@John Smith Pennsylvania is ranked #5 in the country for “most hate groups” as defined by the SPLC. As someone who works in rural Pennsylvania, I can say there is good reason why some call it “Pennsyltucky”

Over 20 years ago I worked on a project that had to be both extra heavy for one part and extra light for the other. The roadway under the bridge was going under the water table so had what’s called a “boat” section that was 4’ thick concrete on the bottom to offset the uplift of being under the water table. The abutment went right up to a tunnel going under the harbor and was built on the roof so had to be as light as possible so used styrofoam for the primary fill.

Hi Grady. We had pipes burst this winter due to freezing, and it got me thinking: How does the city get water to people in the winter without pipes bursting all the time? Perhaps you could do a video on that if you think it would make a suitable topic.

A few years ago I found a huge block of concrete just, sitting on the beach near my house. It was baffling how or why that could've ended up there but a piece of it was broken away and it was actually a block of styrofoam coated in concrete. But I was still very confused. Tried to look it up and found some stuff about styrofoam being used like that in construction, but not really why. This explains it.

Watched these blocks being placed on a project near work and had no idea what the purpose was. I had (incorrectly) guessed maybe it would aid in digging back down in a temporary setup. This now makes perfect sense! They were filling about 35 feet over a newly installed drainage system.

It’s always a good day when there’s a new edition of Practical Engineering. I wonder if lightweight materials might help absorb road noise and vibrations.

Fascinating! I had no idea this was a thing! I have a question, though, Grady... One of the problems with EPS is that it's notoriously unrecyclable and non-bio-degradable. Obviously that's part of _why_ it makes a good lightweight backfill material, but I can't help but notice that they're freshly cast blocks made specifically for this purpose. Could shredded post-consumer/post-industrial styrofoam be used instead, like an aggregate? It'd be denser and a little heavier than the blocks, and weaker, but it would also be basically free (possibly even negative cost). Possibly a good compromise between the engineered blocks and the foamed/expanded aggregates? Or would it be too springy? I'm picturing something kind of like sandbags filled with shredded EPS, so there's some interlocking and added strength, a little like the reinforced aggregate from your early video.

@DerpyPenguin Even if it can be recycled, does it happen much in practice? It took some effort to even locate a recycling place remotely near me that would accept EPS, and it turns out that they don't truly 'recycle' EPS (as in produce new EPS from it) but rather 're-use' it to make home insulation.

@DerpyPenguin Expol, who manufacture EPS products in my area, recycle offcuts and waste EPS by shredding it and casting back into blocks for this sort of use. Just needs the right combination of heat and pressure to make all the bits stick back together.

@Barefoot EPS styro is actually pretty simple to recycle as far as styro materials go. Other forms of styro such as XPS are more difficult if not impossible to recycle.

@Kain Yusanagi Where are you getting that? My understanding is that while it is _possible_ to recycle styrofoam, it's prohibitively expensive, because you can't just melt it down thermally; it takes solvents and a multi-stage chemical process. Plastic recycling in general isn't anything like as successful and common as people tend to be lead to believe, and my understanding is that styrofoam is one of the _least_ recycled, at less than 2%.

Styrofoam can be and is melted down and repurposed. Just because these blocks are freshly cast doesn't mean that the original material is freshly procured. Shredded material in bags also wouldn't be very stable.

This is crazy timing cuz I JUST learned about concrete lifting yesterday, saw some cool Timelapse’s from a company’s channel here on YouTube. They were using polyurethane foam type stuff to fill voids and lift entire stretches of sidewalk, porches, road, whatever. Super neat

When you mentioned the buoyancy of EPS it reminded me of the Fraser valley floods in Canada 2 years ago where the ground water made the eps filling float and that broke the road on top of it.

You have a true gift for taking complex issues and making them easy to understand.

Your videos are so good! Its like what I wished those 'how stuff works' videos should have been.

I love that you have a compression measurement setup in your garage. Well done! Great video.

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Thank you so much for making this. My Father is an engineer and he mentioned this to me in passing a couple of months ago.

I love all your content, very educational. These structural videos always gets me wondering how I can get some of these materials or use these methods at home. Either with my driveway or house foundation. Or hire a company that uses these methods.

I juat love how you put so much thought and effort into your content, and i know you get some kickback from the sponsors, but its of your own volition that you make it in the first place. You contribute to wider human knowlege and i cant thank you enough for that

Grady's new book "Engineering in Plain Site" is a must have! Got it in the mail a few weeks ago and enjoying one section a day and learning tons. Fantastic!

I make Geofoam. It's always cool to see how it and it's alternatives are used to solve design challenges. Thanks for making my day.

The thermal insulating properties of EPS foam have also been used in geothermal areas to reduce heat damage to the pavement. It was interesting watching construction of several hundred yards of roadway in Yellowstone National Park.

@Ithecastic have you ever seen EPS foam get soft in the sun? Because I have seen Asphalt doing that.

Jeez you'd intuitively expect than anything hot enough to damage the road would first melt the foam, but I'm sure they've got it figured out.

On our most recent Alaska trip we watched workers install EPS sheets as part of the Dalton Highway out to Prudhoe Bay. Waiting in yet another construction delay we enjoyed talking to a couple of workers who said the material not only helped by lowering the weight of the road surface, but also acted as insulation against blacktop and vehicle movement-created heat affecting the permafrost under the road.

There's a big highway construction site not far from my place and I saw these huge white blocks. I was wondering what they were about and dismissed "Styrofoam". Wow, was I wrong! Thanks for the great learning opportunity!

Great video. Didn't know so many options existed for lightweight fills.

It not only the weight of the ramp that makes the surface go down, its also because its hard to compact materials in the ramp. This means the traffic will compact as time go by. I have seen it in my own work as one who administrate the maintenance of civil works (bridge, wharf, tunnels, stairs, support wall, ect) (Sorry, I'm coming a bit short in English on some of the specific technical expressions)

I'm a DOT certified inspector and I've worked on a road project where they built up a section of the roadway 3 lanes wide about 40' long and 15' high using styrofoam blocks because they didn't want the weight of the fill on top of some old but still live pipes under the roadway.

03:35 As a NJB fan, I loved how you made sure to show 9 entirely different buildings/businesses being demolished or affected by the hypothetical bridge catering to car traffic.

And it only gets better when you realize how many homes/buisnessnes would have been demolished if this wasn't already a car dependent wasteland.

WE just needed a few more lanes bro. Gotta keep that traffic down, ya hear?!

Especially after NJBs latest short that showed that bicyclists don't need traffic lights 🤣

Now I know why it took over 3 years to complete the overpass in my local area: waiting for compaction. I had thought it should only take a year or less. BTW, letting a small child learn meal prep while at the stove top seems a bit sketchy for later on when they decide to do something 'all by myself'. However, letting them learn at a countertop is fabulous! Props to the parents for taking the time to do this.

When a highway where I live was being extended, one of the huge challenges was a sub soil called leda clay. It's probably one of the most unstable soils around especially if it gets wet. There was no way to reroute the highway, so the engineering solution was to install a capping membrane, then use styrofoam blocks on top to build the bridge embankments. The styrofoam is ballasted with normal aggregate materials and paved. It hasn't shifted in the 10 to 15 years since it was built despite the heavy trucks that run on the highway.

When I saw the title of this video I instantly thought of the SR 99 tunnel project in Seattle. I may be wrong but I thought most of the geofoam used on that project was for temporary fills across the tunnel approach lanes. That SR 99 project would make for some good videos from you, both in the complexity of the tunneling so close to other things, just a few feet in some cases, the repair of the TBM and the complex demolition project of the old viaduct.