Journal of Transportation Technologies, 2012, 2, 113-128
doi:10.4236/jtts.2012.22013 Published Online April 2012 (http://www.SciRP.org/journal/jtts)

Development of Performance-Based Tunnel Evaluation
Methodology and Performance Evaluation of Existing
Railway Tunnels
Sadao Kimura1, Takashi Kitani2, Atsushi Koizumi3
1

Department of Civil and Environmental Engineering, Kanazawa Institute of Technology, Ishikawa, Japan
2
Graduate School of Engineering, Kanazawa Institute of Technology, Ishikawa, Japan
3
Faculty of Science and Engineering, Waseda University, Tokyo, Japan
Email: s.kimura@neptune.kanazawa-it.ac.jp
Received February 29, 2012; revised March 5, 2012; accepted March 16, 2012

ABSTRACTThe concept of performance-based design, which mainly focuses on mechanical performance, has become the international standard, as in the case for ISO. The standardization of tunnel design has not been achieved because it requires
integration of separate specialized fields, such as geotechnical engineering, structural engineering and concrete engineering. It is also required to clarify performance-based criteria for tunnel structures to suit specific use purposes (objectives), establish the concept of survey, planning, design, construction and maintenance based on such criteria, anddevelop proper management systems for operation and maintenance to suit specific tunnel use purposes. To this end, it
is vital to develop a methodology for evaluating and verifying the performance of existing tunnels. This paper presents a
new concept of performance requirements for tunnel structures and describes the method of quantitatively evaluating
the total performance of existing tunnels in relation to the required performance, assuming the total performance to be
based on the Analysis Hierarchy Process.
Keywords: Tunnel; Performance Criterion; Life Cycle Design; Performance-Based Design; Asset Management;
Maintenance; Analysis Hierarchy Process

1. Introduction
In Japan, the development of technological (design) criteria for individual built facilities, such as roads, rivers,
ports and buildings have conventionally been based on
the historical backgrounds (experience), culture and objectives of each facility. In some cases, this individual
development approach created considerable discrepancies among technological criteria when compared to eachother. In other countries on the other hand, while the individual design approach used to be the main practice as
well, ISO2394 [1] and Eurocode 0 have been issued inrecent years as comprehensive design codes that specify
the basics and system of structure design. Following thistrend, the Ministry of Land, Infrastructure, Transport andTourism (MLIT) of Japan formulated the “Basis of
Structural Design for Buildings and Public Works [2]” in
2002. The MLIT National Institute for Land and Infrastructure Management felt it was necessary to set out
principles and define terminology for technological criteria development for code writers, and assigned Japan
Society for Civil Engineering (JSCE) to carry out research. In March 2003, JSCE (Basic Research CommitCopyright © 2012 SciRes.

tee for Formulation of Comprehensive Design Code)compiled “Code PLATFORM ver.1.0 [3]”. Comprehensive design codes represent a new design concept called“performance-based design,” which largely focuses on
the discipline of structural design. Based on this newconcept, existing design codes are now being revised insuch areas as concrete, seismic engineering and geotechnical engineering. The Japanese Geotechnical Society
has already issued a design code for foundation structures called “Comprehensive Foundation Design Code[4]”. This way, the performance-requirements based design system is now being established in Japan as part ofthe efforts to standardize structural design.
However, the standardization of tunnel design has notbeen achieved because it requires integration of separate
specialized fields, such as geotechnical engineering,
structural engineering and concrete engineering.
Therefore, it is necessary to understand the trend ofinternational standardization and formulate comprehendsive design codes or specific design codes for tunnel
structures in consideration for the nation’s expertise inunderground structure design and valuable traditional
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technologies.
On the other hand, it should be noted that the existing
structures have been undergoing deterioration almost at
the same time, notably since the turning of the century.
Figure 1 shows a history of tunnel development in Japandenoted by tunnel length and construction year, featuring
railway tunnels as an example. It has been pointed outthat today’s infrastructure development should place importance on technologies that provide better maintenanceof existing structures to prolong their service life, in addition to new structure development technologies. In
other words, there is a need to shift our behavior focus
from new built environment development (monozukuri),i.e. building new structures as part of the infrastructure to“system development,” i.e. using existing structures in asensible way in consideration for the specific mode ofservice assigned to each structure. This is also the casefor the field of underground structures; structure design
professionals are now required to shift design concept forthe better utilization of underground space in the future.
The current focus on conventional design technologies,
which aim to ensure structural safety based on the notionof new built environment development (monozukuri),should be shifted to the development of a new design
approach called the “Life Cycle Design Method [6]”,which involves close examination of functions of structures to better use the existing built environment and is
employed throughout service life including the maintenance phase. Tunnels and other underground structures
are different from ground structures in that they can notsimply be abandoned once constructed; if an underground space becomes unused due to some defects andabandoned, certain disturbance in the surrounding ground
may be caused in the long run, such as in the form ofsubsidence and deformation of foundations of adjacentstructures.
To serve as the international standard for the maintenance of existing structures, ISO13822 [7] was issued.
Based on the concept of structure reliability and risk
management, it sets forth the basic concepts of evaluating existing structures (e.g. buildings and bridges) by

Figure 1. Change in the railway tunnel length in Tokyo
Metro [5].
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ET AL.

