Japan’s
Infrastructure
Grades 2020 &Introductionof MaintenanceTechnologies

2021.9Japan Society of
Civil Engineers

Contents

Introduction
P.1

Report on Japan’s Infrastructure
Grades 2020
in Terms of Structural Health Condition

Maintenance of Infrastructuresand Introduction of
Maintenance Technologies in JapanA Grade Associated with Infrastructure’s Condition
Summary of Grades among Infrastructures in Japan
Grade Results of Infrastructures

P.2

Roads Section

Roads Section-Bridges
Roads Section-Tunnels
Roads Section-Pavements(Bridges, Tunnels and Road Pavements)

P.4
Railways Section

P.14
Railways Section(Bridges, Tunnels and Tracks)

P.20

P.6
Ports Section(Mooring Facilities and Protective Facilities for Harbors)

Ports Section

P.22

P.8
Rivers Section

Rivers Section(Levees, River structures and Dams)

P.24

P.10
Waterworks Section

Waterworks Section(Pipelines)

P.26

P.13
Sewage Works Section

Sewage Works Section(Pipelines)

P.13

P.28

Introduction
Civil engineering has greatly contributed to the formation of the national land and infrastructure of Japan, and to
Japan's development. However, aging of the structures in the infrastructure has become a major problem. In the
future it is anticipated that aging of the structures will proceed rapidly, and repairs and renewal will increase. It goes
without saying that the structures and infrastructures support society and economic development, and plays animportant role in maintaining the sustainability of our lifestyles. In order to maintain the quality of our lifestyle safely
and securely with limited resources and finance, it is necessary that the public understands the importance of aging
infrastructures’ maintenance and renewal. Securing the necessary budget and personnel for this purpose is of vital
importance for the sustainability in Japan.
Considering the importance of infrastructures, the Japan Society of Civil Engineers (JSCE) decided to evaluate thegrades of Japan's infrastructures as a third-party organization, and in May 2016 published "Report on Infrastructures’
grades". The 2016 Infrastructures’ grade was applied only to bridges and tunnels for roads, where the inspection
and diagnosis had been systematized in advance of the other infrastructures. Thereafter, rivers, sewage, ports,
waterworks, and railways were evaluated, and the grades of their infrastructures were published.
This brochure summarizes these reports on the infrastructures’ grades published in 2020. Also, it introduces thelatest inspection, repair, and strengthening technologies in Japan. We hope that this brochure will contribute towards
the awareness of Japan's infrastructure grades and help to provide the information on Japan’s civil engineering
technology that maintains infrastructures.

Infrastructure Integrity Diagnosis Subcommittee
Japan Society of Civil Engineers

1

Report on Japan’s Infrastructure Grades 2020
A Grade Associated with
Infrastructure’s Health Condition
Roads Section

Facility inspection results and information on the maintenance systems
was collected from published data and surveys, and condition assessment
was carried out by the experts from Japan Society of Civil Engineers. Afterevaluating the data considering the regions and infrastructure owners, thegrades were evaluated as the national average.

Grading Scale
Grade

A

Section

Sound

B

C

E

D

Good

Requires attention

Requires vigilance

Dangerous

Roads
Waterworks
Sewage works

There isno degradationin almost all thefacilities

Degradation isprogressing to acertain extent in thefacilities

Degradation isprogressing in asignificant numberof the facilities, andrepair will be neededin the near future

Degradation isapparent in mostof the facilities,
and repair orstrengthening,etc., is required

There is severe
degradation
overall, and urgent
measures are
requiredRiversPorts
Railways(bridges,tunnels)

There isno deformationin almost all thefacilities

Deformation isprogressing to acertain extent insome facilities

Deformation isprogressing in asignificant number offacilities, and repair
will be required in
the near future

Deformation ofmany facilities isapparent, and repair
and strengthening,etc., is required

Deformation
has progressed
overall, and urgent
measures arenecessary

Railways(tracks)

Tracks areconstantly
maintained in goodcondition by trackstrengthening andcondition monitoring

Track irregularity
has occurred,
but a constantlevel is ensured byperiodic repair

Track irregularity
has progressed in asignificant numberof tracks, and repair
will be required soon

There is trackirregularity in mostof the tracks, andmeasures suchas repair, etc., isnecessary

Track irregularity
has progressed
overall, and urgent
measures are
required

Maintenance system in term of prediction of future integrity status(Actions in order to maintain or recovery integrity)

2

➡

➡

➡

Facility maintenance system(Likely to improve)(Current state likely to be maintained)(Likely to get worse)

If the current management system iscontinued, it is considered that the status of
integrity will improve

If the current management system iscontinued, it is considered that the current
status of integrity will be maintained

Unless the current management system
is improved, there is a possibility that thestatus of integrity will get worse

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

in Terms of Structural Health Condition
Summary of Grades
among Infrastructures in Japan
RailwaysC

Tunnels

D

Road pavements

C

➡ ➡ ➡

Bridges

RiversBridgesB

Tunnels

B

TracksB

Waterworks

CRiver structures

D

Dam

B

➡ ➡ ➡

LeveesPipe facilities

C

➡
➡
➡
➡

Ports
Mooring facilities

C

Protective facilities
for harbors

C

➡
➡

B

➡

Roads

Sewage works
Pipe facilities

Although in many facilities degradation and deterioration are progressing, the current average grade of theinfrastructure is that overall it has not became poor at risk.
However, with the current maintenance management system, it is difficult to improve the infrastructure
condition. It may exhibit significant deterioration in near future without more financial support.

Measures for improving the condition of the infrastructure
System for managing maintenance and budgets
To efficiently perform maintenance, (1) establishing systems, (2) constructing mechanisms, and (3)cultivating human resources, etc., are important, while ensuring the necessary budgets over a long
period of time. In particular, it is necessary to cultivate the maintenance industry considering preventive
maintenance and maintenance as economic activities.
• The public should understand the importance of infrastructure for their lifestyle and for socioeconomic activities, and they should cooperate inproblem solving.
• The national government should provide financial support so that operators can perform appropriate maintenance, and establish systems thatenable sustainable financial measures.
• The national government should implement improvements in the contract system and close cooperation among those involved, in order toconstruct an appropriate maintenance system.
• Operators should establish long-term plans not only for budgets, but also for human resource training and securing human resources.

Implementation of appropriate and effective inspection, diagnosis, and corrective actions
It is necessary to change the focus of maintenance from inspection and diagnosis to repair andstrengthening based on the inspection and diagnosis results. What is required is to change from the current
status in which when a problem occurs on a facility rapid corrective actions are implemented, to preventive
maintenance actions in which the actions are performed before a problem occurs.
• The public should also understand that temporary restrictions on the use of infrastructure will be placed in order to carry out inspection, diagnosis,
and corrective actions.

Development of Effective and Efficient Maintenance Technologies
It is necessary that the cost of maintenance be reduced by preventive maintenance and technical innovation,
so that the burden on the public is reduced in the long-term.
• The Japan Society of Civil Engineers should evaluate the technologies that have been developed and propose easy-to-use technical mechanisms
and inform the public.

