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Engineering Disasters - Highway to Hell
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00:00Coming up in our quest for the world's most incredible engineering disasters.
00:06A skyscraper dropping bolts from the blue.
00:10These bolts are huge. They're the size roughly of a human arm.
00:16A wrecked freeway that became a highway to hell.
00:20It looked like after an earthquake. We don't have earthquakes around here.
00:25And roads in Oregon that are driving residents insane.
00:30It's literally falling apart here.
00:36With big builds, even the smallest mistake can be a huge disaster.
00:45From miscalculations...
00:49To misunderstandings...
00:54These are the engineering catastrophes that only an expert can hope to fix.
01:06First, to the UK and a skyscraper with an unexpected engineering issue.
01:11I wouldn't have thought that something like this would have been happening in London.
01:14This spectacular structure was coming apart at the seams.
01:19It's usually the stock market crashing down that spooks the city.
01:24This was literally a bolt from the blue.
01:30London, England dates back to Roman times.
01:33The city is steeped in architectural history.
01:37But that doesn't mean it's rooted to the past.
01:41The skyline is ever-changing.
01:44With new and revolutionary structures slotting into place beside established historical landmarks.
01:52The London skyline is known for its statement architecture.
01:55The London Eye, the Shard, the walkie-talkie.
01:58But there's one that's bound in infamy.
02:01The cheese grater.
02:03The building's distinctive wedge-shaped profile is designed to protect the views of historic landmarks, including St. Paul's Cathedral.
02:12Journalist Robin Wilson knows the structure well.
02:16The Leaden Hall, also known as the cheese grater, has got its unusual name from its shape.
02:21As you can see, they're rather similar.
02:24Striking, bold shapes, starting with a kind of large base at the bottom and then sort of tapering up.
02:29Also at the side of the building, you can see they've got quite similar teeth.
02:36The 52-storey tower has a tapered glass facade on one side, with steel bracings and a ladder frame to
02:43anchor the building to the ground.
02:47Many tall buildings use a concrete core to provide stability, but the cheese grater is supported by an external steel
02:55superstructure, called a mega-frame.
02:57This exoskeleton is the tallest of its kind in the world.
03:03The steel beams are connected by nodes that transfer forces of around 6,000 tons, with the whole frame connected
03:12by almost 3,000 megavolts.
03:16Crucially, these bolted joints are completely rigid.
03:22When it opened in July 2014, the pioneering construction wowed the world.
03:28But within months, it was clear that something was wrong.
03:32In 2014, two bolts broke and parts of those bolts fell from the Levenport building.
03:39One made it to the ground, the other one was actually caught within the skyscraper itself.
03:44Three months later, another bolt broke, so January 2015.
03:49These bolts are huge, they're the size roughly of a human arm.
03:53Can you imagine a bolt the size of my arm falling from the skyscraper onto a crowded street below?
03:59It's absolutely amazing that nobody was hurt.
04:06If a megabolt from the cheese grater hit a pedestrian, the outcome could have been catastrophic.
04:15Ballistics expert Sharon Fleger-Taylor conducts an experiment to recreate the impact a falling megabolt could have on a person
04:23at street level.
04:26Today we are replicating a bolt of 38.4 kilograms with a dimensions of 75 millimeters by 1,000 millimeters
04:35falling from various heights.
04:37Instead of megabolts, Sharon fires bullets at different speeds to replicate the physical forces involved.
04:50The kinetic energy produced by the bolt is a certain amount, 34-ish kilojoules.
04:58We can actually change the velocity and the weight of a bullet head to ensure that it produces the same
05:06amount of kilojoules.
05:08The lab is set up like a shooting range, with a .50 caliber rifled gun barrel aimed at the target.
05:16This particular bullet has been loaded to produce velocities the same as the bolt will have fallen from the third
05:22floor of a skyscraper.
05:24First, Sharon will demonstrate what could have happened when a bolt fell from the third floor.
05:30A watermelon will take the place of a pedestrian.
05:38As you can see, the bullet has passed all the way through the watermelon.
05:42However, it hasn't caused what we would say catastrophic injuries to it.
05:48The bullet has passed through and gone through the paper.
05:52If this hit you on the hand or the leg, you stand a fairly good chance of seeing the next
05:58day.
06:00If it missed your head, that might be a lucky escape.
06:03But what if a bolt had fallen from the top of the 52-story cheese grater?
