ENHANCED FUNCTIONALITY
FOR AN EXISTING BRIDGE MANAGEMENT SYSTEM
Masato MIYATA, Takuto SHIRAISHI, Takashi NISHIOKA, Seigo NASU
Kochi University of Technology
ABSTRACT: In the high economic growth period 1955-1974 in Japan, there were substantial new
infrastructure needs, so reinforced concrete structures were built. Now Japan continues to use the samestructures, but after the high economic growth period, chloride attack and other deterioration have been
detected. In fact reinforced concrete is not permanent without maintenance. Now reinforced concrete
structures built in the high economic growth period are approximately 30 to 50 years old and some of them
are already deteriorated.
In addition, the national and local governments’ financial conditions are tight, so existing operation andhaphazard maintenance may not be sufficient for future substantial bridge deterioration. In such a situation,
renewed maintenance by the bridge asset management system (BMS) is needed. BMS is expected to include
deciding investment timing of maintenance, calculating and minimizing life cycle cost (LCC), andcalculating and suggesting maximum maintenance effect. In fact BMS can anticipate decision support
systems for consistent bridge safety and quality. In addition, BMS is found to be useful for meeting
accountability requirements. In 2007, national and local governments started operation of BMS. However,
BMSs are now developing and their functional capabilities are not enough for bridge management, so inJapan BMS is not popular.
In Kochi Prefecture there are 2 BMSs, one for a prefectural bridge and another for a national road bridge.
However, there is no substantial functional BMS in operation. Therefore this research will clarify the reasonsfor the smooth operation of the 2 BMS and suggest an improvement element. To improve BMS, it issuggested to use a physical deterioration model with deductive deterioration stage, maintenance methods forrelevant stages, renewal periods for each stage and calculation of minimum LCC with maintenance plan forin-service period. For one bridge, implementing a minimum LCC maintenance plan to the limit of therenewal period is best; however, for substantial bridges this is not implemented because there are budget
constraints for maintenance. In that situation, it is essential to consider a minimum LCC maintenance planand renewal period on all stages, setting maintenance priorities and suggesting a total minimum cost forbridges. This research implements 5 bridge priorities under budget constraint.
KEYWORDS: Bridge Management System (BMS), life cycle cost, maintenance priority
1. Introduction

and Japan still continues to use the same structures.

1.1

However, the deterioration mechanism including

BackgroundIn the high economic growth period 1955-1974 inchloride attack, which was not fully understood atJapan, there were substantial new infrastructure

the construction, has been gradually clarified inneeds, so reinforced concrete structures were built,

recent years, and it has been found that reinforced

concrete structures are not always permanent without

2. Deterioration state of bridges and the necessityof bridge asset management

maintenance. In addition, the reinforced concrete
structures built in the high economic growth period

2.1 Necessity of bridge asset management

are approximately 30 to 50 years old and some ofIf we take it into account that the national roadthem are already deteriorated. As stated in the

network including as major routes has been

1)in the advisory committee concerningcompleted to a certain degree, and consider that

ideal ways of future management and renewal of themany of the bridges in-service are becoming

road structure in 2003, there is a concern that thedeteriorated all together, how we should maintainsocial influence of the increase of the costs required

and manage them is a more important problem thanfor repair and maintenance of aging road structures

to construct new bridges. However, as for the bridge

and the influence of the regulation of traffic etc.

maintenance, the national and local governments

accompanying such repair or maintenance is getting

have conducted the maintenance of the bridges that

more and more serious, along with the advancement

were judged to be deteriorated or not good enough toof the aging of road structure.

be in-service, according to the risk rating based on

proposal

In addition, the national and local governments’inspection results. In addition, their financial

financial conditions are tight, so existing operation

conditions are tight and existing operation andand haphazard maintenance may not be sufficient forhaphazard maintenance may not be sufficient. In

future deterioration. In such a situation, a neworder to predict the future maintenance cost, it ismaintenance and management measure using Bridge

possible to analyze the budget in macro-level andManagement System (BMS) has been getting

predict how much is required in the future byattention. In Kochi prefecture, there are two types of

estimating the maintenance cost based on the

BMS’; one is Kochi version BMS owned by Kochi

maintenance rate as Takahashi et al. 2) did. However,prefecture and the other is a document creation tool

even if the entire budge is calculated or predicted,

for bridge repair budget owned by Tosa National

this is not enough to decide when and what order theRoad Administration office of Shikoku Area

maintenance should be conducted based on the

MaintenanceLand,

prediction. One of the effective ways is to include

Infrastructure and Transport (BMS of MLIT).

bridges into the target of asset management. Asset

However, neither simulation nor maintenance based

management system (BMS), represented by PONTIS

on the result of simulation is carried out, and current

BMS3),

simulation results are not taken into account for the

Administration (FHWA) and American Association

repair. In other words, BMS is not utilized enough toof State Highway and Transportation Officials

meet expectations.

