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Geotechnical & Structural
Automated Real Time
Monitoring and Alert
Systems
Institute of Engineers, Singapore 17th October 2007
Dr G H Tan, SysEng (S) Pte Ltd
Poh Y K, SysEng (S) Pte Ltd
Nick Osborne, Land Transport Authority
Albert Chua, Lee Hung Test Services Pte Ltd
William Tang, DKSH
Seminar Schedules
0900-1000 Real Time Monitoring &Alert
System Overview
1000-1030 Break
1100-1200 Data Loggers,Communication
,Power Supply, Protection,
Data Quality, Accuracy
1200-1330 Lunch
1300-1500 User perspective, Planning
&Operation
1530-1700 Proven Sensors
Straits Times March 24th 2007
`
• SysEng is a System
Engineering Company with
Multi-disciplinary Engineering
Capabilities
• Started in 1994 by Engineers
• To deliver the Right Data , at
the Right Time, at the Right
Place with the Right Price
and the Right Quality to
make the Right Decision
• Vertical Integration as a
One-Stop Shop Engineering
Solution Service to ease the
deployment and support of
complex technologies to
help in the growth of the
client’s business
An Automatic Real Time Monitoring & Alert System to help
Professional Engineers, Consultants and Authorities
monitor Geotechnical and Structural movements 24 x7
without any human effort.
The Benefits are :-
• Equipments & System are leased to clients without Fixed
Overheads, Engineering Team and Investments.
• Pays for Timely, Quality and Reliable data.
• No Hidden Repair and Support costs.
• One time setup fee and monthly monitoring fee to help your
cash flow.
• Leverage on SysEng Engineering Expertise in Sensors,
Electronics, Communication, Software, EMI Noise Prevention &
troubleshooting to support the clients.
• Technical Service Support with 24 Hours Alarm Monitoring
Excavation Works in SingaporeArea of Singapore 700 km2
Area of excavation 250 000 m2 (more than 50% excavation > 20m deep)
• Is it continuous monitoring ? Then what is
continuous then ?
• Is it Real Time Data logging only ? Data
Logging is ONLY one basic component for
Real Time Monitoring and Alert system
• If characteristics move in days, then
monitoring every hour is real time ?
• If characteristics move in hours, then
monitoring every minute is real time ?
Widely used CR10X
Data Loggers & and
Data Logger
Software used in
Singapore , but
these by
themselves are NOT
Real Time
Monitoring & Alert
system
For Continental
Drifts of 50
million years,
Real Time
Duration in this
context is
actually 1
million years
In a Car Crash
of 1/1000 of a
second event,
Real Time
Duration in this
context is
actually
1/100,000 of a
second
In 2003, BCA had to 3
runs on “Avoiding
Failures in Excavation
Works” seminars to
help the Construction
Industry so that
• Lives can be saved
• Assets can be
protected
• Reputation can be
maintained
How could it occur at your site if you use
real time monitoring ? It is better to use a
professional service to protect lives and
your reputation
Korean
Bridge
Collapse
• Seoul, South Korea
• 8AM October 21, 1994
• 1160m truss bridge
• 32 people killed, 20 injured
• Constructed in 1979
• Cause: structural fatigue
• Monitoring is now
mandatory in South Korea
REPAIR, REPLACE, UPGRADE, MAINTAIN
~600,000 bridges in the USA, investment ~$212:
US$20,000,000,000 on bridge repairs in 6 years
In Geotechnical and Structural Real Time
Monitoring & Alert System, these soil and
building movements tend to be man-made.
If there is no excavation works around that
area. Real Time Monitoring & Alert can be
considered to be every hour or even less
frequent. Usually this sufficient for Design
Verification where is enough time to react.
However, if there are continuous excavation
works adjacent with de-watering, jet grouting,
then Real Time Monitoring & Alert is then in
Minutes as there is a need to respond to the
unexpected change in the conditions
What is expected of a Real Time Monitoring & Alert System?
Doctor tells the Nurse:
“Please monitor the patient
and call me immediately if
there is any change in his
condition.”
