Structural Health Monitoring Systems - Cowi

Structural Health Monitoring Systems

COWI Expertise
COWI is an international consultant
that holds a market leading position
in bridge, tunnel and marine engineering.
COWI possesses a wide
range of expertise within core
disciplines related to structural
monitoring systems:
• Planning and design of structural
health monitoring systems
• Data acquisition
• Advanced data transmission
• Data analysis
• Data presentation
• Structural modelling and analysis
• Calibration of FEM and life time
models
• Integration of structural monitoring
systems with bridge maintenance
planning systems
• Establishment of reporting
routines and contingency plans
engineering area. Numerous and
rather sophisticated systems have
been established.
It is the experience of COWI that
an early and thorough discussion
with the future stakeholder(s) in the
Structural Monitoring programme
on the possible objectives and the
various system possibilities that are
available, paves the way for an
efficient and direct path to design,
procurement, installation and operation
of a sufficient and cost efficient
monitoring system.
COWI Services
Examples of COWI’s services from
the various application areas of
Structural Monitoring Systems are
presented in the following pages.
COWI’s ISO 9001 certifi cation
covers structural monitoring.
Structural Monitoring
Structural Monitoring is basically
an activity where actual data related
to civil structures are observed /
measured and registered. This has
been performed through all times by
responsible designers, contractors
and owners with almost identical
objectives - to check that the
structures behave as intended.
Historically the activity has required
specialists, has been time consuming
and hence costly.
This situation has been dramatically
changed by the enormous
development within information
technology in the last two decades.
Structural Monitoring has thus
emerged as a distinct technical
discipline as the new technologies
have been introduced in the civil
COWI made the conceptual design for the
Structural Monitoring System for the
Normandy Cable Stay Bridge, France.
Calibration of monitoring
system by measurement of
suspension bridge hanger
force by the frequency identifi
cation method.

3
The Stonecuttersrs Bridge in Hong Kong
will be equipped with an advanced Wind
and Structural Health Monitoring System
designed by COWI.
Actors/Stakeholders
The planning of structural monitoring
systems must take into account
the interests of the different actors
in a bridge project. The design-,
construction- and operation phases
must be considered according to
these interests. The objectives,
requirements and deliveries deciding
the structure of the monitoring
system may change depending on
whom and what phase the system is
supposed to support.
The typical groups involved
during the construction and service
lifetime of a bridge structure are as
follows
• Owner
• Designer
• Contractor
• Operator
• Researchers/Universities
Based on the large experience of
COWI in designing major bridges
world wide the structural monitoring
objectives for these actors are in
general known by COWI.
Structural Monitoring System
Objectives
The purpose of Structural Monitoring
is the examination and location
of structural condition and possible
damage in the structural elements of
a structure set into the context of
user objectives, requirements and
deliveries.
The initial system analysis shall
cover and answer the following
points according to which user types
and phases in the service lifetime the
system shall support;
• Objective
• Requirements
• Basis
• Scope
• Interfaces
• Deliveries
Structural Monitoring System
Activities
Technically the developed structural
monitoring system will consists of
three major parts to meet this way
to organise the activities:
• Sensing modules placed on the
structure. These modules consist
of various types of sensors
depending on the nature of the
structure. This also includes a
signal collection and conditioning
unit.
• A data communication system for
the transfer of the collected data
to a remote computer.
• A database application, which
collects, stores and processes the
sensor data in real time, in order
to provide an evaluation of the
condition of the structure based
on the above mentioned application
areas
For all bridge structures where the
need for a structural monitoring
system is considered there must be
carried out an initial analyse to map
the deliveries the bridge operator
needs for his particular bridge.
Hereby the extent of the onstructure
installations and the
functions of the data management
and control can be established in
order to secure the most reliable,
easy to operate and cost efficient
system to design and install.

