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with so many people in a really limited
space moving around the city without
coming into each other has always been
quite tough so 150 years ago cities
around the world come up with a new
strategy going underground
on the last count 150 cities around the
world in 55 countries had a railway
system or metro to be fair they're a
great way to get around because you
don't have to bump into buildings you
have to go over rivers and there's no
traffic you're stuck in i bet you're
wondering how do you build these tunnels
that can take a train
well nowadays you probably use a
tunnel-borne machine a tbm or a mall and
these are huge huge machines to dig
through the earth and simultaneously put
concrete shells around the outside of
the tunnel and they can dig tunnels
seven meters from wall to wall
on the railway system the speeds can
vary they can go from a crawling speed
right up to speeds faster than your car
can even go because the rails have to
share the lines with other types of
traffic they can go as fast as they like
sometimes up to 200 miles per hour
that's just one factor about these
amazing subway systems but here's my top
five facts about the underground
the system with the most subway stops
around the world is new york city in the
usa it actually has 468 stations the
world's busiest metro system in terms of
passenger numbers is actually tokyo
subway it has over 8 million passengers
per day that's 3 billion in a year
in south korea seoul subway stations are
super high tech they are 4g and they
have wireless broadband in all the
stations and trains and the seats are
actually climate controlled so they heat
up in winter it's clean it's tacky and
it's known as one of the best in the
world
the first ever underground railway was
right here in london the metropolitan
railway opened in 1863 it's now part of
the metropolitan hammersmith in city and
circle lands
the deepest underground system in the
world is the pyongyang metro system in
north korea and it's 110 meters deep
that's so deep they also use it as a
bomb raid shelter and it takes three and
a half minutes to get to the surface
so traveling on the underground can be
both historical and technological new
trains have been developed all the time
even including ones that could possibly
go under our oceans so make sure you
check out the rest of our videos on the
lonely planet kids playlist on youtube
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popjam and let us know your favorite
facts about the underground in the
comments below
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