Where's the Longest Bridge in the World?

Today’s episode is a followup episode on bridges, which is proving to be one of your most favourite topics. This episode takes us on a journey across an incredible feat of engineering: bridge building! But not just any bridge—we’re talking about the longest bridge in the world. Where is it, how long is it, and how did people even build something so massive? Let’s dive in and find out!

Be sure to also check out "How Do They Get Lights On Top of Really Tall Bridges?" Since, it was posted in October 2024, it's consistently been our most listened to episode. 

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Episode Transcript

I Wonder Podcast (00:03):
Hey there, curious minds, Welcome to
another episode of I Wonder, theshow where we explore the
questions you've been wonderingabout.
Today's episode is a follow-upepisode on bridges and takes us
on a journey across anincredible feat of engineering -
bridge building.
But not just any bridge.

(00:25):
We're talking about the longestbridge in the world.
Where is it, how long is it,and how did people even build
something so massive?
Let's dive in and find out.

(00:46):
What is the longest bridge inthe world?
Drumroll, please.
The longest bridge in the worldis the Danyang-Kunshan Grand
Bridge in China.
This engineering marvelstretches an incredible 102.

(01:15):
4 miles, more than 160kilometers.
To put that into perspective,it's longer than the distance
between New York City andPhiladelphia.
Imagine being on a train andtraveling for over an hour and a
half and still being on thesame bridge.

(01:38):
The Danyang-Guncheng GrandBridge is part of China's
high-speed rail system,connecting the cities of Danyang
and Kunshan on theBeijing-Shanghai high-speed
railway.
It was completed in 2010 andofficially opened in 2011.
The bridge runs through aregion filled with rivers,

(02:01):
canals, farmland - making itessential to keep the railway
elevated for efficiency andsafety.
How did they build it?
Constructing a bridge of thismagnitude was not easy.
It took around 10,000 workers,approximately four years to

(02:24):
complete.
Engineers used 500,000 tons ofsteel and 2.5 million cubic
meters of concrete to ensure thebridge was stable and durable
enough to withstand naturalforces like flooding.
To speed up the constructionprocess, they used

(02:45):
prefabrication.
Large sections of the bridgewere built elsewhere and then
transported to the site wherethey were assembled, like an
enormous puzzle.
The bridge is supported by morethan 2,000 piers, carefully
placed to provide stability andensure the structure could
handle the high-speed trainstraveling up to 186 miles per

(03:10):
hour.
Why do, why do we build bridgeslike this?
Bridges like the Danyang-GunshanGrand Bridge aren't just about
convenience.
They solve real-world problems.
In regions with rivers, lakesor wetlands, building a railway
or road directly on the groundis often impractical or

(03:34):
impossible.
Elevating the railway on abridge not only avoids these
obstacles, but also minimizesthe environmental impact.
By keeping the railway abovethe ground, the bridge protects
vital ecosystems, farmland andwaterways.
Long bridges are also aboutefficiency.

(03:57):
High-speed trains need smooth,straight tracks to maintain
their incredible speeds, andbridges allow engineers to
bypass natural barriers likehills and valleys.
The result is a faster, saferand more reliable route for
passengers.

(04:18):
Are there other long bridges?
While the Danyang-Kunshan GrandBridge holds the top spot.
Other long bridges around theworld are just as impressive.
The Changhua-Kaohsiung Viaductin Taiwan is the second largest
bridge in the world, stretching97.8 miles.

(04:39):
It's also part of a high-speedrail system, showcasing the
importance of really longbridges for modern
transportation.
The Bang Na Expressway inThailand is a 33.5-mile-long
road bridge, which helps toreduce traffic congestion by
spanning urban areas andfarmland.
Then there's the Hong KongZhuhai Macau Bridge, the world's

(05:05):
longest sea bridge.
At 34 miles, it connects threemajor cities and even includes
an underwater tunnel.
Is there a limit to how long abridge can be?

(05:26):
Technically, there's no hardlimit to how long a bridge could
be, but there are practicalchallenges that make extremely
long bridges difficult.
Modern bridges rely onmaterials like steel and
concrete, which are incrediblystrong, but remember, they also
have to support their own weightplus the load of vehicles or
trains At extreme length.
This becomes more challenging.

(05:47):
Engineers are constantlyexperimenting and innovating
with materials like carbon fibercomposites that could make
longer bridges possible in thefuture.
Building a foundation for along bridge is another challenge
, especially in deep water orareas with shifting ground.

(06:07):
Longer bridges must also endureintense natural forces like
strong winds, earthquakes andextreme weather conditions.
Maintenance and cost areadditional factors.
Constructing and maintaining asuper long bridge would require
enormous investments in time,money and resources.

(06:30):
Some engineers have proposedideas for floating bridges which
would rest on pontoons or otherbuoyant structures.
These designs could make itpossible to build bridges and
cross entire seas or evenconnect continents.
For example, at one point therewas a discussion about a bridge

(06:53):
across the Bering Straitbetween Russia and Alaska.
Such a project would faceextreme weather conditions and
logistical challenges, but withadvances in technology, it might
one day be possible.

(07:16):
Long bridges aren't just aboutbreaking records.
They're about connecting people, cities and countries.
They make travel faster andmore convenient, boost economies
by facilitating trade, andsometimes even become iconic
landmarks.
Imagine being on a high-speedtrain zooming across a bridge so

(07:38):
long you can't even see whereit ends.
It's like traveling into thefuture.
These bridges also representhuman ingenuity and
determination.
Building something so massiverequires not just advanced
materials and machines, but alsoteamwork, planning and

(07:58):
creativity.
Materials and machines, butalso teamwork, planning and
creativity.
Every long bridge is atestament to what we can achieve
when we work together to solvebig challenges.
So what's the longest bridge inthe world?
It's the Danyang Kunshan GrandBridge in China, an astonishing
102.4 miles long.
This engineering marvel isn'tjust a record breaker.

(08:21):
It's a symbol of how bridgessolve real-world problems and
connect us in ways we neverthought possible.
Whether it's a long bridge, atall bridge or one that lights
up at night, these structuresshow us the power of innovation
and creativity.

(08:45):
Thanks for tuning in to thisspecial episode about bridges,
and remember, if you have aquestion you're curious about,
submit it on our website,iwonderpodcast.
com, and we might just featureit in our next episode of I
Wonder.
Until next time, stay curiousand keep wondering.