4
Structural Monitoring Decision
Making Process and Objectives
The objective of Structural Monitoring
is to provide the necessary
information of the structural
condition and possible damage in
order to provide the documented
basis for decisions concerning these
matters.
All structural monitoring systems
regardless size operates on different
levels for the management and
control of acquired data. These
levels can be expressed by a generic
model for structural monitoring to
identify strategic, analyse/planning
and operational goals. Using such a
model will ensure that managers on
different levels of the bridge
operation organisation will have the
correct level of information to
support there decisions.
Reporting
Reporting
Reporting
Evaluation
Strategic
Implementation
Evaluation
Analyse/
Planning
Implementation
Evaluation
Operational
Implementation
Generic model for the
organisation of structural
monitoring activities.
Requirements
Requirements
Requirements
Organisation of structural monitoring data
Strategic Reports
Tactical Statistical info…
Operational Data
acquisition Storage
of raw data….
Organisation of Structural
Monitoring Data
The structural monitoring basis is
the acquired data from sensors
installed on the structure. In order
to support the above discussed
organisation of structural monitoring
activities the data must be
organised the same way.
On the operational level there will
be one or several individual data
acquisition systems storing the raw
data in preset formats or databases.
From these raw data statistical
information and sample time series
selected based on the bypass of
preset trigger levels will be passed
on to the analysing and planning
level. Only the results of the
management and control performed
at the analysing and planning level
will be reported at the strategic
level. Alarms affecting the immedial
safety of the bridge will always be
reported instantaneous to all
affected managers in the bridge
organisation.
Prioritisation of Structural
Monitoring Deliveries
Most important for the planning of
a structural monitoring system is the
initial analyse to map the deliveries
the system user needs for his
particular bridge based on the above
discussed considerations to take into
account.
The structural components
assessed to have a need for monitoring
shall be listed in a prioritised list
and grouped as;
• Need to know information
• Nice to know information
• Scientific information.
The list shall be discussed with the
actors; structural bridge designer,
the bridge operator and if a maintenance
unit is planned also the
designer of maintenance activities
according to the actors and their
interests
The storage, processing and
management of monitoring information
shall reflect this list. The
management and control of the
groups shall be put into the shown
generic model.

5
The SuTong Bridge in China is
designed with a sofi sticated structural
monitoring system including all
application areas of structural
monitoring.
Guideline for Structural
Monitoring System Parameters
Objectives
The overall aims for structural
monitoring systems are to
• ensure safe structures
• obtain rational and economic
maintenance planning
• attain safe & economic operation
• identify causes for unacceptable
responses
Application Areas
Design Verification
Structural monitoring systems can
acquire data on loads and structural
responses over long measurement
periods to verify stochastic load
parameters and compare them with
design requirements and calculated
response. Short time monitoring can
include forced loading on a structure.
Maintenance Planning Monitoring
of structures can provide
quantification of degradation rates
and wear which are essential to a
regular updating of information on
structural states. This in turn can
be used in rational planning of
inspection, maintenance activities
and calibration of lifetime models.
User Safety
Structural integrity of critical
elements may be crucial to the
operational safety of structural
systems. Continuous surveillance of
such elements can provide information
or alarms to intervene before
severe consequences develop.
Trouble Shooting
Intermittent and insuffi ciently
understood responses of structures
and associated load parameters
(often wind) can be documented
through automated measuring
campaigns - often of extended
duration.
Example on a SHMS user interface
for the Neva Bridge, Russia,
developed by Futertec, Finland.

6
Low cost Structural
Evaluation Monitoring
System at Naini Bridge,
India. Designed and
supervised by COWI
phase of a Bridge will provide for
the detection of meteorological,
seismic-tectonic, geometrical,
structural data and/or other data
considered being useful to build the
“history” of the Work.
All measurements and detections
can be performed with adequate
periodicity, can include information
related to location, date and time of
the detection, and can be recorded
and made available during the
construction phase and give information
feedback to the bridge
Designer and Contractor.
SMS Design Philosophies
The system design, supervision,
control and QA are always based on
the COWI philosophies for such
systems aiming at, that the system
shall provide an advanced monitoring
of the structure providing few
but clearly understandable data, an
easy to use graphical user interface
and provide low installation costs.
Data Collection Strategies
To achieve the best cost/benefit
and right extent for a monitoring
solution it is important to create a
comprehensive monitoring strategy
as part of the bridge design or
rehabilitation definition documentation.
The strategy needs to consider
the varying needs of the users of the
monitoring information based on
the above mentioned system
considerations. The strategies can be
as follows depending on the bridge
design
• Do Nothing
• Inspection and Ad Hoc Monitoring
• Inspection, few Sensors and
Portable Systems
• Inspection and Fixed Sensor
System
• Inspection utilizing combination
of Fixed Sensor System and
portable system
The physical extent of the Structural
Monitoring System and the chosen
topology shall reflect the monitoring
strategy.
Types of Structural Monitoring
Systems
Typical the following types of
Structural monitoring Systems are
designed
Construction Monitoring
Systems
Monitoring during the construction
Structural Evaluation
Monitoring Systems
For new and larger than experienced
constructions certain specific
parameters are typically monitored
during construction and structural
warranty period to evaluate and
validate the design assumptions.
Such solutions do not need to be
operational on 24/7 basis, nor does
the information need to be available
without delay. The structural
evaluation systems are typically
tailor made to the application based
on high performance but low COST
components and require a lot of
manual intervention and data
analyses.
Structural Health Monitoring
Systems
The purpose of structural health
monitoring systems is to supply
information on all relevant events
related to operation and condition
of the Bridge structure to the
Operator and assist him to take the
necessary corrective actions, either
through manual commands or
automatic responses, if allowed in
advance by the Operator.