classifying them into the following: 1) Expected modification of use purpose, expected repairs, and prolongation of design service life; 2) examination of reliability as
required by the administrator and insurance company; 3)time-dependent deterioration caused by loading and actions; and 4) damages, etc. caused by accidental actions.
The code, however, does not describe how to evaluate
the functions and service performance of a structure toensure its original objectives.
Considering the international trend of standardizationof tunnel structures that focuses on performance criteria
as described above, this paper first reestablishes the performance requirements for tunnel structures proposed by
JSCE, and discusses the concepts of performance requirements for existing tunnels in their maintenance phaseand management strategies based on them [8,9]. The paper goes on to taking existing road tunnels as the example to describe the method of calculating the Total Performance Index designed to comprehensively evaluate
their actual performance at the maintenance phase.

2. Performance Requirements [10] for
Tunnel Structures Based on SpecificObjectives
2.1. Concept of Performance Requirements
The performance requirements for tunnels, which areused for various purposes such as roads, railways, watersupply and sewage systems, power supply, and communication, are designated individually to suit their specificobjectives within the basic performance requirements. It
should be noted that the concept of structural design oftunnel structures is significantly varied among construction methods [11], and thus the specific performancerequirements for a tunnel structure should be developedwith careful consideration of its construction method. In
the mountain tunnel construction method employed forconsiderably strong and highly self-supporting ground,the main structural system that provides a space to construct a tunnel is the natural ground itself, and thus the
purpose of structural design is to maximize its natural
capacity and provide manmade support. On the other
hand, the shielding method, typically urban tunnelingconstruction, is employed where hardly any self-support
capacity is expected. The main structural system here
should be manmade. This is one of the factors that makethe structural design of tunnels difficult. It is thus necessary to identify major factors that differ between tunneling methods. Table 1 shows an example of factors thatdiffer between the mountain and shield tunneling methods (for railway tunnels). When closely examining therequired performance, these differences among tunnelingmethods should be taken into account.
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2.2. Development of Performance Requirement
Specific performance requirements are developed here
based on the basic ones. Table 2 shows an example ofidentification of performance requirements for road tunnels constructed in the mountain tunneling method. The
primary categories for required performance consist of
the basic performance requirements and their descriptions. Secondary categories and subcategories consist ofphenomena used for evaluating the primary categories
and for further evaluating the secondary categories, respectively. This means the performance given by the
primary categories is satisfied if all the subcategory phe-

ET AL.

115

nomena are satisfied. It should be noted here that the
subcategory phenomena consist of those that can directly
be evaluated and those that cannot, and that some ofthem allow quantitative evaluation while others only allow qualitative evaluation due to obscurity. To carry out
the detailed evaluation of individual performance, specific verification indexes should be developed for allphases of planning, design, construction, and maintenance (service) to evaluate the actual performance. Focusing on the maintenance phase, the sections below describe the concept of evaluation of actual performanceand management concept based on performance criteria.

Table 1. Differences in factors between tunneling methods (for railway tunnels).
Mountain tunneling
Mainly mountainous regions and suburbs(frost inside the tunnel considered)
Entrance exists in principle

Construction site
PortalNot necessary to consider construction
load in general

Construction load

The lining concrete does not serve as a structuralmember in general(Plain concrete system in principle)
Roadbed may be disturbed where there
is no invert, affecting the running stability

Lining system
RoadbedShield tunneling
Mainly urban areas(frost inside the tunnel Not considered)No entrance in principle
May be disturbed by construction load
Require measures for stabilizing the cutting face during
construction
The lining (segment) serves as a structural member(Reinforced concrete, steel structure, and composite system)
The closure system consisting of segments creates nodisturbance

Table 2. Performance requirements fragmented (shield tunneling method/railway).
Primary categories

Secondary categories

Subcategories
Ensure safe driving

User safety

Ensure user safety

Not directly threatening to user safety
Ensure safe evacuation of users in emergency
Ensure ride quality

User usability

Ensure user comfort

Not making users uncomfortable or feel insecure
Ensure stability against continuous load

To ensurerequired

Structural

Ensure stability against

Provide necessary seismic performancestability

assumed load

Ensure stability against assumed load change
Ensure stability against assumed construction load

traffic volume

High corrosion resistancesafety andsmoothly

Durability

during the

Ensure durability against
assumed deterioration factors

No deterioration in concrete
Provide high water tightness

required

Satisfy required demands (traffic capacity)

service period
Administrator

Ensure proper utilization

usability

by administrator

Ensure trains can be operated in a stable manner(at the fixed time)
Ensure operation of auxiliary facilities for regular train operation

