Pavement Maintenancein JapanKazuyuki Kubo
Head, Pavement and Earthworks Division
National Institute for Land and Infrastructure Management
Ministry of Land, Infrastructure, Transport and Tourism
Road Conference 2017 International
Symposium

1. Present Status of Roads in Japan - Paved Rate Paved Rate

Unpaved Rate

Unpaved

100
90

80

Percemt

70

60
50

Paved

40
30

20
10
0
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Year
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1. Present Status of Roads in Japan - Pavement Types (2015.4.1)
Asphalt 8,040km
Cement 610km

Motorway 8,650km

Asphalt 22,600km
Cement 1,100km

National Roads 23,700km(Managed by MLIT)

Asphalt 26,800km(for Light Traffic 3,700km)
Cement 1,200km
Not-paved 300km

National Roads 32,000km（Managed by Prefecture andMetropolitan Cities）

Prefectural Roads
129,400km
Municipal Roads
1,027,000km
Total
1,221,000km

Asphalt 82,000km(for Light Traffic 41,600km)
Cement 1,700km
Not-paved 4,200km

Asphalt

Asphalt forLight Traffic

Asphalt 148,000km(for Light Traffic 610,000km)
NotCement 51,000km
paved
Not-paved 218,000km

CementRoad Conference 2017 International
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Asphalt 287,000km(for Light Traffic 656,000km)
Cement 55,000km
Not-paved 223,000km

2. Pavement Monitoring - Annual Measurement ・ Total length (managed by MLIT)
about 24,000km
・ Monitoring length (Annually
Implemented)
about 8,000km/ a year
→ whole network is measured every 3
year
・ Road Surface Measuring Devices
Items Measured*Cracking Ratio*Rutting Depth*Roughness (IRI)
Road Conference 2017 International
Symposium2. Pavement Monitoring - Road Surface Measuring Device -Laser tube

Laser
scanner
Laser beam

Water Cooling System

Electric
Generator

Image reader
Signal processing
Equipment

Light detection sensor

Now, we are on the way tochange this expensive system.

Displacement Gauge
Rutting, Cracks, roughness

Road Conference 2017 International
Symposium2. Pavement Monitoring - Measured Data Rutting ⇒ Rutting Depth (D)
D1

D2

OWP

IWP

D=max(D1 , D2)

Cracking ⇒ Cracking Ratio (C)C=

Cracking area (m2)Section area (m2) ×100

Calculation method of cracking area isdefined by Manual for Pavement Testing
Method (Japan Road Association)

Roughness ⇒ σ
IRI can be conversed from σn = number of data
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Symposium

3. Pavement Database - Display Map -

Click
Here
Map will be
Displayed

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3. Pavement Database - Service Level Check for each Section -Alert
Criteria

Display MCI(=distress level of each pavement),
Cracking Ratio, Rutting Depth, and Roughness
Road Conference 2017 International
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3. Pavement Database - Maintenance Control Index (MCI) -MCI=10 - 1.48C0.3 - 0.29D0.7 －0.47s0.2
C: Cracking Ratio (%)
D: Rutting Depth (mm)s: Roughness (mm)Concept is very close
to PSI in USA• Fullmark=10points• MCI had been used by MLIT as an index for the pavement
management until 2005.
• At present , MLIT uses Cracking Ratio and Rutting Depth as
the important Indices for judgment of repair pavement.
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4. Pavement Condition in National Highways -Cracking Ratio 14,000

Length (km)12,000

Cracking Ratio

10,000
15%

25%

35%

8,000
6,000
4,000
2,000
0

0.0 5.0

5.1 10.0

10.1 15.0

15.1 20.0

20.1 25.0

25.1 30.0

30.1 35.0

Crackig Ratio (%)

Road Conference 2017 International
Symposium

35.1 40.0(2014.3)

40.1 45.0

45.1 -

4. Pavement Condition in National Highways -Rutting Depth -9,000

Rutting Depth

8,000
20mm

Length (km)

7,000

30mm

40mm

6,000
5,000
4,000
3,000
2,000
1,000
0

05

610

11 15

16 20

21 - 26 - 31 - 36 25
30
3540(2014.3)
Rutting Depth (mm)Road Conference 2017 International
Symposium

