Journal of Transportation Technologies, 2012, 2, 113-128
http://dx.doi.org/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
1Department of Civil and Environmental Engineering, Kanazawa Institute of Technology, Ishikawa, Japan
2Graduate School of Engineering, Kanazawa Institute of Technology, Ishikawa, Japan
3Faculty of Science and Engineering, Waseda University, Tokyo, Japan
Received February 29, 2012; revised March 5, 2012; accepted March 16, 2012
ABSTRACT
The concept of performance-based design, which mainly focuses on mechanical performance, has become the interna-
tional 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 engi-
neering. It is also required to clarify performance-based criteria for tunnel structures to suit specific use purposes (ob-
jectives), establish the concept of survey, planning, design, construction and maintenance based on such criteria, and
develop proper management syste ms for operation and maintenance to suit specific tunnel use pur poses. 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) cri-
teria for individual built facilities, such as roads, rivers,
ports and buildings have conventionally been based on
the historical backgrounds (experience), culture and ob-
jectives of each facility. In some cases, this individual
development approach created considerable discrepan-
cies among technological criteria when compared to each
other. In other countries on the other hand, while the in-
dividual design approach used to be the main practice as
well, ISO2394 [1] and Eurocode 0 have been issued in
recent years as comprehensive design codes that specify
the basics and system of structure design. Following this
trend, the Ministry of Land, Infrastructure, Transport and
Tourism (MLIT) of Japan formulated the “Basis of
Structural Design for Buildings and Public Works [2]” in
2002. The MLIT National Institute for Land and Infra-
structure Management felt it was necessary to set out
principles and define terminology for technological crite-
ria development for code writers, and assigned Japan
Society for Civil Engineering (JSCE) to carry out re-
search. In March 2003, JSCE (Basic Research Commit-
tee for Formulation of Comprehensive Design Code)
compiled “Code PLATFORM ver.1.0 [3]”. Comprehen-
sive design codes represent a new design concept called
“performance-based design,” which largely focuses on
the discipline of structural design. Based on this new
concept, existing design codes are now being revised in
such areas as concrete, seismic engineering and geotech-
nical engineering. The Japanese Geotechnical Society
has already issued a design code for foundation struc-
tures called “Comprehensive Foundation Design Code
[4]”. This way, the performance-requirements based de-
sign system is now being established in Japan as part of
the efforts to standardize structural design.
However, 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.
Therefore, it is necessary to understand the trend of
international standardization and formulate comprehend-
sive design codes or specific design codes for tunnel
structures in consideration for the nation’s expertise in
underground structure design and valuable traditional
C
opyright © 2012 SciRes. JTTs

S. KIMURA ET AL. 114
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 Japan
denoted by tunnel length and construction year, featuring
railway tunnels as an example. It has been pointed out
that today’s infrastructure development should place im-
portance on technolog ies that provide better maintenanc e
of existing structures to prolong their service life, in ad-
dition 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 a
sensible way in consideration for the specific mode of
service assigned to each structure. This is also the case
for the field of underground structures; structure design
professionals are now required to shift design con cept for
the better utilization of underground space in the future.
The current focus on conventional design technologies,
which aim to ensure structural safety based on the notion
of 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 struc-
tures to better use the existing built environment and is
employed throughout service life including the mainte-
nance phase. Tunnels and other underground structures
are different from ground structures in that they can not
simply be abandoned once constructed; if an under-
ground space becomes unused due to some defects and
abandoned, certain disturbance in the surrounding ground
may be caused in the long run, such as in the form of
subsidence and deformation of foundations of adjacent
structures.
To serve as the international standard for the mainte-
nance of existing structures, ISO13822 [7] was issued.
Based on the concept of structure reliability and risk
management, it sets forth the basic concepts of evaluat-
ing existing structures (e.g. buildings and bridges) by
Figure 1. Change in the railway tunnel length in Tokyo
Metro [5].
classifying them into the following: 1) Expected modi-
fication of use purpose, expected repairs, and prolonga-
tion of design service life; 2) examination of reliability as
required by the administrator and insurance company; 3)
time-dependent deterioration caused by loading and ac-
tions; 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 to
ensure its original objectiv es.
Considering the international trend of standardization
of tunnel structures that focuses on performance criteria
as described above, this paper first reestablishes the per-
formance requirements for tunnel structures proposed by
JSCE, and discusses the concepts of performance re-
qui rements for existing tunnels in their maintenance phase
and management strategies based on them [8,9]. The pa-
per goes on to taking existing road tunnels as the exam-
ple to describe the method of calculating the Total Per-
formance Index designed to comprehensively evaluate
their actual performance at the maintenance phase.
2. Performance Requirements [10] for
Tunnel Structures Based on Specific
Objectives
2.1. Concept of Performance Requirements
The performance requirements for tunnels, which are
used for various purposes such as roads, railways, water
supply and sewage systems, power supply, and commu-
nication, are designated individually to suit their specific
objectives within the basic performance requirements. It
should be noted that the concept of structural design of
tunnel structures is significantly varied among construc-
tion methods [11], and thus the specific performance
requirements for a tunnel structure should be developed
with careful consideration of its construction method. In
the mountain tunnel construction method employed for
considerably strong and highly self-supporting ground,
the main structural system that provides a space to con-
struct 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 tunneling
construction, 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 make
the structural design of tunnels difficult. It is thus neces-
sary to identify major factors that differ between tunnel-
ing methods. Table 1 shows an example of factors that
differ between the mountain and shield tunneling meth-
ods (for railway tunnels). When closely examining the
required performance, these differences among tunneling
methods should be taken into account.

