Special Feature

Increasing the Level of Infrastructure
Facilities Management
Nobuhiro Segawa, Takumu Kashiwagi, Satoshi Shibata,Toshiyuki Yamada, Yoshihiro Iriyama, Atsushi Ogiwara,
Satoshi Maeda, and Norio Fujikura†
Abstract
The migration from metallic-cable-based communication to optical communication will require sufficient underground space to accommodate optical fiber cables without impediments in terms of quality
and quantity. Therefore, we must provide ways to effectively maintain the existing infrastructure facilities, which are aging and degrading, as well as identify shifts in demand for optical communication. This
article describes our approach to infrastructure facility management aimed at systematizing such measures.

1. Introduction
We are developing strategic management techniques for infrastructure facilities to effectively operate, manage, and maintain facilities that are becoming old and degraded in a situation where opticalbroadband services exist alongside existing telephone system services. Although the amount of infrastructure facilities has remained at about the samelevel in recent years, there are concerns that infrastructure facilities may become strained, especially inurban areas where the demand for traffic is high,because telephone services using metallic cables andbroadband services using optical cables will coexist
for the time being (Fig. 1). In addition, there are concerns over long-term deterioration because more than
20 years has passed since the time of installation for
50% of cable tunnel facilities and for 80% of cableconduit facilities.
On the other hand, in the field of social infrastructure, such as roads and bridges, rational methodology
for constructing, maintaining, and operating theinfrastructure facilities is being developed using theconcept of asset management developed for managing real estate assets. For NTT’s infrastructure facilities, we are investigating facility management techniques that incorporate such concepts to solve quality and quantity problems (Fig. 2). In this article, we
describe the technologies involved in infrastructure
Metallic/optical services coexist ➔ Metallic and optical cables overlap
Lack of facilities
Existing
facilities
Amount Unnecessary
facilitiesof opticalcables

B-FLET’S
Dedicated lines

Generalsubscribers• ADSL• Off talkDifficult tochangeto opticalAmountof metallic
cablesTime

Off talk: Metallic-based voice information service thatmakes use of underutilized telephone call capacity† NTT Access Network Service Systems Laboratories
Tsukuba-shi, 305-0805 Japan
E-mail: n.fujikura@ansl.ntt.co.jp

Vol. 4 No. 6 June 2006

Fig. 1. Quantitative concerns about infrastructure
facilities.

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Special Featurefacilities management.
2. Technologies for optimizing the compositionof infrastructure facilities
Optimizing the composition of infrastructure facilities means evaluating quantitative excesses and defi-

Strategy
Asset management
Establish decision-making
methods for appropriate
level of maintenance/
investment
Database
Improve data accuracy/
reliability
Create highly expandable
data structure
Establish field work
technology
Quality
Lifecycle cost
Analyze/predict causes ofdegradation
Calculate investment for
deteriorated facilities
Establish LCC evaluation
methodQuantity
Optimization of infrastructure
equipment structure
Measure and identify existing
facilities
Identify investment taking into accountdemand for optical equipment
Propose algorithms forinfrastructure improvement plan

LCC: lifecycle cost

Fig. 2. Structure of infrastructure facilities management.

ciencies taking into account shifts in supply anddemand for infrastructure facilities, optimizing measures to solve problems mainly of insufficiency, anddeveloping planning techniques. We created a procedure for diagnosing the status of supply and demandof infrastructure facilities in order to meet NTT’s goalof providing optical access to 30 million of customers
by 2010 (Fig. 3). The fundamental idea is as follows.
First, we identify the availability of infrastructure
facilities in terms of the number of optical fibers thatcan be accommodated, taking into consideration
issues such as multiple cable installation and degradation of infrastructure facilities. Then, we estimate
the amount of work needed to improve infrastructure
facilities and the amount of corresponding infrastructure improvement work by comparing the availability with the expected future demand for optical fibers.
That takes into account the usage ratio of opticalfibers, ratio of optical cable subscribers to total users,and future access methods. Results to date show thatthe amount of investment required for infrastructure
facilities is greatly influenced by two factors:• Ratio of PDS (passive double star) systems to all
optical access systems and• Need for reserved space (additional spacereserved for the installation of at least one opticalcable between manholes)
In the future, we will work to establish optimum
infrastructure facilities management techniques withan eye on cable routing design methods to effectively utilize the existing facilities and the latest transmission technology in access systems.