41 45

46 -

4. Pavement Condition in National Highways -Roughness σ7,000

Length (km)

6,000
5,000
4,000

3,000
2,000
1,000
0

σ (mm) 0.0 -0.6 1.0

1.1 1.5

1.6 2.0

2.1 2.5

2.6 3.0

3.1 3.5

3.6 4.0

4.1 4.5

4.6 -IRI(mm/m) 0.0 -0.8 1.3

1.4 1.9

2.0 2.5

2.6 3.1

3.2 3.7

3.8 4.3

4.4 4.9

5.0 5.5

5.6 -

0.5

0.7

2

IRI = 1.2054 σ + 0.123 (R = 0.92) by PIARC EVEN Project in 1998.

Road Conference 2017 International
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５．Major Point for Pavement Maintenance - New Policy -• There seem somecases of long life
pavement without
frequent repair work
 How to extend repair
cycle



Damaging Factors To Pavement

 Damage to pavement increases with the axle
load to the power of four.
(Figure 1)

 The more HGVs that are on the road, the more
rapidly the asphalt pavement becomes damaged.

If the vehicle is 20 tons, the axle load is 20 times higher than thatof a typical passenger car and the damage to the pavement by
the 20-t truck is 16 million times greater than that of a passenger
car.

Relationship Between HGV Traffic Volume and(Figure 2)
Pavement Damage

Traffic
volumePercentage ofvehiclesthat cause
damageto thepavement(Passenger car: 9%)(Almost 100%)(HGVs: 10%)(FYI)
Residential streets remain healthier when they have less HGVtraffic, unless the street is dug over.

Age of pavement (years)

Yonago Newtown(Tottori Prefecture)(Photo 2)

Tama New Town (Tokyo)More than 250
vehicles and More than 100
vehicles anddirection
directionLess than 100
vehicles anddirection

More than 3,000
vehicles anddirection
More than 1,000
vehicles anddirection

Progression of damage isslow with 1,000 vehicles
and direction.

Pavement is damaged in
the earlier years with morethan 1,000 vehicles anddirection.

 Ensuring the Soundness of Roadbeds Is Important To Reduce LCC(1) Rain water, which penetrates roadbeds due todamaged surfaces, will ultimately reduce the roadbed’s
support and cause damage to the entire pavement
structure.
(2) Repairing roadbeds costs 3 times more than repairing
surfaces and takes 4 times more work.
(3) If the roadbed is already compromised, then repairing
only the surfaces may result in more damage to thesurface in a shorter period of time than normal.
(4) Due to the above factors, it is important to keep
roadbeds sound. Repairing surfaces and other structuresin a timely manner is required.

(Photo 1)

A road which has not been repaired for morethan 30 years. (In a good condition, although
there is some cracking)Source: MLIT data

A road which has not been repaired formore than 40 years. (In a good condition
with no cracking) Pavement Management Today The budget is decreasing and the appropriate
preventive maintenance and repairs are
insufficient.

 About 80% of all prefectures and ordinancedesignated cities, and about 20% of all municipalities,
have implement pavement inspection. (Figure 3)①[Prefectures]

②

③

0%

20%
①

[Ordinancedesignated city
/Special ward]

40%
60%
80%
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未回答
②
③

74%
0%

20%

20%

[Municipality]
0%

100%

12% 14%

40%
60%
80%
未回答
①
②回答割合
③

63%
20%

1,200

19% 2%

79%

40%
60%
回答割合

(Figure 4)

未回答

100%

17%
80%

1,000

<All roadadministrators >

0.6
0.5
0.4

800

0.3

600

0.2

400

0.1

200

0.0

0

(0.1)

100%

(1) Inspections carried out.
(2) The only time inspections were carried out were when the Comprehensive
Road Stock Inspection was carried out.
(3) Inspection has never been carried out.
(1)
(2)
(3)
①
②
③

舗装の…
Pavement
repair cost
舗装維…
Pavement stock

Pavement project cost (trillion yen)

• Financial and humanresource problem
especially in local gov.
 Minimize LCC withefficient management••

Durability of pavement is mostly affected by heavy goods vehicles (HGVs)  the more HGVs that are on the roads, the more rapidly pavement
deterioration occurs
It is important to make sure the layers underneath the roadbed are in a good condition by repairing the surface as needed, in order to reduce LCC.
Although the National Government and Expressway Companies (NEXCOs), as well as 80% of all prefectures and 20% of all municipalities, have
implemented road inspections, standardized data collection and appropriate preventive maintenance/repair has not been sufficiently implemented.