3

Grade Results of Infrastructures

Roads Section
Roads Section (Bridges, Tunnels and Road Pavements)
Bridges

Road pavements

➡

C

➡

D

➡

C

Tunnels• I n the case of bridges and tunnels, many of the facilities operated by cities, wards, towns, and villages have significant aging, and there arelarge differences in the degree of integrity among the facilities for each operator.
• R egarding safety for traveling, there are good road pavements, but also damaged pavements that are not receiving appropriate treatments
can be seen.
• I n the case of maintenance systems, in all cases if they remain as they are the situation is likely to get worse.

Measures to Maintain and Improve Grades• The reasons for the maintenance systems trending downwards are insufficient budget and systems for road maintenance by
local governments. Central government should provide long-term financial and technical support so that local governments canappropriately implement the maintenance cycle and their maintenance system can be improved.
• Road administrators should secure more specialist engineers and budget than before, and formulate plans for cultivating systems
within their organization and specialist engineers and long-term plans for bridges, tunnels, and road pavements including longterm budget, disclose these plans, and then execute them. In particular the local government inspection results for pavements
have only been disclosed in part, so it is necessary that they be disclosed.

BridgesC➡

Prefecturalandordinance
designatedcity roads

City,
ward,
town,
and village
roads

Urban
expressway

National
expressway

B

C

C

B

C

Action desirable
for preventive
maintenance

26 %

2%

2%

2%

Action should betaken soon

53 %

24 %

18 %

32 %

Action should betaken urgently

100 %

94 %

20 %

-

Grades according to operator
and percentage ofrepairs completed
Grade

Percentageof repairs
completed

Nationalroads The grade is the same as last year, C (requires attention). Evaluation for each operator is also the same.
•• Maintenance systems have been evaluated lowly as “likely to get worse” from the current state of maintenance.
There is concern over the low rate of starting repairs, except for central government.
• The degree of integrity of bridges according to operator has been evaluated for each prefecture. It is desirable thateach operator is aware of the network maintenance, and maintains the integrity of each of the bridges they manage
in a good condition.

Measures to be taken• Support from the public for day-to-day maintenance• Understanding of the diversity of bridges, and introduction of maintenance technology in accordance with thecircumstances of the facility operators• Improvement in the overall capability of maintenance engineers in order to reduce omission and variation in
inspections

4

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Tunnels

D

Prefecturalandordinance
designatedcity roads

City,
ward,
town,
and village
roads

Urban
expressway

National
expressway

C

D

D

A

C

Action desirable
for preventive
maintenance

29 %

5%

6%

4%

Action should betaken soon

64 %

26 %

18 %

72 %

Action should betaken urgently

100 %

92 %

85 %

-

Grades according to operator
and percentage ofrepairs completed
Grade

Percentageof repairs
completed

Nationalroads➡

 The grade is the same as last year, D (requires vigilance).
•• Maintenance systems continue to be evaluated as “likely to get worse” from the current state of maintenance.
There is concern over the low rate of starting repairs, except for central government and expressway companies.
• The degree of integrity of tunnels according to operator has been evaluated for each prefecture. It is desirable thateach operator is aware of the network maintenance, and maintains the integrity of each of the tunnels they manage
in a good condition, the same as for bridges.

Measures to be taken• Planned preventive maintenance should be implemented together with urgent and early actions that should
be taken for tunnels• The focus should not be on just the lining surfaces, but also on the ancillary items• The reliability of inspection results should be improved starting from the initial inspection

Road
Pavements

C

Grades according to operator
and percentage ofrepairs completed
Grade
Percentageof repairs
completed

Action desirable
for preventive
maintenancePrefecturalandordinance
designatedcity roads

City,
ward,
town,
and village
roads

Urban
expressway

National
expressway

C

C

D

B

B

19%

16 %

22 %

6%

7%

Nationalroads➡

• The grade is the same as last year, C (requires attention). The evaluation for city, ward, town, and village roads withnew evaluation areas for each operator was also the same as before.
• Maintenance systems are evaluated as “likely to get worse”, the same as previously. Apart from expressways,
it is difficult to maintain the current degree of integrity, due to the effect of reduction in budget for pavements,
postponing areas for repair and improvement, and the increase in the number of complaints, etc.
• The inspection results for prefectural and ordinance designated city roads, and city, ward, town, and village roads
have been disclosed by only some operators, and it is desirable that the inspection results be disclosed.

Measures to be taken• Utilization of pavement inspection guidelines and setting appropriate management standards in accordancewith the importance of roads• For inspections, visual or measuring instrument methods should be selected as appropriate• Appropriate repair and improvements should be implemented including preventive measures, so that thelife of the pavement is extended and the integrity of the subgrade and lower levels is not compromised

5

Railways Section
Railways Section (Bridges, Tunnels and Tracks)
BridgesB➡

Tunnels

B➡

TracksB➡

• O
 verall maintenance is being implemented for bridges and tunnels， and the integrity is generally good.
• T he integrity of tracks tends to be low in sections where the traffic density is low， such as local railways， etc.
• R
 egarding maintenance systems， although local railway operators are currently implementing maintenance， it is necessary for the system
to be further enhanced in the future.

Role of Grading the Railways’ Condition and Points to Note
Target of the Railways Section• The targets among railway facilities are bridges (excluding elevated bridges), tunnels, and tracks.
• 169 railway operators were classified into 3 groups, taking into consideration scale, total length of line, etc., to which was added
the Shinkansen. The integrity of facilities was evaluated for each structure for these 4 groups.
Data used in the evaluation: A questionnaire was sent to the 169 railway operators, and the evaluation was based on the replies.
• The integrity of the bridges and tunnels used the survey results for evaluation of soundness into 4 stages, based on the"Maintenance Standards for Railway Structures"• For tracks, the annual average number of times per km that the maintenance criteria value for track irregularity was exceeded,
was used as track irregularities inspected by the railway operators.
• For the maintenance system, the responses to a questionnaire regarding budgets, personnel, and future plans (human resourse
cultivation, technical development) for maintenance was used.

Measures to maintain and improve the grades• In the railway industry, there should be joint implementation to secure human resources and cultivate and train the humanresources, and new qualification systems established, across organizational boundaries.
• In the railway industry, technical development should be implemented and horizontally deployed, and unification of specifications
for inspection instruments and joint ownership should proceed, across organizational boundaries.
• In the railway industry, promotion of mechanization, ensuring train intervals for work, and levelization of work should proceed fortransformation of working practices and improvement of productivity.
• Local railway operators should review their transport service levels in accordance with the maintenance level, with theunderstanding of local governments, users, etc.
• Central and local governments and major railway operators should enhance their support for local railway operators to ensure
continuation of their operation as a business.
• If it is difficult to ensure safe transport on local lines and the business is not viable in spite of the measures of the railway
operators to maintain and improve integrity and even with enhanced public support, etc., then local governments, users, etc., incooperation with the railway operators should discuss the future transport system, such as whether it is necessary to switch thetransport mode, etc.

6

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Maintenance system• Overall it is considered that if the current management system continues, the current status of integrity can be
maintained.
• It is clear that the local railways, etc., are in a severe environment in all aspects such as budgets, insufficient staff,
human resource development, and technical development. Therefore there is a possibility that it will not be possible
to maintain the status of integrity in the future, and this will be an obstacle to operation of trains.
• It is necessary to enhance the maintenance systems in the future.

