“Bridge collapses tunnel” Examining 740,000 open data December 6, 21:40

“Bridges and tunnels are collapsing.”

Such cases are happening all over the world.


A detailed analysis of the open data of 740,000 bridges and tunnels nationwide revealed that the number of roads that cannot be repaired is increasing.

It also has something to do with the bridges and tunnels that run through your city.

(NHK aging infrastructure coverage group)

*Detailed data analysis results are at the end of the article.

collapsed bridge

When I was researching the deterioration

of road infrastructure, I received such information and headed to the site.

Yusa Town is located by the sea in Yamagata Prefecture.

A 125-meter-long bridge called "Sakae Bridge" fell.

The appearance of the bridge I saw at the site when I arrived was beyond my imagination.

Part of the bridge girder was completely submerged in water and remained as it was.

As I got closer, the wood part had rotted away, and there were major damages here and there, even where it had collapsed.

"It was an important way of life."

As we approached the bridge, there was a sign that said it was closed to traffic.

According to local people, it has been closed to traffic for 10 years because it is in a dangerous state due to aging.

Just like that, it rotted away and fell down.

Shigeru Ishihara (71), who was born and raised in the Shiraki area where the bridge crosses, recalls that the Sakae Bridge, which was built in 1956, was an important community road that supported the area.

Mr. Shigeru Ishihara:

“There are farmlands and forests in the district across the river, but because the bridge cannot be used, we have to make a detour of several kilometers, making it difficult to manage. That's what the residents think."

"I can't fix it even if I want to"

Why did this happen?

We asked Mr. Yoshimitsu Ota, who is in charge of bridge maintenance in Yuza Town.

After the bridge was closed to traffic, they considered repairing or replacing it, but it was not possible.

In addition to the fact that it had already decayed to the point that it was difficult to repair, it would cost a huge amount of money to replace it.

The town's annual budget for maintenance of the bridge is about 100 million yen to 200 million yen.

However, it was estimated that several billion yen would be required to replace the Sakae Bridge.

In addition, it is said that the lack of manpower is also affecting.

Mr. Ota is the only civil engineering specialist in town.

Most of the road maintenance work that requires specialized knowledge is handled by one person.

There are more than 100 bridges in the town, but it is said that the aging infrastructure that cannot be fixed continues to increase.

Chief Yoshimitsu Ota, Civil Engineering Section, Community Life Division, Yusa Town

“If the town can do it, we would like to do something about it. I couldn't quite move, and I've come to this day."

Reality of aging seen by data

"Even if you want to fix it, you can't fix it." This kind of situation is spreading all over the country.

This time, I tried to investigate using open data.

We used data published by the government on the inspection and repair of more than 700,000 bridges, tunnels, and other "road infrastructure" nationwide.

The result.

There are 33,390 bridges and tunnels across the country that have not been touched despite the fact that inspections indicate that countermeasures are required.

You can see that it is distributed all over the country, from urban areas to rural areas.

It is said that there is a risk of serious accidents and damage if left unattended.

Among the infrastructure that required countermeasures, there were cases where repairs could not be made in time and accidents that could affect human lives occurred.

The national government aims to complete repairs within five years after it is determined that countermeasures are necessary.

Therefore, we newly obtained data on bridges and tunnels that had not been repaired for more than five years through a Freedom of Information Request and added them to our analysis.

The result.

The number is 7041 (as of March 2022).

Ninety percent of the bridges and tunnels are managed by municipalities, and the data revealed that there are bridges and tunnels spread across the country like Yusa Town, where "even if you want to fix them, you can't fix them."

For repairs that do not progress, the country

Ten years ago, in December 2012, nine people died when the Sasago Tunnel on the Chuo Expressway collapsed, triggering the national government to take measures to deal with the aging road infrastructure.

After the accident, the government mandated road infrastructure inspections once every five years.

They tried to prevent accidents through early inspection and repair.

However, how does the government perceive the current situation in which repairs are not progressing as a result?

Ministry of Land, Infrastructure, Transport and Tourism, Road Bureau, National Highway and Engineering Division,

“Although we have continued to implement safety measures for aging infrastructure, we are aware of the current situation where measures have not progressed sufficiently due to the tight budget and personnel, especially for small local governments. In order to prevent an accident like the Sasago Tunnel from happening again, we will continue to do our utmost to implement sustainable countermeasures against aging infrastructure.”

The only solution is to remove

As we interviewed, we also learned that the maintenance and management of a huge number of bridges and tunnels puts pressure on local governments' finances.

Under such circumstances, the “removal” of infrastructure has begun.

"We can't postpone it any longer,"

says Mitsuharu Sugiki, who is in charge of road management in Toyama City.

Toyama City has about 2,300 bridges.

The maintenance cost for the bridge, which is about 1.5 billion yen per year, will be repaired and renewed all at once in the future.

It would be difficult to maintain all the bridges at the cost of 16 times the current cost.

Mitsuharu Sugiki, Toyama City Road Structural Conservation Division Manager

“Originally, the city’s mission is to maintain bridges for a long time, and we would like to avoid removing them if possible. Someday, someone has to make the decision, and I think it's now."

Prioritize with “Bridge Triage”

What Toyama City has adopted is "Bridge Triage," which prioritizes each bridge.

In this method, bridges are divided into 4 groups from 'A' to 'D' according to their importance.