Hospital = Construction Site
Patient = Excavation works
Doctor = Consultant
Nurse = Instrumentation Specialist
Call Immediately = Real Time Monitoring of 10min
Real Time Monitoring & Alert requires Real Time Responses
• This is achieved with
Real Time Sensor Measurement,
Real Time Data Logging,
Real Time Data Processing,
Real Time Analysis,
Real Time Alert to be sent to the Right Person
Important is the organization to react to this Alert
If any part of the information flow chain fails, then the entire system fails
It is NOT a solution as the site problem needs a specialist
diagnostic and hence specific solution to the
problem
Real Time Sensor Measurement
Real Time Data Logging
Real Time Data Processing
Real Time Analysis
Real Time Alert to be sent to the Right Person
Important is the organization to react to this Alert
There are many ways to configure
Data Loggers into a Real Time
Monitoring & Alert Systems with
various method of Communications or
Telemetry
Communications
Nicoll Highway Court of Inquiry has taught us a valuable lesson that
having data in the instrument and then getting information only after
24 hours is NOT Real time. The system can fail with 999 readings
and NOBODY is even aware of such systematic failures !
Three Points highlighted in by the
inquiry
1. The Real Time System used is an
in-correct Real Time System
2. If sensor is not working with “999”
readings and nobody is alert about this
error
3. Alerts are send via email only once a
day
This was the system Deployed for Real Time Monitoring &
Alert System is Actual Only Real Time Data Logging !
Upload 0000 hrs
Email Alert
only @
0000 hrs !
next day
Walers buckle More Walers buckle
Some Real Time Monitoring Systems are
defined from the moment when the data is
available at the server. These systems do
not take into account the delay in getting
the sensor data to the server
Sensor data
collected on sites
can have hours to
days delay before
they are send to
the server
Real Time Monitoring &
Alert System is the
time when the sensor
data is collected till
when it reaches the
end users
Real Time Monitoring
& Alert is
Analyzing the data
immediately into
information for the
user to take informed
decision
Real Time Monitoring & Alert
• Systematic data management is required to
avoid information overload and condense
huge information into information the human
user can handle
• Simplify the human interface for easy
interpretation and de-skilling of decision
operations
• Real Time Continuous Monitoring by
Computers need the same corresponding
Real Time Continuous Analysis by computers
also !
Real Time Monitoring System
gives SMS Alerts within 10
minutes,hence earlier reaction
time for crisis management
SMS Alert
System Design Steps for a
Remote Monitoring System
•Objective of Monitoring
•Approach to fulfill Objective
•Implementation of Approach
•Constraints of Approach
•Verifying Approach and
Constraints
Objective of Monitoring
•Who wants the results ?
•Is it to verify the Design ?
•Is it to check the
Construction Quality?
Approach to fulfill Objective
•What sensors to use ?
•Accuracy of sensors w.r.t.
System accuracy ?
•Environmental Protection ?
•Power & Communication
availability ?
•Data Storage on site ?
Implementation of Approach
•Cost effectiveness of signal
flow chain ?
•Accuracy of System ?
•Site condition ?
•Cost of Communication ?
•System&Component support ?
•On site support ?
Typical Dangerous Answer
to be careful :
•I want everything but forgot to
ask how much it will cost
•No Cost Limit (To his
customer or to you ?)
•I want the best only but forgot
to mention price constraints
The infamous
Dr Frankeinstein use
the Best of Everything
to create a Monster who is
made from parts from
different suppliers. A system
has to consider the working
strength and weakness of
all parts
Design Parameters for
Remote Monitoring System
•Sensors selection and location
•Transmitting results from sensor to
central data logger
•Amount of data measurement and
data transmission
•Noisy
•Signal degradation from sensor
to signal conditioner
Sensor
Signal
Conditioner
Data
Logger
High Electro Magnetic
Interference or Unwanted signal
sources from Motors, Arc
welding Equipment, Heaters,
Inverters, etc
Digital Signal
with 1.1 valueAnalogue
Signals
Use of a Fast Fourier
Transform (FFT)
Spectrum Analyzer to
check the Signal to
Noise Ratio to verify
Quality of Signal
presented to the ADC
Readout gives 1.1value
= 1.05(Sensor) + 0.05(Noise)?
= 0.9 (Sensor) + 0.2 (Noise) ?
= 0.5 (Sensor) + 0.6 (Noise) ?
When the actual signals coming into the
input, checking the signal inputs to the
data logger is important as the signal
has high noise, but the data logger has
a simple RC network, the signal still
goes through and the waveform
measured is no longer the true level but
a signal which is reconstructed due to
aliasing
This is a well
known
measurement
Error !
