- 17 minutes ago
Expanse illustrates the technical achievements of erecting the world's most fascinating bridges...
在面临巨大挑战, 如环境危机, 社会断裂或太空探索困境时, “韧性”, Resilience 是生存与发展的最关键要素, "Bridging The Expanse" 指连接广阔空间、差距或未知领域 ....
在面临巨大挑战, 如环境危机, 社会断裂或太空探索困境时, “韧性”, Resilience 是生存与发展的最关键要素, "Bridging The Expanse" 指连接广阔空间、差距或未知领域 ....
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TechTranscript
00:01Bridges have always been part of our narrative, part of the very fabric of society.
00:07It's always been important for people and places to connect and bridges do that literally.
00:15Few other structures represent our ability to solve problems.
00:20I think a great bridge provides both form and function.
00:25Transforming our everyday lives.
00:28It provides an incredibly important way of bringing the world together.
00:33Learning from the masters and their disasters, we continue to innovate and progress.
00:41The conquest of nature, the conquest of gravity, there's something spiritual about them.
00:48Wherever we build incidental, ornamental or monumental spans, we succeed in bridging the expanse.
01:04It's going down. Highway's coming down. Highway just went down.
01:11Designing bridges with a lifespan worthy of their considerable cost is often easier said than done.
01:21For the best laid plans of engineers and architects, often go awry.
01:30It is difficult enough to design a bridge that will remain aesthetically relevant for 120 odd years, let alone one
01:39that maintains its resilience.
01:49Bridges are exposed to a lot of different vulnerabilities.
01:52There are vulnerabilities during construction. There are vulnerabilities post-construction, be it seismic, hydraulic or flooding, vehicle or vessel impacts.
02:05All of these things are taken into account during the design process.
02:10Obviously, there are always extreme events that occur that are outside of what can be expected.
02:19But I think engineers really try to take all of those probabilities into account when they're designing and constructing bridges.
02:29Because we have to accept the fact that we don't know everything, we need to design things that are resilient.
02:41The Bosphorus Strait in Turkey is one of the busiest waterways in the world.
02:49In 2017, 43,000 vessels plied its waters.
02:56Nearly three times as much traffic as through the Suez Canal.
03:02The first structure to span this frenzied flow was in every sense resilient and a significant milestone in the evolution
03:13of bridges.
03:20The first bridges were ways to get across a stream, a river, an obstacle.
03:26But now we connect cities, towns, countries and even continents.
03:33The first Bosphorus Strait in Turkey.
03:35The first Bosphorus bridge, as its name suggests, was the foremost span linking the two halves of Istanbul.
03:42The cultural and economic heart of Turkey.
03:48More significantly, perhaps, it was also the first bridge to connect the continents of Asia and Europe.
04:02Renamed the 15th July Martyrs Bridge, the 1560-metre structure is a gravity-anchored suspension bridge.
04:13So its main cables are attached to the road deck rather than the ground.
04:20Its understated 165-metre steel towers hold the deck 64 metres above sea level.
04:30More than enough clearance for most of the ships making use of the frantic shipping lanes below.
04:39Inclined hangars, as opposed to a more traditional vertical configuration, were used on the assumption they would improve the aerodynamic
04:49stability of the bridge.
04:53A hypothesis that has since been disproved.
04:58But not before engineering firm Freeman Fox & Partners had applied the same arrangement on the Humber.
05:10Work has already begun on a bridge that will have a main span of 1410 metres.
05:16That fragile-looking trellis on Humberside's skyline has a big future.
05:30When it was completed, the Humber Bridge was the longest span in the world and remained so for a very
05:36good long while.
05:39Just over 1400 metres main span between the towers.
05:45It was a suspension bridge, very similar to the Severn Bridge which had been done in the 1960s.
05:51It was a deeper box this time, but it repeated the inclined hangars which had been used at Severn as
05:58well.
05:58And were also used with the first bridge across them.
06:02Unfortunately, the same cannot be said of structures that have had to place their piers in the middle of much
06:09narrower or infinitely busier shipping channels.
06:19A 1500-foot section of this five-mile concrete bridge was ripped out by an oil tanker that got out
06:24of control in Lake Maracabo, Venezuela.
06:26Five people plunged to their deaths as four cars crashed into 40 feet of water.
06:38Ship impact is a big thing.
06:40And there have been lots of examples where bridges have been demolished.
06:44From barges or ships.