06:09The same experiment, but how will the melon fare against a much higher velocity shot?
06:22Fatal.
06:25With such devastating potential, engineers had to find a solution to the megabolt problem.
06:31First, they needed to know why the bolts had failed.
06:38When inspected, they discovered the fallen bolts had undergone a process known as hydrogen embrittlement.
06:49Put simply, it's a process in which hydrogen atoms diffuse into a metal structure.
06:57The atoms slowly recombine to form hydrogen molecules in gas form that create pressure inside the metal.
07:06Ultimately, the metal becomes brittle.
07:09The easiest way to think about it is the metallic atoms are like marbles,
07:13and the hydrogen atoms are like grains of sand.
07:16The grains of sand can fit in between the marbles,
07:18and if too many grains of sand get in there, they start to push the marbles apart.
07:22With brittle megabolts in such a rigid structure,
07:25there was a risk that more might plummet to the ground.
07:32Engineers needed a fix, and fast.
07:39In 2014, London's Leidenhall building wowed the world.
07:44But only months later, three bolts fell from the structure.
07:49Engineers quickly pinpointed the cause.
07:52Damage in the bolts, known as hydrogen embrittlement.
07:56Because hydrogen embrittlement develops over time,
07:58it's very difficult to test whether or not the bolts will be susceptible to it
08:02before they're put in place.
08:05What's more, it's a phenomenon rarely found in big-budget projects.
08:10As far as I'm aware, other buildings certainly of this size
08:14haven't had issues around hydrogen embrittlement.
08:17But when it happens, reversing it is difficult.
08:20As engineer Peter Desnyerk explains.
08:22When it comes to hydrogen embrittlement,
08:25if we know it is a process that is present in our elements,
08:28we can try to regain its original properties by heating them up to very high temperatures,
08:34allowing the hydrogen to escape from the materials.
08:38Unfortunately, in existing buildings, when the building has been erected,
08:41it's much harder to actually heat the elements in the construction to such a high temperature.
08:47So quite often, the only solution we have is to actually remove the elements
08:52and replace them by elements with the proper properties.
08:56The integrity of almost 3,000 megabolts was now uncertain.
09:00So engineers had only one choice.
09:02With a potentially lethal situation like this, there was only one solution, and that was replace all the bolts.
09:11So at the end of the investigation, one of the subcontractors on the job actually replaced all the 3,000
09:16bolts on the scheme.
09:17At great cost, the CEO at the time actually said that it could cost them up to 6 million pounds.
09:25To ensure that hydrogen embrittlement wouldn't be a problem in the future,
09:29the new bolts were treated with a cutting-edge process called thermal diffusion,
09:34coating them with a protective anti-corrosion layer.
09:39Buildings of the future would probably still be built with our nowadays materials,
09:44such as concrete, steel, wood, glass and so on.
09:48But at the same time, new materials are being developed.
09:54With the cheese grater, the engineers' swift response averted the danger.
09:59But this won't stop architects pushing the boundaries of engineering and design.
10:05With the advent of new technology and materials, new lessons will be learned along the way.
10:16Next, we head to Germany and a construction catastrophe that's causing carnage for a once sleepy town.
10:25It's a massive problem.
10:29You can't sleep at night.
10:33Unfortunately, it's just not calm.
10:36This cutting-edge engineering project has turned into a bottleneck blunder.
10:41This is a road to know.
10:48The Autobahn, Germany's famous highway.
10:51The lifeblood of this fast-moving country's infrastructure.
10:56First created in the 1930s, the network now consists of almost 8,000 miles of road.
11:04And it's still growing.
11:09In 2005, a new 175-mile stretch of Autobahn was opened, connecting inland Germany with its north coast.
11:18You can see why they'd add a new stretch of road here.
11:22It really sped things up for all the tourists heading from Germany's cities to the coast.
11:29As well as cutting travel time, the road's other goal was to bypass rural villages, easing congestion.
11:40Journalist Lutz Reuter explains why this new highway was considered a triumph.
11:46People around here were very happy because all the other small roads, they are not in a very good condition.
11:55It has a nickname around here. It's called the Küstenautobahn, which means the coast Autobahn.
12:01People come here for the nature, for animals they can't see in other parts of Germany anymore.
12:07Cars reach their destination faster and bypass the small villages along the way. Win-win, right?