S. KIMURA ET AL. 115
2.2. Development of Performance Requirement
Specific performance requirements are developed here
based on the basic ones. Table 2 shows an example of
identification of performance requirements for road tun-
nels constructed in the mountain tunneling method. The
primary categories for required performance consist of
the basic performance requirements and their descrip-
tions. Secondary categories and subcategories consist of
phenomena used for evaluating the primary categories
and for further evaluating the secondary categories, re-
spectively. This means the performance given by the
primary categories is satisfied if all the subcategory phe-
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 of
them allow quantitative evaluation while others only al-
low qualitative evaluation due to obscurity. To carry out
the detailed evaluation of individual performance, spe-
cific verification indexes should be developed for all
phases of planning, design, construction, and mainte-
nance (service) to evaluate the actual performance. Fo-
cusing on the maintenance phase, the sections below de-
scribe the concept of evaluation of actual performance
and management concept based on performance criteria.
Table 1. Differences in factors betwee n tunneling methods (for railw ay tunne ls).
Mountain tunneling Shield tunneling
Construction site Mainly mountain ous regions and su burbs
(frost inside the tunnel considered) Mainly urban areas (frost inside the tunnel Not considered)
Portal Entrance exists in principle No entrance in principle
Construction load Not necessary to consider construction
load in general
May be disturbed by construction load
Require measures for stabilizing the cutting face during
construction
Lining system The lining concrete does not serve as a structural member in general
(Plain concrete system in principle)
The lining (segment) serves as a structural member
(Reinforced concrete, steel structure, and composite sys-
tem)
Roadbed Roadbed may be disturbed where there
is no invert, affecting the running stability The closure system consisting of segments creates no disturbance
Table 2. Performance requir eme nts fr agme nted (shield tunneling method/railw ay).
Primary categories Secondary categories Subcategories
Ensure safe driving
Not directly threatening to user safety User safety Ensure user safety
Ensure safe eva cuation of users in emergency
Ensure ride quality
User usability Ensure user comfort Not making users uncomfortable or feel insecure
Ensure stability against continuous load
Provide necessary seismic performance
Ensure stability against assumed load change
Structural
stability
Ensure stability against
assumed load
Ensure stability against assumed construction load
High corrosion resistance
No deterioration in concrete
Durability Ensure durability against
assumed deterioration factors Provide high water tightness
Satisfy req uired demands (traffic capacity)
Ensure trai ns can be operated in a stable manner
(at the fixed time)
Administrator
usability
Ensure proper utilization
by administrator
Ensure operation of auxiliary facilities for regular train operation
Ensure safe & easy inspection
Maintainability Ensure provision of proper
maintenance Ensure safe & easy repair
Minor impacts on ground water
Minor impa cts on surrounding grounds
To ensure
required
traffic volume
safety and
smoothly
during the
required
service period
Impact on
surroundings
Minimize impact
on surroundings Minor impacts on surround ing real estates