(AASHTO) in 1991, attracted attention as a new

Bureauof

MinistryofdevelopedbytheFederalHighwaymeasure of bridge maintenance and management.
1.2

Objectives

Asset management is an idea of asset management to

The objectives of this study are to demonstrate themaximize asset value by appropriately operatingproblems and reasons that the existing two BMS’ inproperty in consideration of risk and profitability, etc.

Kochi prefecture are not utilized enough, and to

4)

propose a system of operating level, improving basic

management for public structures, especially the one

function of the BMS in order to find out the reasonsthat specializes in bridges, BMS is expected toand to overcome the problems.

compute the lifecycle cost (hereinafter LCC),

Furthermore, in the light of the idea of asset

propose the minimum LCC, and decide investment

one bridge group, it is possible to establish thetiming of maintenance based on the long term

priority level by finding the minimum LCC of theprediction of deterioration, aiming at making bridges

group based on the minimum LCC of each bridge

last long. In addition, because BMS is an effective

undertool in order to fulfill the accountability and can be a

management is carried out while all bridges can keep

decision making system to realize the stable supply

being in-service.

thecondition

that

the

maintenanceof infrastructure service, especially of bridges, it canbe assumed that it is extremely effective to meet thesystem such as expense support system for
maintenance project for long lasting life plan.

5)

3.2 Target bridges
In this study, we will choose five bridges (Ananai,
Aki 2nd, Awanoura, Enokawa, and Sukawa), which
are RC-T girder bridges along the coast and likely to

3. Problems of BMS and proposal for function
improvement

have chloride attack, and conduct chloride attack
simulation and LCCA targeting them.

3.1 Proposal for function improvement
Since the BMS of MLIT focuses on the function
to compute the cost for next maintenance, this study

3. Maintenance method, and setting the extent of
repairs and amount ofdeterioration

attempts to propose the improvement of functions
focusing on the prefectural BMS. Firstly, we will
predict the deterioration of bridges and find out thedeterioration state. Then, we will make scenarios formaintenance and management of the bridges bycombining several or similar methods that are

Fig. 1 Definition of progressive deterioration stages

suitable for the deterioration state. Currently, theprefectural BMS has no scenarios and just chooses

4.1.1 Initiation stage

only one method for preventive maintenance andAccording to the Standard Specification forbreakdown maintenance, respectively. Therefore, theConcrete Structures: Guidelines for Application bysame method has to be repeatedly used while bridges

Civil Engineering, initiation stage is defined as aare in-service. We will also predict the deterioration

period until the concentration of chloride ion at theof bridges according to the existing researches andposition of protective covering of steel lumber

some assumptions, focusing on how chloride attack

reaches the critical concentration of corrosion

progresses based on our scenarios. Using different

generation. 7) Each stage described later is also based

scenarios, it can be expected that there may beon the definition stipulated in the Standard

differences in the deterioration state. At the sameSpecification for Concrete Structures. In order totime, we will conduct lifecycle cost analysis

express the phenomenon of the infiltration and(hereafter, LCCA), and try to judge which scenario

diffusion of chloride ion into concrete, in general,

during in-service will lead to the minimum LCC.

the second law of Fick is used, and therefore, it isMoreover, repairing several bridges at the same

also used in this study.

period is impossible when there is a budget
constraint. Therefore, it is necessary to decide thepriority level for repair. Assuming all the bridges as⎛x ⎞C ( x, t ) = C 0 ⎜⎜1 − erf⎟⎟ + C ( x,0 )2 D ⋅t ⎠⎝(1)

propagation stage is defined as a period from theC ( x, t ) ：depth x (cm),

beginning of the steel ber corrosion to the occurrence

Concentration of chloride ion in time t (year):of the corrosion crack. 5) The concentration of the(kg/m3)chloride ion at the propagation stage is assumed tobe between 1.2 and 2.0 kg/m3.