12:14Well, not quite.
12:17Just 12 years after opening, this efficient expressway had become a highway to hell.
12:26The end of September 2017, the road just collapsed.
12:32It started with one part, direction into the east, and a couple of days later, the whole road was closed
12:43down.
12:43This is definitely not the thing you'd expect from a country that's so famous for its roads.
12:48A section of new Autobahn had completely collapsed, leaving a 130-foot-long hole in the highway.
12:56Thankfully, no one was hurt.
12:59But the disaster wasn't over yet. Within five months, the damage had more than doubled.
13:08Head of highways, Ronald Norman, was sent to assess the damage.
13:14In October last year, the motorway collapsed, here on the right side, where the bulldozers are.
13:21A few months later, the other side of the road went too.
13:25This caused the road's foundation to fail, and the highway collapsed.
13:34With this crucial transport artery out of action, Ronald's top priority was to establish what had caused the foundation to
13:43fail.
13:47Ecologist Dr. Gerald Jurrasinski knows this area well, and was brought in to consult.
13:53When I heard that the Autobahn was collapsing, I first thought, my really first thought was,
13:59that shows that you should not underestimate a peatland.
14:05This area of Germany is well known for its peaty soil.
14:10Peat is formed as decomposing vegetation, such as trees and leaves, get crushed, and settle in a water-rich environment.
14:20Peat retains a high moisture content, making it soft and soggy.
14:27Peat can be found in bogs and moors, so it's no surprise that it's up to 97% water,
14:33which is not ideal for building heavy structures on.
14:37Northern Germany is essentially one massive peat bog, stretching across 8,500 square miles, and it's deep.
14:47These peatlands extend 6, 7, 8, sometimes 10 metres into the depth,
14:53and therefore you don't have to underestimate them when you want to construct something on them.
15:01This peat, that's our problem.
15:03It's about 20 to 30 feet thick here.
15:06Over millennia, a lot of peat has accumulated.
15:09It's a completely normal phenomenon, so we knew that it was there.
15:14Engineers knew the peat was there all along.
15:17The truth is, you can build on peat, if you do it properly.
15:24One solution to building over unstable ground is to treat it like water.
15:29You should look at it like a very, very slow river.
15:35You know, the water is flowing through it.
15:37They built the autobahn here, and there you see that it's like a bridge, and that's good.
15:42Most of this highway was built like a bridge, and it still stands, for good reason.
15:49The large piles are driven through the peak, down into the bedrock, creating a solid foundation on which to build
15:57the road.
16:00However, with the section of collapsed autobahn, the engineers had tried a new engineering technique, designed to save time and
16:08money.
16:10But as with anything untested, there was no guarantee of success.
16:19In 2017, near Germany's north coast, a huge stretch of highway completely collapsed.
16:28The engineers who constructed this section, twelve years earlier, had used a new technique to build over soggy, peat-rich
16:36ground.
16:38We have thousands of thin pillars under the road here.
16:42They are seven inches thick, and made of concrete.
16:45These pillars carry the whole roadway.
16:48In 2,300 feet, there are 80,000 pillars on which we laid the road.
16:53Thousands of mini-friction piles were driven into the peak.
16:57Cheaper and quicker to build than the bridge technique.
17:00In theory, the vast number of piles would support the road above, without needing to reach solid bedrock.
17:07But in reality, it didn't work.
17:11A new, innovative process was used to bridge this peak land.
17:15And it was wrong for this location.
17:19The loads on top of the piles were too heavy.
17:22And because of that, we got forces spreading it sideways.
17:25And the roadway tore apart.
17:27And then, it collapsed.
17:31The weight of the highway, combined with the high moisture levels in the peak, caused the mini-piles to splay
17:37outwards, on both sides of the road.
17:41This resulted in the catastrophic failure of the road above.
17:44It seems the mini-friction piles were the wrong choice for this location.
17:50The road builders should have gone beneath the peat, with their, like, grounding work.
17:56And what they did, with these small pylons of concrete, just through the peat, it was not enough.
18:02It's always good to see engineers thinking outside the box.
18:05But this time, their experiment didn't pay off.
18:09To ensure that the repair job will be sound, Ronald Norman's team is surveying the extent of the peat problem
18:16every step of the way.
18:18We want to investigate where the different layers are located, what actually happened after the ground ruptured, how the earth
18:26moved.
