Transportation Feats of the World: Journey across the Akashi Kaikyo

InTrans / Jun 22, 2017

Transportation Feats of the World: Journey across the Akashi Kaikyo

Go! Magazine

posted on June 22, 2017

We’re traveling across the globe to highlight the greatest of transportation feats! So, what’s the next stop on GO! Magazine’s tour of the Seven Great Transportation Feats of the World?

This time, we’re heading to Japan to visit what is considered this island nation’s finest engineering feat: the Akashi Kaikyo Bridge.

Also called the “Pearl Bridge” because of its’ light display, the Akashi Kaikyo is the longest suspension bridge in the world, measuring over 12,000 ft. long. Linking the Japanese cities of Kobe and Iwaya, crossing over the Akashi Strait, it serves as a critical transportation link across the inland body of water.

History of the Akashi Kaikyo

Like many feats of transportation before it, the Akashi Kaikyo Bridge was built out of necessity.

The Akashi Strait, an international shipping canal connecting the Pacific Ocean to the Sea of Japan, proved to be a dangerous crossing point. Before the Akashi Kaikyo, boats and ferries were used to carry passengers and vehicles across the waterway. It wasn’t until 1955, when a strong storm caused two ferries to sink and the death of 168 people, that the public and Japanese government decided enough was enough.

The bridge was originally intended to be both a railway as well as a road bridge. However, the plan was limited to a road-only bridge with six traffic lanes (three in each direction) by the time construction began in May 1988. Over 100 contractors were hired for the job and construction lasted almost a decade. The bridge was officially opened for traffic in April 1998 and today serves as the safest passage across the Akashi, with over 23,000 vehicles using it daily.

Akashi Kaikyo Bridge under construction in 1995. Photo via Wikimedia Commons.

Stretching the limits

The Akashi Kaikyo Bridge is a suspension bridge, meaning it’s held in tension rather than compression. What that means is that the bridge “deck,” or the load-bearing portion of the bridge, is hung with steel cables that transfer the weight of the load to the bridge towers.

Suspension bridges are different than regular bridges, where the load is supported by steel supports underneath the bridge. Regular bridges are used for smaller gaps, usually over streams and highways, whereas suspension bridges are usually used to cross larger bodies of water. However, most bridges utilize a combination of both suspension and regular bridge engineering techniques.

But the Akashi Kaikyo is no ordinary suspension bridge—it’s the longest suspension bridge in the world! The bridge measures 12,831 ft. long, or about 2.43 miles. That’s the length of over 42 football fields! And it’s almost 1,000 ft. tall, situated 200 ft. above the water.

Akashi Kaikyo Bridge crossing the Akashi Strait. Photo by Tysto via Wikimedia Commons.

It has three different “spans” or distances between bridge towers: a center span and two spans on either side. The Akashi Kaikyo currently holds the record for the longest center span of any suspension bridge, measuring in at about 6,500 feet (1.237 miles). However, the Canakkale 1915 Bridge in Turkey is expected to surpass that center span record once completed.

Feat of transportation

Aside from its length, the Akashi Kaikyo Bridge is designed to hold up even under Japan’s most relentless and extreme weather conditions. It can withstand 178 mph winds, harsh sea currents, and earthquakes measuring up to an 8.5 magnitude.

Japan is located on what is known as the Pacific “ring of fire,” meaning it’s located on the edges of several different continental and oceanic tectonic plates. Much of the earth’s seismic activity occurs at these plate boundaries, making Japan subject to high seismic and volcanic activity.

Aerial view of the Akashi Kaikyo Bridge over the Akashi Strait. Photo from NASA.

For example, the Akashi Kaikyo was put to the test in 1995 when the Great Hanshin earthquake hit Kobe, the city on Japan’s northernmost bank. This 6.9 magnitude earthquake killed over 6,000 people and destroyed over 100,000 buildings, but the bridge towers remained standing.

But, how did the Akashi Kaikyo survive? Inside the towers, there are devices called “dampeners.” Each device weighs 10 tons and hangs on a frame. Dampeners are designed to sway and shift to counteract tremors that could otherwise cause the towers to be knocked over.

Journey across the Akashi Kaikyo

So, what do you think? Would you take a journey across the Akashi Kaikyo Bridge?

You could see it for yourself! The Akashi Kaikyo now serves as one of Japan’s many popular tourist attractions. There’s even a guided tour called “Bridge World” that allows tourists to learn more about the bridge’s construction, take a tour, and even look out over the top.