Structural health monitoring system
Class
1 2 3 4
ENVIRONMENTAL EFFECTS*
Air temperature SL SL SL SL
Air and surface humidity L SL SL
Precipitation SL SL
Pavement water veil SL SL
Ice formation SL SL
Athmospheric pressure
SL
Solar radiation
SL
LOAD EFFECTS*
Wind Tower top & girder level L L SL SL
Traffic Load and traffic count SL SL SL
Structural temperature Girder, tower and cables L SL
Seismic/tectonic activity Seismic activity and tsunami SL SL
Correlation at midspan
L
STRUCTURAL RESPONCE
Corrosion Concrete reinforcement splash zone SL SL SL SL
Joint relative displacement SL SL SL SL
Special element responce L SL SL
Stress/Strain Fatigue orthotropic deck L L SL
cable anchorage L L
Dynamic motion Global bridge behaviour L L
Cables L L
Concrete creep In situ concrete SL SL
Stress/Strain Global bridge sectional forces L
Global structural positioning
L
GEOTECHNICAL RESPONCE
Ground settlement and inclination SL SL SL
Ground pressure L L
Interstitial pressure L L
Special element responce SL SL
* eventually supplied by external weather station / traffic control center / Seismic-tectonic measurement station
class
1 Important for all bridges
2 Necessary for minimum maintenance planning
3 Necessary for an optimal health monitoring and traffic control
4 Nice to know, may be monitored if problem arises
Bridge size
S: Short span
L: Long span
Making it easier for a single
expert to advice on several bridges
simultaneously.
• User interfaces can vary depending
on need. The same data can be
visualized on a monitoring
computer or on the mobile phone
of the bridge manager.
• Data analyses is separated from
its consumption thus enabling
usage of optimised platforms for
each need.
7
The monitoring and control activity
is necessary in order to:
• to check the physical-environment,
structural and traffic
conditions of the Bridge
• to identify, verify and notify
anomalous events and situations,
such as trespassing of attention
and/or criticality thresholds in the
monitored area
• to constitute the infrastructure’s
history, through data collection
and elaboration
• to constitute the data base
necessary for the infrastructure’s
management and maintenance
• to visualize the status of the
systems on displays in the Control
Room
• to assist the Operator in his
management of the Bridge and the
traffic on the Bridge
The creation of a historical file of
collected data will support the
development of maintenance and
management strategies, as well as
the planning of short, medium and
long term interventions.
Each monitoring device (equipment,
system) will be located,
addressable and able to transmit/
receive data to/from a centralized
database server.
Monitoring Parameters
Depending on the chosen monitoring
strategy, the bridge type and the
environment it is placed in the
parameters to be monitored must be
optimised.
The shown table summarises the
potential parameters to include.
Deferens’s for short and long span
bridges are shown together with the
importance of the monitoring
parameters.
User Interface
The trend in all monitoring applications
is towards use of universal and
standards based web interface. The
clear advantages of this approach
are:
• Number of simultaneous users/
viewers is limited by server and
bandwidth capacity only.
• Bridge personnel can easily relay
questions to an off-site expert.
The UI (User Interface) has to be
extremely simple as the users are
often not as skilled or motivated as
people were during construction.
Even very small user interface
problems when repeated day after
day year after year get to be
intolerable. The interface must offer
only the absolutely necessary
numbers and try hard not to
overwhelm the user with unnecessary
data. Another role of the
monitoring system and its UI is
when something unexpected and
sudden happens. In this situation
the user interface must give only the
most critical information, it must
not limit the users options, but it
must do all it can to minimize the
total load on the user. The UI will
send automatic alerts to pre-defined
persons, both with SMS or other
means, and free the person on the
spot to do the deciding what to do.