S. KIMURA ET AL. 116
3. Performance Criteria Based Performance
Criteria [12]
3.1. Concept of Management Based on
Performance Criteria
“Performance criteria based management” means a stra-
tegic management in consideration of the lifecycle of the
tunnel through deter mination of evaluation ind exes based
on performance requirements at all phases of planning,
survey, design, construction, and maintenance and through
execution of performance verification based on such
evaluation indexes. Figure 2 shows the management
procedure based on pe rf o rmance criteria.
The basic concept of performance-criteria based man-
agement is to evaluate and verify the actual performance
based on the same performance requirements for each
phase of planning and design, construction, and mainte-
nance (service) according to the use purpose (objectives)
of a tunnel. To describe this concept, the maintenance
phase 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 the
development of remedies for individual troubles, and
does not take the procedure of identifying the perform-
ance 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 man-
agement is largely different in that it estimates future
conditions based on the evaluation/verification of actual
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 admin-
istrator. It should be noted, however, that the evalua-
tion/verification items used in the evaluation/verification
of actual performance are not very different from con-
ventional inspection items; each inspection item serves as
a performance verification index or alternative perform-
ance 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 the
basic performance requirements. The figure shows some
examples of performance verification indexes that allow
quantitative evaluation, corresponding to the basic per-
formance requirements. Some performance verification
indexes are designed to evaluate by employing an analy-
sis or statistical approach based on the yield strength of
members, cracking and other data obtained in tunnel in-
spection. As mentioned before, some indexes allow quan-
titative evaluation and some do not. It is thus practical to
base comprehensive performance verification on a rating
method using verification criteria consisting of five or so
grades. In so doing, it becomes possible to weigh the
priority of each performance requirement in terms of
such conditions o f target tunnel structure as use purpose,
tunneling method, owner strategies and serviceability.
For performance verification indexes that are difficult to
evaluate quantitatively, the Analytic Hierarchy Process
and other appropriate approaches, which will be men-
tioned in later sections, are employed to manage quanti-
tative evaluation. The Total Performance Index is ob-
tained by performing evaluation /verification of actual
Figure 2. Procedure for performance-based management.

S. KIMURA ET AL. 117
Figure 3. Concept of evaluation/verification method for current performance corresponding to the required performance.
performance in the manner described above for each
tunnel or span. This way, integrated management of the
actual performance of tunnel structures becomes possi-
ble.
3.2. Prediction of Future Conditions
In performance-based management, it is required to en-
sure tunnel performance with minimum costs during the
target service period or the actual service period that ex-
tends beyond the former. This concept is presented in
Figure 4. To ensure the required performance in accor-
dance with a reduction in the actual performance level, it
is necessary to take measures for preven tive maintenance
or preventive management [14]. However, evaluation of
the actual performance often involves considerable un-
certainties because, as mentioned before, tunnel struc-
tures are constructed in highly uncertain ground.
That means even where the average actual perform-
ance meets performance requirements, the required per-
formance may not be achieved when the damage prob-
ability shown in Figure 5 is taken into account. In such
cases, emergency remedies are required. Thus, the prop er
procedure for tunnel structures should be to frequently
perform inspection to check the actual performance and
ensure preventive management that provides repairs be-
fore 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 con-

S. KIMURA ET AL. 118
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 to
inspection frequency. In the case of road tunnels for ex-
ample, inspections are carried out almost every five years
(every two years in more frequent cases) in general. An
extremely low inspection frequency increases uncertain-
ties. A reduction in the prediction accuracy is directly
reflected 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 such
factors as the use purpose, social functions, administra-
tor’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 of
each tunnel and consider a suitable management method.
Table 3 shows the service levels derived from service-
ability and correspond ing basic methods of management.
The service levels are from “low” to “high”. Tunnels
categorized as “high” are defined as those such as ex-
pressways in urban areas having particularly significant
social roles, which require detailed inspections and con-
tinuous monitoring at the maintenance phase and evalua-
tion/verification of actual performance using indexes that
allow numerical expression to a maximum extent. Tun-
nels categorized as “low”, on the other hand, are neces-
sary for the society but are not very busy or subject to
particularly tight budgetary restrictions by the adminis-
trator. Such differences in serviceability should also be
taken 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]
The procedure for evaluating/verifying the actual per-
formance by rating consists of identification of evalua-
tion/verification indexes or alternative indexes for each
item of performance requirements; determination of
standard performance values in five grades for each in-
dex; calculation of actual performance values; integrate
the values to obtain the Total Performance Index; and
perform evaluation/verification using the Total Perform-
ance Index. Tables 4(a) and 4(b) show an example of
relationship between performance requirement items and
performance verification/alternative indexes derived from
past design documents and inspections (shield tunnel-
ing/railway tunnels).
This approach allows integrated quantitative evalua-
tion of changes with time in the actual performance of
individual tunnels and is effective in formulating mid- to
long-term strategies. Tunnel structures required to pro-
vide a high level of serviceability need in-depth study of
the probability of local damage and performance dete-
ri o r ation, and more detailed evaluation/verification through
an increased frequency of inspection, continuous moni-
toring of locations having trouble risk, and calculations
and statistical analysis using the insp ection 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.

