The Øresund Bridge: Connecting Sweden and Denmark

Hello and welcome back to another episode of Megaprojekts! This one… Oh, how do you pronounce an O with a slash through it? Help me out, pronunciation wizard! Øresund. I'm sorry. I'm trying my best. Øresund Bridge. That's what this video is about. Let's jump in. This Megaprojekt may have the word bridge in its name, but it's really much more than that. The Øresund Bridge, which connects Denmark and Sweden, is now one of those iconic structures known around the world that has begun to define the early 21st century. Part bridge. Part island. Part tunnel. This is a true marvel of modern engineering. The Danish call it Øresundbrun. The Swedish call it Øresundsbrun. Why languages? Why? But let's just call it the bridge, alright? If you happen to watch the wildly popular detective drama with the same name about a murder committed halfway across it, you'll probably know all about it. I haven't seen that show. If I did, I'd probably know how to pronounce it, wouldn't I? The Øresund Bridge is the longest combined road and rail bridge in Europe, and it stretches nearly 16 kilometers, that's 10 miles, connecting the greater Copenhagen and Malmö areas. But, as I said, this is much more than just a bridge. If you're coming across from Sweden about halfway across the Øresund Sound, the stretch of water between the two countries, the bridge dives down into an artificial island and disappears into a tunnel, only to reappear 4 kilometers, 2.5 miles later, next to Copenhagen Airport. So why? Why such an intricate combination of bridge, island and tunnel? Well, keep watching, and you'll find out. That'll be good for my watch time. Let's just say, from the outset, here there are few pieces of engineering around the world quite as spectacular as the Øresund Bridge. It's not the tallest, it's not the longest, and it's probably not even the most visually striking. you're passing through the pinnacle of modern engineering. Building something like this would've been unimaginable 50 years ago, but the idea of connecting Denmark and Sweden goes back to the second half of the 19th century. The giant leap forward taken during the Industrial Revolution showed that, in theory, a bridge connecting the two countries across the Øresund Sound was at least possible, though cost and obscure economic benefits were huge stumbling blocks. Instead, the two countries focused their efforts on the tried and tested sea transportation, as it remained significantly easier and cheaper. In 1865, Swedish engineer Claes Adelskog submitted a proposal to the King of Sweden, Karl XV. Look at you, you legend with an easy-to-pronounce name! To build a railway tunnel beneath the Øresund Sound, but this was turned down in 1889. An underwater railroad tunnel between Helsinor and Helsingborg was also rejected, both again due to exorbitant costs and a lack of need for it. This began to change at the dawn of the 20th century. The new form of transportation arrived and would go on to revolutionize how we travel. The automobile gave people a level of freedom that had been unheard of until that point, and suddenly the idea of a bridge across the Sound became a whole lot more enticing. During the 1930s, there were serious discussions surrounding the project, involving some of the leading Nordic engineers at the time, but as you probably know, the 1930s in Europe Europe started to go downhill fairly rapidly, and both governments made the quite sensible decision that with the build-up of arms throughout Europe, it probably wasn't the best time to begin a giant construction project. Discussions picked up again in the 1950s and rumbled on for the next few decades, but vehement opposition from farmers, environmentalists and, eventually, both governments appeared to torpedo the proposal once and for all. By the early 1990s, things had changed. The collapse of the USSR offered a glimpse of a tighter global connectivity, and there was also the fact that both Denmark and Sweden were in the midst of serious financial crises. So what better way to boost the economy and encourage trade than building one of the world's greatest engineering projects right on your doorstep? In 1991, both the Danish and Swedish governments issued a bilateral agreement on the building of the Åresund Bridge, and 126 years after the first proposal was submitted, the project finally got its green light. But there was, of course, a long way still to go. Several factors meant that simply building a massive suspension bridge across the Åresund Sound was out of the question. Its proximity to Copenhagen Airport meant that tall, man-made objects were seen as far too risky. After all, the last thing you want after building such a superb structure is for a plane to smash into it in thick fog. But the bridge also couldn't be too low, as the Sound sees heavy boat traffic. The second issue was how to combine a road and rail connection. A traditional cable suspension bridge often looks wonderful, but it's normally far too shaky for trains that, rather annoyingly, prefer a nice, flat, vibration-free surface. Whatever design would be used, it would have to stretch the boundaries of modern engineering. A design contest was initiated, both as a way of garnering a wide selection of ideas, but also to gain plenty of publicity. The final design was composed to have work drawn from Jörgen Nissen and Klaus Faber-Hansen, and Ove Arup and partners, and Nils Gimsing and George Rodner, and it was ambitious to say the least. The design called for a bridge measuring 8km, 5 miles, that would travel from the Swedish coast to the small island roughly in the middle of the Sound. Oh, we should add that there weren't actually any suitable islands in that particular stretch of water, so an artificial island would have to be created. On this newly formed island, the road and rail line would then disappear into a black hole and travel 4km, 2.5 miles, through the Dragden Tunnel before re-emerging on the Danish side of the Sound. The most visually impressive section of the Orsund Bridge must be the bridge itself. To be fair, that's probably because you can't actually see the rest of it. As I mentioned earlier in the video, a transitional suspension bridge would have been unsuitable for train travel, so designers went with a cable-stayed design, which can transfer the massive weight through multiple cables back to the main towers. The bridge consists of four main support towers, each 204m high, equivalent to a 60-story building, and has 160 separate cables. Its towers are completely unconnected from one another, a design feature chosen so that in the worst-case scenario that a plane was to hit one of them, the bridge would in theory remain standing. A four-lane road passes along a horizontal girder that runs the length of the bridge, with two railway tracks running beneath the road. The height of the bridge leaves 57m, 187ft of headroom, for shipping to pass under the main span. The four support towers are connected to giant foundations that were first constructed on land. Each foundation