john keys risk management on tunnelling projects warwick university msc course london bridge...
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John Keys
Risk Management on Tunnelling Projects
Warwick University MSc course
London Bridge Associates
Introduction to Risk Management
Identification of tunnelling risks Risk analysis and risk assessment tools
Introduction to the Risk Workshop
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What is risk management? - Definitions
Hazard is something with the potential to cause harm or change the desired outcome
Risk is the likelihood of a hazard occurring x consequence of a hazard
Risk Analysis is the process of identifying risk factors and the quantification of those factors (estimating likelihood and magnitude of impacts)
Risk assessment is the tool whereby risks are evaluated in terms of their likelihood and consequence and mitigation measures identified
Risk Mitigation is the process of developing a plan to respond or deal with risk on a project
Risk Register is a method for recording the project risks for subsequent management
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Risk Assessment process
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Likelihood
Co
nse
qu
ence
Initial Risk
Residual Risk
Hierarchy of Risk reduction
Eliminate at Source
Control
Monitor
Unacceptable Risks
Negligible Risks
AL
AR
P
Zo
ne
Tolerable only if risk reduction is impracticable or if the cost is grossly disproportionate to the improvement gained
Tolerable if cost of reduction would exceed the improvement gained
Risk cannot be justified except in extraordinary circumstances
What risk assessment tools are available?
Risk assessments can be undertaken using either
Qualitative judgements (high / medium / low risks )
or
Quantitative values (numerically as derived from case histories / databases)
Consider practicality of assessments
Availability of reliable data Diversity of each tunnel’s characteristics
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What risk assessment tools are available?
Risk Analysis tools
Fault tree analysis
Event tree analysis
Decision tree analysis
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Why do we need Risk Management?
Why do we need Risk Management?
Identification of tunnelling risks?
The Joint Code states:
“Hazards shall be identified and evaluated on a project-specific basis and their consequent risks shall be identified and quantified by Risk Assessments through all stages of a project “
Project Development Stage (conceptual design) Detailed Design Stages Procurement Stage Construction Stage Operational stage for any stipulated maintenance period.
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Joint Code of Practice for TunnellingSection 8 – Design
Clause 8.3.1. states
“The fundamental objective of the design process is that of achieving a robust design, that is a design where the risk of failure or damage to the Tunnel Works or to a Third Party from all reasonably foreseeable causes, and including health and safety considerations, is extremely remote during the construction and the design life of the Tunnel Works. High consequence but low frequency events that could affect the works or a Third Party shall also be considered”
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Joint Code of Practice for TunnellingSection 8 – Design
Clause 8.3.4 states“The design process shall include, where appropriate, sensitivity studies to assess the impact of:a) construction tolerancesb) variation in geotechnical design valuesc) variation in materials characteristicsd) variation in workmanship and geometrye) methods of construction and the implementation of
mitigation/contingency measuresf) natural perils exposure in the region of the project
such as flood, storm, seismic or tidal effects
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Joint Code of Practice for TunnellingSection 8 – Design
Clause 8.5.1. states
“The Designer shall ensure that adequate construction expertise is available to undertake formal reviews of the design to assess and confirm the appropriateness of the design in terms of Constructability, including health and safety considerations in relation to BS6164”
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Risk Assessment and Control Measures
Work Activity / Brief description
Tunnel excavation
Risk Assessment No 1 Date: xx/xx/xxxx Sheet No of .
Name of Contractor XYZ Co Ltd Project: XXXXXXXXX
No Hazardous event
Persons at risk Including Nos
Evaluation Criteria
Risk Rating
Priority Rating
Control Measures
Persons at risk Including Nos
Evaluation Criteria
Risk Ratin
g
Residual Risk
Priority Rating
Likelihood
Severity 1 to 36 H / M / L Likelihood
Severity 1 to 36 H / M / L
1 Poor Ground conditions in the faulted zone lead to rock falls and /or a tunnel Collapse
10 4 6 24 H Design additional support measures for tunneling through the fault zone
10 2 6 12
M
2 Inundation of the tunnel when excavating through the fault
10 5 6 30 H Advance probe drill to dewater zone
10 2 6 12 M
3 Fire on diesel plant operating in the tunnel
10 3 6 18 H Install automatic fire suppression
10 1 6 6 L
4 Operative struck by moving plant when excavating
1 3 5 15 15 Provide remote control system
0 0 0 0 0
5 Trips and falls 10 3 1 4 4 Good House keeping
10 1 1 1 L
Likelihood - (1) Remote, (2) Unlikely, (3) Possible, (4) Likely, (5) Probable, (6) Highly Probable Severity - (1) Minor Injury (2) First Aid (3) Illness/Lost time, (4) Reportable, (5) Major Injury, (6) Fatality Risk Rating - Likelihood * Severity - Expressed as a number between 1 and 36 Priority Rating - This will either be Low (1 to 6 ), Medium (7 to 17) or High ( 18 to 36)
Questions?
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Risk Management Workshop
Dry Creek Road Tunnel Project
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Dry Creek Road Tunnel Project
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Dry Creek Road Tunnel Project
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Dry Creek Road Tunnel Project
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Background to the project• $400m road tunnel in Australia• Ring road around the town of Yarra Awali• Client designed scheme• Funded by state taxes• Environmental constraints
• Golf course• Residential areas
• West Portal in a flood plain
Dry Creek Road Tunnel Project
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Background to the project• Detailed design • 3km long 110m2 excavated face area• Boreholes / seismic surveys / Previous
borehole data• Tunnel alignment
• Minimise environmental impact• Steep gradients• Over burden• Utilities• High rise luxury hotel• Portals positioned to minimise impact• Conservation area and a flood plain• Old Quarry• Geology• Hydrology
Dry Creek Road Tunnel Project
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Background to the project
Historical Land use• Ground water extraction for irrigation• Small dwellings still extract water• Local brewery• Abandoned quarry on west side
Dry Creek Road Tunnel Project
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Background to the project
Contractual • NEC form of contract with all risks
transferred to the Contractor• Pain / Gain incentives• Design and Construct Contract • Novated design - NATM
methodology• Contractor to price risks• 1 month to bid the works
Dry Creek Road Tunnel Project
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Background to the project
• NATM construction method • Alternative designs• Cheapest tender submission $400m• Contractor lacked resources• JV Board decision on passing on risk
Dry Creek Road Tunnel Project• You are the construction company for the Dry Creek Road Tunnel project. • You have a meeting tomorrow with a group of Insurance Companies • The Insurer company have asked you to identify all the key risks and
convince them that you have the risks under control before they will provide cover to the project
Task 1• Your brief is to identify the top risks associated with the project and what
control measures you will be putting in place to manage those risks. • Rank the risks in order of priority starting with the highest risks first and an
explanation why you perceive these risks as priorities.
Task 2• Identify the actions and measures the Client and the Designer should have
put in place to ensure that the project had the greatest chance of success.
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