JR Hokkaido,
Shikoku, Kyushu
Quasi-major private
railways
Third sector
railways➡

B

Local private
railways
Third sector
railways
Freight railways

B

Current grad• The status is good, whether viewed overall or by operator. However,
it is still necessary to continue to determine the status by inspection,
analyze and evaluate the results, and perform the necessary repairs,
etc.

Maintenance system

AB

JR Hokkaido,
Shikoku, Kyushu
Quasi-major private
railways
Third sector
railways

B

Local private
railways
Third sector
railways
Freight railways

D➡

Grade and
Maintenance system

JR East, Central,West Major private
railways
Public metros

Fig. Inspection of a bridge(using an elevated working platform)➡

• O verall it is considered that if the current management system
continues, the current status of integrity can be maintained.
• It is clear that the local railways, etc., are in a severe environment
in all aspects such as budgets, insufficient staff, human resource
development, and technical development. Therefore there is apossibility that it will not be possible to maintain the status of integrityin the future, and this will be an obstacle to operation of trains.
• It is necessary to enhance the maintenance systems in the future.

Tracks➡

B➡

B

JR East, Central,West Major private
railways
Public metros➡

Grade and
Maintenance system

ShinkansenBB• The status is good, whether viewed overall or by operator. However, it is still necessary to continue to determine thestatus by inspection, analyze and evaluate the results, and perform the necessary repairs, etc.

Tunnels➡

B

Local private
railways
Third sector
railways
Freight railways

Current grad

Shinkansen

B

B

➡

A

➡

➡

Grade and
Maintenance system

JR Hokkaido,
Shikoku, Kyushu
Quasi-major private
railways
Third sector
railways➡

B

Shinkansen➡

Bridges

JR East, Central,West Major private
railways
Public metros

Current grad• Overall the status is good, but local railways, etc., are at the “requires
vigilance” level.
• In particular in those lines with low density of transport in the local
railways, etc., deformation of the tracks frequently occurs and there
is a possibility that they will be unable to implement appropriate
maintenance.

Maintenance system• O verall it is considered that if the current management system
continues, the current status of integrity can be maintained.
• It is clear that the local railways, etc., are in a severe environment
in all aspects such as budgets, insufficient staff, human resource
development, and technical development. Therefore there is apossibility that it will not be possible to maintain the status of integrityin the future, and this will be an obstacle to operation of trains.

Fig. Track realignment using a multiple tie
tamper7

Ports Section
Ports Section (Mooring Facilities and Protective Facilities for Harbors)
Mooring facilities(quaywalls, jetties, etc.)

C ➡

Protective facilities for harbors(breakwaters, etc.)

C ➡

• T
 he status of integrity of mooring facilities such as quaywalls and jetties and protective facilities for harbors such as breakwaters, etc., in theports of Japan is that deterioration is progressing in many facilities, and repairs will be necessary soon.
• It is likely that the maintenance systems for port facilities can maintain the current status, but there are some facilities where sufficientmaintenance is not able to perform because of restrictions of budget, personnel, etc.

The target facilities of the ports section are• Typical facilities in ports, namely mooring facilities (quaywalls and jetties, etc.) and protective facilities for harbors (breakwaters,etc.).
• The target was nationally-owned facilities and port management body-owned facilities, and excluded the facilities of private
businesses.
• The other types of port facilities such as waterways and basins, etc., can not be sufficiently assessed with the concept of degree of
integrity, so they were excluded.

Fig. Port facility(Japan Dredging and Reclamation Engineering Association)

Measures to maintain and improve the grades• National and other port management bodies (local bodies such as prefectures, cities, etc.) should perform proper maintenancebased on a maintenance plan formulated for each facility. In addition an asset management plan should be formulated for eachgroup of facilities, to promote the optimized maintenance for the port as a whole.
• In the case of facilities where aging has progressed to a serious extent and facilities that are not being used because of changes
in loading and unloading formats, etc., the port management bodies should investigate effective use of their existing stock byconversion of use or renewal, so that the port as a whole is revitalized.
• National and other port management bodies should continue their efforts to secure and cultivate human resources and to improve
technical capability, both for their own staff and also the staff of private sectors.
• There are ports that have not yet sufficiently developed their infrastructure, and there are some ports that have not progressedwith seismic measures. Therefore in the future it is necessary to perform appropriate maintenance in a planned manner, inparallel with proceeding the necessary infrastructure development.

8

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Results of mooring facilities (quaywalls, jetties, etc.)

Grade and Maintenance system

National facilities

Facilities owned by port management bodies

C ➡

C ➡

Current grade• T here are many facilities in which aging has progressed, and repair will be necessary soon.
Maintenance system• It is considered that if the current management system is continued, the current integrity status will be maintained.
Note:• T he occurrence of deterioration or damage could lead to a serious accident such as collapse of an apron that would involve users
performing loading and unloading, or ordinary users of ferries or cruise ships, etc.

• If the degradation or damage progresses further, not only will the repairs be very costly, but also it will not be possible to use the facility
for a long period of time, and this could cause major loss to the local economy.

• In the case of mooring facilities, inspection, diagnosis, and repair are being implemented based on a maintenance plan formulated foreach facility. However there are facilities in which it is not possible to carry out sufficient maintenance, due to restrictions of budget,
personnel, etc.

Results of protective facilities for harbors(breakwaters, etc.)

Grade and Maintenance system

National facilities

Facilities owned by port management bodies

C ➡

C ➡

Current grade• T here are many facilities in which aging has progressed, and repair will be necessary soon

Maintenance system• It is considered that if the current management system is continued, the current integrity status will be maintainedNote:• T he occurrence of deterioration or damage could increase the wave height within the port, cause flooding of the hinterland, and affect not
only the safety of users performing loading and unloading and ordinary users of ferries, etc., but also the safety of facilities and people in
the hinterland.
• If the degradation or damage progresses further, not only will the repairs be very costly, but also if the breakwater is damaged then it will
not be possible to use the mooring facilities behind it, and this could cause a major loss to the local economy.
• In the case of protective facilities for harbors, inspection, diagnosis, and repair are being implemented based on a maintenance plan
formulated for each facility. However there are facilities in which it is not possible to carry out sufficient maintenance, due to restrictionsof budget, personnel, etc.

9

Rivers Section
Rivers Section (Levees, River Structures and Dams)
GradesOverallRiver structures

D

Central government

C

Prefectures, etc.

C

Central government

C

Prefectures, etc.

D

Civil engineering structures

B
Mechanical and electricalequipments

A

Prefectures

A

Central government, Japan
Water Agency

B

Prefectures

B

➡

Dams

Central government, Japan
Water Agency

➡

C

➡

Levees

MaintenancesystemBy administrator

Overall evaluation• It is not possible to be optimistic about the condition of levees and river structures.
• Regarding the condition of dams, Civil engineering structures are sound, but Mechanical and electrical equipments, etc. areunsound because of their aging.
• It is necessary to enhance the budget and personnel for maintenance of river management facilities. In particular it is necessary
for prefectures to develop a system that enables to inspect, evaluate, and repair their facilities.