measured 1,500 square meters, weighed 18,000 tons and reached 22m in height, and they were all lowered into trenches dug into the Sound 17m deep. Once the foundations were in place, construction could begin to slowly raise each of the four towers. When they reached 44m, the crossbeam was added, and at 80m, a steel box for the cables was also installed, with additional boxes every 12m. The horizontal girders where the road and railway lines run were then added, with each section measuring 140m in length, 23m wide, and weighing 5.5 million tons each. Again, these were first constructed on land, then installed during a painstakingly slow process where they were gradually winched up from a truly heavy, weight-lifting barge. In total, the bridge weighs 82,000 tons, which, for comparison, is about eight Eiffel Towers. In August 1995, dredging work began in the Oresund Sound that would eventually create the artificial island of Perberholm. The island was formed almost exclusively of dredged seafloor material, which is great if you simply want to build a landmass that could accommodate people and small structures, The first step was to build a perimeter that the island would eventually fill, and to do this, 1.8 million tons of large quarried stones were brought in from Sweden. This perimeter was carefully set using GPS, and measured 12km in length when completed. Then came the mammoth job of actually dredging enough seafloor material to create the island. This was done with some absolutely colossal pieces of machinery. Most notably, the largest dip dredger in the world, the Chicago, with a shovel capable of digging up 22 cubic meters of seabed in a single scoop. That's about 776 cubic feet, by the way. The material was then transferred onto floating barges and moved to the island area, where smaller diggers piled the seabed up to create the island. Perberholm is 4km long, with an average width of 500m and a height of 20m. And this being built by the rather thoughtful Scandinavians, the entire island has been designated as a nature reserve. Seen very much as a natural experiment, the island has thrived since its creation, and is now home to over 500 separate plant species. To add a little spice, or sting, in 2005, environmental researchers discovered the venomous hobo spider on the island, a creature only found in certain spots of Denmark. It's believed to have traveled there by train, which seems rather appropriate considering its name, Hobo. As I just mentioned, the fact that Perberholm was built entirely with seafloor material meant that engineers needed to find another way of inserting 4km worth of tunnel under the Orison Sound. The word inserting might sound a little strange when talking about a tunnel, but essentially, that's exactly what happened. With tunneling out of the question, the Drogden Tunnel was actually formed of multiple concrete tunnel segments built at a Danish facility that were then placed inside a tunnel trench that had been dredged from the Danish coast to the island of Perberholm in the middle of the sound. This trench was 11m deep, 46m wide, and had a total of 2 million cubic meters of seabed excavated from it. To kill two birds with one stone, or several billion stones if you really want to be finicky, the material removed from the trench also made up part of Perberholm, and was transferred there via purpose-built pipelines. The 20 segments were outrageously big, each measuring 175m long, 38m wide, and 8.5m high. They included five tunnel sections, two for cars, two for rail transportation, and one for emergency use. Each piece weighed a massive 55,000 tons, that's four times the weight of the Brooklyn Bridge in case you're interested, and also included 40,000 tons of reinforced steel bars, which acted as the frame, which was then filled with concrete. All 20 segments used a combined 7.5 trillion liters worth of concrete, 1.9 trillion gallons, which is enough to build a pavement around the entire Earth… twice. The segments were all sealed shut, which allowed them to be floated out into the sounds. I know this sounds unbelievable, but it did really happen. They were then lowered into the trench, with the entire stretch then backfilled to create a tunnel that hadn't actually been tunneled, if I'm making any sense here. And perhaps unsurprisingly, considering the complexities, it was while building the tunnel that the project faced its most dramatic moments. An eagle-eyed worker on one of the barges suddenly noticed something metallic in a pile of rock that had been brought up from the sea floor. Taking a closer look, he was horrified by what he saw. The Chicago had dredged up an unexploded bomb from World War II, and had dumped it unknowingly on the barge. Miraculously, it hadn't gone off, and the site was quickly evacuated. The Danish Navy was called in to defuse the bomb, and everyone breathed a sigh of relief. But things weren't over. Another bomb was soon discovered, and the decision was taken that no area could be dredged until it had been swept for bombs first. Astonishingly, a total of 16 Allied bombs from the Second World War were discovered during the construction of the Øresund Bridge, but fortunately all of them were defused safely. The Øresund Bridge took nine years to build, and despite finding far too many unexploded bombs for comfort, it was finished three months ahead of schedule. Rare on megaprojects! It officially opened to the public during several open days between the 9th and 12th of June in the year 2000, and was inaugurated with plenty of gusto on the 1st of July of that same year. It cost a total of 30.1 billion Danish Kroner, about $4.5 billion at the time, which equates to roughly $6.9 billion today. Broadly speaking, the Øresund Bridge has been a great success, and in its busiest year in 2017, on average just over 20,000 cars passed over the bridge every day, and roughly 14,000 rail commuters passed across the Øresund Sound. Since its opening, nearly 250 million people have crossed the Øresund Bridge either by car or rail. It is, however, not cheap to drive on. The total cost for a single trip currently is $50, though there are considerable discounts for frequent users. With this kind of pricing, it's not surprising that the bridge will have effectively paid for itself by the year 2030. This is a wonderful bit of engineering which broke countless records for size and distance. It was a project that faced serious hurdles because of its location, but one which engineers and designers were able to safely navigate around. As I said right at the start of today's video, this is one megaproject that really gives you a sense of grand achievement, and where humans have pushed the boundaries of what's possible. And as we've seen, this is a bridge that's so much more than just a bridge. So I really hope you enjoyed this video. If you did, please don't forget to check out SideProjects, it's the sister channel of this channel, Megaprojects, where we cover things on a smaller scale that are no less interesting. Find a link to it below and thank you for watching.