C0 : Concentration of chloride ion on the surface(kg/m3)

D ： Diffusion coefficient of appearance of chloride
3

4.1.3 Acceleration Stageion (cm /year)

Acceleration stage is defined as a period when theerf ：Error function

corrosion speed increases due to the occurrence ofC ( x,0) ： Concentration of initial chloride ion

corrosion crack. With regard to the correlation

content (kg/m3)

between the concentration of the chloride ion and thesteel bar, the rehabilitation study group of concrete

Table 1 Value of C 0 vs distance from coast

structures of Japan Concrete Institute attempted to3Distance from coast

C0 (kg/m )calculate the reduction in area of the steel bar undershore line (0)9the assumption that corrosion progresses thoroughly0<distance<0.1km

4.5

on the surface of the steel bar. 13)

0.1<distance<0.25km

3Kodama et al. 6) assume and use various coefficients.

0.25<distance<0.5km

2

In this study, we use the assumption of Kodama et al.

0.5<distance<1.0km

1

1.0km<distance0

Vreduction =Initial chloride ion content is assumed to be 0.3
based on the Standard Specification for Concrete
Structures. In general, the diffusion coefficient ofordinary Portland cement is used for prediction ofregular chloride ion. Blast furnace slag cement isused for mending, and it is assumed to use thediffusion coefficient for blast furnace slag cement.

)(log D = 19.5(W / C ) + 0.14(W / C ) − 8.47 + log 3.15 ⋅ 10 7
2

)

(2)
In the case of blast furnace slag cement:

(

)

(

log D = 19.5(W / C ) + 13.8(W / C ) − 5.74 + log 3.15 ⋅ 10 7
2

)

(3)

According to the Standard Specification for
Structures

by

Civil

t

(4)

Vreduction : Volume reduction

a : Coefficient that correlates the amount ofcorrosion to crack width = 1500 (mg/cm3)

c : Initial crack width due to corrosion = 0.005(cm)

φ : Steel bar diameter =1.3 (cm)γ Fe : Mass per unit volume of steel bar = 7850

α : Relational coefficient of corrosion speed andwidth of crack = 220 (mg/cm3/year)t : Time (year)
Kodama et al. assumes the acceleration stage
starts when volume reduction reaches 1%, and ends
when it reaches 20%. In this study, we use thisassumption.

4.1.2 Propagation stage
Concrete

φγ Fe

α

⋅ea

(mg/cm3)

In the case of ordinary Portland cement:(

4ac

On the other hand,Engineering,4.1.4 Deterioration stage

4.2.3 Surface coating method (SC)

Deterioration stage is defined as a period when thedecrease of withstand load is remarkable because of
an increase in the amount of corrosion. Kodama et al.
defines it as deterioration stage when volume
reduction exceeds 20%. Therefore, it is reasonable toassume that collapse of the bridge which entered thedeterioration stage would occur in near future. The

SPC = AU × AS × MG × 20000(7)

SPC : Cost of surface coating method
AU : Area of base of main girder
AS : Area of both side faces of main
girder

MG : Number of main girders

BMS of MLIT assumes that bridges at thedeterioration stage should be updated; namely, a new

4.2.4 Cathodic Protection Method (CP)construction is necessary. However, unlike a pier thatshows deterioration evenly, it is necessary to conduct
someassumption

for

the

prediction

of

the

deterioration of a bridge if it is near the coastline.
4.2 Calculation of restoration cost

(8)
(9)
(10)

iEC : Initial cost of Cathodic Protection Method

The cost of restoration was calculated based on
the interview with Mr. Sakamoto, SHO-BOND
Corporation, and information proposed by the New
Technology Information System (NETIS)iEC = AU × 80000
rEC = AU × 25
eEC = AU × 7000

7)ofrEC : Electricity a year (every year from the secondyear)

eEC : Power supply exchange cost (once in 20
years)

Ministry of Land, Infrastructure and Transport.
4.2.1 All patch repair method (PR)CSCost = AU × MG × 150000(only the first year)

5. Deterioration prediction of bridges
5.1 Assumption in deterioration prediction(5)

In this study, the ratio of the concentration of the

CS Cost : Cost of all patch repair method

chloride ion (concentration of partial chloride ion),

AU : Area of base of main girder
MG : Number of main girders

which will be computed in the deterioration
predictions later on, is assumed to be 80% of theentire main girders. It is assumed that the remaining
20% is the value immediately before the passive

4.2.2 Partial patch repair method (PR)Partial patch repair method is a construction work

state is destroyed by the chloride ion, that is, the lastthat restores part of main girders. In this study,

value of the propagation stage, and the weighted

provisionally assuming that section restoration isaverage efficiency is the concentration of theapplied to 20% of the area of all types of girders, we

chloride ion (whole chloride ion concentration).

calculate the costs.