In order to protect the areas from flooding,• It is necessary to raise the level of river improvement, and to perform appropriate
maintenance• We evaluated the status of the “maintenance” in this diagnosis.

The target facilities of Rivers Section were,• Levees, river structures (floodgates, sluice gates, and sluice pipes), and dams ofRiver management facilities defined in the River Act• [Levees and river structures (floodgates, sluice gates, and sluice pipes)] The facilities
managed by central government, prefectures and ordinance-designated cities• [Dams] The facilities managed by central government, prefectures, and Japan Water Agency(Power generation dams, water supply dams, agricultural dams, landslide dams, etc., were excluded in the target facilities)

Measures to maintain and improve facilities• The Japan Society of Civil Engineers should continue to disseminate information regarding the importance of maintenance of rivermanagement facilities, and promote understanding of the public for enhancement of budgets and personnel.
• River administrators should formulate and implement inspection and evaluation methods in accordance with the current circumstances oflevee management, based on the understanding of the levee characteristics that extend in long distances and with many invisible parts.
• Dam administrators should maintain facilities by securing budget and performing thorough repair based on evaluation by asset
management, to keep the functions and benefits of dams as long as possible.
• In rivers managed by prefectures, etc., cooperation between central government, prefectures, etc., and the Japan Society of Civil
Engineers should be strengthened to enable the prefectures, etc., to carry out sustainable and appropriate river management. Central
government should support the creation of systems and frameworks, and the Japan Society of Civil Engineers should provide technicalsupport and advice. Prefectures, etc., should categorize the management sections in accordance with the properties and importance ofrivers, formulate their maintenance plans by themselves, and develop management systems for implementation of these plans.

10Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Results of Levees
Levees

Grade

➡

C

Grade

Levees managed by central government

Levees managed by prefectures, etc.

C

C

Current grade• T here are many places where there is damage, cracking, etc., in the bankprotection of levees, that it could cause deformation to progress impairing thefunction of the levee.
• It is desirable to take preventive actions.
• In levees managed by prefectures, etc., it is necessary that the targets of inspection be
categorized in accordance with the characteristics and importance of rivers, categories
are defined for the methods of performing inspection and evaluation, and inspection andevaluation methods are formulated in accordance with the conditions on site.

Maintenance system• Maintenance systems are being institutionalized in which inspection is performedat least once per year, and maintenance plans are being formulated, etc.
• There are concerns over insufficient budgets and personnel for maintenance. It
is becoming difficult to succeed knowledge and experience.

Fig. Erosion on the slope of a levee

Results of River Structures (floodgates, sluice gates, and sluice pipes)
River structures

Grade

D

➡

Grade

River structures managed by central
government

River structures managed by
prefectures, etc.

C

D

Current grade• There are many places where there is cracking or steps in box units, etc., andthere is concern that if this damage progresses it could impair the functions of
the structures.
• It is desirable to take preventive actions early.
• In river structures managed by prefectures, etc., classification of the degree of
deformation and grasp the state is insufficient. It is necessary that the targets ofinspection be categorized in accordance with the characteristics and importanceof rivers, the rules of performing inspection and evaluation be defined by
the categories, and the inspection and evaluation methods be formulated inaccordance with the conditions on site, just as for levees.

Maintenance system• Maintenance systems are being institutionalized in which inspection is performedat least once per year, and maintenance plans are being formulated, etc.
• I n addition there are concerns over insufficient budgets and personnel for
maintenance, under aging in progress.

Fig. Crack in a sluice pipe

11

Results of Dams
Dams

B

Grade

Dams managed bycentral government
and Japan Water Agency

Dams managed by
prefectures

Civil engineering structures

A

A

Mechanical and electrical equipments

B

B

➡

Grade

Current grade The status of Civil engineering structures in dams is sound.
•• The status of Mechanical and electrical equipments are good overall, but it is necessary to perform maintenance, repair, and renewal
depending on the equipments age.

Maintenance system• Daily managements, periodic inspections (every 3 years), and comprehensive dam inspections (every 30 years) are institutionalized.
Systems for maintenance have been developed.
• It is necessary to integrate a wide range of technologies. The number of engineers with extensive experience is becoming fewer. It isnecessary to strengthen the management system for skill succession, budgetary aspects and personnel aspects.

Fig. Concrete block from a dam excavated during dam re-development (soundeven though more than 50 years had passed)

12Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Fig. Corrosion in an emergency spillway (crest gate)

Waterworks
SectionWaterworks Section (Pipelines)
100,000 ormore

30,000 or
more

10,000 or
more

Less than
10,000

Grade

C

C

C

D

D

Maintenance system

➡

➡

➡

➡

Pipes

C➡

➡

600,000 or
more

Size of water supply populationNote:• The grade was the same as last year C (requires attention). For populations 10,000 or more the evaluation dropped from C to D.
• E valuation of maintenance systems has changed from “Likely to get worse” to “Current status likely to be maintained”, reflecting the fact that index values at
small utilities are tending to improve. However, there has been no change compared with last year regarding the result by the size of water supply population.

Measures to Maintain and Improve Grade• The central government should provide technical and financial support for water utilities.
• Local municipalities should promote wide area cooperation, in order to strengthen the basis of the water supply utilities.
• Water supply utilities should make efforts to secure human and financial resources.
• Research institutions should investigate development of technologies that can be carried out more efficiently.
• Academic and industrial associations, and educational institutions should continue to undertake human resource cultivation andtechnical capability improvement.

Sewage Works
SectionSewage Works Section (Pipelines)
Pipes

➡

B

Note:

Size ofpopulationGrade

23 wards of Metropolitan Tokyo
Ordinance-designated cities

300,000 ormore

100,000 ormore

50,000 or
more

Less than
50,000

C

B

B

A

A

• Regarding grades, overall the evaluation is B (good). However, in the major cities it is C (requires attention).
• R egarding maintenance systems, the length inspected and the number of technical staff per total length have decreased in Japan as a whole. In particular,
there is concern that the percentage reduction is significant in the medium and small municipalities, so the evaluation remains “likely to get worse”.

Measures to Maintain and Improve Grade• Central government should investigate measures to promote wide area cooperation, and to secure budgets, such as publicprivate partnerships, together with sewage works utilities.
• Utilities should expand their asset management initiatives.
• Research institutes and private companies should carry out research and development to improve the efficiency of pipe
maintenance and renewal.
• Academic and industrial associations, and educational institutions should continue to undertake human resource cultivation andtechnical capability improvement.
• Users should take care to use the facilities properly, such as by not discharging oil, etc.