S. KIMURA ET AL. 119
Table 3. Concept of serviceability-based management.
Service level Low
Low traffic volume/ Deterioration not
progressed/Mountainous region
High
High traffic volume/ Deterioration highly progressed/
Important route/ Emergency transportatio n route
Performance criteria User safety/Usability/Structural stability/Durability/Administrator usability/
Maintainability/ Impacts on the surroundings
Performance verification i ndex 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
Performanc e verification
method at maintenance phase Rating based on results of inspection (+ sim p le measurements) Verification using numerical indexes, mainly derive d from measur ements
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
4.3. AHP-Based Evaluation of Actual
Performance and Current Inspection
Evaluation [16]
ance of a tunnel by the Analytic Hierarchy Process
(“AHP”) using lining data obtained from daily and regu-
lar inspections (observation/measurement data inside the
tunnel). The Total Performance Index, TPI per tunnel
span is given by The actual performance is evaluated in AHP using the
inspection results for railway tunnels constructed in the
shield tunneling method. Two types of single track shield
tunnels, i.e. a small-to-medium box segment section.
1
N
ii
i
TPIP C


 (1)
Rating tunnels using performance evaluation criteria
based on the interior view of lining drawn from the re-
sults of inspection on 350 rings of box segment section,
TPI is calculated using Equation (1). The results are
compared 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 exist-
ing method, the soundness of tunnels is assessed in rela-
tion to: a) Users (safety and usability); b) Structural sys-
tems (load-bearing capacity and durability); c) Adminis-
trator (maintenance); and d) Progressiveness and (com-
mon) characteristics of disturbance. Judgment criteria are
defined for each of the following cases: 1) Disturbance is
caused by external force (cracking); 2) By material dete-
rioration; and 3) By water leakage. The soundness of
tunnels is evaluated by th e judgment categories shown in
Table 7, and then the timing of remedies is determined.
The probability distributions of a set of TPI for each
judgment result by the existing method are shown in
Figure 7.
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, construc-
tion 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 require-
ments 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 the
target route and section. The performance evaluation
criteria are defined in five grades for each required per-
formance subcategory, i.e. 1) Undergoing no perform-
ance deterioration or assumed to be so; 2) Undergoing
slight performance deterioration; 3) Undergoing per-
formance deterioration; 4) Undergoing remarkable per-
formance deterioration; and 5) In need of immediate
remedy), wh ich are scor ed 1, 3, 5, 7, and 15, respectively.
Tables 6(a) and 6(b) show examples of performance
evaluation criteria for railway tunnels constructed in the
shield tunneling method.
In the case of box segment, the average values of TPI
are 1.006, 1.074, 1.335, and 2.446 for Judgment Cate-
gory S, C, B and A, respectively.
It is thus indicated that TPI more or less represen ts the
otal results obtained in the existing method. These re- t