06:46Large bridges is a very important consideration.
06:49That's a big determination on what form the bridge will be.
06:56Even modest bridges across rivers are all designed to ship impact these days.
07:08It is impossible for engineers to guarantee their structures won't be hit.
07:12So they plan for that eventuality in their design.
07:18Taking steps to improve their resilience to limit the risk of catastrophic failure.
07:26In those accidental situations, there would inevitably be some damage.
07:30What we do want to make sure is that the risk of that bridge collapsing is acceptably low.
07:38Bridges are protected from vessel impacts in various ways.
07:41We've designed many structures to withstand the impact of vessels.
07:47An island is a good solution because the ship basically grounds itself.
07:53But if you're not able to put an island in place, then you've got to either design the piers themselves
07:59to absorb that impact.
08:01Or you might use a fendering system.
08:06You can compare that to a fender on a car.
08:08That the bumper is designed to take the blow and protect the vehicle.
08:11And in this case, the fender is designed to protect the bridge or the pier that is really subject to
08:18the arid vessel.
08:21One bridge spanning the balmy waters of Tampa Bay would push the boundaries of bridge resilience.
08:29The $244 million, 6.7 kilometer long Bob Graham Sunshine Skyway Bridge opened in 1987.
08:45The Bob Graham Sunshine Skyway Bridge was historic for this hemisphere.
08:51Because it was the first use of single towers with single planes of stays.
09:07My father, Gene Figg, who inspired me to be a bridge engineer, was the one who helped to envision that
09:18design.
09:22Today, it still is the longest precast segmental span in the United States.
09:311,200 foot span between the towers.
09:34It has 175 feet of vertical clearance for the navigation vessels underneath it.
09:42So it was a very large and very tall structure for its time when it was built in the mid
09:49to late 80s.
09:50But its monolithic proportions are not the skyway's only defensive innovation.
09:56The structure is shielded by 36 concrete dolphins designed to withstand the impact of an 87,000 tonne ship.
10:07The necessity for these protective structures was born out of horrific tragedy.
10:13Florida's picturesque at the right time of the year, but the land of sunshine is getting her first big blow
10:18of the season.
10:19Howling wind and blinding rain.
10:21The signboard behaves like a weathercock gone mad.
10:23And if your car doesn't blow over, the trees probably will, which makes driving rather dangerous.
10:27The original Sunshine Skyway met its end in 1980, when a tanker veered off course, losing its way in a
10:36southern squall.
10:39Reduced visibility and strong winds conspired against the tanker's crew, who were unable to correct its course before it slammed
10:49into a support pier, collapsing the southbound span, plunging 35 people to their deaths.
11:07When the Bob Graham Sunshine Skyway Bridge alignment was developed, it was done in a way that would be safer
11:15for ship traffic.
11:18What the Skyway Bridge did was advanced technology.
11:24Now, bridges were actually designed for ship impact.
11:29The beautiful lines of the Sunshine Skyway are undeniable.
11:34And in the 80s, the vertical clearance beneath the bridge was more than adequate for the tallest vessels accessing Tampa
11:42Bay.
11:44But now, many of the world's largest ships would struggle to fit beneath it.
11:50The explosion in volume and bulk of large seafaring vessels plying our waterways has compromised the functionality of more than
11:59one span around the globe.
12:02To make way for a more height-sensitive crossing, some bridges have suffered the violence of demolition, while others have
12:12had to step it up quite literally.
12:16The Carreinte Canal, which winds through the French city of Martigues, has presented at times a bit of a poser,
12:22especially if you want to get over to the other side.
12:27The authorities decided to jack up the entire centre span, a method used for the first time on the continent.
12:36Like French baking, it rises splendidly to the occasion.
12:39And there's no doubt about it, the French really are fast workers.
12:49One historic span in America that required a makeover to cope with the tall ship dilemma was Othmar Amman's Bayonne
12:57Bridge.
13:02Rather than replacing the whole bridge, the cost-effective decision was taken to realign its deck and roadway approaches.
13:13The functionally improved and yet, many would argue, aesthetically compromised Bayonne opened in 2019 with a navigational clearance of 66
13:27metres.
13:32While functionality can't be ignored, one can't help but lament at the necessity of such sacrifices.
13:40Which begs the question...
13:47A bridge is a feat of engineering, but it's also a leap of the imagination.
13:56It is a structure that is beautiful.