13

Maintenance of Infrastructures and Introduction
Roads Section
Roads Section-Bridges
Current Status of Facilities• There are about 720,000 road bridges in Japan• The percentage of facilities that have been constructed more than 50 years ago was 27% in March 2019, and will be 52% in March
2029, so the percentage is increasing rapidly• The administrators of road bridges include the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), the expressway
companies, prefectures and ordinance designated cities, etc., and cities, wards, towns, and villages. Cities, wards, towns, andvillages account for 66%, and prefectures and ordinance designated cities, etc., account for 26%, so together these local publicbodies manage more than 90% of the total number of road bridges.
(bridges)
Percentage of (total number of)bridges more than 50 years old
As of FY 2019
As of FY 2029

MLIT
Expressway companies
Cities, wards, towns, and villages

Prefectures and ordinance-designated cities

Fig. Number of bridges according to year of construction (from 2020 MLIT White Paper)

Overview of Periodic Inspection• In accordance with the amendment of the Road Act of 2013, from 2014 close visual inspection must be carried out at a frequency
of once in five years (technologies that supplement, replace, or enhance close visual inspection can also be utilized)

Fig. Close visual inspection of a bridge (bridge inspection vehicle, elevated working vehicle, construction scaffold)
Table. Categories of Integrity Diagnosis

Category

14

Condition

I

Sound

II

Preventive action stage

There is no impairment to the function of the structure, but it is desirable that action be takenfrom the point of view of preventive maintenanceIII

Action required soon stage

There is a possibility of impairment of the function of the structure, so action should be taken
soon

IV

Urgent action stage

There is impairment of the function of the structure, or there is a high possibility that this will
occur, so action should be taken urgently

There is no impairment to the function of the structure

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

of Maintenance Technologies in Japan
Judgment
category III

Exposure of deck slab reinforcement*Deck slab: underside of the bridge

Judgment
category

Scouring of bridge pierFig. Examples of judgment categories III and IV in damaged locations• Inspection must be performed by a person with knowledge and skill, and the diagnosis of integrity is categorized in four levels.
• The (recommended) qualification for inspection engineers is a qualification requiring a certain level of technical capability,
operated by private sector organizations, etc., registered as a "Ministry of Land, Infrastructure, Transport and Tourism Registered
Qualification"• Road administrators maintain a certain level of quality of inspection, diagnosis, and maintenance, by using those with nationallyregistered qualifications

Inspection and Diagnosis Technologies (more efficient inspection and more advanced diagnosis using new technologies)

Repair and strengthening technology (improvement of constructability and durability by utilizing new materials and new
methods)

15

Roads Section-Tunnels
Current Status of Facilities• There are about 11,000 road tunnels in Japan• The percentage of tunnels that were more than 50 years old was about 20% in March 2019, and for tunnels of total length less than
100 m, which are mainly in cities, towns, and villages, the percentage had already exceeded 50%.
• The administrators of road bridges include the Ministry of Land, Infrastructure, Transport and Tourism, the expressway
companies, prefectures and ordinance designated cities, etc., and cities, wards, towns, and villages. Prefectures, ordinancedesignated cities, cities, towns, and villages manage about 70% of the tunnels

Fig. Number of tunnels of each administrator according to year of construction (2018 Road Maintenance Yearbook)

Overview of Periodic Inspection• In accordance with the amendment to the Road Act of 2013, from 2014 close visual inspection must be carried out at a frequency
of once in five years (technologies that supplement, replace, or enhance close visual inspection can also be utilized)• Besides deformation of the tunnel main structure, attention is also focused on the hazards of ancillary items such as lighting, etc.,
or their connection members falling• During inspection, emergency measures are taken, such as knocking off fragments of lining concrete if there is concern that it
could fall off• Inspection is carried out by personnel with proper qualification or experience in road tunnels• Diagnosis of integrity in inspection is carried out in 4 categories• Integrity is categorized by external forces, material degradation, and changes in water leakage, diagnosed by reference toguidelines for the occurrence of cracking, separation, and spalling.
Table. Categories of Integrity Diagnosis

I

CategorySound

Condition
There is no impairment to the function of the structure

II

Preventive action stage

There is no impairment to the function of the structure, but it is desirable that action
be taken from the point of view of preventive maintenanceIII

Action required soon
stage

There is a possibility of impairment of the function of the structure, so action should
be taken soon

IV

Urgent action stage

There is impairment of the function of the structure, or there is a high possibility that
this will occur, so action should be taken urgently

Fig. Examples of judgment category IV in damaged locations

16

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Inspection and Diagnosis Technologies(more efficient inspection and more advanced diagnosis using new technologies)
Traveling measurement vehicle

appearance

Measured while traveling at a
speed of 50 to 70 km/h

Shoo�ng situa�on

Example of deformed development drawing

Separa�on of antenna
and wall:3m

laser

Image (camera)

radar

Goals of support such as eﬃciency improvement and labor saving of tunnel inspec�on / diagnosis in general by comprehensively
integra�ng cameras, lasers, radars, close-up visual inspec�ons, and tapping sound inspec�ons to make appropriate judgments.

(Extract from inspection support performance catalog)(Extract from SIP Project introductory document)(Extract from SIP Project introductory document)

Traveling measurement technology(image measurement)This is technology to improve the eﬃciency of inspection
utilizing an image-taking system mounted on a vehicle,
as technology to support close visual inspection

Laser percussion inspection
This is technology to determine the internal structure of
the tunnel walls by laser percussion, to detectseparation, spalling, etc.

Traveling measurement technology (image, laser, radar)
This is a technology to increase the eﬃciency of inspection
by measurement of cracking, deformation, separation, andcavities in the rear while traveling at high-speed

Repair and strengthening technology (improvement of constructability and durability by utilizing new materials and new
methods) Ultra-thin skeleton ﬂaking disaster preven�on coa�ngComplete

Preparatory work

(Preven�on of ﬂaking, Surface protec�on)

Final

Coa�ng

Base

Glass con�nuous ﬁber sheet

surface treatment

Coa�ngBase adjustment

Standard cross sec�on

Coa�ngHigh pressure cleaning
Or KerenPrimer work
Before construc�onsurface treatment

Landmass correc�on work

Material used

PCL board installa�on status

Repeated number of layers

Base material(Undercoat impregnant coa�ng)
Carbon ﬁber pas�ng work
(Topcoat impregnant coa�ng)

Primer work

Landmass correc�on work

Carbon ﬁber pas�ng work

Finish paint work

MBS Clear Guard

Glass con�nuous ﬁber sheet

Construction example(Extract from NETIS)
Measure to prevent concrete fragments from falling by
bonding sheets(repair construction)(Extract from PCL Association)
Repair method by wrapping the interior of a tunnel withcircular arc-shaped precast concrete slabs divided into
small units

Finish paint work

Complete

Strengthening the interior surface of a tunnel byapplying carbon ﬁber sheet to the surface of lining
concrete

17

Roads Section-Pavements
Current Status of Facilities• The total length of roads in Japan as of the end of March 2019 was about 1.2 million km• The total length of paved roads including pavements for light traffic is about 1 million km (percentage of paved roads is 82.5%)• More than 90% of the total length is managed by local administrators
Kind of Road
Natl. Expressways
General Natl. Highways
Prefectural Roads
City, Town, and Village
Roads
Total

Pavement
Stock (km)Percent(%)

9,021
55,583
125,689
821,519

0.9
5.5
12.5
81.2

1,011,812Percentage(Total Road Length) (1,226,489)

82.5

Fig. Total length of paved roadincluding pavements for lighttraffic (Source: the Annual Reportof Road Statistics 2020)

Pavement Inspection Guidelines

The “Pavement Inspection Guidelines”, which describes the basic concept of pavement inspection, was issued by the Roads Bureauof the Ministry of Land, Infrastructure, Transport and Tourism in October 2016, with the objective of achieving efficient maintenanceand rehabilitation for life extension of pavements by preventing base course damage.
Table. Diagnosis levels in the Pavement Inspection Guidelines

Diagnosis level

Severity

I

Good

Low

II

Maintenance stage of surface layer function(for flexible pavements)"

Moderate

Maintenance stage (for rigid pavements)
High
Rehabilitation
stage

III

III-1
(for flexible pavements)

The service life of a surface layer will exceed thedesign period. Base course is assumed to be stable.