``A'' A bridge that is on a main road and considered indispensable

``B'' A bridge that is close to a main road and is highly necessary

``C'' A bridge that is familiar and used in daily life

``D'' A bridge that is considered to be of low importance... In principle, repairs are not performed, and removal is considered when it is dangerous.

Based on this idea, the city has indicated a policy to remove the two bridges.

One of them is the "Boiwa Bridge" built 50 years ago.

If a new bridge were to be built, it would cost more than 1 billion yen.

In addition, there are relatively few users, and there is a detour 3 kilometers away, so it was decided to remove it.

Residents want to stay...

For many years, the Heiwa Bridge was a familiar bridge for local residents to use to commute to supermarkets and hospitals.

Kiyoshi Yamamori, who lives nearby, understands the city's view that all bridges cannot be maintained as they are, but believes that they should be preserved for the benefit of the region.

Mr. Kiyoshi Yamamori:

“It would be unavoidable to 'triage' and remove it based on its importance.However, I don't think the importance of this rock bridge is low.I think there is certainly a problem with financial resources. However, bridges that are important and necessary in the event of a disaster must still be preserved.”

Toyama City listens to the opinions of these residents, but it has no choice but to remove it in order to protect the infrastructure of the entire city.

The number of bridges that need to be removed is expected to increase in the future, and it will continue to be difficult to navigate how to organize the infrastructure.

Toyama City Manager Sugiki

"This is a very difficult decision to make. I am very sorry for the inconvenience caused to the residents, but the longer it takes to make a decision, the greater the burden on the next generation."

“Discussion between local governments and residents”

Professor Ichiro Iwaki of Nihon University's Faculty of Engineering, who is familiar with the maintenance of road infrastructure, points out that it is necessary to change the way infrastructure measures are taken.

He says that it is desirable for residents to be involved in setting priorities, given the current situation where demolition must be considered.

Professor Ichiro Iwaki, Nihon University College of Engineering

“Infrastructure is essential for local residents, but now that it is aging due to lack of financial resources, we will not be able to use it in good condition for the next 10 or 20 years. , We will enter an era in which we will select what to give up and what to abolish.At that time, it will be important to conduct activities to determine the degree of importance and priority in discussions between local governments and residents.Local governments will be 10 and 20 years from now. It is necessary to carefully explain the future infrastructure situation, have residents participate in decision-making, and actively discuss what to do with regional infrastructure.”

to protect a safe infrastructure

Bridges and tunnels that we usually pass through.

From data analysis and interviews, we have come to see the reality that even that safety is no longer taken for granted.

As the population continues to decline, how should we protect our infrastructure?

I would like to continue the interview in the future.

Please let us know about the challenges related to aging infrastructure such as bridges and tunnels in your city.

NHK News Post

Analysis result details

This time, NHK analyzed the status of measures as of March 2022 by manager based on the "National Road Facility Inspection Database" published by the Ministry of Land, Infrastructure, Transport and Tourism and data obtained from information disclosure requests. .

1 Classified by administrator

Bridges and tunnels are classified by administrators, such as local governments, national governments, and road operators.

An analysis of trends by manager reveals that the percentage of bridges that have not been repaired out of bridges that need to be repaired is 33% for the national government, 37% for prefectures, 63% for ordinance-designated cities, and 63% for municipalities. became 60%, etc.

Compared to the national government, municipalities account for nearly double the number of bridges for which measures have not been taken.

There was a tendency for the ratio of bridges that could not be started to increase as the scale of administration became smaller, such as the national government, prefectures, and municipalities.

A similar trend was also seen in the percentage of bridges for which countermeasures have not been taken beyond the five years required by the national government.

2 By prefecture

Next is the situation by prefecture.

The number of bridges for which measures have not been taken is 648 in Niigata Prefecture, 537 in Fukushima Prefecture, 406 in Yamaguchi Prefecture, 356 in Nagano Prefecture, and 281 in Miyagi Prefecture.

It cannot be said unconditionally that a large number of bridges means that countermeasures are not progressing.

A similar trend was also observed for bridges for which countermeasures have not been taken beyond the "5 years" required by the government.

3 Ordinance-designated cities/municipalities

Next, we will look at analysis data for ordinance-designated cities/municipalities, which account for the largest percentage of the total.

Looking at the municipalities with a large number of bridges that need countermeasures but have not been completed, Okayama City has 605, Niigata City has 465, Nagaoka City in Niigata Prefecture has 333, Tottori City has 247, and Hiroshima City has 234.

Local governments in areas where there are many rivers, where there are many bridges to manage from the beginning, and where bridges tend to deteriorate due to salt damage due to salt damage, etc., tend to have many bridges that have not been taken care of. rice field.

A similar trend was observed for bridges that had not been repaired for more than the five years required by the government.



Hiroki Uchiyama Joined the Bureau

in 2011

After being in charge of disasters, he will be in charge of the Ministry of Land, Infrastructure, Transport and Tourism from 2021 Covering

housing issues and infrastructure measures.


Economic Department reporter

Akira Taruno

Joined in 2012 In

charge of the automobile industry for two years, and from 2022 in charge of the Ministry of Land, Infrastructure, Transport and Tourism



Keijiro Saito

Joined in 2010 Taking

up the challenge of data analysis when raising children Currently studying programming in addition to GIS


Network News Department Reporter

Eiji Akioka

After working at the Otsu Bureau of the News Bureau, he is currently

in charge of data analysis in the data visualization team "NMAPS".


Network News Department Director

Akino Kakiuchi Responsible

for data analysis and visualization at "NMAPS"