14:01Fundamentally, bridge design has to start with the structural demands.
14:06It has to be safe, it has to be reliable, it has to be economical.
14:12But if you only consider those requirements of a structure, you don't get any joy.
14:19I think beauty is important, but what's most interesting about that is trying to decide what beauty is.
14:26For me, a beautiful bridge is a bridge which is efficient, which is an elegant way of making the crossings.
14:33So its form should reflect the way that the structure is working.
14:38That's what a beautiful bridge is for me.
14:43Beauty is in the eye of the beholder.
14:46When I was a young engineer, I was always told that beauty is in the eye of the most senior
14:51beholder.
14:56It takes effort to make them beautiful, but you also need good ideas, good engineering, and a good eye.
15:05And when you look at bridges in different cities, different places, it's almost a continuum that some are towards the
15:11sculpture and some are towards the structure.
15:13And I think there's a place for all of them.
15:23The evolution of bridge engineering has long been linked to advances in materials and construction processes.
15:33But one giant leap forward in the 1980s came about through modeling.
15:40An airplane designer sketches on a computer display console with a light pen.
15:45Such simulations save enormous amounts of time.
15:57Design software started off with just basic computer calculation features.
16:04Back when I started in this industry, we were doing these 80 column cards, these manila cards, and using a
16:09punch machine to get the data files put together.
16:12Running them up to a service bureau where the numbers would crunch overnight and get printed out.
16:18And we'd come back and get a box of fanful paper the next morning and pour through it and try
16:22to make sense of it all.
16:24Little did we realize at the time just how digitally driven society would become off the back of the invention
16:32of the personal computer.
16:35Year on year as this new technology evolved, civil engineers kept pace, marching lockstep towards a wholly digital future.
16:47Computer technology has really advanced bridges, both technically and visually.
16:55Technically, we're able to run models in three dimensional analysis with time dependent effects that allow us to look at
17:04so many more options than we were able to do before.
17:11From a visual standpoint, the technology allows us to create animations, realistic renderings and details of what a bridge will
17:24look like.
17:25It's not uncommon that you'll look at a picture of a bridge and find yourself asking yourself is that a
17:33bridge that's been built yet or is that a picture of what it's going to look like.
17:40Design is one half of what we do. Communication is the other half.
17:46Being able to communicate design in a way that is really widely understood is very important.
17:59And so these three dimensional technologies really have allowed us to share in a way the visual characteristics of different
18:07bridge ideas or concepts with owners and other interested parties that prior to that we really had no way to
18:15do.
18:17So it's really revolutionized our ability to communicate ideas and understand the context of bridges.
18:24We can do virtual realities so people can experience it before it's built.
18:32And that helps to give people an opportunity to make a decision over the details of a bridge.
18:41And it creates more engagement, more communication, more ability to make a bridge that is truly a very important gateway
18:51for that community.
18:56One of the other new technologies which is emerging in structural engineering is the use of sensors that more and
19:02more we can actually track in real time the behavior of a structure.
19:09We work with this concept of having a digital twin.
19:14So we've got a physical bridge and we have a digital version of that bridge.
19:19And one of the things that's really exciting is to think about how that physical model and digital model could
19:24talk to one another throughout the life of the structure.
19:26So we could understand how it's performing and make sure that we're optimizing the way in which we're maintaining it.
19:37Computer modeling, even in its infancy, helped to improve the safety of new and existing structures.
19:45It also allowed new and often complex technologies to emerge.
19:52Particularly on infrastructure developments that were destined to break new ground.
19:58In Japan, disaster recently struck in the form of earthquake and tidal wave.
20:04Any bridges built across the land of the rising sun, by necessity, requires resilience.
20:13For the entire nation straddles the Pacific ring of fire.
20:17One of the most active earthquake zones on the planet.
20:23Including a whopping 20% of all the world's largest, with a magnitude of 6.0 or more.
20:33Between 1970 and 1999, the nation pushed the boundaries of engineering innovation.
20:40By building not one, but three giant bridge systems across the Seto Inland Sea.
20:46An area often subject to the vagaries of violent typhoons, tsunamis and earthquakes.
20:55The bridge systems consisted of 16 long span structures.
21:00The world's first and only paired cable stay bridges.
21:05And the world's longest suspension bridge, the Akashi Kaikyo Bridge.
21:17The Akashi Kaikyo Bridge component was put through a rigorous earthquake test, for real.