8
Bridge Rating, Maintenance
Management and Feedback
An important part of the inspection
and monitoring programme is the
execution of special inspections and
technical investigations when
necessary. These inspections and
investigations are initiated due to
e.g. unexpected SMS measurements,
extended damages or indication of
beginning failure of the components.
Most of the data evaluation and
modelling is expected done on the
basis of special inspections.
Maintenance inspection by COWI at the main cable of Small Belt Suspension
Bridge in Denmark, in order to update Bridge Maintenance System database.
Bridge owner
External Consultant
Owner
Server
SdM
Bridge
External Bridge
Inspector
1
Ordinary use of BMS and
downloading of selected bridges for
on site activities
5
Transfer of updated inventory data
and inspection data from the Pocket
PC to the inspectors PC
2
Extraction of basic data for on site
activities:
• Inventory data
• Inspection data
• Condition data
6
7
Quality assurance of the transfered
data
Uploading of the updated and
quality assured data
2a
Transfer of the basic data for on site
activities along with a setupprogramme
for the Pocket PC from
owner to the external consultant
3
4
Transfer of basic data for on site
activities from the inspectors PC to
the Pocket PC
On site activities:
• Inventory data Update
• Principal Inspection
• Special Inspection
5a
5b
Quality assurance of the transfered
data by the external consultant
Transfer of the updated and quality
assured data from the external
consultant to owner

9
Event control system
The system will consider as an Event
every signalling of anomaly, breakdown,
accident, unforeseen event,
intrusion, sabotage that generate an
alarm, as well as all planned
activities that influence the Work’s
safety, traffic or durability.
The management of particularly
serious events, such as earthquakes,
calamities, human actions, etc., will
provide the information concerning
the evaluation of consequences and
the planning of intervention,
evacuation, coordination, etc.
In the following some examples on
event control is shown
High Wind Events
Whenever the aerodynamic pressure
on a vehicle is calculated to be
above the acceptable limits for
different classes of vehicles an alarm
will be flashed to the operator on
the SCADA room wall screen and
the Traffic Monitoring Systems
manager’s screen.
Information concerning the actual
aerodynamic pressure can be
computed based upon real time data
collected by the SMS. The aerodynamic
pressure will be calculated
for:
• Aerodynamic pressure on vehicles
and wagons on bridge (for
standard classes of vehicles)
• Aerodynamic pressure on the
bridge deck
• Aerodynamic pressure on the
bridge structure
Weather Alarm
Operational Status Monitor: Meterological Monitoring
North Road Girder
Wind anemometer
Rain gauge
Water veil
Rail Girder
Air temperature
Surface humidity
South Road Girder
Wind anemometer
Rain gauge
Water veil
Event Management Initiates Automatically
Alarm wind speed > limit
North Road Girder
Wind anemometer
South Road Girder
Wind anemometer
Traffic information Alarm personel Weather forecast
Simulation and prediction monitor: Weather simulation
Windspeed
25 m / s
20 m/
s
15 m/
s
10 m/
s
Measurement
Prediction
Events:
Close bridge
Reduced speed
Close for light vehicles
Warning
Event 1 Event 2 Time
Update: - Bridge servicibility level update based on predictions
- Information to relevant autorities and regional traffic information
- SMS service to frequent bridge users
Weater Status Monitor: Wind Speed Distribution
5,0
Hourly Mean Transverse Wind Speed [m/s]
Minute Gust Transverse Wind Speed [m/s]
6,8
5,1
6,7
8,3
9,5
Wind
6,9
8,3
9,2
11,4
Weather Status Monitor: Wind Rose
5,2
7,2
5,7
7,7
6,2
8,3
5,8
7,9
No event
Warning
Alarm
Structural Weather Correlation Monitor:
Wind Induced Sectional Forces
5,2
7,1
9,1
6,8
5,0
5,0
7,9
8,2
6,8
7,0
9,4
11,1
Hourly Wind Speed and Direction at Midspan (Period 1. Aug. 2011 - 21. Feb. 2012, 10:00)
350 0 10
340
20
Wind Evolution During
330
30
Last 7 Hours:
320
40
9:00 to 10:00
310
50
8:00 to 9:00
7:00 to 8:00
300
6
60
6:00 to 7:00
5:00 to 6:00
4:00 to 5:00
290
4
70
3:00 to 4:00
280
2
80
270
260
250
240 8m/s
120
110
90
100
Girder Transverse Bending Moment
Girder Midspan Sectional Forces at Extreem Windeyent
SILS Design Capacity
ULS Design Capacity
SLS2 Design Capacity
SLS1 Design Capacity
SLS1 Wind Speed
SLS2 Wind Speed
ULS Wind Speed
SILS Wind Speed
Aerodynamic
Stability Limit
40 44 47 54 60 75
Hourly Mean Transverse Wind Speed at Midspan
Event on Feb. 3, 2012
(wind speed > 44 m/s)
20:00 - 21:00
19:00 - 20:00
18:00 - 19:00
17:00 - 18:00
16:00 - 17:00
15:00 - 16:00
14:00 - 15:00
230
10m/s
130
220
12m/s 140
210
150
200 160 Bridge Orientation
190 180 170