S. KIMURA ET AL. 120
Table 4(a). Performance requireme nts fr agmented (shie l d tunneling method/railway).
Performance requirements
Primary categories Secondary categoriesSubcategories Performance evaluation items
Ensure good railway track alignment1Amount of tra c k d i s p l a c e ment (any
impacts on driving safety)
2Amount of displ a cement in tunnel
alignment
3
Conditions of any cracking or loosening
of 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)
Ensure safe driving
4Exposure of tracks to leaked water
Ensure safe
driving
Ensure proper construction gauge 5Leeway outside the construction gauge
No flaking occurr ed 6
Conditions of any cracking or loosening
of segments/secondary lining and of any
corrosion, etc. in reinforcement\cement in
a region(s) that may threaten driving
safety (e.g. directly above the tracks)
Not directly
threatening to user
safety
No water leakage occurred 7Conditions of any water leakage in a region(s) that may threaten driving safety
(e.g. platforms/concourse ceiling)
User safety Ensure user
safety
Ensure safe
evacuation of
users
in emergency
Allow proper layout/usage of
disaster prevention equipment and
provide evacuation routes for users 8Leeway outside the construction gauge
(clearance from disaster prevention
equipment and room for evacuation)
Ensure ride quality Ensure good alignment and avoid any tunnel deformation that affects
riding comfort 9Amount o f track displacement
(any impacts on riding comfort)
User
usability Ensure user comfort Not making users
uncomfortabl e or
feel insecure
No water leakage/cracking that
makes users uncomfortable o r feel
insecure is observed 10 Development of water leakage/
cracking in a region(s) visible to users
(e.g. platforms/concourse ceiling)
11 Amount of tunne l convergence
12 Development of cracking or damag e in segments or secondary lining
(structural deformation)
Ensure stability
against
continuous load
Provide necessary load-bearing
performance against continuous load
13 Stress intensity or stress resultant of
lining obtained in deformation analysis
Provide necessary
seismic
performance
Lining provides necessary seismic
performance against earthquake
motions assumed during service life 14 Identification of s eismic performance
and damage level by analysis
15 Amount of tunnel convergence and linear
displacement
Ensure stability
against assumed
load change
Provide required load bearing
capacity against impacts by
neighboring co nstruction work and
load condition changes caused by
change in surrounding environment
assumed during service life
16 Stress intensity or stress resultant
of lining obtained in impact analysis
Ensure stability
against
assumed
load
Ensure
stability
against
assumed
load
High corrosion
resistance
Lining provides necessary seismic
performance against earthquake
motions assumed during service life 17 Not evaluated in the maintenance phase
18 Presence of cracking/loosening, etc.
in segments and secondary lining
19 State of corrosion in rebars, bolts
and splice plates
High corrosion
resistance
Rebars & steel segments with
minimum speed of rust development
in steels, e.g. bolts and splice plate
20
Degradation indexes, e.g. cover
concrete, remaining non-carbonated
depth, chloride concentration, and
water content
No deterioration in
concrete No erosion or de terioration in liming concrete 21 State that cracking/erosion of segments and secondary lining
Durability
Ensure
durability against
assumed
deterioration
factors
Provide high water
tightness
Minimize inducing any wa t er leak
that may cause deterioration of
lining/equipment 22 Occurrence of water leakage

S. KIMURA ET AL. 121
Table 4(b). Performance requirements fragmented (shield tunneling method/railway).
Performance requirements
Primary categories Secon dary categories Subcategories Performance evaluation items
Satisfy requi red
demands
(traffic capacity)
Provide an inner space that
accommodates the required
number of railway tracks.
En-sure the alignment is
designed to allow the required
train speed.
23Not evaluated in the maintenance phase
24
State of e.g. cracking and loosening
in the regions of segments/secondary
lining that affect auxiliary facilities
involved in train operation.
25 State of corrosion in steels in a region(s) that may affect auxiliary
facilities involved in train operation
Ensure trains can
be operated in
a stable manner
(at the fixed time)
Prevent the occurrence of
water leakage or flaking that
may obstruc t the functions of
auxiliary facilities involved in
train operation
26 State of water leakage in regions that affect auxiliary facilities
involved in train operation
Allow proper lay-out/usage of
auxiliary facilities involved in
train operation 27 Allowances outside the
construction gauge, esp. in relation
to auxiliary facilities
Administrator
usability
Ensure proper
utilization
by
administrator
Ensure operati o n of
auxiliary facilities
for regular train
operation Water inside the tunnel is
properly drained to avoid any
impacts on auxiliary facilities 28 Conditions of drainage facilities
(e.g. blockage of drain ditches)
Ensure safe & easy
inspection
Allow safe & easy daily
patrolling, inspection and
cleaning 29
Allowances outside the
construction gauge (escape
space used during
patrolling/inspection)
Maintainability
Ensure
provision
of proper
maintenance Ensure safe
& easy repair
Allow installation of
scaffoldings and stockyards
for repair/reinforcement works
Proper margin for repair
/reinforcement provided in the
inner section
30 Not evaluated in the
maintenance phase
31 Changes in the groundwater
level in surrounding areas
32 Groundwater quality in
nearby areas
Minor impa cts
on ground water
Minimize g round-water leve l
changes
Do not affect groundwater
contamination o n th e
surroundings 33Water leakage survey inside
the tunnel
34 Amount of ground surface displacement
in surrounding areas
Minor impa cts
on surrounding
grounds
Minimize ground surface
settlement/upheaval
35Occurrence of water leakage
Minor impa cts
on surrounding
real estates
Impacts on adjacent
buildings/buried utilities
are within the allowable range 36Amount of displacement
or development of cracks
in neighboring properties
Impact on
surroundings
Minimize
impact on
surroundings
Minor vibration
and noise in the
surroundings
Minimize impact of vibration
/noise on the surrounding due
to operation of train 37 Vibration/noise levels
of ground surface
and surrounding buildings