21:29While under construction, the area was hit by a magnitude 6.9 earthquake.
21:35On January 17th, 1995.
21:41In 20 tumultuous seconds, the Great Hanshin earthquake obliterated tens of thousands of structures.
21:50Claiming the lives of 6,433 people.
22:00Turning highways and overpasses into origami fans, it brought the smouldering city of Kobe to its knees.
22:12As ruptured gas pipes ignite new fires across the city, the firefighters do not lack the will, but they are
22:18running out of water.
22:20The epicenter of this destructive quake was only 10 kilometers from the site of the span.
22:28And yet, the strongest, longest, tallest, and with a $3.6 billion price tag, most expensive suspension bridge on Earth
22:42prevailed.
22:45The Akashi Kaikyo Bridge in Japan is, at the moment, not for long, but at the moment, the longest span
22:52in the world.
22:55But it has a span of 1,991 meters.
22:59It was designed initially for 1,990.
23:05But while it was being constructed, the towers were up and the main cables were up, luckily nothing else.
23:12The January 1995 Kobe earthquake happened.
23:17The ancient earthquake moved the towers literally a meter apart from where they were designed to be.
23:24The ground just got bigger between them.
23:28So the bridge is actually 1,991 meters long.
23:32The cable is a little bit less saggy than it was, and so they had to adjust to all the
23:36lengths of the hangers and so on.
23:38But the bridge remains 1,991 meters long.
23:44The Akashi Kaikyo was designed with a lifespan of 200 years, nearly double that of most modern bridges.
23:54Every element is state-of-the-art, rendered on a monumental scale.
24:01The cables alone contain enough high-strength steel wire to stretch around the Earth seven times.
24:09And their placement involved an entirely new twist on the practice of aerial spinning.
24:20With this super long span, you've got these two towers, which are very, very tall, and incidentally they're not parallel,
24:26because they're perpendicular to the Earth's surface.
24:30You had to string a cable across from one to the other. Of course you've got to build the cables.
24:35And how do you start?
24:37In this case, what they did, they used a helicopter to take a wire across from one side to the
24:42other.
24:43And this cable is built using a thing called preformed parallel wire strands.
24:48The first time it was done, where they take the wires and they assemble them into strands, 127 wires each,
24:54and they pull them across from one side to the other until they've got the entire bundle.
24:59And these cables, I think, they're about just over a meter diameter by the time they've compressed them and wrapped
25:06them.
25:07And in this case, also dehumidified them, so the dehumidification inside the cable to keep the wires dry so they
25:14don't corrode.
25:15These days, when we do new suspension bridges, we always introduce dehumidification, because frankly, a corroded main cable is no
25:23joke.
25:24Corroded cables were the least of anyone's worries back in 1989, when the Loma Prieta earthquake hit San Francisco.
25:36Prepare yourselves! Prepare yourselves! Shut off the gas! Shut off electricity!
25:42Store water in your bathtub! Don't expect services for 72 hours! Prepare yourself for nightfall!
25:51The Loma Prieta earthquake happened during the World Series.
25:56And the World Series, then, was between the San Francisco Giants and the Oakland A's.
26:00So to have an earthquake the day of one of those games was coincidental, incredibly coincidental.
26:10It was a major disaster for San Francisco. It collapsed freeways, it collapsed the Double Deck Freeway, the Nimitz Freeway,
26:17killed over 50 people there.
26:20The earthquake happened at 5.17 in the afternoon, which normally is heavy commute time.
26:26But because there was a World Series game on, a lot of people were home already.
26:33So the freeways were relatively quiet.
26:39Had that been a regular day, the death toll would have been much, much worse.
26:49The Golden Gate was unharmed by the incident.
26:54But the Bay Bridge, between Oakland and San Francisco, suffered irreparable damage.
27:06Most branches of engineering, engineers learn their lessons in labs or factories.
27:11They get to test what they design.
27:14But with the scale of what we do, you don't have that opportunity.
27:17So what we learn, out of all that, is not just how to design something for a big event, but
27:25that as engineers, we need to be able to design things that are resilient.
27:32The new asymmetrical cable stay span, one that could withstand an 8.5 magnitude earthquake, was completed in 2013.
27:43With a life expectancy of around 150 years, the new San Francisco-Oakland Bay Bridge should be able to handle
27:51anything the San Andreas Fulch throws at it.
27:54And that's what design standards give us.
