The Sparrow's Song on a Snowy Night

Onii-chan, yesterday’s blizzard was crazy, huh…(´∀`)

JR was totally down.

When you saw the huge delay on the board, you were like “nope, not waiting for this” right? (>_<)

Taking the subway instead was totally the right call!

I took the Tozai Line, and something caught my attention.

Ooh ooh, what what? (´∀`)

Why does the subway make this “chirp chirp” sound?

Chirp chirp… (´∪｀)

Yeah yeah, you can totally hear it when waiting on the platform.

I thought maybe sparrows, but it’s underground so that’s weird.

Onii-chan, I looked into it! (≧∇≦)

Tell me.

So the answer is…

Rubber tires! (´∀`)

Rubber tires?

Yep yep!

Sapporo’s subway is the only rubber-tired metro in Japan! (´∀`)

Regular trains run on steel wheels on steel rails, right?

But Sapporo is different~

Like car tires?

Exactly!

They’re actual radial tires filled with nitrogen! ♪

A 7-car train has 112 driving wheel tires alone! (´∀`)

Don’t they get flat?

They totally do!

In 2023, they actually had to suspend service because of a flat tire! (ﾟ∀ﾟ)

That’s why they inspect every 6 days and do detailed checks every 3 months.

So how does that connect to the chirping sound?

HERE’S where it gets interesting! (≧∇≦)

Trains run on electricity, right?

Yeah.

The pantograph collects positive electricity…

And the used electricity needs to be released into the ground! (´∀`)

Normal trains do that through steel wheels to steel rails?

Right right! Onii-chan, you’re sharp! (≧∇≦)

But rubber tires… don’t conduct electricity! (´∀`)

Oh, right. Rubber is an insulator.

So Sapporo’s subway has this special part.

It’s called a “negative current collector”! (´∀`)

Sapporo’s subway has this metal rail called a guide rail running down the middle of the track! (´∀`)

The train grips this guide rail with rubber guide wheels on both sides…

But to release electricity, there’s also a metal “negative current collector” rubbing against it! ♪

Metal scraping against metal.

Exactly!

And the guide rail has joints where sections connect, y’know?

At those joints, the collector briefly separates… then touches again! (´∀`)

That’s when the sound happens?

Ding ding ding! (≧∇≦)

The “clank” of metal scraping metal…

Echoes in the underground space and becomes that “chirp chirp” sound! ♪

So that’s why it sounds like sparrows.

Yep yep!

You hear it a lot right before stations, on curves, wherever there’s lots of joints! (´∀`)

Does every line have this sound?

Actually, it depends on the line! (´∪｀)

The Tozai and Toho lines grip a flat guide rail from both sides, so it resonates more! (´∀`)

The Namboku Line rubs against the top surface, so it’s way quieter! ♪

I’ll check next time I ride the Namboku Line.

Onii-chan, did you know?

Japan has 9 public subway systems…

But only Sapporo has this chirping sound! (´∀`)

The only one in Japan?

Yep! (≧∇≦)

And worldwide, only 12 cities have rubber-tired metros! ♪

Sapporo was the 5th city in the world to adopt rubber-tired metros! (´∀`)

Why did they choose rubber tires in the first place?

Two reasons! (´∀`)

Between Hiragishi and Minami-Hiragishi stations on the Namboku Line, there’s an elevated section where it goes from underground to above ground! (´∀`)

It’s a super steep slope!

Steel wheels would slip…

But rubber tires have way more friction, so they can climb! ♪

Back in the day, the transportation bureau chief visited Europe…

And was totally impressed by how quiet the Paris metro was! (´∀`)

He decided “Sapporo’s gotta have this too!” ♪

It is pretty quiet.

Right?! Besides the chirping, it’s sooo quiet! (≧∇≦)

Steel wheels go “clack-clack” and are super noisy…

But rubber tires have less vibration and smoother acceleration! ♪

Oh oh, one more thing, Onii-chan!

Sapporo’s subway uses a method that’s unique in the world! (≧∇≦)

What do you mean?

Paris and Montreal’s rubber-tired systems still use steel rails as backup! (´∀`)

But Sapporo…

Completely rail-free!

Both driving wheels and guide wheels are ALL rubber tires! ♪

This is called the “Sapporo Method”! (≧∇≦)

Going its own way.

Ehehe, that’s so Sapporo, right? (〃´∪｀〃)

I never knew a sound I hear all the time had such a story behind it.

The JR being down and taking the subway detour led to solving this mystery! (´∀`)

Blessing in disguise, I guess! ♪

Now I’ll think of the negative current collector every time I hear that chirping.

Right right! (≧∇≦)

Thinking “oh, that’s electricity being released right now”…

Makes you feel like a train expert, doesn’t it! ♪

So yeah, today we solved the mystery of the subway’s chirping sound! (´∀`)

Learned something new.

To sum it up…

• The chirping is from the negative current collector touching the guide rail

• Needed because rubber tires don’t conduct electricity

• Only in Sapporo in all of Japan

• The subway’s “voice” that hasn’t changed for over 50 years

…something like that! ♪

Looking forward to the next ride.

Ehehe~ (〃´∪｀〃)

Thanks for looking into this with me today, Onii-chan! ♪

…Oh, by the way.

What?

Netsuki chirps too, y’know! (´∀`)

…Aren’t foxes supposed to go “kon kon”?

When I’m hungry, I go “chirp chirp”! (≧∇≦)

…Is dinner ready yet? ♪