18:27And that is what they are currently investigating for us.
18:31That is very important.
18:33That is the old embankment, which has subsided now.
18:36And here below is where the peat begins.
18:39You were down about 20 feet, weren't you?
18:42Yes, we were at 20 feet.
18:44For this massive road repair, the engineers intend to rebuild the entire section with much larger piles that will go
18:52past the peat and down as far as the bedrock.
18:55I can't help but think why they didn't build the whole road like that in the first place.
19:02Meanwhile, the diverted traffic will continue to take a toll on the local roads.
19:07Now you can see construction signs coming up.
19:11They lead to probably one of the biggest construction sites in Germany right now, definitely one of the most spectacular
19:19ones.
19:22The official speed limit right now is 60 kilometers per hour, but there is so much traffic that we can
19:28only go 15 kilometers per hour right now.
19:34The village of Landorf should have benefited from the bypass, but is now congested with many thousands of cars a
19:41day.
19:44It's disturbing our sleep because you can hear it through the heaviest windows and the thickest walls.
19:51Now there's traffic. You see yourself. Trucks drive through here. So the amount of fine dust from vehicle pollution is
20:00immense.
20:02We've taken all the heavy trucks off the highway here. We exchange industrial goods here, and our guests and tourists
20:08come here.
20:09Now they have a detour. We send them all through a village with very narrow streets and sharp bends.
20:15It's no longer a smooth drive. There's a lot of congestion. We have this unique event, and that is our
20:22problem now.
20:28Many people are angry because they are afraid that the construction will take many years.
20:35Three years may sound like a long time, but in highway terms, this is actually good going.
20:44When we are putting roads down in a landscape like this, we have to really read the landscape and better
20:50understand how the processes in nature are working.
20:57You might think it's easy to construct something on peat or in the peat land or on a river bank
21:03or whatever, but then, yeah, sometimes nature strikes back.
21:08You've got to try new solutions to old problems, and often they do pay off. Even though sometimes they end
21:17in failure, it's these experiments that push forward the boundaries of engineering.
21:29For our next construction catastrophe, it's off to Portland, Oregon, and an engineering issue that's become a growing epidemic.
21:39Some people think it's a conspiracy by the city to make driving so unpleasant that people take public transit.
21:44And this is an issue which is driving people mad.
21:48This construction conundrum is so bad, people are desperate.
22:01Portland, Oregon. Once known as a gritty port town, it's now a forward-thinking city.
22:09Portland is a city that so many people love. It's one of the hippest upcoming cities in the U.S.,
22:15but it's got one major problem, and that's its roads.
22:23The city stretches over 140 square miles, with almost 5,000 miles of roads.
22:31Maintaining the infrastructure here is an ongoing challenge for engineers, made worse by Portland's wet climate.
22:39With around 160 rainy days a year, Portland ranks third on the list of wettest cities in the U.S.
22:49Freezing winter storms combine with heavy rain to trigger a major engineering problem.
22:55Portland's streets have reached breaking point.
23:01Portland, Oregon. The city's cold and wet climate is causing an engineering epidemic.
23:08Thousands of potholes.
23:10While some might be small, the scale of the problem is huge.
23:16As local journalist Marty Smith demonstrates.
23:20Oh, my God, look at these.
23:23Everyone agrees that the streets of Portland are in bad shape.
23:29And no one can agree on how to pay for that.
23:32You can't convince somebody that the street needs to be fixed and we need to put money into it until
23:36it's literally falling apart and your teeth are chattering out as you go over them.
23:41Like, here's the giant one right here.
23:46The real costs of this engineering epidemic spiral ever higher, with damaged tires, suspension, car bodies, and even injuries to
23:56pedestrians.
23:59Heavy traffic and mother nature caused the damage, but there's a fundamental problem with the way the roads are built.
24:07Road surfaces in America are made of asphalt.
24:10And this is largely an aggregate of gravel and tar and other things.
24:16Binding gravel and sand with tar, known as bitumen, creates a hard-wearing asphalt surface for our roads.
24:25Airdem Koleri is an asphalt expert.
24:28So you make the asphalt mixture by using the asphalt binder.
24:32So this is the black part.
24:33And then you heat this to high temperatures.
24:35And then you mix this with the aggregates and recycled asphalt material to produce these asphalt concrete mixes you see
24:42here.
