Friday, 5 December 2014

The Longlist: Akashi Kaikyo Bridge aka the Pearl Bridge

If you look closely, you might notice a new tab in the horizontal green bar at the top of this page. It says "Longlist". If you click on it, it explains a little more about my Longlist, but basically it's for all the other great man-made spectacles in the world that haven't quite made my shortlist. I don't feel the need to research them or visit them, but as long as this blog is about the world's best man-made structures, they deserve some kind of mention. Today, the Akashi Kaikyo Bridge, also known as the Pearl Bridge, in Kobe, Japan.

Take a look at the Golden Gate Bridge, the classic mighty suspension bridge, and once the biggest one on earth. I visited it in August of this year.

Uh-huh. Pretty impressive. The towers are 227 metres from top to water, and the main suspension span in the middle is 1280 metres. Now, let's take a look at the Akashi Kaikyo Bridge, which from now on I'm going to call by its supposed nickname of the Pearl Bridge, because it's a lot easier to write.


Well, that looks pretty impressive too, if you ask me. I'll give you the numbers in a minute, but let's put it and the Golden Gate Bridge side by side by the powers of my photoshop skills.

Forgiving my attempts at photoshop if you will, suddenly the Golden Gate Bridge looks a lot punier. The Pearl Bridge's towers are 283 metres to the Golden Gate's 227, the main span is a whopping 1991 metres to the Golden Gates 1280 metres. It would have been 1990 metres long, but during the construction in the mid-90s, an earthquake pushed the towers an extra metre apart and the engineers just ran with it. It's King Kong versus Godzilla, only the Japanese have given Godzilla a modern revamp and put him on the steroids.

And King Kong's beating has only just begun.

The nation of Japan is composed of several islands. The main one is Honshu. Most of the famous stuff in Japan is in Honshu, such as Tokyo, Kyoto's many temples, the world's shortest escalator, and vending machines selling schoolgirls' underwear. But there are some other useful island too.

It's Shikoku we're interested in here. For most of history, aside from swimming the only way to get there from Honshu was by boat. In the 20th Century, ferries criss-crossed the sea and straits, but while this did the job, it's not the speediest way to link islands. Plus, it could be dangerous. In 1955, rough seas and poor visibility caused two ferries to collide, killing 168 people. And so, a bridge was planned. But not just any bridge. A mega-bridge. No, three mega-bridges. The Pearl Bridge is just one small component of one of the most ambitious network of bridges and crossings ever planned anywhere.

It is called the Honshu-Shikoku Bridge Project. Well, what else would you call it? We needn't be concerned with the precise details, but it involves three separate crossings linking the two islands, of which the Pearl Bridge is just one part of one crossing.

The first of the three crossings to be opened was in 1988, after ten years of work. It comprises eleven different bridges strung together, using five small islands that lie between Honshu and Shikoku. All the bridges are large, but three of them are very large. At the time of writing, they are the 18th, 29th, and 32nd largest suspension bridges in the world - for comparison, the Golden Gate Bridge is the 12th largest. But of course, the Golden Gate Bridge is just a single bridge connecting two landmasses: this crossing connects two landmasses via five smaller landmasses and uses eleven bridges, some of them almost the equal of the Golden Gate Bridge. Oh, and they're all double-decker. It's over eight miles long in total. The Golden Gate Bridge is only a little longer than the bridge in the bottom-left corner of the photo below.

The Pearl Bridge was next to be opened, in 1998, and we'll get to that in a moment, but the third crossing of the trio was opened just a year later. It consists of motorways and ten bridges, totalling 37 miles. Three of these bridges are suspension bridges that run together, and collectively are called the Kurushima-Kaikyo Bridge. Individually, they are the 25th, 26th, and 63rd largest suspension bridges in the world.

This is some background information on the epic series of bridges that the Pearl Bridge belongs to. After ten years of work, the Pearl Bridge was opened in 1998, linking Honshu to an island called Awaji. The 32-mile-long Awaji acts as a go-between, and another bridge (which just so happens to be the 36th biggest suspension bridge on the planet) then takes over, connecting Awaji to Shikoku.

So far we've had the 18th biggest suspension bridge in the world, the 25th, the 26th, the 29th, and so on, but these are all just warm ups. The Pearl Bridge is the biggest suspension bridge in the world, at least when judged by the main span between its two towers, which is usually how these things are judged. Just for good measure, the two towers are also the tallest suspension bridge towers in the world. This all comes with all the usual large numbers and comparisons. There's 181,000 tonnes of steel, which would require 25 Eiffel Towers to be melted down. There's enough wire in the cables to round the world seven times. It's big.

