Cities & Town

100th anniversary of construction of Hario Radio Tower/針尾送信所建設100周年

This article can be read in about 9 minutes.

Congratulations on our 100th blog!
Today’s blog is about the Hario Radio Tower, which also celebrates its 100th anniversary this year 2022.
Hario Radio Tower is the only existing communication tower that used long wave frequency in Japan.
It’s located in Sasebo city, Nagasaki prefecture.

Hario Radio Tower started its construction in 1918 and completed in 1922.
Japanese-Russo War awoke the Imperial Japanese Navy of the need to enhance radio communication.
There are three reinforced concrete towers which are situated in a regular triangle with a side of 303 meters.
The height of its tower is 136 meters. 
The diameter is about 12 meters at the bottom, while the top is about 3 meters.
The thickness of its concrete at the bottom is around 80 centimeters, while the top is around 25 centimeters.

It cost one million five hundred and fifty thousand yen, which is the same value of the current 25 billion yen.
One tower cost roughly three hundred thousand yen, which is equivalent to the current 5 billion yen.
The price proved that it was one of the significant national projects.

The designer was Mr. Yoshida Noboru who was also an engineer.
Around that time, Japan made three radio towers including Hario Radio Tower. 
Since another two were made of reinforcing steel bar, these are not existing anymore.

How to have made it?
Hario Radio Tower was made of reinforced concrete.
The tower was built little by little, which means it was divided into 100 segments with 136 centimeters. 
You can see the traces of the formwork from the outside(See the photo below).

Every 136 centimeters, the floor and scaffold were made. 
There are four reinforcing steel bars that crossed each other remaining inside of the tower, which used to be the foundation that supported the floor and removed the floor wood every time one segment had completed(see the photo below). 

The concrete and other materials were lifted manually, while the winch was used for lifting the antenna wires (see the photo below).

You can also see some small windows in the middle. 
These were used for lighting during the period of the construction, however, there is no way to access there now.
Above the 6 meters foundation, the first segment was built and one segment was made with three layers of concrete. 
It took 48 hours to dry one segment, hence it took at least 200 days per tower.
As a trivia, the ballast and pebbles were carried from Karatsu city, Saga prefecture to make high quality concrete. 
It’s 60 kilometers far from there.
In order not to damage reinforced steel rods, all the pebbles were washed one by one with fresh water and wiped by local people.

According to the research, only two centimeters out of 80 centimeters over 100 years are damaged by salty sea wind even though it’s located next to the ocean. 
So, an expert says that Hario Radio Tower will survive for another 100 years.

During the high period, it transmitted signals toward the troops and warships in South East Asia, China and the South Pacific Ocean.  
The major communication around 1922 was long wave frequency, however shortly after around 1935, it was shifted to the short wave.

Since there are aircraft warning lights around the top of the towers, some need to go up to check them three times a year. 
The ladder has around 600 steps. 
It takes roughly 30minutes to go up to the top, while leaning on his back on the wall for a break. 
According to the person who went up, going down to the ladder is scarier than going up because he has to look down the bottom between the ladder.  

Hario Radio Tower is the remaining treasure which shows how amazing Japanese technology has been.
The tower might give the message that we should learn something important, that we may have forgotten due to the advancement of technology, from the past. 

【Translation for language learners of either English or Japanese】/英語・日本語学習者向け翻訳 えいご ・  にほんごがくしゅうしゃむ  ほんやく

祝!100 回ブログ投稿

針生送信所は、1918 年に建設が始まり、1922 年に完成しました。
一辺 303 メートル(1,000寸)の正三角形に配置された鉄筋コンクリートの塔が三つあります。
塔の高さは 約136 メートルです。
直径は底部がおよそ 12 メートル、頂部が 3 メートルです。
コンクリートの厚さは底部が約 80 センチメートル、頂部が 25 センチメートルです。

155 万円(現在の 250 億円)費やしました。
一つの塔は約 30 万円(現在の50億円)かかりました。


塔は 136 センチメートルずつ 100 回に分けて作りました。
136 センチメートルごとに、床と足場を作りました。
6 メートルの基礎の上に 1 段目が建てられ、1 段は 3 層に分かれていました。
1段が乾燥する為に 48 時間かかりますから、単純計算で数なくとも 200 日以上はかかりました。
針尾から 60 キロメートル離れています。

調査によると、針尾の無線塔は海に面しているにも関わらず、100 年間で 80 センチメートルの内、たったの2 センチメートルしか、海風によって腐食しませんでした。
専門家は、針生送信所はあと 100 年は保つだろうとみています。

1922年当時の主流は長波でしたが、程なくした 1935 年には短波に移行しました。

航空障害灯が塔の頂上にありますので、年に 3 回点検の為に上る必要があります。
梯子は約 600 段あります。
上まで、途中背中を壁に付けて休みながら、およそ 30 分掛かります。




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