24:43So these are two samples that we produced in the lab.
24:46So you can see that they look brand new because they have black color on top.
24:49It's actually taken from a highway section in Oregon.
24:52And when you compare this to our lab sample, so you can see the color is very different.
24:56So asphalt is also aging over time and oxidizing.
25:00And this oxidation is actually making the asphalt more brittle and reducing the cracking resistance of asphalt.
25:07The surface starts out strong and flexible, but age, weather, and wear and tear take their toll.
25:15As the road turns brittle, it cracks, allowing Oregon's wet and cold climate in to wreak havoc.
25:23But the cracking is only the start of the problem.
25:26A long history of resurfacing roads by laying new on old, like wallpaper, makes things much worse.
25:35Michael McGee heads up one of Portland's road maintenance teams.
25:40The water hits the surface and it works its way through the cracks.
25:43It makes its way to the next layer of cracks and it gets down there and it wants to go
25:46down.
25:47And you can see the cracking that's occurred on top of this in this large pothole.
25:51And then below that is the layer of the asphalt that was before that.
25:55That might be 15, 20 years old.
25:57And you can see the cracking that's existed in that part of the road.
26:01And then here's probably the original roadway, which is probably 50 or so, 60 years old.
26:07And I bet if we opened this up, we'd see even more cracking.
26:10So when we have these really deep potholes, that's because it's gone through layer after layer after layer of asphalt.
26:17Because we have cracks below cracks below cracks.
26:21The asphalt surface sits on older layers, resting on rock, gravel and sand, known as aggregate.
26:29When new, the surface is waterproof, but with age, small cracks form.
26:34As water gets under the asphalt, the aggregate expands and the cracks in the asphalt grow.
26:39As trucks and cars pass over the weakened surface, it breaks up and is forced out, creating a pothole.
26:48So you can see, if you look beyond here, you'll see that we have surface cracking.
26:51A lot of them call it alligator cracking because it looks like alligator skin.
26:55All those cracks right now, there's water that's seeping down below there.
26:59And it's going to reach that next layer.
27:01And as people drive over it, so this is a future pothole that's going to come if we don't do
27:07something with it.
27:09During the winter of 2016, Portland's pothole problem got much worse as the city was hit by a barrage of
27:16storms, the heaviest snowfall since 1995 and 10.4 inches of rainfall.
27:23It was Portland's wettest winter on record.
27:28The pothole problem escalated, and by spring, the city was receiving around 50 pothole-related complaints a day, an increase
27:38of over 350%.
27:41With their roads crumbling, engineers have only two options.
27:45Repair the potholes one by one or resurface the entire road.
27:50To fully fix the road is about $150,000 per mile.
27:57And that's just the road to take out the road surface and put it back, not including any utility work
28:02or other things.
28:03Just to fix this one individual pothole cost is about $500.
28:09Resurfacing is not only costly, but disruptive to road users.
28:12So, for now, the crews are tackling Portland's potholes one by one.
28:22They heat it up the surface to make sure that they try to get it up to temperature and make
28:26sure there's no more moisture or any debris in there.
28:35The binding agent, or tack, is also heated to remove water.
28:39The team knows just when to stop heating and call in the asphalt truck.
28:45And that's what they call turn or break, and that's how they know when it turns black that it's ready
28:50to go.
28:51That's essentially the glue that helps everything, gives it a head start to stick.
28:56There's also an art to knowing how deep to fill the hole for a smooth ride and to prevent a
29:03new hole from forming too soon.
29:05The trick of that is with the crosswind is making sure you get the right amount of mix in there.
29:10You saw that you left it a little bit high because when it compacts it, it's going to go back
29:15down a little bit.
29:15So, you have to judge how much asphalt to put in there to make sure that it doesn't end up
29:21too low or too high.
29:22This is a very low-volume street, not a lot of traffic, but we still want it smooth.
29:27We want it smooth for the people that use the road, but also when it's smooth, it's going to be
29:32a lot more durable
29:33because then the wheel will just go right over the top of it.
29:37Meanwhile, the key to smoother roads in Portland lies in advances in road surfacing technology
29:43to make them more flexible and crack-resistant.
29:47The new strategies are using polymers in asphalt mixes.
29:50So, this is, for example, a polymer-modified mix that is used in Oregon.
29:53We're using some rubberized asphalt, putting some rubber into the asphalt mix to improve the flexibility of the asphalt mixes.