III-2(for flexible pavements)

The service life of a surface layer will fall below
than the design life. Base course is assumed to be
deteriorated.

Road Categories and Inspection Viewpoints
Table. Viewpoints of inspection and diagnosis in accordance with road category

Category
A

18

Major
category

Minorcategorye.g. Highstandard
national
highwaysViewpoint of inspection and diagnosis
Paved roads in this category are required to serve a high-level of service
such as high-speed traveling. Pavement inspection and diagnosis must be
implemented by use of a surface characteristics survey vehicle due to thedifficulties of visual inspection.

B

High traffic volume roads(Rapidly deteriorate with highvolume traffic)

Pavement inspection must be implemented more than once every 5 years
with arbitrary inspection methods. For flexible pavements, the diagnosis isbasically performed on the basis of the criterion in terms of the crack ratio,rut depth, and IRI of which thresholds are decided by an administrator inaccordance with the designed service life. For rigid pavements, the diagnosis
is based on the condition of joints and the severity of crack in a slab.

C

Low traffic volume roads(Slowly deteriorate with low
volume traffic)

Pavement inspection must be planned appropriately, but no frequency
is specified. For flexible pavements, the diagnosis is performed on thebasis of a specific index or the combination of indices in accordance withpavement distress characteristics. For rigid pavements, the diagnosis isbased on the condition of joints and the severity of crack in a slab.

De.g.
Residential
roads

Pavement surface management can be relied on the outcomes of road
patrol for daily inspection. The inspection and diagnosis following thePavement Inspection Guidelines is not mandatory.

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Inspection Technologies
Various pavement inspection devices have been developed depending on the application with the development of sensing
technologies in recent years.
Accelerometer (body)

Accelerometer (axle)

Surface characteristics survey
vehicle: It enables three typicalsurface characteristics (cracking,rutting, and longitudinal roughness)to be obtained simultaneously

Response type road roughness
measuring system: It enables
roughness of a road surface to bemeasured using accelerometers
mounted on a general passenger
vehicleInspection system using mobile
devices: It enables brief roadsurface inspection using a motion
sensor built into the device orcamera images

Inspection device using image
processing technologies: It
enables crack detection in a roadsurface to be detected on the basisof AI technologies from video
imagesOverview of Treatment• In the maintenance stages for short to medium term, sealant injection in cracking and/or overlay on rutting should be executed toprevent inundation into under surface layers.
• In the rehabilitation stages for medium to long term, surface and/or binder course should be replaced mainly by applying mill andoverlay.
• In the sections with early-aged deterioration categorized into the diagnosis level of III, a rehabilitation plan considering basecourse replacement must be developed by detailed survey.
Designed Service Life

Diagnosis Level

Performance Curves

I

Durability over Expectation
Maintenance
Maintenance &Rehabilitation

II

Detailed Survey

III
Service Life

Short

MediumPlanned Rehabilitation

Long

Fig. Optimization of treatment against service life and diagnosis level for road category B

19

Railways Section
Railways Section
Current Status of Facilities
Since opening of the first railway between Shimbashi and Yokohama in 1872, the framework for many routes had been completed
World War II. Then, throughout the period of postwar reconstruction and the era of high economic growth, etc., transport between
cities and commuting transport was strengthened, and development of the Shinkansen progressed. As a result, from the earlystages standards of inspection, etc., were defined, organizations and rules were instituted and modified, and maintenance wasconducted systematically in accordance with the facility in each age.
It is difficult to provide alternative transport to railways, so maintenance construction work is mainly carried out at night time inthe short period of time when the trains are not running. In particular, in the case of civil engineer structures such as bridges andtunnels, due to the conditions such as working environments, working hours, the cost and time for replacement of the structuresand replacement of their large-scale members is greater than for new construction. Therefore, the basic concept of maintenanceof these facilities is early detection of defects by inspection, and early repair in order to ensure life extension. The average age ofcivil engineering structures is more than 60 years, which is higher than for other infrastructure, and many structures are morethan 120 years old. On the other hand, the track facilities include rails, sleepers, and ballast, and deterioration such as trackirregularity and wear of track proceeds in accordance with train travel, so the structures have been designed on the assumption of
repair or replacement at a certain frequency, and they have been maintained using various inspection periods and repairmen andreplacement criteria which are defined for each constituent material.

Fig. Age distribution of railway bridges and tunnels(From Infrastructure Maintenance (Railways) Special Committee Report, June 2020 [Japan Society of Civil Engineers])

Overview of Periodic Inspection
At present the standards regarding inspection of railway facilities are prescribed in the "Technical Regulatory Standards on
Japanese Railways", based on the Railway Operation Act.

Fig. Categories of railway structure inspections

20

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Table. Standard Soundness of railway structures and relationship to degree of deformation, etc.
(From Standards of Maintenance of Railway Structures and Commentary (Structures))Soundness

Effect on operation safety andsafety of passengers and the
publicExtent of defectAction, etc.

AA

ThreatSeriousUrgent action

A1

An eventual threat Threat whenan external force acts in an
abnormal situation

There is defect that isprogressing, reduction of
performance is also progressing

Action to be taken soon

A2

Future threat

There is defect, etc., that could
cause reduction of performance

Action at the necessary timeB

Will become integrity A if it
progresses

Will become soundness A if it
progresses

Actions such as monitoring, as
necessaryC

At present no effectSlightAt the next inspection. inspect
the details as necessaryS

No effect

None

None

A

Inspection, Diagnosis, and Repair Technologies (Mechanization, Systematization)
Inspection of track facilities and civil engineering structures is mainly carried out visually
by engineers, but with the progress in ICT this is being made systematic in various
ways and the introduction of instruments is progressing. Also, maintenance work is
becoming mechanized in response to changes in working patterns and in preparation for
insufficient labor in the future.
In addition, in the case of track facilities, the structures are becoming more resistanceto deterioration with the replacement of timber sleepers with concrete sleepers andthe introduction of continuous welded rails with fewer joints. The industry is working to
reduce the future labor requirements for maintenance and reduce the lifecycle costs.