10
Structural Event
In case a pre-set threshold values of
the SHMS is exceeded the system
will generate an event warning or
alarm based on the severity. The
event will be passed on to the event
manager and be classified as a
structural event. From here the
event will automatically be passed
on to the bridge rating module.
Here the event will be given a rating
based on preset weighing functions
taking the importance of the
structural component and the
distance to other similar components
into account.
The result of the rating is stored
in the Bridge Inventory. The
operator will have a graphical front
end to the inventory. Here he can at
all times se the current state of all
structural components and their
actual rating. The graphical front
end can be used to take immediate
decisions concerning the operation
of the bridge if a alarming condition
is shown or by the works maintenance
planning manager for the
optimisation of maintenance works
and coordination of different
maintenance works to be carried
out at the same locations at the
same time on the bridge.
Structural Warning and Bridge Rating Alarm
Operational Status Monitor: Structural Monitoring
North Road Girder
Girder acceleration
Road temperature
Steel temperature
Internal air temperature
Internal air humidity
Internal surface humidity
Strain gauge
GPS
Dynamic inclinometer
Rail Girder
Girder acceleration
Steel temperature
Internal air temperature
Internal air humidity
Internal surface humidity
Strain gauge
Warning Sectional force > design limit
South Road Girder
Girder acceleration
Road temperature
Steel temperature
Internal air temperature
Internal air humidity
Internal surface humidity
Strain gauge
GPS
Dynamic inclinometer
Cross Beam
Steel temperature
Internal air temperature
Internal air humidity
Internal surface humidity
Strain gauge
Bridge Rating Monitor: Structural Health Overview
Work maintenance
planning system
- Change of maintenance plan
- New inspection tasks
No event
Warning
Alarm
Automatical update of Bridge Rating
Alarm: Bridge Element Rating > Limit for Maintenance Action
Automatical Alarm Message
Maintenance Management
Work
order
Structural
simulation
- Caculation effect of warning
- New monitored tests
Inspection and Monitoring Program
Inspection and Monitoring Planning
Superficial
Inspection
SMS
Principal
Inspection
Special
Inspection and
Technical
Investigation
Maintenance
Inspection
Conversion of
WASHMS data
to be used in
Rating
Modelling, e.g.
establishment of
thresholds
Rating of Components
based on Models
Corrective Maintenance of Components
Preventive Maintenance of Components
Procedures Instructions Procedures Instructions