30:01There are also different strategies like using fibers to improve the strength of asphalt concrete materials.
30:07For example, they are using fibers coming from bulletproof vests and they are recycling those
30:12and using those to improve the cracking resistance of asphalt mixes.
30:16The process of patching Portland's potholes seems to be a never-ending story.
30:23Frustrated with the road's shortcomings, local businessmen like Trey Shannon have found alternative means of raising revenue.
30:33We thought as a business it would be great to create a pothole donut,
30:37which is basically a bar that's dipped in chocolate with Oreos and then that was the lane.
30:41I think we sell these for $275 or something and maybe, you know, 10% of sales or something could
30:47go to help with the roads.
30:49Imagine if 500 businesses did it.
30:52Maybe just the community itself could fix these problems as opposed to just putting it on city government for sure.
31:04Until money can be found for a long-term solution, Trey has decided to take matters into his own hands.
31:13So here's what we're doing. We're going to fill this hole here with some donuts and see if we can...
31:18I hit this thing every day on my way to work. It just drives me crazy.
31:21So I think, yeah, right here, let's throw some donuts in there, Kevin.
31:24There we go. And I think a couple of cake ones. I love it. That's probably good.
31:29I think it's me trying to be an outstanding citizen in a way.
31:33Well, let's see what happens here.
31:34That donut right there that's got the eyeballs, that's the Portland cream.
31:37So that's the official donut of Portland, Oregon.
31:40Yeah! See that? It looks great. It's phenomenal. It just squirted perfectly.
31:45It's got the whole thing. It's all level.
31:47As much as I like the idea, I don't think the donuts are going to cut it in this case.
31:52Civil engineering at its best.
31:59For this next calamity, we head to Greece and a deserted mountain village.
32:05It looks like a war zone. Like, what happened here?
32:08What seemed a small engineering decision might have caused a sudden catastrophe.
32:14I've heard about a moving house, but a moving village?
32:24The village of Rapoto in the central Greek uplands perches on the sloping sides of Mount Koziakas.
32:31When most of us think of Greece, we think of these vacation spots, these beaches.
32:35But in actuality, much of Greece inland is these rugged mountains.
32:41This picturesque village, famed for its orchards, was home to over 300 families.
32:49Until one night in 2012, when the entire village started sliding down the mountainside.
33:04Greece, April 12th 2012. The village of Rapoto was hit by a massive landslide, with dozens of houses slipping down
33:14the hillside.
33:16You'd see a house collapse and wonder what's happening.
33:20Everything was fine until this disaster hit.
33:25The whole village was destroyed.
33:31Villagers like Ajira Siolos will never forget that night.
33:37I recall there was panic. We didn't know where to go.
33:40We ran away from the landslide, so at least we didn't die.
33:44Forget about the houses and our things. We didn't want people to get killed.
33:49The event is still painful for Georgios Rubis to talk about.
33:54People panicked, started throwing things out through the windows, picked them up and fled.
33:59It was a disaster. That's what happened here.
34:03Overnight, residents were forced to flee.
34:06Damage to the architecture and infrastructure was catastrophic.
34:12This was the old stone school, built in 1954.
34:16And over here, there was a cafe and a grocery shop.
34:20There was another shop over there.
34:23The tragedy still haunts Rapoto resident, Aris Zanis.
34:27With around a hundred people, the village was full of life.
34:35But after what happened, we had to leave.
34:42The village looks like it's been abandoned for decades.
34:45And it's hard to believe that this was a thriving place, just back in 2012.
34:50Although sudden, the landslide wasn't the first in the area.
34:53It had always been a risky place to build a village.
35:02The area's steep gradient, soft ground and high water content was a known recipe for disaster.
35:10As geologist Vassilis Marinos explains.
35:16We are in the heart of Greek mountains, and it's a very interesting geological environment to be in.
35:24This area here, this material where the village stands, it's a very weak one.
35:30It's very soft. It has deformed a lot from tectonical process through mountain building.
35:37The mountains in the area are made up of limestone, with a layer of weak rock called fleisch lying on
35:44the top.
35:45The unstable rock gathers in valleys.
35:48The center of Rapoto sits right on top of a pile of fleisch.
35:52The mountains were formed millions of years ago, and left areas of hard rock and areas of soft rock.