Pavement stock (thousand km)• Difference inpavement life (repair
cycle) between heavy
and light traffic road
 Classify road networkby heavy traffic Level•

Cracking ratio (%)

For heavy traffic (trunk)roads,

1
As with bridges and tunnels, the Maintenance Cycle shall be established to extend the life of pavement
and*1: Life Cycle
Costreduce LCC* .

未回答

FY

5.Major Point for Pavement Maintenance -Settlement of Target Service Life Roads with Rapid Progression of Damage• Set Target Lifetime
 Pay more attention
to shorter lifetime
pavement Recommend
preservation orreconstruction
rather than repair
work such as cut &overlay
 Monitor pavement
condition every
five years or
longer Visual observation
or equipmentaided

 In order to protect roadbeds, surfaces must be efficiently repaired in a timely manner.
 Management is required to increase the life of roads, this can be achieved by creating a targeted
lifetime for the pavement.
 An inspection at least once every 5 years is prescribed.

 Use of 3 stages for evaluation is recommended.

6. Inspection of Asphalt Pavement
6-1. Roads with rapid progression of damage (Type A and B)(1) Inspection Methods- Setting the pavement life
The road administrator shall appropriately set the targeted lifetime for the pavement,
according to the repair work history in the same area and HGV traffic volume classification.
- Frequency of inspection
The road administrator shall appropriately set a frequency of inspection, while taking into
consideration that a frequency of once every five years is recommended.
- Inspection method
In light of the characteristics of each road, the road administrator shall set the standard forproper management to understand the pavement condition through appropriate methods
including visual observation and equipment-aided observation.
* targeted lifetime for the pavement
Number of years set as a targeted lifetime for the pavement. The intention is to extend the life of pavement through granular control, including removal of severely damaged sections in
the early years and implementation of appropriate actions depending on the service years and damage level of the asphalt pavement, which has a wide variety in deterioration levels.

5. Major Point for Pavement Maintenance -Identify Damage LevelLonger life
Sound or average
condition:
No need toconsider structural
re-design(2) Evaluation of Soundness
In the light of the criteria set by the road administrator, pavement shall be appropriately evaluatedusing information from the inspection (e.g. cracking ratio, rutting depth and IRI).
* Use of 3 stages for evaluation is recommended.
Type
I

Good

Damage level: low: In the light of the criteria, the deterioration level is low and the pavement surface is in a good condition.

II

Phase to keep surfacefunctioning

Damage level: medium: In the light of the criteria, the deterioration level is medium.

Repair phase

Damage level: high: In the light of the criteria, the deterioration level is high and (expected to be) beyond the permissible level(soon).

III

Shorter life
Undesirable
condition:
Need to consider
structural redesign

Condition(III-1: Surface repair)Service years of the surface exceed the targeted lifetime for the pavement (i.e. layers under the roadbed are thought to be ina good condition).

(III- 2: Replacement ofroadbed)Service years of the surface do not exceed the targeted lifetime for the pavement (i.e. layers under the roadbed are thought tobe damaged).

* Recommended management standards are provided.
-Type A road: cracking ratio of 15-20%, rutting depth of 20-25 mm, IRI of 3.5 mm.
-Type B road: cracking ratio of 20-40%, rutting depth of 20-40 mm, IRI of 8 mm.

(3) Actions
Based on the evaluation results, the necessary actions shall be taken to implement the pavement repair in an efficientmanner.
* Actions shall be taken based on proper repair design by comparing several LCC scenarios, including a change toconcrete/composite pavement and reinforced roadbed by cement stabilization.

(4) Records
Results of the inspection, evaluation, and actions shall be recorded and kept as long as the pavement is in service.
For type A roads, appropriate methods may be used depending on the road characteristics at each phase of inspection, evaluation, action, and recording,considering the required service level for high-speed running roads.