And that would appear to be the main appeal: sheer size. Suspension bridges are usually a fairly graceful style of bridge, and this appears no exception: a gigantic, graceful behmoth spanning the Akashi Strait it takes its name from. The entire length is a fraction under 2.5 miles. Covered in almost two thousand lights that light up in 28 different patterns, I guess it must look very pretty at night. But in form, it's nothing unusual. It looks like most other suspension bridges. Just super-sized.

Of course, size isn't everything. If it were, my quest would be very easy - I'd just visit the biggest bridge, the biggest skyscraper, the biggest pile of bricks, and the biggest statue, and my job would be done. There are many other factors involved, such as looks, impact, fame, age, distinctiveness, and the story behind it all. These are the kind of things that give the Golden Gate Bridge its celebrated status. Sure, its size is very significant, but a full-on World Wonder is the whole package. Let me honest, the Pearl Bridge looks fine, but it hardly stands out among all the other huge suspensions bridges out there. I can't speak for its fame within Japan, but without Wikipedia's list of longest bridges, it's unknown in the wider world. There's no great tale behind it, no Golden Gate Bridge Joseph Strauss figure, or triumph-over-adversity voyage into new realms of engineering. Or perhaps there is, but the Japanese just haven't hyped it the same. How much of a Wonder is hype? Some, anyway.

Still, the Pearl Bridge troubles me. One of my key criteria is the Wow Factor. Look at the size of the thing. The Golden Gate Bridge is big enough, and it has plenty of wow. If I visited Kobe, can I imagine not being blown away by this thing? It may not have the Golden Gate Bridge's handsome orange tan, but its sheer immensity counts  for a lot. My suspicions are that suspension bridges are the new cathedrals: huge and magnificent structures, but the sheer number and repetition of them makes them a little less special. In one sense, this is a great shame; in another, what lucky people we are to be blessed with so many wonderful structures. At some stage in the next few years, I intend to visit Japan and visit the three candidate Wonders I have there; hopefully, I will have the time to check out the Pearl Bridge too. Perhaps I'll look at it and realise, "Yeah, the Golden Gate Bridge really is something special." Or perhaps I'll realise that the sheer might of a modern day Godzilla is too much for a geriatric King Kong.


  1. Your last two paragraphs hit the nail on the head. Why is the Golden Gate Bridge more iconic, and deserving of being a Wonder, than the Pearl Bridge? For the same reason that a 19th century neo-gothic cathedral, however large and spectacular, cannot compare to a true 12th/13th century gothic cathedral. I believe St John the Divine in New York (neo gothic) is one of the biggest cathedrals in the world - but I notice it doesn't figure in your short or long lists (I hope you won't ruin my comment by looking it up and adding it in!!!).

  2. First, pardon my use of "feet" as that measuring method is one I can easily recall facts for and associated interesting comparisons. Unfortunately there are no pedestrian walkways on the Akashi Kaikyo Bridge, thus experiencing like I did by way of walking across it during opening ceremonies back in 1998 is not possible, but it was the best way to get a feel for its size. I like your photoshop comparison. Just realize that ALL 3 spans of the Golden Gate at 6,450 feet can fit between the towers of the AKB of 6,532 feet. You are correct when you mention that the distance between towers (mainspan) is the common method used to measure scale. The AKB mainspan exceeded the previous record holder by 1,906 feet - the largest single jump in mainspan length. Below is a list of suspension bridges holding the record since the Brooklyn Bridge and how their mainspans bettered the previous record in ().

    1881 Brooklyn United States 1,595.5 feet (327.5 feet)
    1903 Williamsburg United States 1,600 feet (4.5 feet)
    1924 Bear Mountain United States 1,632 feet (32 feet)
    1926 Ben Franklin United States 1,750 feet (118 feet)
    1929 Ambassador United States 1,850 feet (100 feet)
    1931 George Washington United States 3,500 feet (1,650 feet)
    1937 Golden Gate United States 4,200 feet (700 feet)
    1964 Verrazano Narrows United States 4,260 feet (60 feet)
    1981 Humber United Kingdom 4,626 feet (366 feet)
    1998 Akashi Kaikyo Japan 6,532 feet (1,906 feet)

    In the 18 years since the Akashi Kaikyo's opening in 1998 there have been four bridges constructed with mainspans that have entered the 5,000 foot category. Still none come within 1,000 feet of the Akashi Kaikyo's 6,532 feet.

    2009 Xihoumen China 5,413 feet
    1998 Great Belt Denmark 5,328 feet
    2016 Izmit Bay Turkey 5,085 feet
    2012 Yi Sun-sin South Korea 5,069 feet

    Now consider that when looking at a suspension bridge you are not just looking at the mainspan, but usually the accompanying side spans as well. The entire package makes for majestic beauty with the gracefully sweeping "M" of the combined spans. The AKB three spans total 12,832 feet. Two Golden Gate Bridges placed end to end would be only a barely discernable 68 feet longer at 12,900 feet (6,450 feet X 2). The AKB three span total bettered the previous record 7,400 feet of the Mackinac by 5,432 feet! The AKB literally beat the Mighty Mac by a mile (5,280 feet)! But that bettering was a quantum leap when compared to the three span records going through suspension bridge history.