Maintainability

Ensure provision of proper

Ensure safe & easy inspection

maintenance

Ensure safe & easy repair
Minor impacts on ground water

Impact on

Minimize impact

surroundings

on surroundings

Minor impacts on surrounding grounds
Minor impacts on surrounding real estates

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3. Performance Criteria Based Performance
Criteria [12]3.1. Concept of Management Based on
Performance Criteria“Performance criteria based management” means a strategic management in consideration of the lifecycle of thetunnel through determination of evaluation indexes basedon performance requirements at all phases of planning,survey, design, construction, and maintenance and throughexecution of performance verification based on such
evaluation indexes. Figure 2 shows the management
procedure based on performance criteria.
The basic concept of performance-criteria based management is to evaluate and verify the actual performancebased on the same performance requirements for eachphase of planning and design, construction, and maintenance (service) according to the use purpose (objectives)of a tunnel. To describe this concept, the maintenancephase of existing tunnel structures is highlighted here.
Conventionally, in the maintenance of existing tunnel
structures, inspection, evaluation and remedial measures
have been carried out or devised by setting individual
criteria [13]. Such maintenance basically focuses on thedevelopment of remedies for individual troubles, anddoes not take the procedure of identifying the performance criteria, evaluating/verifying the actual performance,and devising necessary remedies. In practice, future
measures are only considered on an as-needed basis
within the limited budgetary restrictions.
On the other hand, performance-criteria based management is largely different in that it estimates future
conditions based on the evaluation/verification of actual

ET AL.

current performance, and makes decisions on the timing
and method of remedies by employing the life cycle cost
optimization approach based on the strategies of administrator. It should be noted, however, that the evaluation/verification items used in the evaluation/verificationof actual performance are not very different from conventional inspection items; each inspection item serves asa performance verification index or alternative performance verification index used for evaluating or verifying
the required performance.
Figure 3 shows only the basic principles of evaluating/verifying the actual performance, as compared to thebasic performance requirements. The figure shows someexamples of performance verification indexes that allow
quantitative evaluation, corresponding to the basic performance requirements. Some performance verificationindexes are designed to evaluate by employing an analysis or statistical approach based on the yield strength ofmembers, cracking and other data obtained in tunnel inspection. As mentioned before, some indexes allow quantitative evaluation and some do not. It is thus practical tobase comprehensive performance verification on a rating
method using verification criteria consisting of five or so
grades. In so doing, it becomes possible to weigh thepriority of each performance requirement in terms ofsuch conditions of target tunnel structure as use purpose,tunneling method, owner strategies and serviceability.
For performance verification indexes that are difficult toevaluate quantitatively, the Analytic Hierarchy Process
and other appropriate approaches, which will be mentioned in later sections, are employed to manage quantitative evaluation. The Total Performance Index is obtained by performing evaluation /verification of actual

Figure 2. Procedure for performance-based management.
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Figure 3. Concept of evaluation/verification method for current performance corresponding to the required performance.

performance in the manner described above for eachtunnel or span. This way, integrated management of theactual performance of tunnel structures becomes possible.

3.2. Prediction of Future Conditions
In performance-based management, it is required to ensure tunnel performance with minimum costs during thetarget service period or the actual service period that extends beyond the former. This concept is presented in
Figure 4. To ensure the required performance in accordance with a reduction in the actual performance level, it
is necessary to take measures for preventive maintenanceor preventive management [14]. However, evaluation of
Copyright © 2012 SciRes.

the actual performance often involves considerable uncertainties because, as mentioned before, tunnel structures are constructed in highly uncertain ground.
That means even where the average actual performance meets performance requirements, the required performance may not be achieved when the damage probability shown in Figure 5 is taken into account. In suchcases, emergency remedies are required. Thus, the proper
procedure for tunnel structures should be to frequently
perform inspection to check the actual performance andensure preventive management that provides repairs before the important actual performance, even if it is at the
local level, becomes short of the required level [15]. It
should also be noted that the inspection frequency conJTTs

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ET AL.

trator. Such differences in serviceability should also betaken into consideration in the management method.

4. Evaluation/Verification of Actual
Performance of Tunnels by Rating
4.1. Concept of Evaluation/Verification of Actual
Performance of Tunnels by Rating [15]Figure 4. Concept of maintenance optimization strategy.

Figure 5. Concept of damage probability.

siderably affects the accuracy of prediction of future
conditions based on the current conditions. Figure 6
shows the concept of prediction accuracy in relation toinspection frequency. In the case of road tunnels for example, inspections are carried out almost every five years(every two years in more frequent cases) in general. An
extremely low inspection frequency increases uncertainties. A reduction in the prediction accuracy is directlyreflected in preventive management policies; it is thus
necessary to properly determine the inspection frequency
according to the serviceability of the tunnel.

3.3. Tunnel Serviceability
The serviceability of a tunnel structure depends on suchfactors as the use purpose, social functions, administrator’s operation size, and financial resources, and is hence
affected by the social roles and importance of the tunnel.
It is thus necessary to determine the serviceability ofeach tunnel and consider a suitable management method.
Table 3 shows the service levels derived from serviceability and corresponding basic methods of management.
The service levels are from “low” to “high”. Tunnels
categorized as “high” are defined as those such as expressways in urban areas having particularly significant
social roles, which require detailed inspections and continuous monitoring at the maintenance phase and evaluation/verification of actual performance using indexes thatallow numerical expression to a maximum extent. Tunnels categorized as “low”, on the other hand, are necessary for the society but are not very busy or subject toparticularly tight budgetary restrictions by the adminisCopyright © 2012 SciRes.