Quantitative diagnosisof equipment
Identify availability of infrastructure
equipment at the fiber optical core level
Identify availability ofexisting optical cores
Calculate number of opticalcores needed in the future

Determine amount of workfor cable improvement

Deterioration of
infrastructure facilities
Spare spacein conduit
FTTH ratio

PDS/SS ratio

Composite stateof PDS service
Number of aerial
wiring blocks
Calculate investment

Determine amount of work for
infrastructure facility improvement
Reflect in improvement plan
FTTH: fiber to the home
SS: single starFig. 3. Quantitative simulation of infrastructure facilities for the switch to optical communications.

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NTT Technical Review

Special Feature

Conduit degradation
phenomena(steel conduit)
BrokenClogged with
Defective
earth andjoint
other foreignmaterial
44
Bent
10
10
Flattened20

Bridge conduit degradation
phenomena

Steel
V-tube damaged
disengaged,
4
etc
13

Corroded
52

Rust on steel,painted film
degraded
83

(%)

(%)

Totally corroded

Rust and degraded paintTunnel degradation phenomena(in open-cut method tunnel)

Manhole degradation phenomena(example of on-site application)
Result of sampling survey
Salt
Alkaline- damage
Neutraaggregate
lizationreaction+ saltdamageExternal
1 1 damage
2
5
Alkalineaggregate
Honeycomb,
reactionetc.
555Neutralization(unit)+ salt damage
Cracking

Tunnel degradation phenomena(in shield-method tunnel)
Corrosion of skin plate(pitting corrosion)

Honeycomb: Cracked surface
generated at the botom of astructure member by theprecipitation of coarse
aggregates in the concrete

Exfoliation of concrete by
expansion due tocorrosionof reinforcing bars

Fig. 4. Examples of degradation in infrastructure facilities.

3. Lifecycle cost evaluation techniques
There are concerns about the deterioration anddegradation of infrastructure facilities. Typical examples of such deterioration are shown in Fig. 4. Theyshow the following visible characteristics:• Cable conduits: Corrosion of metal tubes• Bridge conduits: Corrosion of steel tubes andtube attachment fixtures• Manholes: Salt damage to concrete*1 and reduction of durability caused by corrosion of reinforcing bars by long-term neutralization with age*2• Open-cut method cable tunnel: Deterioration of*1 The strength of structural bodies is reduced by cracks or by reductions in cross-sectional area of reinforcing steel as the result ofaccelerated corrosion caused by chloride ions in concrete.
*2 Reinforcing steel is easily corroded if the environment ceases to bealkaline as a result of carbonation caused by CO2 penetrating concrete from the air.

Vol. 4 No. 6 June 2006

reinforced concrete caused by corrosion of reinforcing bars and water leakage from junctions• Shield method cable tunnel: Corrosion of steel
segments and water leakage from junctions
Since there is concern that management costs will
increase in the future as the result of these types ofdeterioration, we need to optimize the methods ofmanaging and maintaining the facilities and minimize the cost of such management and maintenance.
Therefore, we are aiming to establish management
and maintenance techniques based on lifecycle cost
evaluation techniques. These techniques let us estimate the lifecycle cost once we have identified thestate of deterioration of facilities, and they enable us
to determine the most economical timing in terms of
total cost that allows cost equalization.
The concept of this lifecycle cost assessment
method is shown in Fig. 5. To establish it, we must
estimate the deterioration status of various kinds offacilities. We are currently analyzing the degradation
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Special Feature

Evaluation process
Identify current status of existing
facilities and defect phenomena

Predict temporal transitionof facility degradation

Analyze and formulatedegradation mechanism

Formulation of
degradation process

Uncertainty
Status Decay curve

LCC
calculation

LCC (1) < (2)
Cost

Cost
reduction

Costequalization

Optimum inspection/
repair method

Selection of
optimum time
Cost

Compress

Maintain

MaintainGood(2)