The Data will show No Change in readings !
Actual Movements
If measuring a cyclic change, it is better to measure faster and then
reduce the rate after the characteristics are known, a faster change is
when measured at slower rate give WRONG information !
70dB Sensor 60 dB 90 dB Signal 50 dB 16 Bit ADC
Wiring Conditioner Wiring Data Logger
In the whole signal flow from sensor to the Data
Logger, the weakest part is only 50 dB !
Signal to Noise Ratio in the Data Flow Chain
Instrument readings in chart form
Average Axial Force in Level 3 Strut 21-A
-200
0
200
400
600
800
1000
1200
1400
1600
09-Jan
10-Jan
11-Jan
12-Jan
13-Jan
14-Jan
15-Jan
16-Jan
17-Jan
18-Jan
19-Jan
20-Jan
21-Jan
22-Jan
23-Jan
24-Jan
25-Jan
26-Jan
27-Jan
28-Jan
29-Jan
Date
Force (
kN
)
S21-3-A Trigger S21-3-B
Case History for Temporary Struts Automated Monitoring
In the International Workshop of
ITU, this paper showcased the
Advance Wire-less application
deployments in Singapore.
SysEng M2M Real Time
Monitoring System was
described in this prestigious
workshop
SysEng M2M application in
Construction site Temporary
Strut Force Real Time
Monitoring & Alert System
Mar 2004 - “Real Time Monitoring Systems in Tunnel & Deep Excavation Projects” at
Geotechnical Conference, Malaysia
Aug 2004 - “Real Time Monitoring and Alert Systems for Civil Engineering applications
using Machine-to-Machine Technologies” at International Conference on Structural
and Foundation Failures, Singapore
Jan 2005 - “Evolution of Remote Structural Health Monitoring Systems with M2M
Technologies” at Society of Experimental Mechanics, IMAC XXII Florida, USA.
Oct 2005 - “Ubiquitous Real Time Monitoring and Alert applied to Excavation Works” at
4th International Symposium on New Technologies for Urban Safety of Mega
Cities in Asia, Nanyang Technological University, Singapore
Nov 2005 - “Real Time Monitoring and Alert in Excavation Works using Machine to
Machine (M2M) Technologies” at 2nd International Conference on Structural
Health Monitoring of Intelligent Infrastructure, Shenzhen, China
Mar 2006 - Improving Instrument Data Quality from Excavation sites to the Right
person to make the Right Decision at the Right Time, International Conference and
Exhibition on Tunneling and Trench less Technology, Malaysia
Apr 2006 - Conference Paper Automatic Real Time Monitoring using M2M Technology”
in Seminar on Instrumentation Monitoring for Underground and Tunneling
Construction Safety in Chengdu Railway Co. Ltd and Southwest Research Institute
of China Railway Engineering, Chengdu China
Real Time & Alert System presented in
numerous Civil Engineering Conferences
The eMonitoring Real Time Monitoring & Alert System has
many Smart Technologies to detect various fault conditions to
ensure that the entire system has Higher Service Uptime.
The Smart Technologies detect when:-
•Individual sensor cable faults of open or short circuits
•Data Logger Backup Battery Health status
•Data Logger cannot send sensor data to the Central
Monitoring System (CMS) for processing as well as its sub-
systems
•Wire-less GPRS and Internet Data Communication not
available
It automatically monitors the entire system every 60 seconds
and alerts SysEng support staff to correct the situation in a
proactive way. This makes it more reliable than human-
supervised monitoring system.
The System automatically sends SMS Alerts when sensor cables are cut,
VWSG Cables cut
SMS Alert
automatically
pushed to all
users
The System automatically sends them SMS Alerts when :-
On-site RTU/Data Logger
has not send Sensor
data to the on-line
Central Server System
On-site RTU/Data Logger
Backup Battery Voltage
falls below 11.0V
SMS Alert
VWSG Sensor reading
has exceeded its Alarm
Limit
Case History of Real-time Monitoring
and Alert System Deployed in C821
• 92 VW Strain gages and 5 VW load cells (with 4 VW sensors per load cell) are monitored every 10 minutes.
• Monitoring frequency every 10 minutes with 112 x 6 x 24
(= 16,128) Readings per day !