27:57They give us a tool against which we can check and make sure that we're happy that those essential requirements
28:02that we need of the structure are satisfied before it is built.
28:06Seismic design codes for bridges in the United States are completely different than they were in the early 1980s.
28:13Much for the better.
28:17In civil engineering, ensuring the functionality and safety of a structure comes first and foremost.
28:25During the 80s and 90s, our bridge builders took some truly innovative strides.
28:33But this period also saw a rise in emphasis on a structure's form.
28:40As the engineers' aesthetically driven counterparts reemerged in the bridge building field.
28:48Until the 17th century, you had usually an architect designing the overall structure and then an entrepreneur building it.
28:56Then the engineer appeared in the 17th, 18th century and progressively expelled the architect, who was no longer in charge
29:03of significant things.
29:04And today it's true there is a return of architects.
29:08You can have invention, you can have new form, you can have a surprise, which really opened the way to
29:14a very interesting perception of bridges.
29:19I think bridges needed a stark attack for a little while at least.
29:25Few bridge designers have developed as robust a reputation in this space as Santiago Calatrava.
29:35A Swiss-born Zurich-based artist with a prodigious portfolio.
29:41I think Calatrava's a really important figure, particularly in the sort of latter part of the 20th century and into
29:50the 21st century.
29:52He was probably the first to show the potential of really creating civic pride and creating these sort of very
30:01dramatic sculptural bridges.
30:04He kind of opened your eyes to the possibility that bridges could have this sort of special place in the
30:10city.
30:11He's an engineer, he's an architect, he's an artist, and he brings all of those things together to create these
30:19wonderful, beautiful, iconic structures.
30:26The Margaret Hunt Hill Bridge in Dallas is a landmark bridge.
30:30It's a roadway bridge, and it's a cable-stay bridge.
30:35One of the interesting features is that the cables are supported by an arch, but a transverse arch.
30:44Typically what happens is the longest cable goes to the highest point, and that's to keep the angle of the
30:49cables as efficient as possible.
30:51In this particular case, the longest cable actually comes to a lower point, and then the cables sequentially move around
30:57to create this extremely beautiful array of cables.
31:02It's a phenomenal design feature.
31:13The Samuel Beckett Bridge in Dublin, Ireland is a fantastic bridge.
31:18It's actually an operable bridge. It swings and it moves around.
31:21And when you look at the typology of this, you know, kind of pile-on, kind of cable-stay, you
31:26wouldn't actually assume that that was its intent and purpose.
31:30It's extremely elegant.
31:34The Sundial Bridge in Reading, California is absolutely one of my favorites.
31:39I think, from a contextual point of view, it fits in with that surrounding landscape.
31:46It's called the Sundial Bridge because of the way the tower's aligned with the Sundial that's around the tower.
31:53That part of it's interesting. It's a beautiful bridge, and it fits the site very well.
31:58It has a presence, but it has a delicacy and a touch that comes from an artist, an engineer, and
32:04an architect, which is Mr. Caltraver.
32:13One of the more challenging locations Calatrava had to contend with was the pristine Bow River in Calgary.
32:24Which required a departure away from his signature asymmetrical bridges.
32:33We couldn't go too far down in terms of the profile of the bridge because of the flood level.
32:39There was a flight path coming across which prohibited putting in something that was going to be tall, a mass
32:45structure or even an arch structure.
32:48So the idea of something that was going to span 125 meters, it fit within that narrow profile.
32:56I thought Mr. Calatrava came up with a phenomenal solution in terms of a truss and adopting what is a
33:02very conventional structural object,
33:05but really making it beautiful and making it iconic and a landmark.
33:11It's built with a pair of steel trusses that are curved around the walking space.
33:19And then it has plexiglass on the sides of it.
33:23So you can see through it, but it's protected.
33:35While Calatrava has always been able to bring an artistic and architectural sensitivity to his own work,
33:43contractors and engineers often outsource this particular skill set.
33:52If you take people like Calatrava, they are both architects and engineers, they are architects who are more tech prone.
34:00But sometimes, yeah, the architect is just there for the overall elegance of proportion and design.
34:07So it does create tension now and then.
34:11I don't see engineering and architecture necessarily as two different things.
34:15I see it very much as the two professions that collaborate and speak the same language at the end, if
34:21it's successful.
34:23They bring a dimension, a perspective.
34:27They have a better understanding of the sort of human, social, cultural factors very often, because it's part of the
34:34way they've been trained.