5. Major Point for Pavement Maintenance -Case of Local Road Roads with Slow Progression of Damage

For low volume (local) roads“broken, then repair”
Less need for monitoring or
efficient management ofpavement conditions

For more efficient pavement
management,“ready for future repair”
Budget plan for repairment is
Recommended to be laid by
local gov.

 Development and implementation of an inspection plan are prescribed.
 Use of 3 stages for evaluation is recommended.

6. Inspection of Asphalt Pavement
6-2 Roads with slow progression of damage (Type C and D)(1) Inspection Methods-Development of an inspection plan
The road administrator shall appropriately develop an inspection plan considering the totalroad length, replacement timing, and local characteristics.
- Inspection method
In light of the characteristics of each road, the road administrator shall set the standard forproper management to understand the pavement condition through appropriate methods
including visual observation and equipment-aided observation.
* For reference of inspection planning, the deterioration curve for roads with slow progression of damage isprovided in the appendix.
*If intervals between inspections becomes too long, it is recommended that information from regular patrols isused to complement the inspection.

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5. Major Point for Pavement Maintenance - Patrol and Treatment (2) Evaluation of Soundness

Pavement isthinner andmore simple
than trunkroads
There is lessdifference
betweensurface andstructural repair

In the light of the criteria defined by the road administrator, pavement shall be appropriately
evaluated based on the information obtained from the inspection.
* Use of 3 stages for evaluation is recommended.
Type

Condition

I

Good

Damage level: low: In the light of the criteria, the deterioration level is low and thepavement surface is in a good condition.

II

Phase to keepsurface function

Damage level: medium: In the light of the criteria, the deterioration level is medium.

Damage level: high: In the light of the criteria, the deterioration level is high and(expected to be) beyond the permissible level (soon).
* Recommended management standards are provided.
Roads with slow progression of damage: Cracking ratio (20% to 40%), rutting depth (20 mm to 40 mm)
III

Repair phase(3) Actions
Based on the evaluation results, necessary actions shall be taken to implement thepavement repair in an efficient manner.
(4) Record
Results of the inspection, evaluation, and actions shall be recorded and kept as long as the
pavement is in service.
For type D roads, regular patrols may be deemed as proper inspections in order to identify surface damage,take actions, and record the log. Road Conference 2017 International

Symposium6. Trials to Reduce LCC - Performance-Based Contract for Asphalt Pavement Work  Both the administrator and the contractor shall identify challenges and explore solutions to assure the long-term quality of theinfrastructure.
 To this end, the administrator should require the contractor to assure a level of performance of the infrastructure for a certain
period of time even after the completion of the work, in order to encourage the contractor to do the work carefully. In thisway, road pavement will become more durable and last longer.

<An Illustration of Long-term Performance Assurance>•

Currently, an inspection is carried out upon completion of work before the infrastructure is put into use.
However, some infrastructure deteriorates faster than others over time, thus requiring proper repair
regardless of the time period after delivery.
With a long-term performance assurance, rapid deterioration of pavement, as shown “Pavement A” in the
figure below, can be prevented. This will help extend the life of the pavement.

Desirable
C>B>A

Under previous and manner,condition just after construction
would be checked, and found nodifference among A, B and C
Under performance-based contract,
It will become possible to evaluate
C>B>A

Inspection uponcompletion of
construction

Set the performancerequirements to beachievable through normal
work.
Note: Failing to meet therequirements will result in a
penalty charge or reworking

Rutting depth of
8 mm or less inthis case“Better construction work for longer life”

Deterioration level(in terms of rutting depth)•

Performance checkafter a certain period(3 years in this case)

Average years before thefirst repair is performed
Age of pavement (years)

Avg. 5.5 mm in this caseRequired
performance

Pavement A

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Pavement B

Deterioration levelthat requires repair

Pavement C

ICT (Information and Communications Technology in the Pavement Field)
 To increase productivity, “ICT Pavement” (ICT-enabled paving work) has been introduced in FY2017.
 Necessary technical standards and estimation standards were developed in FY2015 and came into
effect in April 2017.
(1) Pre-measurement
by laser scanner(3) Work using ICT-enabled grader(2) Designing and planing of
construction based on ICT-enabled 3D
measurement(4) Labor-saving in inspection

OK
Auto-calculation

Laser scanner allows an areabased (high-density) 3D
measurement in a short period oftime.

i-Construction

From the difference between 3D
measurement-based design data and premeasurement data, the actual amount ofwork necessary is automatically estimated.
Measurement

Orderer
ICT-enabled construction equipment isself-operated using 3D design data.