• The results were sent to secured web-site every 10 minutes.
• SMS alert to contractor and consultants when measured strut force exceeding 70% of design value
In Business Times
23th March 2003,
SysEng was
featured at the
center page by
IDA as a State of
the Art Wire-less
Technology
System Developer
for Automatic
Tunnel Monitoring
System. This is the
innovative method
of deploying Wire-
less and
Inforcomm
Technologies for
Tunnel Monitoring
• LTA code of practice allows less than 15mm
movements along the segments
• Tunnel distortion allowable is 1/2000
• Continuously monitors the prisms every 8
hours per day for 7 days a week
• Reliable System up time with financial penalty
imposed for delay or loss of data
• Real time measurement and immediate data
transmission of results
• Immediate alerts if the movement exceeds
70% of allowable movement
Typical Set-up of Automated Tunnel
Monitoring System
Glass prism as reflectors
Range 20 to 100m
Accuracy +/- 1.0mm + 1ppm
Semi-automated system with manual data retrieval and manual alert system
Fully automated system with automatic data retrieval and SMS alert system
Automatic Information push
Manual Information pull
Tunnel Monitoring Timing Chart of sensor readings till end user
SMS alert
Time for one Measurement cycle
50 mins
50 prisms Tx Data
2 mins
Analyze
1 min
SMS Alert
2 mins
A Total of 55 mins per Measurement cycle with the
longest time taken by Prism measurements
At 3 Measurement cycles per day
00:00 08:00 16:00
GSM
• With 1 prism , X,Y,Z movements (3 points) are measured
• In one segment, there are 4 prisms.
Hence 12 data points per segment
• With 500 rings, there are 6,000
points per measurement cycle
• One day there is 3 measurement
cycles
• Hence one day the user is overload
with 18,000 data points to analyze !
With Real time system and more
data collected, end user gets
information overload !
Design Requirements
·Continuous monitoring of Displacement
and Strain gages to monitor the load
·Duplicate Strain gage sets
·Continuous data transmission to the
central data logger
·Smart Event driven data storage rather
than continuous logging
·Different threshold for alarming using
GSM/SMS and Paging
Configuration
Level 33
RS485
Network
Level 53
RS485
Network
Level 65
RS485
Network
2.4 GHz
Highway
Central Data
Logging Station
SMS Alert
System
• 18 Strain Gages and 1 temperature sensors are mounted onto the bridge
• The data is logged every 10 minutes and send back to a website for
computation for sensor calibration into
• Real time is used so that the effect of strain changes during the post
tensioning can be tracked continuously
Real Time System for Highway Bridge
Widening Post Tensioning at KJE
Pasir Panjang Semi-Expressway
Balanced pre-cast cantilever construction
5 spans instrumented with VWGs
Instrumentation for Monitoring (1997)
Three segments of one span instrumented with a total of:
• 12 strain gauges
• 12 stress cells
• 40 temperature sensors
7 equal bays
@ 4000 each
232731
13 245678910111232 131416 151718192021222325 24262728293031333536373839404143 4244 34
MALAYSIA
SINGAPORE
3 equal bays
@ 3200 each148007 equal bays
@ 4000 each
3 equal span
@ 3200 each148007 equal span
@ 4000 each
3 equal bays
@ 3200 each
2000
closure segment
40m 92m
6 equal bays
@ 4000 each
3 equal bays
@ 3200 each
48m
Location of instruments
in span segments: top 23/31, below: 27
SG3 SG1
SG2 SG4
SG3,PC3SG1,PC1
SG2,PC2
T11T12T13T14T15T16T17T18T19T20
T1T2T3T4T5T6T7T8T9T10
SG4,PC4
VWT1 VWT2
VWT-Temperature sensor.
T-Thermocouple
SG-Strain gauge
PC-Pressure cell
Segment 31 Sensors
Example of response data:
segment 31 strain, stress, temperature
600
650
700
sg 3
0
2
4
pc 3
d s
760 780 800 820 840 860 88025
30
35
time/days since 29-Apr-0097
T 3
° C
Monitoring
Base
Station
Flood
Gate
4 x Water Level Sensor
Video Camera
Voltage & Lightning
Surge protection,
Stabilizer from
Power Generator inlet
Monitoring Overview