S. KIMURA ET AL. 122
Table 5. Weighting factors given by evaluation by tunnel engineers.
Primary
categories weight factor (SD*) Secondary categories weight factor (SD*) Sub categories weight factor (SD*) No
Avoid any tunnel deformation
that may obstruct the ensure
safe driving
0.052
(0.128) 1
Ensure good alignment and avoid
any tunnel deformation that may
obstruct the ensure safe driving
0.050
(0.148) 2,5
Ensure safe driving for users 0.152
(0.222)
Prevent the occurrence of water
leakage or flaking that may
obstruct the ensure safe driving
0.050
(0.210) 3,4
Not directly threatening
to user safety 0.092 (0.197) -(nothing) - 6,7
User
safety 0.317 (0.125)
Allow disaster prevention
equipment to function in
emergency
0.073
(0.191) -(nothing) - 8
Ensure ride quality 0.079
(0.235) -(nothing) - 9
User
usability 0.124 (0.075) Not making users
uncomfortable or feel insecure 0.045 (0.235) - (nothing) - 10
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
Structural
stability 0.211 (0.093)
Ensure stability against
assumed construction load 0.037 (0.134) -(nothing) - 17
High corrosion resistance
of steel 0.041 (0.162) -(nothing) - 18,19,20
No deterioration in concrete 0.037
(0.160) -(nothing) - 21
Durability 0.128
(0.085)
Provide high water tightness 0.049
(0.209) -(nothing) - 22
Satisfy requir ed demands 0.011
(0.188) -(nothing) - 23
Ensure trains can be operated
in a stable manner
(at the fixed time)
0.015
(0.199) -(nothing) - 24,25,26
Allow proper layout/usage of
auxiliary facilities involved
in train operation
0.005
(0.235) 27
Administrator
usability 0.037 (0.017)
Ensure operati o n of
auxiliary facilities for regular
train operation
0.010
(0.162) Water inside the tunnel is properly
drained to avoid any impacts on
auxiliary facilities
0.005
(0.235) 28
Ensure safe & easy inspection 0.031
(0.213) -(nothing) - 29
Maintainability 0.056
(0.037) Ensure safe & easy repair 0.025
(0.213) -(nothing) - 30
Minor impacts on
ground water 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
Impact on
surroundings 0.127 (0.077)
Minor vibration and noise
in the surroundin gs 0.037 (0.178) -(nothing) - 37
Total (1.000) (1.000) (1.000)