    1866 John A Roebling United States 295 / 1,057 / 292 1,644
    1883 Brooklyn United States 930 / 1,596 / 930 3,456 (1,812)
    1931 George Washington United States 610 / 3,500 / 650 4,760 (1,304)
    1937 Golden Gate United States 1,125 / 4,200 / 1,125 6,450 (1,690)
    1957 Mackinac United States 1,800 / 3,800 / 1,800 7,400 (950)
    1998 Akashi Kaikyo Japan 3,150 / 6,532 / 3,150 12,832 (5,432)

    I find it incredible that three span totals through history went from 3,000, 4,000, 6,000, 7,000 feet categories, then the AKB opened it up to well within the 12,000 feet category. Since the completion of the AKB there have only been two suspension bridges to enter the 8,000 feet category -

    1998 Great Belt Denmark 1,755 / 5,328 / 1,755 8,838
    2016 Izmit Bay Turkey 1,857 / 5,085 / 1,857 8,799

    Now the amazing fact about the AKB that has not been touted is that there were no fatalities during its construction.

    1. Hi Patrick, thanks for one of the most comprehensive comments I've ever received, brilliant stuff and it really emphasises the sheer scale of the Akashi Kaikyo Bridge. Just as the Burj Khalifa thumped the nearest opposition for tallest structure, the Akashi Kaikyo Bridge beats its competition (perhaps even more emphastically) by a considerable margin. Yet, its world profile is almost non-existent.

      You say you walked across it during opening ceremonies? If you come back to this blog, I'd be interested to hear more about this and how it came about.

    2. There was a several day period prior to the opening of the bridge where they permitted 80,000 people to walk across the bridge each day. It was by lottery, and I was fortunate enough to be picked. Writing in 1996 to the Honshu-Shikoku Bridge Authority, I found a sympathetic soul (English speaking too) to my inquiries about the bridge and how I may get a chance to walk across it. I also was invited to join the leading procession at the start of the first day's celebration, but chose instead to walk during my lottery time several hours later that same day with thousands of others as I did not want to be in the spotlight. I ended up there anyways - being the topic of conversation as I was the very rare Caucasian among the throngs of Japanese bridge walkers. Many approached me to ask where I was from, and of my impressions of the bridge. I was told they were honored somebody would come from so far away to see their bridge. One couple befriended me and bought me lunch when we got to the far end of the bridge before turning around. Some asked (upon finding out I'm a US citizen) how I thought the Akashi Kaikyo compared to the Golden Gate.

      Some things to note... the towers of the AKB would have been considerably higher had the Japanese not develop stronger steel for the wires within the main cabls. Shorter towers places more tension on the wires, thus the towers of the AKB would have been 40 meters taller if the same strength steel used in the Golden Gate's main cable wires were used instead. Also, stronger steel meant just a single 42 inch diameter cable was needed on each side, instead of a pair of 36 inch cables on each side as originally planned before the development of the stronger steel. The tower foundations for the Akashi Kaikyo are three times deeper than those of the Golden Gate. The 14 tug boats it took to tow / push each caisson into position is a testament to the size of each caisson and the strength of the currents in the strait. You already mentioned about the earthquake. The AKB was earthquake ready from the start. The Golden Gate started a Seismic Retrofit in 1998, with a scheduled completion in 2021. The Akashi Kaikyo was also built to withstand typhoons from the start. The Golden Gate had to get a Torsional Resistance Retrofit in the mid 50s following a storm in 1951.

      I've liked suspension bridge since I was 5 years old - living in Philadelphia and the couple of suspension bridges we would have to use to get across the Delaware River. Never had much interest in skyscrapers. I feel its just a matter of keep piling on top to make a higher one. Spanning longer distances is where I feel pushing the limits of design and materials takes place. I figure man first had the need to get over something (a river / chasm) before figuring out how to pile more people on top of each other. Sure, the Akashi Kaikyo Bridge lacks the setting the Golden Gate is in, but consider this... the country that has experienced the one single most devastating man made device in history, had gone on in a bit over 50 years time to construct the pinnacle of bridge engineering. Just 24 hours after standing at mid-span on the AKB - a $5 billion structure, I was standing at the original Ground Zero - Hiroshima. What extremes of devastation and construction.

      BTW, I enquired with my Japanese contacts within the Honshu-Shikoku Bridge Authority as to why was the mainspan not made to be just 10 meters (33 feet) longer to 2,000 meters - making it the first to exceed 2 kilometers. I was told that they could have easily done so using the conventional calculations up to that time, but further researched for the optimal placement of the tower foundations and 1,990 meters is what they came up with.


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