The procedure for evaluating/verifying the actual performance by rating consists of identification of evaluation/verification indexes or alternative indexes for each
item of performance requirements; determination ofstandard performance values in five grades for each index; calculation of actual performance values; integrate
the values to obtain the Total Performance Index; andperform evaluation/verification using the Total Performance Index. Tables 4(a) and 4(b) show an example ofrelationship between performance requirement items andperformance verification/alternative indexes derived frompast design documents and inspections (shield tunneling/railway tunnels).
This approach allows integrated quantitative evaluation of changes with time in the actual performance ofindividual tunnels and is effective in formulating mid- tolong-term strategies. Tunnel structures required to provide a high level of serviceability need in-depth study ofthe probability of local damage and performance deterioration, and more detailed evaluation/verification throughan increased frequency of inspection, continuous monitoring of locations having trouble risk, and calculations
and statistical analysis using the inspection data obtained.

4.2. Evaluation of Actual Performance by the
Analytic Hierarchy Process [16]This section explains evaluation of the actual perform-

Figure 6. Inspection frequency and accuracy of predicting
future conditions.
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Table 3. Concept of serviceability-based management.
Low
Low traffic volume/ Deterioration notprogressed/Mountainous region

Service level

High
High traffic volume/ Deterioration highly progressed/
Important route/ Emergency transportation route

Performance criteria

User safety/Usability/Structural stability/Durability/Administrator usability/
Maintainability/ Impacts on the surroundings

Performance verification index

Select indexes that allow numerical expression to a maximum extent

Design method

Presumptive design

Performance design

Monitoring

Inspection + Simple measurements as needed

Inspection + Measurements

Soundness evaluation method

Rating in principle

Performance-based evaluation method

Performance verification
method at maintenance phase

Rating based on results of inspection(+ simple measurements)

Verification using numerical indexes,
mainly derived from measurements

Prediction method for
future conditions

Deterministic prediction(residual strength)

Prediction with uncertainties considered,e.g. through probabilistic approach

Decision making through
LCC optimization

Life cycle costs assuming
inspections and repairs

Perform optimization of life cycle costs

ance of a tunnel by the Analytic Hierarchy Process(“AHP”) using lining data obtained from daily and regular inspections (observation/measurement data inside thetunnel). The Total Performance Index, TPI per tunnel
span is given byN

TPI   Pi  Ci

(1)

i 1

where score given by the performance evaluation criteria,
weighing factor derived from evaluation by advanced
engineers, and the number of required performance
evaluation item.
Table 5 shows an example of weighing by evaluation
by advanced engineers engaging in the design, construction and management of tunnels, citing railway tunnels
constructed in the shield tunneling method.
By going through the procedure described above, each
evaluation value (TPI) for each construction span is
rep-resented numerically for all performance requirements in an integrated way. The probability distributions
that represent the route and a set of TPI per section give
total generalized evaluation of actual performance of thetarget route and section. The performance evaluation
criteria are defined in five grades for each required performance subcategory, i.e. 1) Undergoing no performance deterioration or assumed to be so; 2) Undergoingslight performance deterioration; 3) Undergoing performance deterioration; 4) Undergoing remarkable performance deterioration; and 5) In need of immediate
remedy), which are scored 1, 3, 5, 7, and 15, respectively.
Tables 6(a) and 6(b) show examples of performance
evaluation criteria for railway tunnels constructed in theshield tunneling method.
Copyright © 2012 SciRes.

4.3. AHP-Based Evaluation of Actual
Performance and Current Inspection
Evaluation [16]The actual performance is evaluated in AHP using theinspection results for railway tunnels constructed in theshield tunneling method. Two types of single track shieldtunnels, i.e. a small-to-medium box segment section.
Rating tunnels using performance evaluation criteria
based on the interior view of lining drawn from the results of inspection on 350 rings of box segment section,
TPI is calculated using Equation (1). The results arecompared against those of existing inspection evaluation
implemented [17] (hereinafter, the “existing method”),
the validity of AHP-based quantitative performance
evaluation method is examined. According to the existing method, the soundness of tunnels is assessed in relation to: a) Users (safety and usability); b) Structural systems (load-bearing capacity and durability); c) Administrator (maintenance); and d) Progressiveness and (common) characteristics of disturbance. Judgment criteria aredefined for each of the following cases: 1) Disturbance iscaused by external force (cracking); 2) By material deterioration; and 3) By water leakage. The soundness oftunnels is evaluated by the judgment categories shown in
Table 7, and then the timing of remedies is determined.
The probability distributions of a set of TPI for eachjudgment result by the existing method are shown in
Figure 7.
In the case of box segment, the average values of TPI
are 1.006, 1.074, 1.335, and 2.446 for Judgment Category S, C, B and A, respectively.
It is thus indicated that TPI more or less represents thetotal results obtained in the existing method. These reJTTs

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ET AL.

Table 4(a). Performance requirements fragmented (shield tunneling method/railway).
Performance requirements
Primary categories

Secondary categories

Performance evaluation items
Subcategories

Ensure good railway track alignment

12

Ensure safe
driving

Ensure safe driving

3

4
User safety

Ensureuser
safetyNot directly
threatening to user
safetyEnsure safe
evacuation ofusers
in emergency
Ensure ride quality
User
usability

Ensure user
comfortNot making users
uncomfortable orfeel insecure

Ensure stability
againstcontinuous load

EnsureEnsure stability
stability
againstagainstassumedassumedload
load

Provide necessary
seismic
performance
Ensure stability
against assumed
load changeHigh corrosion
resistance

Durability

Ensuredurability against
assumeddeterioration
factors
No deterioration in
concrete
Provide high watertightness

Copyright © 2012 SciRes.