S. KIMURA ET AL. 123
Table 6(a). Performance evaluation criteria used in AHP (shield tunne ling 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 displac ement
in tunnel alignment Differential leveling and tunnel center line survey
3
Conditions of any cracking or loosening
of 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)
• Location, length, width and range of cracking and corrosion: Visual observation
and 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 visual
observation by chipping
4 Exposure of tracks to leaked water • 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 loosening
of segments/secondary lining and of
any corrosion, etc. in reinforcement
\cement in a region(s) that may threaten
driving safety (e.g. direct ly above the
tracks)
• Location, length, width and range of cracking/damage: Visual observation
and visible images
• Loosening range : Hammering and infrared camera
• Crack Pattern: Unfolded view of deformation
• Progressiveness: Marking, p hotographing, and cracking gaug e
• State of steel corrosion: Self potential, polarization resistance, and visual
observation by chipping
7 Conditions of any water leakage in a region(s) that may threaten driving
safety (e.g. platform s/concourse ceiling) • Location and amount of water leakage and visual ob servation
8 Leeway outside the construction gauge (clearance from disaster prevention
equipment and room for evacuation) • Measurement with a clearance car and visual inspection
9 Amount of track displacement
(any impacts on riding comfort) • Measurement of amount of track displacement and train oscillation
10 Development of water leakage/ cracking in a region(s) visible to users
(e.g. platforms/concourse ceiling) • Visual observation
11 Am ount of tunnel conv ergence • Amount of convergence: Convergence gauge and electro-optical distance meter
12 Development of cracking or damage in segments or secondary lining
(structural deformation)
• Location, length, width and range of cracking/damage: Visual observation
and 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 visual
observation by chipping
13 Stress intensity or stress resultant of
lining obtained in deformation analysis
• Displacement: Convergence measurement and measurement of openings
and joint offsets between adjacent segments
• Strain and stress of members: Strain measurement
• Strength and deforma tion characteristics of lining concrete: Strength test
(boring test, rebound hammer method, hammering & sounding, and anchor
pullout method), and elastic modulus test
14 Identification of seismic performance
and damage level by analysis
• Characteristic values of materials: Design characteristic values of materials,
measurement of strain in the actual structure, and stren g th t e st a n d d ynamic
elastic modulus test on the actual structure
15 Am ount of tunnel conv ergence and
linear displacement
• Amount of crown settlement: Differential leveling and electro-optical distance meter
• Amount of convergence: Convergence gauge and electro-optical distance meter
• Amount of linear displacement: Differential leveling and electro-optical
distance meter
• Crack patterns: Visual observation
16 Stress intensity or stress resultant of
lining obtained in impact analysis
• Displacement: Convergence measurement, measurement of openings and joint
offsets between adjacent segments
• Strain and stress of members: Strain measurement
• Strength and deforma tion characteristics of lining concrete: Strength test
(boring test, rebound hammer method, hammering & sounding, and anchor
pullout method), and elastic modulus test
17 Not evaluated in the maintenance phase -

S. KIMURA ET AL. 124
Table 6(b). Performance evaluation criteria used in AHP (shield tunneling method/r ailway tunnels).
No Performance evaluation items Monitoring items the monitoring method is parenthesize d
18 Presence of cracking/loosening, etc.
in segments and secondary lining
• Location, length, width and range of cracking/flaking: Visual observation
and visible images
• Loosening range : Hammering and infrared camera
• Crack patterns : Unfolded view of deformation
• Progressiveness: Marking, p hotographing, and cracking gaug e
19 State of corrosion in rebars, bolts
and splice plates
• State of corrosion of exposed steels: Visual observation and measurement
of thickness red uction due to corrosion
• State of corrosion of steels in concrete: Self-potential polarization resistance
electromagnetic wave radar and visual observation by chipping
• Progressiveness: Photographing and rust fluid status
20
Degradation indexes, e.g. cover
concrete, remaining non-carbonated
depth, chloride concentration, and
water content
• Cover depth: RC radar, chipping and scaling
• Remaining no n-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 concentration
of leaked water, exposure to rainwater, exposure to sunlight, tem p erature and humidity
21 State that cracking/erosion of
segments and secondary lining
• Cracking: Bleeding of gel, location/length/width/range/depth of corrosion and scaling,
visual observation, hammering, measurement of thickne ss reduction due to corrosion
• Crack patterns : Unfolded view of deformation
• Progressiveness: Marking, p hotographing and cracking gauge
• Physical property deteriorati on of lining concrete: Strength test, elastic modulus test,
physical prope rty test (e.g. alkali content, aggregate reaction, microstructure,
and chemical composit ion)
• Environmental conditions: Concentration of toxic substances in leaked water,
water supply status, exposure to sunlight, temperature and humidity)
22 Occurrence of water leakage • Location of water leakage: Visual inspection • Quality of leaked water: Water quality test
• Changes in water leakage: Sensor measurement
23 Not evaluated in the maintenance phase -
24
State of e.g. cracking and loosening in
the regions of segments/secondary
lining that affect auxiliary facilities
involved in train operation.
• Location, leng th, width and range of cracking: Visual observation and visible images
• Loosening range : Hammering and infrared camera
• Cracking patterns: Unfolded view of disturbance
• Progressiveness: Marking, p hotographing, and crack gauge
25 State of corrosion in steels in a region(s) that may affect auxiliary
facilities involved in train operation
• 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 ,résistance
electromagnetic wave radar and visual observation by chipping
• Progressiveness: Photographing and rust fluid status
26 State of water leakage in regions that affect auxiliary facilities
involved in train operation
• Location of water leakage: Visual inspection
• Quality of leaked water: Water quality test
27 Allowances outside the construction gauge, esp. in relation to auxiliary
facilities • Measurement with a clearance car and electro-optical distance meter
28 Conditions of drainage facilities
(e.g. blockage of drain ditches) • Location and status: Visual observation and photographing
29 Allowances outside the construction
gauge (escape space used during
patrolling/inspection) • Measurement with a clearance car, visual observation and electro-optical distance meter
30 Not evaluated in the maintenance phase -
31 Changes in the groundwater level
in surrounding areas • Water level measurement
32 Groundwater quality in nearby areas • Water quality test
33 Water leakage survey inside the tunnel • Visual inspection and photographing
34 Amount of ground surface
displacement in surrounding areas • Ground surface displacement: Observation of ground fissure and subsidence and displacement measurement
35 Occurrence of water leakage • Amount of leaked water: Visual observation, phot o g raphing and measurement
of amount of l e a k ag e
36 Amount of displacement or development of cracks in
neighboring properties
• Amount of displacement: Di s placement measurement
• Cracking: Cracking s u rvey, e.g. crack width
37 Vibration/noise levels of ground
surface and surrounding buildings • Vibration/noise level: Measurement of v ibration and noise