Equalization

RepairRepairEstimate lifecycle cost(1)
Establish inspection and repair
methods to reduce total cost

Inspect

Inspect

Poor
Available period

Available period

Year

Prioritize for cost equalization

Fig. 5. Concept of lifecycle cost (LCC) evaluation method.

mechanisms of various facilities as a prerequisite tothat estimation. From the results of analyzing thecauses of degradation of metal tubes for cable conduit, for example, we have found that the generationof rust is greatest in places within 10 m of manholes.
For the manholes themselves, we are analyzing thedegradation mechanisms of concrete by performing
on-site sampling and by studying the results of previous research. And for cable tunnels constructed using
the open-cut method, we are investigating the relationship between the degree of exposure and thedegree of corrosion of reinforcing steel. An exampleof this analysis is shown in Figs. 6 and 7.
In the future, we will formulate the deterioration
process based on these analysis results and reflect itin the minimization of maintenance and management
costs by establishing a method of calculating the lifecycle cost.
4. Infrastructure facilities database technology

50 m or more2%

10 to 50 m
19%

0 to10 m
79%

About 80% are within 10 m

MH

MH
Most defects occur at a
position close to a manhole (MH)Fig. 6. Degradation analysis of metal conduit.

Sufficient data about the current status of facilities
is indispensable to reflect efforts on facilities management effectively in maintenance and management
work. Therefore, we are developing database technology that takes into account future infrastructure
facilities management work. It involves the following
elements.
• Time-space database that uses chronological information that expresses the location, form, and shape20of facilities• Application of XML (extensible markup language)
to enable the consolidation of various information
including graphics, photographs, and video• Application of GIS (geographical information systems) in expressing time-space data
• Coordination with other systems having an international standard interface
NTT Technical Review

Special Feature

Photograph of sampled core

Concentration (wt%)
Low
High

Analysis with EPMA

Concrete surface
Carbon distribution(neutralized)

0

20

40

60

80

Chloride salt distribution(salt damage)

0

20

40

60

80

Depth from surface (mm) Depth from surface (mm)Fig. 7. Analysis on concrete sampled from manholes, including beach sand. (EPMA: electron probe microanalysis)

Infrastructure database

GPS satellite

Monitor for displaying conduit’s
linear measurements
PDA

Horizontalview
Vertical view
GPS antenna for
position measurement

On-site monitoring

3-axis gyro sensor

Conduit linear measurement system
PDA: personal digital assistantFig. 8. Outline of conduit position measurement system.

• Field work technology• RFID (radio frequency identification) technology
as a user interface• Digital watermarking and voice recognition technologies as supplemental technologies to single
input• Infrastructure position measurement utilizing GPS(global positioning system)
Here, we will explain the conduit position measurement technology as one example among thosementioned above. It precisely measures the positionof a conduit using gyroscopic and GPS techniquesand generates drawing data (making a database) on aVol. 4 No. 6 June 2006

global coordinate system (Fig. 8). In this system, it ispossible to obtain linear data about the position of aconduit in an absolute coordinate system by taking
measurements in latitude, longitude, and altitude
absolute coordinates between two existing manholes
using GPS and by measuring linear data about the
conduit between two manholes using gyroscopic
technology. From these measurements, it is possible
to obtain accurate linear data about a conduit between
two manholes that is not affected by factors such as
road construction. The concept of a future infrastructure database utilizing these technologies is shown in
Fig. 9.
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Special Feature

Field survey data
Temporary registration

Master system
Explicit/implicit
phase description

Next-generation facilities
management system
Entry system
Temporaryregistration
XML database

GIS engine
Data Time spacemodel analysis

Confirmation
Registration
Attributes
XML database

Uncoupled inner tube
Tag

ManholeTime space
database

International
standard IF

Work database replication

Other systems

Work database
replication
Location guidancewith PDA

ManholeIF: interface

Fig. 9. Concept of future database technology.