Amount of displacement in tunnelalignment
Conditions of any cracking or looseningof segments/secondary lining and of any
corrosion, etc. in rebars in a region(s) that
may threaten driving safety(e.g. directly above the tracks)
Exposure of tracks to leaked water

Ensure proper construction gauge

5

No flaking occurred

6

No water leakage occurred

7

Allow proper layout/usage ofdisaster prevention equipment andprovide evacuation routes for users

8

Leeway outside the construction gauge(clearance from disaster prevention
equipment and room for evacuation)

9

Amount of track displacement(any impacts on riding comfort)

Ensure good alignment and avoid
any tunnel deformation that affects
riding comfort
No water leakage/cracking thatmakes users uncomfortable or feel
insecure is observed

Provide necessary load-bearing
performance against continuous load

Lining provides necessary seismic
performance against earthquake
motions assumed during service life
Provide required load bearing
capacity against impacts byneighboring construction work andload condition changes caused bychange in surrounding environment
assumed during service life
Lining provides necessary seismic
performance against earthquake
motions assumed during service life

Rebars & steel segments withminimum speed of rust development
in steels, e.g. bolts and splice plate

No erosion or deterioration inliming concrete
Minimize inducing any water leakthat may cause deterioration oflining/equipment

Leeway outside the construction gauge
Conditions of any cracking or looseningof segments/secondary lining and of any
corrosion, etc. in reinforcement\cement ina region(s) that may threaten driving
safety (e.g. directly above the tracks)
Conditions of any water leakage in aregion(s) that may threaten driving safety(e.g. platforms/concourse ceiling)

Development of water leakage/
10 cracking in a region(s) visible to users(e.g. platforms/concourse ceiling)
11 Amount of tunnel convergence
Development of cracking or damage in
12 segments or secondary lining(structural deformation)
Stress intensity or stress resultant of
13
lining obtained in deformation analysis
14

Identification of seismic performanceand damage level by analysis

15

Amount of tunnel convergence and linear
displacement

16

Stress intensity or stress resultant
of lining obtained in impact analysis

17 Not evaluated in the maintenance phase18
High corrosion
resistanceAmount of track displacement (anyimpacts on driving safety)

Presence of cracking/loosening, etc.
in segments and secondary lining

State of corrosion in rebars, bolts
and splice plates
Degradation indexes, e.g. coverconcrete, remaining non-carbonated20
depth, chloride concentration, andwater content
State that cracking/erosion of21
segments and secondary lining
19

22 Occurrence of water leakage

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Table 4(b). Performance requirements fragmented (shield tunneling method/railway).
Performance requirements
Performance evaluation items
Primary categories

Administrator
usability

Ensure proper
utilization
byadministrator

Secondary categories

Subcategories

Satisfy required
demands(traffic capacity)

Provide an inner space that
accommodates the required
number of railway tracks.
En-sure the alignment isdesigned to allow the required
train speed.

Ensure trains canbe operated ina stable manner(at the fixed time)

Ensure operation of
auxiliary facilities
for regular train
operation

Maintainability

Ensureprovisionof proper
maintenance

Minimize
impact on
surroundings

Copyright © 2012 SciRes.

Not evaluated in the maintenance phase24

State of e.g. cracking and loosening
in the regions of segments/secondarylining that affect auxiliary facilities
involved in train operation.

25

State of corrosion in steels in aregion(s) that may affect auxiliary
facilities involved in train operation

26

State of water leakage in regionsthat affect auxiliary facilities
involved in train operation

Allow proper lay-out/usage ofauxiliary facilities involved intrain operation

27

Allowances outside theconstruction gauge, esp. in relation
to auxiliary facilities

Water inside the tunnel isproperly drained to avoid any
impacts on auxiliary facilities

28

Conditions of drainage facilities(e.g. blockage of drain ditches)

Prevent the occurrence ofwater leakage or flaking that
may obstruct the functions ofauxiliary facilities involved intrain operation

Ensure safe & easyinspection

Allow safe & easy daily
patrolling, inspection andcleaning

29

Allowances outside theconstruction gauge (escapespace used during
patrolling/inspection)

Ensure safe
& easy repair

Allow installation ofscaffoldings and stockyards
for repair/reinforcement works
Proper margin for repair/reinforcement provided in the
inner section30

Not evaluated in themaintenance phase

31

Changes in the groundwaterlevel in surrounding areas

32

Groundwater quality innearby areas

33

Water leakage survey inside
the tunnel

34

Amount of groundsurface displacementin surrounding areas

35

Occurrence of water leakage

Minor impacts
on ground water

Impact on
surroundings

23

Minor impacts
on surrounding
grounds

Minimize ground-water levelchanges
Do not affect groundwatercontamination on thesurroundings

Minimize ground surface
settlement/upheaval

Minor impacts
on surrounding
real estates

Impacts on adjacentbuildings/buried utilities
are within the allowable range

36

Amount of displacement
or development of cracks
in neighboring properties

Minor vibrationand noise in thesurroundings

Minimize impact of vibration/noise on the surrounding due
to operation of train

37

Vibration/noise levelsof ground surface
and surrounding buildings

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ET AL.