Track maintenance in the past

Track maintenance in the past

Multiple
inspection
train forinspectionof Shinkansen
Shinkansen
Multiple
inspection
train
for inspectionofShinkansen tracks and electrical equipment(Doctor Yellow)

Tunnelusing laser
laser lightlight
Tunnel inspection
inspection vehicle
vehicle using(vehicle taking images of the surface of tunnel
linings)

Mechanicalvehicle correcting
correctingtrack
trackirregularity
irregularity
Mechanical vehicle(Multiple tie tamper)

tracks and electrical equipment (Doctor Yellow)((vehicle
vehicle taking images of the surface of tunnel linings)(Multiple tie tamper)

Monitoringat highfrequency
Monitoringat highfrequency
usingusing
operatingtrains

Vehiclechecking
for obstacles
aroundtracksusing
Vehiclechecking
for obstacles
aroundtracksusing laser light(structure gauge measurement vehicle)

Mechanizationof Shinkansen
lcontinuous
Mechanizationof Shinkansen
welded rail replacement

21

Ports Section
Ports Section
Current Status of Facilities• There is a total of 993 ports in Japan. Of these, large-scale ports include strategic international hub ports (5 No.), international hub
ports (18 No.), and major ports (102 No.).
• From the point of view of international competitiveness of ports, there is still insufficient large water depth mooring facilities, and
it is necessary that development proceeds in accordance with the increase in size of shipping in the future.
• On the other hand, there are many facilities that are aging, and facilities for which seismic countermeasures have not progressed.
• About 14,300 mooring facilities have been developed in the ports of Japan, with a breakdown according to ownership of nationallyowned facilities about 1,900, and port management bodies-owned facilities about 12,400.
• The percentage of mooring facilities more than 50 years old was about 10% in March 2014, and this is expected to increase rapidly
to about 60% in March 2034.
• At present about 21,600 protective facilities for harbors have been constructed in Japan's ports, with a breakdown according toownership of nationally-owned facilities about 1,700, and port management bodies-owned facilities about 19,900.
• Note that besides ports, there are fishing ports throughout Japan, and their number is 2,806.

Percentage of mooring
50facilities that are more than 50 years in service
March
H36 2024
3March
H26 2014
3

About 10%After 10 years

About
35%
35%

March32034
H46

After 10 years

About
60%
60%

About 5,000 facilities ** Number of mooring facilities in strategic international hub ports, international hub ports,
4.5mmajor ports, and regional ports(water depth 4.5 m or more): From Ports and Harbours Bureau, Ministry of Land, Infrastructure, Transport and Tourism
Fig. Aging of port facilities

Overview of periodic inspection• Port facilities are subjected to severe environments from the actions of high waves, strong winds as well as saltwater, so aging
and accidental damage can easily occur.
• Most of the facilities are submerged in the sea, so it is not possible to easily determine the state of degradation and damage.
• Therefore, for each facility a maintenance plan is formulated, and inspection, diagnosis, and repair is implemented based on this
plan.

22

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Table. Inspection frequency based on Inspection and Diagnosis Guidelines for Port Facilities

Category of facility

Prioritized inspection-and-diagnosis
facility

Ordinary inspection-and-diagnosis
facility

Importance of the facility

Facilities that could have a major
effect on human life, property, or
socioeconomic activity

Daily inspection

The port operator sets the appropriate cycle

General periodic inspection anddiagnosis

At least once in 3 years

At least once in 5 years

Detailed periodic inspection anddiagnosis

At least once 10 to 15 years

At least once during the design
service life
When extending the design service
life

Facilities other than those listed on
the left-hand side

Latest Inspection and Diagnosis Technology
Much of the work associated with inspection and diagnosis of port facilities is on or in the sea, and there are also facilities thatpeople cannot approach, so there is a great demand for labor saving and fully automated work.
Three-dimensional shape measurement using a green laser mounted on a UAV• This is a technology for three-dimensional survey by a UAV with green laser equipment, in order to efficiently and safely
determine the status of the parts of a facility on land and in water• Data can be acquired over a wide range at once for the shapes of structures and their elevations on land and in water• Also, measurement can be performed in a short period of time, work underwater is not necessary, and it is possible to avoid
entering into hazardous areas, so in addition to improving the efficiency of the work, the safety of the work is also secured.

Flatness on top surface

Movement and dispersion of blocks
Fig. Example of shape measurement (detached breakwater)

23

Rivers Section
Rivers Section
Present status, roles, and characteristics of river management facilities• River management facilities are basic infrastructure to prevent damage due to flooding, as well as to increase public benefits
received from rivers.
• Rivers, as public entities, are changed by natural processes such as floods, etc., and human daily activities, so these affect various
changes in river management facilities.
• [Levees] The total length of levees managed by central government, prefectures, etc., is about 62,000 km, of which about 20% ismanaged by central government, and about 80% is managed by prefectures. Levees are extremely long continuum structures, andthe collapsion at even one point during a flood loses their control function over the whole area.
• [River structures] Floodgates, sluice gates, and sluice pipes are equipped across levees. They are fundamental river control
facilities, which are fully closed to prevent backflow of the flood water during flooding. There are about 28,000 facilities in Japan(of which there are about 1000 floodgates, and about 27,000 sluice gates), of which about 32% are managed by central government
and about 68% are managed by prefectures, etc. Most of the facilities were constructed up to about 1985, so they will be moredeteriorated in the future.
• [Dams] Dams are fundamental social assets with various purposes such as controlling floods, maintaining the proper functionof running water, replenishing irrigation water, and generating hydroelectric power, etc. There are about 580 dams as rivermanagement facilities in Japan. A high level of safety is required as a result of the importance of dams, but at the same time theircomprehensive renewal is difficult.

24

Fig. Floodgate during a flood

Fig. Levee during a flood

Fig. Dam

Fig. Inspection sluice pipe

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Overview of the inspection and evaluation of river management facilities• [Levees] Levees are made from soil in principle. The materials forming the levees are non-uniform after they have been
constructed and modified many times throughout the past. In addition, there are constructed in floodplains having a complex
geological structure. No two have the same structure, so their safety is checked based upon many years of experience, etc.
• [River structures (floodgates, sluice gates, sluice pipes)] The material of these structures is different from that of the levees, which
are made of soil, so it is important to inspect the changes such as leakage along the boundary surfaces, ground level up at thefacilities on weak foundations, cavitation, etc.
• [Dams] It is necessary to maintain over a long period of time the function and the safety of dams, as fundamental structure, byperforming maintenance effectively and efficiently, and utilizing the long-lived properties of dam bodies.
• Inspection and evaluation of levees, and river structures (floodgates, sluice gates, and sluice pipes) must be carried out at least
once a year by visual inspection in accordance with "Guidelines for Inspection and Evaluation of River Control Facilities such as
Levees, Etc., and Waterways".
• Inspection and evaluation of dams includes daily inspection, visual inspection at least once a year, as well as periodic inspectin bya person other than the dam administrator at least once every 3 years.