11
Evaluation of structural
response
The evaluation of structural
response will be based upon real
time structural events collected by
the SHMS. Structural events will be
passed on from the event manager
to the Bridge Rating Module
The rating system will provide
rational basis for prioritisation of
inspections and maintenance on
primary and secondary structural
components. The categories,
primary and secondary components,
will be related to a load capacity
analysis model. Secondary components
may be out of function
without collapse of the entire
structure.
The rating system will be based
on the results from the principal
inspection and the structural
monitoring system (SHMS). By
using these two in combination the
additional inspections and maintenance
work can be initiated in a
proactive manner.
Fatigue Damage n N
(millionth of life)
Maximum Stress Range max (MPa)
40
30
20
10
Strain
gauge no.
Fatigue Monitor
Structural Status Monitor: Stress Cycle Counting
Maximum stress cycle range at trough/deckplate weld: Stress cycle histogram for strain gauge No. 3:
60
Constant amplitude fatigue limit
Constant amplitude fatigue limit
50
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Strain gauge no.
Last predicted fatigue damage at worst
instrumented point (strain gauge no 4):
n
100 years: 0,32
N
n
200 years: N 0,84
3
2010 2011 2012
4
Last Prediction
Slow Lane
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Maximum stress range identified strain gauge no. 3
Cut -off limit
Simulation and Prediction Monitor:
Cumulative Fatigue Damage
Today
Next Prediction
Measured
Predicted
Stress Range (MPa)
Automatical alarm message if:
∆σmax > constant amplitude fatigue
limit
Maintenance Management
Automatical alarm message if:
n
Miner sum increase ∆Σ N > 0.005
past
year
Cut -off limit
Number of cycles
Work
order
Work maintenance
planning system
- Change of maintenance plan
- New inspection tasks
Structural
simulation
- Calculation of alarm effect
- New monitored tests
Fatigue monitoring of outriggers at the
Øresund Bridge. Strain gauges located at
selected outriggers are monitored by an
on-line monitoring system calculating the
Miners sum in real-time. Results are
compared with a ABACUS model of
details for analyses of strain distribution.
Photo: Pierre Mens

Offices abroad
Selected Major Bridge Project
Headquarters:
Latvia
COWI Latvia
Tel.: +371 7 369 804
COWI is a leading northern
European consulting group. We
provide state-of-the-art services
within the fields of engineering,
environmental science and
economics with due considera-
COWI A/S
Parallelvej 2
DK-2800 Kongens Lyngby
Denmark
Tel.: +45 45 97 22 11
Fax: +45 45 97 22 12
E-mail: cowi@cowi.com
Internet: www.cowi.com
Lithuania
UAB COWI Baltic
E-mail: info@cowi.lt
Internet: www.cowi.lt
Norway
COWI AS
E-mail: kontakt@cowi.no
Internet: www.cowi.no
tion for the environment and
society. COWI is a leader within
its fields because COWI’s 3300
employees are leaders within
Contact:
Jacob Egede Andersen
Senior Specialist
Major Bridges
jca@cowi.com
Spain
Covitecma, S.A.
Ingenieros Consultores
E-mail: tb@covitecma.es
Internet: www.covitecma.es
theirs.
Erik Yding Andersen
Chief Project Manager
Bridges, Marine & Foundation
Engineering Division
eya@cowi.com
America
Middle East
Bahrain
COWI-ALMOAYED GULF W.L.L.
Consulting Engineers and Planners
E-mail: caghq@batelco.com.bh
Internet: www.cowi-almoayed.com.bh
USA
Ben C. Gerwick, Inc.
Consulting Engineers
E-mail: info@gerwick.com
Internet: www.gerwick.com
Canada
Buckland & Taylor Ltd.,
E-mail: mail@b-t.com
Internet: www.b-t.com
Dubai, U.A.E.
COWI-ALMOAYED GULF W.L.L.
E-mail: cowidbx3@emirates.net.ae
Internet: www.cowi-almoayed.com.bh
Oman
COWI & Partners LLC
Consulting Engineers and Planners
E-mail: cowioman@omantel.net.om
Internet: www.cowi-almoayed.com.bh
www.cowi.com
Cup anemometer.
Europe
Belarus
Kampsax Representative,
BELANDOR Engineering Consultants
Tel.: +370 5 210 76 10
Belgium
COWI Belgium SPRL
E-mail: cowi@cowi-belgium.be
Germany
ETC Transport Consultants GmbH
E-mail: info@etc-consult.de
Internet: www.etc-consult.de
Hungary
COWI Hungary Ltd
E-mail: zsl@cowi.hu
Internet: www.cowi.hu
Qatar
COWI Qatar
E-mail: cowi@qatar.net.qa
Far East
China
jpz@cowi.com
Internet: www.cowi.cn
Hong Kong
E-mail: lhe@cowi.com
India
Kampsax India Private Limited
Tel.: +91 12 434 82 59
Korea
COWI Korea Co., Ltd.
Tel.: +82 31 712 0500
021-1700-022e-06a