Table 5. Weighting factors given by evaluation by tunnel engineers.
Primary
categories

weight factor(SD*)

Secondary categories

Ensure safe driving for users
User
safetyUserusability

Structural
stability

Durability

0.124(0.075)0.211(0.093)0.128(0.085)Total(1.000)

Copyright © 2012 SciRes.

0.052(0.128)1

Ensure good alignment and avoid
any tunnel deformation that may
obstruct the ensure safe driving

0.050(0.148)2,5Prevent the occurrence of waterleakage or flaking that may
obstruct the ensure safe driving

0.050(0.210)

3,4

-

6,7

Allow disaster prevention
equipment to function in
emergency

0.073(0.191)-(nothing)-

8-(nothing)-9- (nothing)-

10

Not making users
uncomfortable or feel insecure

0.079(0.235)0.045(0.235)

Ensure stability against
continuous load

0.088
(0.146)-(nothing)-

11,12,13

Provide necessary seismic
performance

0.039(0.099)-(nothing)-

14

Ensure stability against
assumed load change

0.047(0.088)-(nothing)

-

15,16

Ensure stability against
assumed construction load

0.037
(0.134)-(nothing)-17

High corrosion resistanceof steel

0.041(0.162)0.037(0.160)0.049(0.209)0.011(0.188)-(nothing)-

18,19,20-(nothing)-

21-(nothing)-

22-(nothing)-

23-(nothing)-

24,25,26

Allow proper layout/usage ofauxiliary facilities involvedin train operation

0.005(0.235)27

Water inside the tunnel is properly
drained to avoid any impacts on
auxiliary facilities

0.005(0.235)28

Ensure ride quality

No deterioration in concrete

0.015(0.199)0.037(0.017)0.127(0.077)

Avoid any tunnel deformationthat may obstruct the ensure
safe driving-(nothing)

Ensure operation of
auxiliary facilities for regulartrain operation

Impact on
surroundings

No

0.092
(0.197)

Ensure trains can be operated
in a stable manner(at the fixed time)

0.056(0.037)weight factor(SD*)

Sub categories

Not directly threatening
to user safety

Satisfy required demands

Maintainability

0.152(0.222)0.317(0.125)

Provide high water tightness

Administrator
usability

weight factor
(SD*)

0.010
(0.162)-(nothing)-

29-(nothing)-

30

Minor impacts on
ground water

0.031(0.213)0.025(0.213)0.027(0.152)-(nothing)-

31,32,33

Minor impacts on
ground surface

0.027(0.120)-(nothing)

-

34,35

Minor impacts on
surrounding real estates

0.036(0.162)-(nothing)-

36

Minor vibration and noisein the surroundings

0.037(0.178)-(nothing)-

37

Ensure safe & easy inspection
Ensure safe & easy repair(1.000)(1.000)JTTs

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Table 6(a). Performance evaluation criteria used in AHP (shield tunneling method/ railway tunnels).
No

Performance evaluation items

Monitoring items The monitoring method is parenthesized

1

Amount of track displacement(any impacts on driving safety)

Amount of track displacement

2

Amount of displacementin tunnel alignment

Differential leveling and tunnel center line survey

3

Conditions of any cracking or looseningof segments/secondary lining and of
any corrosion, etc. in rebars in aregion(s) that may threaten
driving safety (e.g. directly above
the tracks)

4

Exposure of tracks to leaked water••

Location, length, width and range of cracking and corrosion: Visual observationand visible images
Loosening range: Hammering and infrared camera
Crack Pattern: Unfolded view of deformation
Progressiveness: Marking photographing, and cracking gauge
State of steel corrosion: Self potential, polarization resistance, and visualobservation by chipping
Location and amount of water leakage: Visual observation
Quality of leaked water: Water quality test

5

Leeway outside the construction gauge•

Measurement with a clearance car and electro-optical distance meter•6

Conditions of any cracking or looseningof segments/secondary lining and of
any corrosion, etc. in reinforcement\cement in a region(s) that may threaten
driving safety (e.g. directly above thetracks)Location, length, width and range of cracking/damage: Visual observationand visible images
Loosening range: Hammering and infrared camera
Crack Pattern: Unfolded view of deformation
Progressiveness: Marking, photographing, and cracking gauge
State of steel corrosion: Self potential, polarization resistance, and visualobservation by chipping

7

Conditions of any water leakage in aregion(s) that may threaten driving
safety (e.g. platforms/concourse ceiling)•

Location and amount of water leakage and visual observation

8

Leeway outside the construction gauge(clearance from disaster prevention
equipment and room for evacuation)•

