Current Status of Japanese Road Bridges and Future Perspective

HIROAKI TERAMOTO

Ministry of Land, Infrastructure and Transport

Numbers of bridges by type of material(only bridges over 15m)

　　　　 Classification Total

Steel bridges

RC bridges PC bridges Others

National expressways 6,510 1,977 1,941 2,284 308 National highways 22,542 10,719 3,161 8,027 635 Prefectural roads 31,361 12,310 6,064 12,196 791 Municipal roads 82,108 31,130 14,536 32,715 3,727 Total 142,521

(100%) 56,136 (39%)

25,702 (18%)

55,222 (39%)

5,461 (4%)

Distribution of bridges for completion year

0

5,000

10,000

15,000

20,000

25,000

30,00019

26～

30

1931

～35

1936

～40

1941

～45

1946

～50

1951

～55

1956

～60

1961

～65

1966

～70

1971

～75

1976

～80

1981

～85

1986

～90

1991

～95

1996

～20

00

The others

PC bridges

RC bridges

Steel bridges

Num

ber

of b

ridg

es

0

5,000

10,000

15,000

20,000

25,000

30,00019

26～

30

1931

～35

1936

～40

1941

～45

1946

～50

1951

～55

1956

～60

1961

～65

1966

～70

1971

～75

1976

～80

1981

～85

1986

～90

1991

～95

1996

～20

00

The others

PC bridges

RC bridges

Steel bridges

Num

ber

of b

ridg

es

Road Work Budget in JAPAN (2005)

Total investment

in road projects in JAPAN

￡ 50.96 billion (100%)

National Road Projects

￡ 11.47 billion (22.5%)

Projects undertaken by local governments

￡ 30.65 billion (60.1%)

Operation of Toll Roads

￡　 8.84 　 billion

(17.4%)

Maintenance

& repair

￡ 1.44 billion

Construction, operation & others

National Highways Maintenance Budget(2005)

Maintenance and Repair (￡ 1.44Billion)

Maintenance

￡ 1.10 Billion

( 77 %)

Improvement

￡ 0.33 Billion

(23%)

Repair work for Structure: (35%)

Repair of bridges and tunnels, Pavement

Daily Maintenance : (13%)

Road cleaning, Planting etc.

Road Patrol : (9%)

Minor Repair Work : (18%) Repair for retaining walls, drains etc.

Others : (2 %)

Emergency restoration for disasters

Countermeasures for earthquakes : (11%)

Reinforcing of substructures, Prevention for bridge fall

Disaster prevention : (12%)

Slope protection

Type of Inspection in JAPAN

Usual Inspection

Periodic Inspection

Special Inspection（ Salt Damage, ASR, Fatigue…）Disaster Inspection ( Earthquake, typhoon…)

Damage of Road Bridges in JAPAN

(the Results of Periodic Inspection)

Damage level Description Percentage(%)

A There is no damage, or damage is so little that there is no need for

repair. 5.9

B Repair may be necessary depending on the condition. 81.4

C Prompt repair or other remedial action is required. 12.8

E Emergency measures must be taken. 0.0

Total 100.0

Fatigue cracks on girder

Damaged gas pressure weld point (main reinforcements)

Breaking at corner of the shear reinforcement

Breaking of reinforcing bars by ASR

Dropping-off of concrete of RC Slab

Causes for bridge reconstruction (National highways and prefectural roads)  

Steel bridges PC bridges

Cracking and peeling of concrete

(Chloride attack)16.7%

Damage of RC slab

33.3%

Cracking andpeeling of concrete50.0%

The 　 others 6.8%

Damage ofRC slab

67.2%

Corrosion of 　 steel member26.0%

Chloride damage of PC girder

Air Salt in Winter (climate)

Tsukuba

Narita Airport

Tokyo

Kansai AirportOsaka

Kyoto

Tokyo to Tsukuba 50kmTokyo to Osaka 560km

N

S

MonsoonRome

latitude

Maintenance cost for a deteriorated concrete bridge

A Bridge

0

100

200

300

0 10 20 30 40

Age (year)

Sum

of

cost

Prediction by the results of Inspection

(example) Chloride Damage in concrete

at cover depth– If Cl- exceeds 1.2kg/m3 or will exceed 1.2kg/m3

within next 10 years,

Planning of Repair should be undertaken.

Case 1 ： Preventive repair (Minimizing Life Cycle Cost)Case 2： Repair at the repairable limit state

T₁ T₂ T₃

yearEvaluation

period

Cost

Case 1

Case 2

T₁ T₂ T₃

yearEvaluation

period

Soundness

Smallrepair

Smallrepair

Largerepair

Case 1

Case 2

Relation between type of repairs and cost

Bridge DimensionsInspection

Properties of structure

Database

Prediction of Future Soundness

Comparison of Type of Measures,Minimizing of Life Cycle Cost, 　 Budget Restriction / Social Situation

Investment Analyzing

Risk based Prioritization

Decision of Management Plan

Execution of Measures or Maintenance

Evaluation of Present Soundness

Asset Management Flow of Bridges Maintenance

SUMMARY ( Needs in JAPAN)

(1) Inspection of Local Road Bridges

( needs to make a New Act/Law)

(2) Improve the Forecast Model of Deterioration

( the Methods of Life Cycle Cost Analysis )

(3) Develop Non-Destructive Test Techniques

(4) Develop Prioritization System of Maintenance

(5) Make the Market of Maintenance-Works

more Attractive and Profitable

Thank you for your attention!

END