SCSCost = CSCost × 0.2

5.2 Deterioration prediction of bridges(6)

SCSCost : Cost of partial section restoration

Here we will attempt to predict the deteriorationof the main girders of five bridges. Since thedistance from the coast is known, it is possible toknow the value of C 0 . The figure below shows thedeterioration prediction of the concentration of theTable 2 Deterioration progress stage and number ofchloride ion for 50 years after the installation. As foryears each bridge takes before entering thethe values for the stages after the acceleration stage,

deterioration stage

we use volume reduction. However, we use theconcentration of chloride ion for the periods, such as

Bridge namethe acceleration and deterioration stages.
7

Aki 2nd Bridge
Sukawa Bridge

Concentration of chloride ion （kg/m3）

6

Number of years

Deterioration
progress period

before entering thedeterioration stage

Aki 2ndAcceleration

2

AnanaiAcceleration

9

Awanoura

Acceleration

9

Enokawa

Initiation-

SukawaAcceleration

2

5

4

Ananai Bridge Awanoura Bridge

3

2

Enokawa Bridge
1

0
0

5

10

15

20

25

30

35

40

45

50

Passiing years

Initiation Stage

Propagation Stage

Acceleration Stage

Deterioration Stage

6. Establishment of maintenance management
scenario and analysis of lifecycle cost

Fig. 2 Prediction of the concentration of chloride ion

6.1 Calculation of minimum LCC of individual
bridgeAs shown in Figure 2, setting the installation year

As for Enokawa bridge, if it is likely to enter theas zeroth year, we can know the present (2007)

propagation stage, we should assume it to be a target

concentration

theof preventive maintenance, but it should remain

concentration of the chloride ion that the result

in-service while it is at the initiation stage Therefore,shows is that of the partial chloride ion. Then, it is

it is assumed not to conduct mending on Enokawa

necessary to calculate the concentration of the entire

bridgechloride ion. Firstly, we assume that the proportion

maintenance can be applied to other bridges, it isof the concentration of the partial chloride ion to thenecessary to obtain minimum LCC after examining

main girders is 80%, and the chloride ion

all the applicable mending methods.

ofchlorideion.

However,while

in-service.

Becausebreakdown

concentration of the remaining 20% is that of theweighted

averageof

thesechlorideion

concentrations, the concentration of the entire

10 million yen

stage just before the accelerate stage. By the

6

5

4

chloride ion can be obtained. After obtaining the3concentration of the entire chloride ion, it will be2

possible to estimate the deterioration progress period1

to which the bridge belongs now. Table 2 shows how0many years it will take each bridge to progress fromthe present stage to the next deterioration stage. In
this study, we assumed that Enokawa bridge will notenter the deterioration stage while it is in-service.

year
CP

PR

PR and SR

PR and CP

PR and SC at the end of same stage

PR and CP at the end of same stage

Fig. 3 LCC for mending maintenance applicable toAki 2nd Bridge

10 million yen

LCC as bridge group

6

5

In Chapter 6, the maintenance plan of the4minimum LCC for each bridge was computed from3

an individual bridge. Moreover, the renewal period is2

calculated by presuming the deterioration stage, and1

the maintenance cost of each bridge required after0

the renewal period, namely at the next stage, can be
year
CP

PR

PR and SR

PR and CP

PR and SC at the end of same stage

PR and CP at the end of same stage

estimated. With our estimation, the total cost of themaintenance at the present stage is 79.15 million yen.
The cost at the next stage is 100.33 million yen,which shows that it is the most appropriate to

Ananai Bridge

conduct the repair at the present stage. Because the

10 million yen

Fig. 4 LCC for maintenance method applicable to6

bridge targeted this time has been in-service for 60

5years and it has to continued being in-service, the4cost at the next stage was estimated to be higher.