S. KIMURA ET AL. 125
Table 7. Judgment categories acc or ding to the existing method (for railway tunnels).
Structure State
State that threatens operational safety, safety of passengers, public safety, guarantee of regular train operation
that might cause this state
Deterioration that threatens operational safety, safety of passengers public safety, guarantee of regular train operation
and which requir e emergency countermeasur es
Progressive deterioration that cause the performance of structures to drop, or heavy rain, floods, or earthquakes
that might impair the performance of structures
A
Deterioration that might cause a future perform ance drop of structures
B Deterioration that might resul t in a future soundness rank of A
C Slight deterioration
S Sound
Figure 7. TPI probability distributions by judgment cate gory
in the existing method (Box segment section).
sults indicate that the results of both methods may be-
come consistent if the scores are determined more ap-
propriately. Now, the performance requirements, which
determined TPI, are categorized according to the primary,
secondary and sub categories to examine which of these
categories affect TPI and identify the influencing factors.
The results are shown in Figure 9 through Fi gure 11.
Figure 9, where the judgment result is “A” in the ex-
isting method, shows that the primary categories greatly
affecting TPI are found to be “user safety” and “struc-
tural stability”. Figure 8 shows that in the existing me-
thod, “cracking and water leakage” is the most common
major factor, which is almost the same as the major fac-
tor that determined TPI in the existing method. More
detailed analysis of influencing factors using the sub
categories are shown in Figure 10. It is shown in Figure
10, where the judgment result is that the most influence-
ing secondary categories are “stability against continuou s
load” and “not directly threatening to user safety”. Fig-
ure 11 judged as “A” also shows that the most influenc-
ing subcategory is “Prevent the occurrence of water
leakage or flaking that may obstruct the ensure safe
driving”. Figure 8 shows that in the existing method, “(1)
Disturbance by external force” and “(3) Disturbance by
water 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 fac-
tors 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 are
most 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 perform-
ance” 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 re-
sults such as the interior views of lining obtained in the
existing 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 maintenance
phase for existing tunnels. Citing existing road tunnels, it
went on to explaining how to perform calculations in one
of the approaches to comprehensively evaluate actual
performance in the maintenance phase, namely the Total
Performance Index.
In evaluating/verifying the actual performance based
on performance criteria, although it is po ssible to quanti-
tatively evaluate the actual performance, there is a lack
of empirical data to be used for determining the thresh-
olds in verification. Future research should focus on the
collection of actual data to carry out technological stud-
ies to enhance the accuracy of evaluating/verifying the
actual performance.
Currently in Japan, each owner and administrator is
studying management methodologies for tunnel struc-
tures on an individual basi [18]. Unfortunately, their s

S. KIMURA ET AL. 126
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).

S. KIMURA ET AL. 127
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 each
other to discuss further to develop performance criteria
and management methodologies based on such criteria.
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