34:38Bridges that simply make a statement for the sake of making a statement tend to go out of fashion.
34:43But the ones that have been very carefully thought about where engineers and architects work very well together tend to
34:49have a longevity.
34:53With the 20th century winding down, a new bridge building giant was set to emerge.
35:04Largely isolated from the global community for almost 50 years, China's shadow now loomed large on the international landscape.
35:16China has been practicing grand infrastructure projects for a very long time.
35:21We can go back over a thousand years to the building of the Grand Canal.
35:27Of course, we go back even further than that to talk about the one great infrastructure project spanned over millennia,
35:34the Great Wall of China.
35:38The Chinese do big infrastructure projects, and I think they do it probably better than anyone else in the world.
35:47There is little doubt China is making up for lost time.
35:58We go back to 1949 when Mao Zedong united the People's Republic of China for the first time, a country
36:05that was extremely poor.
36:08Through the 1950s and 60s, there was this heavy industrialisation push with the primary motivation to catch up with the
36:16West.
36:18Now they didn't succeed in doing that.
36:22It's from the late 1990s onwards that you start to see an absolute explosion of railways, highways, ports that really
36:33put China on their global infrastructure map.
36:36The pace of bridge construction in China has really been astonishing.
36:42It's the largest development of infrastructure since the Industrial Revolution.
36:49China has developed a road network and a high speed rail network with a pace that is really quite unprecedented.
36:59How this has totally transformed the nation is most apparent in the old port city of Shanghai, a city historically
37:08divided in two by the Huangpu River, the final tributary of the Yangtze before it enters the East China Sea.
37:19Today, the river is crossed by eight bridges and 10 tunnels, but the first to span the Huangpu was the
37:26Nunpu, the fourth largest cable stay bridge in the world at the time.
37:35Several dramatic circular approaches helped ensure the main span had sufficient clearance to accommodate 55 ton container ships.
37:47Completed in under three years, the Nunpu stimulated the economic development of Shanghai and fast tracked the rise and rise
37:58of Pudong, China's capital of capital.
38:04The pace of development is not really driven by any special technologies, not even really by sheer labor force. It's
38:16really driven by political will.
38:20Something China clearly had in space.
38:27We can design a bridge quickly, but that's no good if it then takes a very long time to decide
38:33whether to move to the next stage.
38:38Expedient and economical, cable stay bridges hit their stride as the world raced towards the 21st century.
38:50Granted, they were not yet suitable for extra long sea crossings, but for mid-range projects with modest budgets, they
38:59were indispensable.
39:05With this cable stay bridge, once you build the towers, you can immediately start launching the roadway deck from either
39:12tower.
39:13And as the deck can't levers out from the towers, the cables can be attached.
39:20So it's a much faster process. There's less materials involved, typically. And so it is a more economical, faster design.
39:36As China's prosperity grew domestically, the attention of the international community turned to one of its former territories.
39:45For the better part of the century, China could only watch as the British benefited from the trade nexus that
39:53was Hong Kong.
39:55And civil engineering projects were crucial to the colony's success.
40:01With freight terminals, airports and, of course, bridges, facilitating the region's economic might.
40:10As the 20th century drew to a close, one suspension bridge would become the symbol of Hong Kong's colonial past
40:17and China's growing place on the international stage.
40:25The suspended bridge deck of Chumar Bridge is a steel truss structure, fabricated in the UK and Dubai, shipped to
40:32China, where they were assembled into 18-metre long bridge segments.
40:37And then from there, taken by barge around by sea, to be lifted up onto the bridge on the cables,
40:42like a kind of Newton's cradle, if you remember those.
40:47And not until they're all joined together do you know that you've got the right geometry and the engineer who
40:52did the calculation breathes a sigh of relief.
40:59Connecting specifically the islands of Tsingyi and Ma 1.
41:05With a main span of 1,377 metres, Tsing Ma still holds a record for the longest suspension bridge in
41:15the world, capable of carrying trains.
41:21The Tsing Ma Bridge is part of the Lantau fixed link, which connects Lantau Island with Hong Kong.
41:28And Lantau is where the new airport, the Cheplak Cock Airport was being built back in 1980s.
41:39And they needed a bridge to get to the new islands.
41:42And this bridge was going to carry not only vehicle traffic, but also the airport railway, the MTR.