New technology for improving inspection and evaluation• It is necessary to perform facility inspection more safely, effectively, and efficiently as the inspection is expected to increase as
dams and other facilities age.
• Robots, etc., are being introduced for underwater maintenance in places where inspection has been performed in the past by
divers.
anual for Utilization of Robots in Underwater Inspection, February 2019 (Draft) Preparation of "Dam Body" edition and "Dam Spillway"* M
editionDam body
Underwater robot

Underwater robot

25

Waterworks
SectionWaterworks Section
Present status of facilities
About 680,000 km of pipeline has been installed in the national land of Japan (as of 2016), of which about 15% has exceeded its
statutory service life. On the other hand the rate of pipeline replacement is low at 0.75%, and in recent years that percentage
is reducing. Therefore, by a simple calculation it will take 130 years or more to renew all the pipelines, so it is likely that thepercentage of pipelines that exceed their statutory service life (40 years) will further increase. Of the total, about 630,000 km iswater distribution pipe for distributing water to users, which is subject to diagnosis.

replaced
1.8

12.1

12
10
6

6.3

7

7.1

1.39

1.4

1.26

1.2

10.5

1.0

1.16
1.00 0.97

0.8

0.94 0.88 0.87
0.79 0.77 0.77 0.79 0.76 0.74 0.75

0.6

4

0.4

2

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

0.0

2003

2016

2015

2014

2013

2012

2011

2010

2009

2008

0.2

2007

0

1.54

2002

6

8.5

1.6

2001

8

7.8

9.5

13.6 14.8

Rate of renewal of pipes (%)

14

2006

Percentage of total length ofpipes exceeding the statutory
service life (40 years) (%)

16

Source: Statistics on water supply
Fig. Aging of pipes

Fig. Rate of pipeline replacement

Overview of periodic inspection
With the amendment of the Water Supply Act, there is an obligation to perform inspection, maintenance, and repair of facilities, andguidelines have been formulated for daily inspections and periodic inspections.
Maintenance of water supply facilities is based on preventive maintenance, but almost all the water supply pipes are buried
underground, and water is always flowing in a full state, so inspection of the inside and outside of the pipes is difficult.
Therefore, in addition to water leakage surveys, information is collected through surveysof the buried environment, such as surveys of the condition of the road surfaces, etc. Repair
and strengthening is performed by renewal of pipes based on the concept of time-planned
maintenance, taking into consideration the material of the pipes.

Inspection and diagnosis technologies 
Maintenance using water leakage surveys
It is anticipated that the integrity of pipes worsens as the number of years since installation
increases. In particular, there is a possibility of water leakage from pipes that have exceeded
their statutory service life. Checks for water leakage are carried out at night time when the noiselevels are low, using water leak detectors to listen to the road surface.

26

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Provided by : Tokyo Metropolitan
Government Bureau of Waterworks

Periodic water quality monitoring
As pipes age, there is concern about the impact on water quality such as turbidity, etc. Periodically precise surveys are conductedusing instruments such as the ICP-MS shown in the photo, for the water quality standards up to 51 items, to ensure the safety of thewater.

Provided by : Tokyo Metropolitan Government Bureau of Waterworks

Repair and strengthening technologies: Seismic resistant pipes with flexibility
Seismic resistant ductile cast-iron pipes have joints that expand, contract, deflect, and have a pullout prevention function. Therefore,
when suspended they bend as shown in the photograph. In this way seismic resistance is provided, which also contributes towards
prevention of water leakage.
In addition, various types of water leakage survey technology and technology for utilizing water leakage history information are
utilized.

Provided by: Japan Ductile Iron Pipe Association

27

Sewage Works
SectionSewage Works Section
Present status of facilities
The coverage of wastewater management facilities, such as sewage works, wastewater treatment facilities in agricultural village,
and septic tanks in Japan is about 91.7%. The percentage is as high as 99.6% in cities of population 1 million or more, and as low as
81.1% in local municipalities with a population of less than 50,000.
The coverage of sewage works is 79.7%, with 99.3% in cities of population 1 million or more, and 52.5% in local municipalities of
population less than 50,000, so there is a large population using the other wastewater management facilities in local municipalities.
Note that in the case of areas where wastewater treatment has not spread, each prefecture is reviewing its development plans ofwastewater management facilities, taking into consideration the changes in the local circumstances such as population reduction,
based on the "Manual for Developing Prefectural Plan for Sustainable Wastewater Management Systems".
About 480,000 km of sewage pipes have been laid throughout Japan (as of 2018), and the length has increased by about 14% in the
10 years since 2008. About 4% has exceeded the standard service life of 50 years as of 2018, but this is expected to increase rapidly
after 10 years to about 14%, and after 20 years to about 33%.

100

99.3%

99.6%

Others:0.3 million (2.8%)
81.1%

Coverage (%)

80

Septic tanks:
1.2 million (9.3%)

60

52.5%

40

Sewage works:
10.1 millions (79.7%)

20

0Total > 1000 500-1000 300-500 100-300 50-100<50126.84

29.94

11.17

17.51

30.91

17.46

19.86

116.36

29.83

10.60

16.42

28.30

15.11

16.11

Population size
(thousand)Total pop.
(million)
Covered pop.
(million)Fig. Percentage of population served with wastewater management at the end of FY 2019 (from survey by the Ministry of the Environment, Ministry of Land,
Infrastructure, Transport, and Tourism, and the Ministry of Agriculture, Forestry and Fisheries)

16
14
12

Rapid increase in aging pipes

10
8
6
4

50 years exceeded
about 19,000km

2018

2012

2015

2009

2006

2003

2000

1997

1994

1991

1988

1982

1985

1979

1976

1970

1973

1967

1964

1961

0

1958

2
<1956

Total length of pipes by the year of
installation (1,000 km)

18

Fig. Total length of pipes as of end FY 2018 (prepared from Ministry of Land, Infrastructure, Transport and tourism document)

28

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

Overview of periodic inspection
In 2015 the maintenance and repair standards were established (amendment of the Sewerage Service Act). There is an obligation
to perform inspection at the frequency of at least once every five years in locations where the possibility of corrosion is high, andthe results and scheduled measures are published as "Sewage Pipes Maintenance Yearbook". In addition, stock management(SM) is promoted based on "Guidelines for Implementation of Stock Management in the Sewage Works" (2015). The following are
implemented: (i) acceleration of 13 initiatives such as study groups, self-diagnosis by SM reports, etc., (ii) development of databasefor maintenance information and standardization of a maintenance cycle utilizing SM plan formulation for efficient repair andreplacement, (iii) publication of inspection results and corrective actions.

Repair and strengthening technologies
Various technologies have been developed in order to reduce the effect on the livelihood of the residents and the repair andreplacement cost.

• Overall judgment of the interior of a pipe from above groundusing a pipe camera that can check the inside of a pipe
• Surveys using cameras with direct view only, checking by
developed views, and automa�c recogni�on of its shape
Fig. Pipeline inspection system using wide-angle camera(documents provided by the Ministry of Land, Infrastructure, Transport and Tourism)

Inspection and diagnosis technologies
From 2011, the national government has supported for technical verification and development of guidelines for innovativetechnologies at actual scale facilities. There has been success in establishing guidelines for various new technologies such as
pipeline inspection and diagnosis, etc.

• Renewal of pipelines by construc�ng a
new pipe inside the exis�ng pipe,
keeping the ﬂow capacity• Open excava�on work is not required,
so the cost and the eﬀect on road
traﬃc is reduced

Winch

Hydraulic unit

FeederDrum of profiling material

Pipe making
machineFig. Development pipe renewal technologies(document provided by the Ministry of Land, Infrastructure, Transport and Tourism)

29

Yotsuya 1-chome, Shinjuku-ku, Tokyo Japan
160-0004
Tel : +81-3-3355-3452
Fax : +81-3-5379-0125

Japan’s Infrastructure Grades 2020 & Introduction of Maintenance Technologies

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