Measurement with a clearance car and visual inspection•

Measurement of amount of track displacement and train oscillation•

Visual observation•

Amount of convergence: Convergence gauge and electro-optical distance meter•

Location, length, width and range of cracking/damage: Visual observationand visible images
Loosening range: Hammering and infrared camera
Crack Pattern: Unfolded view of deformation
Progressiveness: Marking ，photographing, and cracking gauge
State of steel corrosion: Self potential, polarization resistance, and visualobservation by chipping
Displacement: Convergence measurement and measurement of openings
and joint offsets between adjacent segments
Strain and stress of members: Strain measurement
Strength and deformation characteristics of lining concrete: Strength test
(boring test, rebound hammer method, hammering & sounding, and anchor
pullout method), and elastic modulus test
Characteristic values of materials: Design characteristic values of materials,
measurement of strain in the actual structure, and strength test and dynamic
elastic modulus test on the actual structure
Amount of crown settlement: Differential leveling and electro-optical distance meterAmount of convergence: Convergence gauge and electro-optical distance meterAmount of linear displacement: Differential leveling and electro-opticaldistance meter
Crack patterns: Visual observation
Displacement: Convergence measurement, measurement of openings and joint
offsets between adjacent segments
Strain and stress of members: Strain measurement
Strength and deformation characteristics of lining concrete: Strength test
(boring test, rebound hammer method, hammering & sounding, and anchor
pullout method), and elastic modulus test

9
10
11

12

Amount of track displacement(any impacts on riding comfort)
Development of water leakage/
cracking in a region(s) visible to users(e.g. platforms/concourse ceiling)Amount of tunnel convergence

Development of cracking or damage
in segments or secondary lining(structural deformation)

•
•
•
•
•

•
•
•
•

•
•
•
•
•

13

Stress intensity or stress resultant oflining obtained in deformation analysis

14

Identification of seismic performanceand damage level by analysis

15

Amount of tunnel convergence andlinear displacement

•
•

•

•
•
•
•
•

16

Stress intensity or stress resultant oflining obtained in impact analysis

17

Not evaluated in the maintenance phase

Copyright © 2012 SciRes.

•
•

-

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ET AL.

Table 6(b). Performance evaluation criteria used in AHP (shield tunneling method/railway tunnels).
No

Performance evaluation items•

18

Presence of cracking/loosening, etc.
in segments and secondary lining

19

State of corrosion in rebars, bolts
and splice plates

•
•
•
•
•
•

20

Degradation indexes, e.g. coverconcrete, remaining non-carbonateddepth, chloride concentration, andwater content

•
•
•
•
•

21

State that cracking/erosion ofsegments and secondary lining

•
•
•

•

22

Occurrence of water leakage

23

Not evaluated in the maintenance phase
State of e.g. cracking and loosening in
the regions of segments/secondarylining that affect auxiliary facilities
involved in train operation.

24

•
•
•
•
•
•
•
•

25

26

27
28
29
30
31
32
33
34
35
36
37

State of corrosion in steels in aregion(s) that may affect auxiliary
facilities involved in train operation
State of water leakage in regionsthat affect auxiliary facilities
involved in train operation
Allowances outside the construction
gauge, esp. in relation to auxiliary
facilities
Conditions of drainage facilities(e.g. blockage of drain ditches)
Allowances outside the construction
gauge (escape space used during
patrolling/inspection)
Not evaluated in the maintenance phase
Changes in the groundwater levelin surrounding areas
Groundwater quality in nearby areas
Water leakage survey inside the tunnel
Amount of ground surface
displacement in surrounding areas
Occurrence of water leakage
Amount of displacement ordevelopment of cracks inneighboring properties
Vibration/noise levels of groundsurface and surrounding buildings

Copyright © 2012 SciRes.

Monitoring items the monitoring method is parenthesized
Location, length, width and range of cracking/flaking: Visual observationand visible images
Loosening range: Hammering and infrared camera
Crack patterns: Unfolded view of deformation
Progressiveness: Marking, photographing, and cracking gauge
State of corrosion of exposed steels: Visual observation and measurementof thickness reduction due to corrosion
State of corrosion of steels in concrete: Self-potential polarization resistanceelectromagnetic wave radar and visual observation by chipping
Progressiveness: Photographing and rust fluid status
Cover depth: RC radar, chipping and scaling
Remaining non-carbonated depth: Measurement of carbonation depth chloride
concentration:
Measurement of chloride concentration Water content: Water content test
Environmental conditions: Measurement of airborne saline matter, chloride concentrationof leaked water, exposure to rainwater, exposure to sunlight, temperature and humidity
Cracking: Bleeding of gel, location/length/width/range/depth of corrosion and scaling,visual observation, hammering, measurement of thickness reduction due to corrosion
Crack patterns: Unfolded view of deformation
Progressiveness: Marking, photographing and cracking gauge
Physical property deterioration of lining concrete: Strength test, elastic modulus test,
physical property test (e.g. alkali content, aggregate reaction, microstructure,and chemical composition)
Environmental conditions: Concentration of toxic substances in leaked water,water supply status, exposure to sunlight, temperature and humidity)
Location of water leakage: Visual inspection
Quality of leaked water: Water quality test
Changes in water leakage: Sensor measurement
Location, length, width and range of cracking: Visual observation and visible images
Loosening range: Hammering and infrared camera
Cracking patterns: Unfolded view of disturbance
Progressiveness: Marking, photographing, and crack gauge•

State of corrosion of exposed steels: Visual observation, measurement of thickness
reduction due to corrosion
State of corrosion of steels in concrete Self-potential polarization ,résistanceelectromagnetic wave radar and visual observation by chipping
Progressiveness: Photographing and rust fluid status••