Design andWork planWork

Laser scanner data-based inspection
reduces documentation work by half.

Inspection(3)
Partly ICT-based work

Conventional method(1)
Measurement(2)

3D datacreation-Improved work efficiency-No leveling work means
less workers

Design andWork plan

Work

(4)
2D datacreation
Inspection

Plan and cross-section

Manual measurement

Amount of work is
estimated from paperbased drawings

Leveling string is set

Work based on
the leveling

Repeated measuring andwork until it is shaped

Inspection by drilling

ICT (Information and Communications Technology) in the Pavement Field

ICT is introduced in a phased manner depending on the project phases (from construction tomaintenance/management) and purposes (from streamlining to quality enhancements).

[Purpose][Phase 1 (from 2017 onward)][Phase 3][Phase 2]

Improved work
efficiency(Construction)

Roadbed work
(Introduction of MC grader)

Consider expansion of ICT-enabled work including asphalt paving andcutting overlays(Introduction of MC finisher, MC cutting machines)

Improved work
efficiency(Work management)

Management of completed
surface(Laser scanner)

Quality Control (density)
Non-destructive technology

Area-based management ofcompleted surface

ICT pavement
Effects: construction period
and labor are reduced
Improved managementlevel (maintenance /management)

Management of compaction by ICT-enabled roller
Acceleration sensor

Research andDevelopment

Firm ground

Stored point clouddataManagement of long-term
performance(Laser scanner)

Quality control by ICT
Effects: Unevenness of quality isaddressed and labor-saving in quality
controlMeasurement of surface characteristics after the roadis opened to public

Big Data
SystemCollect

Quality Improvement(Work / work
management)

Analyze
Utilize

Stored quality data

Analysis on the long-term fluctuation of face shape data obtained from iConstruction

Consideration toward ideal
work/work management toimprove long-term performanceWhat is expected results of applying ICT in the Pavement Field?
[Beneficial Effects for Long-term Performance Assurance System] Laser scanner improves measurement of completed surface, helping to address issues concerning thelong-term performance evaluation system.
 Area-based quality control will help address unevenness of quality, extend the life of the pavement andreduce the costs, which are what the long-term performance assurance system aims to do.
Measurement of completed surface by laser scanner[Challenges]-Measurement of completed surfaces just after theconstruction (initial setting) does not necessarily cover all
the sections that need to be evaluated for long-term
performance assurance work.
-Initial measurement points may not be accurately identified
in some cases.

Quality control by ICT-Area-based quality control using acceleration sensors will help
address unevenness of quality between constructors, extend
the life of pavement, and reduce the costs.

[Conventional Method][Solution]-It is possible to obtain initial values wherever the rutting
occurs by using a laser scanner to carry out an area-based
measurement just after the completion of the work.
-Accurate location of the initial measurement points can beobtained by using point cloud coordinates.
Laser scanner(area-based measurement)

Conventional method(line-based measurement)[i-Con]Acceleration sensor-based quality control may identify locations with arelatively lower rigidity. By applying another rolling compaction, thequality of pavement will be improved and unevenness can beaddressed immediately and without additional damage.
Vibration roller

Measurement
point(At an interval of
20 m)

The existing quality control
criteria requires the
digging of a given spot toevaluate the density by thesand replacement method,which may cause
unevenness in the qualityof the pavement.

Area-based measurement of rigidity

Image of evaluation

Spot with less rigidity

Acceleration sensor

Rutting

ICT is effective,• not only for good
construction• but also for 2D or 3D
construction data
For performance-based
contract, 2D or 3D
construction data is very
effective to understandthe reason of theirperformance, such as
local insufficientcompaction or unevenmaterial
ICT will encourage andassist performancebased contract andfinally contribute toextend pavement life

Thank you for your attention!

Road Conference 2017 International
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