41:48The Tsing Ma Bridge is a double level bridge, because the bridge deck is a tube.
41:53And the rail travels on the lower level, effectively in a tunnel.
41:57So when you're on the train, if you're coming into Hong Kong from the airport, you would never know that
42:01you're on a bridge.
42:04Not only did the designers have to take road and rail traffic into consideration,
42:09they also had to contend with the weather.
42:12For the area is frequently subject to typhoons.
42:17And the nature of a typhoon is such that the wind loading that it imposes on a structure is extremely
42:23high.
42:33The Tsing Ma Bridge had to be designed for the aerodynamic effects of that strong wind.
42:38So the suspended deck of the Tsing Ma Bridge is a steel truss structure with this cladding on the outside,
42:44which makes it aerodynamically stable and encloses the lower deck.
42:49It's a sheet of steel, which makes it an aerofoil shape so that the wind passes over it as smoothly
42:55as possible.
42:56The bridge was designed so that in a typhoon condition, a mild typhoon,
43:00they will divert the traffic from the upper level, where it's exposed to the wind,
43:05to the lower level where it's not.
43:08If the big typhoon comes, no, they close the bridge and tough, you don't get your airflow.
43:12But then no flights are going anyway.
43:18Come, see this bridge, one of the foremost monuments of our time.
43:27And put your confidence in the people who built it.
43:35The Tsing Ma Bridge and the Lantau Link was completed in 1997.
43:39A very significant year in Hong Kong because it was the year in which Hong Kong was handed back to
43:43the Chinese,
43:44having been part of the UK for a very long time.
43:51So it was a very significant moment when the bridge was opened and then handed back to the Chinese.
44:03With the 21st century coming to a close,
44:06the next decade would see the rise of some truly gigantic structures.
44:12putting to good use the lessons of the last century, these massive engineering enterprises made use of all bridge typologies
44:21and technologies,
44:22often in the same structure.
44:27And around the same time that Hong Kong was being welcomed back into China's embrace,
44:32one such structure was being completed.
44:37Banning the roughly 16 kilometres of open ocean between Denmark and Sweden,
44:42this ambitious civil engineering project required three very different components.
44:49A cable stay bridge,
44:51an artificial island
44:54and an undersea tunnel.
44:58The Oresund Bridge is an engineering feat, there's no doubt about that.
45:05One of the things that is unique about it is it connects together two different countries,
45:11which brings with it a certain scale.
45:14So the Oresund Link has provided a lot of prosperity to the region
45:18and I think it just demonstrates the potential of creating a fixed link
45:23and what it means in terms of development for that region.
45:30The bridge accounts for half the length of the link,
45:33with two 204-metre towers supporting the main 490-metre span.
45:49It's located quite close to Copenhagen Airport, so there was a restriction to the pylon height.
45:56Also since it's spanning a straight, so it's crossing the navigation channel,
46:01there are quite significant ship impacts to account for.
46:07For the train traffic, the electrification and the signalling is different on the Swedish side and on the Danish side.
46:14Sometime during the design, somebody had to make a decision
46:18whether we make the transition from one system to the other.
46:23Needless to say, Mother Nature provided her own share of challenges as well.
46:29In adverse weather conditions, there will be ice built up on the stay cables.
46:33And of course, for the safety of the users of the bridge, it's important to make sure that the ice
46:38does not drop on the traffic lanes.
46:41And there have been a few occasions where it was necessary to close the bridge until the ice had been
46:46removed from the cables.
46:55I think the best bridges respect nature.
47:00The forces of nature are beyond our control.
47:04We understand them as best we can, and we try and put a man-made structure within the environment that
47:12will survive in nature.
47:15What we do as engineers is real.
47:18We don't learn from earthquakes or from floods.
47:22It's catastrophic for people.
47:23People die if we don't do these things right.
47:27In terms of new technology, most bridge engineers are conservative by nature.
47:32And this is a reflection, I think, of the fact that what they produce is intended to last the design
47:37life of a hundred plus years.
47:40We know that a lot changes over that period.
47:43So we're working with concepts around designing for adaptability, or designing for resilience, or designing with embedded technology that can
47:52tell us about how a bridge is really performing.
47:56And all of these things are woven into many decisions associated with sustainability.
48:05Recognizing that we need to be protective of our natural resources, how we use them, how we advance technology.
48:16To improve our sustainability and think about our future as it relates to the beautiful things that Mother Nature has
48:26given us.
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