Location of water leakage: Visual inspection
Quality of leaked water: Water quality test•

Measurement with a clearance car and electro-optical distance meter•

Location and status: Visual observation and photographing•

Measurement with a clearance car, visual observation and electro-optical distance meter••

Water level measurement•••

Water quality test
Visual inspection and photographing
Ground surface displacement: Observation of ground fissure and subsidence anddisplacement measurement
Amount of leaked water: Visual observation, photographing and measurementof amount of leakage•••

Amount of displacement: Displacement measurement
Cracking: Cracking survey, e.g. crack width•

Vibration/noise level: Measurement of vibration and noise

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Table 7. Judgment categories according to the existing method (for railway tunnels).
Structure State
State that threatens operational safety, safety of passengers, public safety, guarantee of regular train operationthat might cause this stateA

Deterioration that threatens operational safety, safety of passengers public safety, guarantee of regular train operation
and which require emergency countermeasures
Progressive deterioration that cause the performance of structures to drop, or heavy rain, floods, or earthquakesthat might impair the performance of structures
Deterioration that might cause a future performance drop of structures

B

Deterioration that might result in a future soundness rank of A

C

Slight deterioration

S

Sound

Figure 7. TPI probability distributions by judgment category
in the existing method (Box segment section).

sults indicate that the results of both methods may become consistent if the scores are determined more appropriately. Now, the performance requirements, which
determined TPI, are categorized according to the primary,secondary and sub categories to examine which of thesecategories affect TPI and identify the influencing factors.
The results are shown in Figure 9 through Figure 11.
Figure 9, where the judgment result is “A” in the existing method, shows that the primary categories greatly
affecting TPI are found to be “user safety” and “structural stability”. Figure 8 shows that in the existing method, “cracking and water leakage” is the most common
major factor, which is almost the same as the major factor that determined TPI in the existing method. Moredetailed analysis of influencing factors using the subcategories are shown in Figure 10. It is shown in Figure
10, where the judgment result is that the most influenceing secondary categories are “stability against continuousload” and “not directly threatening to user safety”. Figure 11 judged as “A” also shows that the most influencing subcategory is “Prevent the occurrence of waterleakage or flaking that may obstruct the ensure safe
driving”. Figure 8 shows that in the existing method, “(1)Copyright © 2012 SciRes.

Disturbance by external force” and “(3) Disturbance bywater leakage” are the most common major factors,
which are almost the same as those that determined TPI
in the existing method.
These indicate that on the whole, the determining factors of judgment results in the existing method and TPI
are more or less consistent. In the case of box segment
section, those judged as “A” in the existing method aremost affected by cracking and water leakage, while in
TPI, the non-presence of flaking or water leakage that
may threaten user safety under “User safety performance” is most influential.
These results show it is possible to comprehensively
quantify the actual performance of tunnel structures by
employing AHP using already available inspection results such as the interior views of lining obtained in theexisting method.

5. Conclusions
This paper outlined the concept of performance criteria
for tunnel structures and a management methodology
based on that concept to be used in the maintenancephase for existing tunnels. Citing existing road tunnels, itwent on to explaining how to perform calculations in oneof the approaches to comprehensively evaluate actual
performance in the maintenance phase, namely the Total
Performance Index.
In evaluating/verifying the actual performance basedon performance criteria, although it is possible to quantitatively evaluate the actual performance, there is a lackof empirical data to be used for determining the thresholds in verification. Future research should focus on thecollection of actual data to carry out technological studies to enhance the accuracy of evaluating/verifying theactual performance.
Currently in Japan, each owner and administrator isstudying management methodologies for tunnel structures on an individual basis [18]. Unfortunately, their
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Figure 8. Judgment deformation according to the existing method.

Figure 9. Major factors of primary category (Judged as “A” in the existing method) (Box segment section).

Figure 10. Major factors of secondary category (Judged as “A” in the existing method) (Box segment section).
Copyright © 2012 SciRes.

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Figure 11. Major factors of sub category (Judged as “A” in the existing method) (Box segment section).

studies are not widely shared in practical terms; tunnel
administrators and engineers should cooperate with eachother to discuss further to develop performance criteria
and management methodologies based on such criteria.

REFERENCES[1]

ISO2394, “General Principles on Reliability For Structure,” 3rd Edition, June 1998.

[2]

MLIT, “Basis of Structural Design for Buildings andPublic Works,” Octorber 2002.

[3]

JSCE, “Basic Research Committee for Formulation ofComprehensive Design Code: Principles, Guidelines andTerminologies for Structural Design Code Drafting
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[4]

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[5]

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[6]

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[7]

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[8]

S. Kimura, “Structural Design Method’s Stream of International Standardization and Needs of Tunnel Structural
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Copyright © 2012 SciRes.

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[10] N. Sano, “A Study on Tunnel Functions and Performance(in Japanese),” 2007 JSCE National Convention, Ken-14
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[14] K. Nakamura, H. Hosonuma, M. Takada, H. Ohtsu and K.
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Tunneling, Chengdu, September 2007, pp. 267-277.
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ET AL.
[18] JSCE, “Advanced Design and Management for Tunnels
Based on Performance Codes (in Japanese),” Tunnel Library 21, October 2009.

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