35:59The area where the village was built, was soft.
36:02The central part of the village, all this material has slided, and not the flanks of the village.
36:09And this is due to the nature of the ground.
36:12Where people still live in their better rock masses, they don't have this kind of weak soft material like in
36:20the center.
36:21Weak and unstable, fleisch is prone to landslides.
36:25Whether triggered by earthquakes, volcanic activity, or water saturation,
36:31gravity takes over and pushes the fleisch down the slope.
36:35The result? A landslide.
36:38In many cases, these areas are areas where the ground has landslided in the past,
36:45in very old times, hundreds of years ago, thousands of years ago.
36:50It was a known problem that the ground moved a little every year.
36:56But it wasn't just natural causes that triggered Rapoto's catastrophic landslide.
37:04Another possible factor was the decision to end a 50-year-old engineering project.
37:13In the 1960s, after a period of heavy rain, Rapoto experienced a substantial landslide.
37:20Buildings and roads were destroyed.
37:24We had landslides in the village in the past, but never such a big one.
37:32The build-up of water was threatening Rapoto, so mountain streams were diverted around the village using man-made channels.
37:40This prevented the ground becoming waterlogged and unstable, and kept the village safe for years to come.
37:52By the 1980s, Greece was experiencing growth.
37:58Engineers built heavier structures in the village, including a large hotel.
38:05The hotel construction was funded by a European Union program.
38:14The church started being built in 1986 or 1987.
38:20Despite the development, the drainage systems around Rapoto were keeping the fragile ground dry, for now.
38:27You could say they were setting themselves up for a fall.
38:34In 2011, an engineering decision may have left the Greek village of Rapoto on the brink of disaster,
38:43when a decades-old program to divert water around the village was suspended.
38:51The water passages, the streams, were closed up,
38:54which led all this water to cause erosion under the surface and allowed this damage to occur.
39:00Water built up in the soft-flesh rock beneath Rapoto, and gravity did the rest.
39:07The water is the principal factor that triggered this landslide.
39:12And the water from the infiltration, from the rain, this created the big landslide problem.
39:20If you don't divert it, that water's got to build up somewhere.
39:23And in this case, it's going to be underground.
39:25And if you already have an unstable foundation, that's going to lead to trouble.
39:29Trouble that was always lurking.
39:31If they hadn't closed up the streams, the disaster probably wouldn't have happened.
39:37In an area prone to landslides,
39:40whether to spend money in hopes of preventing the inevitable is always controversial.
39:46Although costly, the building of pile walls is one engineering solution to consider,
39:51as geologist Marius Vassilis explains.
39:56We may have found some technical solutions in order to stabilize it.
40:00Drain it with building pile walls in this large landslide.
40:05In different levels, you have to build this pile wall, not just one pile wall.
40:09And I discussed about the width of the landslides, almost 300 meters, and all this mass coming down.
40:15So you have to retain big forces into that.
40:19So you have to spend millions in order to stabilize this mass.
40:23A pile wall is made by hammering a row of columns or piles into the ground.
40:28Standing adjacent to each other, they form a wall.
40:32Here, to stabilize the slope, they would need to reach bedrock.
40:36And, to support such a large area, there would need to be more than one wall up the mountainside.
40:43Mountain sides could be shored up using pile walls.
40:46And these are kind of huge concrete blocks that are placed underground.
40:49Now, to do so here, you'd actually have to destroy the entire village.
40:53And it would cost millions.
40:55This would be, again, a very expensive solution.
40:58That's why this would be, in my experience, not a feasible solution.
41:07Since the disaster of 2012, Marius has been monitoring the region for ground movement.
41:15His studies have revealed that the town has slid around six inches more in six years.
41:22The length of the landslide is around 800 meters, roughly.
41:28The width of the landslide is about 300.
41:31With no cure in sight for Opodo, instead, it's important engineers learn lessons from the disaster.
41:39When the ground is destined to shift, it's better to build elsewhere.
41:44The church bell no longer chimes. There is no village anymore.
41:51No one will ever return here.
41:55This really feels like a paradise loss.
41:58And there is no cultural weakness.
41:58To be a peropologist.
41:59The man that is, I'll talk to you quickly.
42:02Thanks, guys.
42:02In this video, we're going to talk to you quickly.
42:03Our progress is, community development.
42:03Thank you very much, no part of our story.
42:03We're here.
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