3

However, in the case of the bridges whose in-service2

years is short (e.g. 10 years), there is a possibility

1that the estimated maintenance cost at the next stage

0

and after the next is lower, and in that case it is
year
CP

PR

PR and SR

PR and CP

PR and SC at the end of same stage

PR and CP at the end of same stage

possible to leave it as it is at the present stage.
Present Stage

4.26

Next Stage

5.77

33.97

7.38

33.54

Fig. 5 LCC for maintenance method applicable to

10 million yen

Awanoura Bridge

44.21

9.43

40.92

6
0

20

40
Aki 2nd Bridge

60

Ananai Bridge

Awanoura Bridge

80
Sukawa Bridge

100
1 million yen

54Fig. 7 Maintenance costs at the present stage and the

3

next

2

1

6.2 Priority level of maintenance under budget0

constraint
year
CP

PR

PR and SR

PR and CP

PR and SC at the end of same stage

PR and CP at the end of same stage

Because maintenance and management budgets
have a limitation, to execute all the maintenance atthe same time can be impossible. Therefore, it isFig. 6 LCC for maintenance method applicable tonecessary to take it into account that there is a case

Sukawa Bridge

where no bridge is required to be repaired at thepresent renewal stage, and, at the same time, it is

6. Decision of priority level based on analysis ofnecessary to set up the priority level by investigating

lifecycle costwhich bridge should be repaired at the renewal stage

6.1 Maintenance and maintenance plan of minimum

and which should be at the next stage. As for adeciding factor of the priority level, under the budget

types as follows:

constraint, it will be possible to determine which
bridge should be repaired at the present stage and●Aki 2nd → Ananai → Awanoura → Sukawa

which ones should be at the next stage if we find out●Aki 2nd → Ananai → Sukawa → Awanoura

the priority level with which the total cost required●Ananai → Aki 2nd →Awanoura → Sukawa

for maintenance and mending of five bridges. Under●Ananai → Aki 2nd → Sukawa → Awanoura

the budget constraint, if the higher the budget●Awanoura → Aki 2nd →Ananai→ Sukawa

allocated for each year, the higher the possibility of●Awanoura → Aki 2nd → Sukawa → Ananai,

conducting maintenance at the present stage
becomes, but if the lower the budget allocated forwhere the total cost becomes 86,533,614 yen. Wheneach year, the higher the possibility of conducting

everything can be executed at the present stage, themaintenance at the next stage becomes. In this study,

investment of 7,379,730 yen is required.

we will make combination of maintenance methods
using the results of the LCCA of each bridge under aspecific budget constraint. In this calculation,

7. Conclusion
We conducted predictions of physicalchanges of LCC accompanied by the transition ofdeterioration by chloride attack on the RC bridges,

each deterioration progress stage are taken intoand showed the deterioration state of the existingaccount.

bridges. Furthermore, we conducted LCCA, which
was not included in the existing BMS’ of MLIT and
4

i

i =1

j

∑L

Kochi version, and were able to calculate the(11)

Lij :Maintenance plan to minimize LCC at the stage

j in i bridge
j : Each deterioration stage (Initiation, Propagation,

minimum LCC for each bridge by setting the durable
periods and deterioration process after the mendingby maintenance methods. In addition, it became
possible to show the priority of the maintenancewhich makes the total costs minimized under thebudget constraint.

Acceleration, Deterioration)
REFERENCES
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maintenance and repair budget for five bridges is 10

2) Hironao TAKAHASHI and Hiroshi YOKOTA:

million yen in one year and that reserving fund is

Development

possible. There are 24 combinations of themaintenance and mending cost for port facilities andmaintenance order of four bridges. It is apparent thatmeasurement of future trend, Japan Society of Civil

among the 24 combinations, only a limited number

Engineers,of combinations makes it possible to conduct the

pp.135-140, 2001.

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ofthe

Collected

Department

estimation

Papers,ofmodel

No.679for

6-51,

Transportation ： AssetManagement Primer, 1999

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Public Works Management Journal, pp12-15, 2006.9

priority level that minimizes the total cost has six5) JapanSocietyof

Civil

Engineers,

Standard

Specification for Concrete Structures: Guidelines for
Maintenance and Management, 2001.
6) Japan

Concrete

Institute,Studyrehabilitation of concrete structure, 1998.
7) http://www.kangi.ktr.mlit.go.jp/EvalNetis/

groupof