5. Future development
We will integrate the infrastructure facilities management technology incorporating the concept ofasset management to derive a systematic process andmethod that can reduce maintenance and management costs of infrastructure. Through these activities,

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we plan to develop and provide various timely andeffective measures to extend the lifecycle of infrastructure facilities that continue to degrade but that
we still need to use for a long time as infrastructure
inventory to achieve our target of 30 million of optical service subscribers.

Nobuhiro Segawa

Satoshi Shibata

Manager, Plant Planning Department, Network Business Headquarters, NTT East.
He received the B.E. degree in civil engineering from Chuo University, Tokyo, in 1987. He
joined NTT in 1987 and has mainly been
engaged in the design of cable tunnels. He wastransferred to NTT Access Network Service Systems Laboratories in 2001 and to NTT East in
2006. He has been engaged in research on underground telecommunication facilities, especiallyon technologies for optimizing the compositionof infrastructure facilities.

Research Engineer, Civil Engineering Project,
NTT Access Network Service Systems Laboratories.
He received the B.E. degree in civil engineering from Akita University, Akita, in 1990. He
joined NTT in 1990 and has mainly been
engaged in the design of cable tunnels. In 2003,
he was transferred to NTT Access Network Service Systems Laboratories and is currently
engaged in research on underground telecommunication facilities, especially concerning lifecycle cost evaluation technology.

Takumu Kashiwagi

Toshiyuki Yamada

Research Engineer, Civil Engineering Project,
NTT Access Network Service Systems Laboratories.
He received the B.E. degree in agricultural
engineering from Tokyo University of Agriculture, Tokyo, in 1991. He joined NTT in 1991 andhas mainly been engaged in the introduction of
new technology for underground telecommunication facilities. In 2003, he was transferred to
NTT Access Network Service Systems Laboratories. He is currently engaged in research onunderground telecommunication facilities, especially concerning lifecycle cost evaluation technology. He is a member of Japan Society of Civil
Engineers (JSCE).

Research Engineer, Civil Engineering Project,
NTT Access Network Service Systems Laboratories.
He received the B.E. degree in civil engineering from Kitami Institute of Technology,
Hokkaido, in 1985. He joined NTT in 1985. In
2004, he was transferred to NTT Access Network Service Systems Laboratories. He has been
engaged in research on underground telecommunication facilities.

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Special Feature

Yoshihiro Iriyama

Satoshi Maeda

Research Engineer, Civil Engineering Project,
NTT Access Network Service Systems Laboratories.
He received the B.E. and M.E. degrees in civilengineering from Gifu University, Gifu, in 1994
and 1996, respectively. He joined NTT in 1996.
In 1998, he was transferred to NTT Access Network Service Systems Laboratories. He has been
engaged in research on underground telecommunication facilities, especially on no-dig technology, and conduit position measurement systems.
He is a member of JSCE.

Research Engineer, Civil Engineering Project,
NTT Access Network Service Systems Laboratories.
He received the B.E. and M.E. degrees in civilengineering from Gifu University, Gifu, in 1992
and 1994, respectively. He joined NTT in 1994.
In 2005, he was transferred to NTT Access Network Service Systems Laboratories. He has been
engaged in research on underground telecommunication facilities.

Atsushi Ogiwara

Norio Fujikura

Manager, Urban Engineering Center, Metropolitan Regional Division, NTT InfraNet.
He graduated from the Department of Civil
Engineering at Nagano National College ofTechnology, Nagano, in 1980. He joined Nippon
Telegraph and Telephone Public Corporation(now NTT) in 1980. In 2004, he was transferredto NTT InfraNet. He has been engaged inresearch on underground telecommunication
facilities, especially maintenance of cable tunnels. He is a member of JSCE.

Senior Research Engineer, Civil Engineering
Project, NTT Access Network Service Systems
Laboratories.
He received the B.E. and M.E. degrees in civilengineering from Waseda University, Tokyo, in1982 and 1984, respectively. He joined Nippon
Telegraph and Telephone Public Corporation(now NTT) in 1984. In 2004, he was transferredto NTT Access Network Service Systems Laboratories. He has been engaged in research onunderground telecommunication facilities. He isa member of JSCE and the City Planning Institute of Japan.

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