TREE RISK ASSESSMENT
Tree Risk Assessment What has ISA done and why?
Tree Risk Assessment What has ISA done and why? What is risk assessment and how does it fit within the context of risk management?
Tree Risk Assessment What has ISA done and why? What is risk assessment and how does it fit within the context of risk management? What are the various approaches to risk assessment?
Tree Risk Assessment What has ISA done and why? What is risk assessment and how does it fit within the context of risk management? What are the various approaches to risk assessment? Why did ISA introduce a new approach?
Best Management Practices
TRAQ Qualification
Risk Assessment Research Scientific journal, Risk Analysis Public Safety and Risk Assessment - David Ball and Laurence Ball-King Arboriculture & Urban Forestry
Risk Assessment Standards ISO 31010 Risk Management-Risk Assessment Techniques AS/NZS ISO 31000:2009 Risk management Principles and guidelines American National Standards Institute (ANSI) A300 part 9 Risk Assessment
Risk Assessment Research Common sense risk management of trees NTSG
Risk Assessment Consultation Dr. Seth Guikema, Johns Hopkins University Martin Norris, Australia >75 arboriculture industry BMP reviewers from 13 countries
Risk Management Principles It is impossible to maintain trees free of risk; some level of risk must be accepted to experience the benefits that trees provide.
Risk Management Principles
Risk Management Principles Trees provide a wide variety of benefits to society
Risk Management Principles Trees provide a wide variety of benefits to society Trees are living organisms and naturally lose branches or fall
Risk Management Principles Trees provide a wide variety of benefits to society Trees are living organisms and naturally lose branches or fall The risk to human safety is extremely low
Risk Management Principles Trees provide a wide variety of benefits to society Trees are living organisms and naturally lose branches or fall The risk to human safety is extremely low Tree owners have a legal duty of care
Risk Management Principles Trees provide a wide variety of benefits to society Trees are living organisms and naturally lose branches or fall The risk to human safety is extremely low Tree owners have a legal duty of care Tree owners should take a balanced and proportionate approach to tree safety mgmt.
Risk Management Principles Trees provide a wide variety of benefits to society Trees are living organisms and naturally lose branches or fall The risk to human safety is extremely low Tree owners have a legal duty of care Tree owners should take a balanced and proportionate approach to tree safety mgmt. The National Tree Safety Group (NTSG), United Kingdom
Risk Assessment Establishing the context Risk Assessment Risk identification Communication and consultation Risk Risk analysis Risk Risk evaluation Monitoring and review Risk treatment
Risk is not a measured attribute
Quantitative or Qualitative Quantitative assessment Estimates values based on Risk = Probability x Consequences Qualitative assessment Ratings of risk, typically based on likelihood and consequences
Other Approaches Semi-quantitative Pseudo-quantitative factor x + factor y + factor z = risk rating
Matrix Approach National and international standards Corporate governance Homeland security Airport safety Sarbanes-Oxley act Risk management software
Matrix Advantages Clear, systematic framework Convenient documentation of rationale Relatively simple inputs and outputs Requires no calculations Need not quantify consequences
Matrix Approach Commonly used when quantitative data are limited or unavailable Provides opportunities to train consultants and practitioners Facilitates decision-makers in establishing risk tolerances
Matrix Limitations High subjectivity in rating factors Low resolution Not necessarily comparable to risk assessed using other methods
Matrix Limitations In some cases, with poorly constructed matrices, and with negatively correlated probablilities and consequences, matrices can be worse than useless.
Tree Risk Matrix Likelihood of Failure & Impact" Consequences of Failure" Negligible" Minor" Significant" Severe" Very Likely" Low" Moderate" High" Extreme" Likely" Low" Moderate" High" High" Somewhat likely Low Low Moderate Moderate Unlikely" Low" Low" Low" Low"
Tree Risk Likelihood of failure LIKELIHOOD Likelihood of impact RISK CONSEQUENCES
Likelihood Likelihood of failure Defects Loads Response growth Likelihood of impacting a target Target occupancy rate Target protection factors Direction of fall
Likelihood Matrix Likelihood Likelihood of Impact" of Failure" Very Low" Low" Medium" High" Imminent" Unlikely" Somewhat Likely" Very Likely" likely" Probable" Unlikely" Unlikely" Somewhat Likely" likely" Possible" Unlikely" Unlikely" Unlikely" Somewhat" Likely" Improbable" Unlikely" Unlikely" Unlikely" Unlikely"
Likelihood Matrix Likelihood Likelihood of Impact" of Failure" Very Low" Low" Medium" High" Imminent" Unlikely" Somewhat Likely" Very Likely" likely" Probable" Unlikely" Unlikely" Somewhat Likely" likely" Possible" Unlikely" Unlikely" Unlikely" Somewhat" Likely" Improbable" Unlikely" Unlikely" Unlikely" Unlikely"
Likelihood Matrix Likelihood Likelihood of Impact" of Failure" Very Low" Low" Medium" Imminent" Unlikely" Somewhat Likely" likely" Probable" Unlikely" Unlikely" Somewhat likely" Possible" Unlikely" Unlikely" Unlikely" Improbable" Unlikely" Unlikely" Unlikely" High" Very Likely Likely Somewhat" Likely" Unlikely
Likelihood Matrix Likelihood Likelihood of Impact" of Failure" Very Low" Low" Medium" Imminent" Unlikely" Somewhat Likely" likely" Probable" Unlikely" Unlikely" Somewhat likely" Possible" Unlikely" Unlikely" Unlikely" Improbable" Unlikely" Unlikely" Unlikely" High" Very Likely Likely Somewhat" Likely" Unlikely
Consequences Value/importance of the target Amount of/effects of Injury Damage Disruption
Tree Risk Matrix Likelihood of Failure & Impact" Consequences of Failure" Negligible" Minor" Significant" Severe" Very Likely" Low" Moderate" High" Extreme" Likely" Low" Moderate" High" High" Somewhat likely Low Low Moderate Moderate Unlikely" Low" Low" Low" Low"
Tree Risk Matrix Likelihood of Failure & Impact" Consequences of Failure" Negligible" Minor" Significant Severe" Very Likely" Low" Moderate" High Extreme" Likely" Low" Moderate" High High" Somewhat likely Low Low Moderate Moderate Unlikely" Low" Low" Low Low"
Tree Risk Matrix Likelihood of Failure & Impact" Consequences of Failure" Negligible" Minor" Significant Severe" Very Likely" Low" Moderate" High Extreme" Likely" Low" Moderate" High High" Somewhat likely Low Low Moderate Moderate Unlikely" Low" Low" Low Low"
Levels of Assessment Level 1 Limited Visual Level 2 Basic Level 3 Advanced
Basic Tree Risk Assessment Form Tool for systematically recording data Mandatory for TRAQ course Not required for assessing tree risk
TRAQ Short course with lectures, activities, manual, and workbook, case studies 2.5 days Written exam + performance-based exam Good for five years
Reasons for TRAQ Systematic process" for assessing tree risk. " Confidence" in professional and ethical decisions." Standardized" process throughout the industry. "
TRAQ Objectives The qualified professional will: Comprehend the fundamentals of limitedvisual and basic tree risk assessment as defined in ISA s Best Management Practices: Tree Risk Assessment
TRAQ Objectives Understand the principles of advanced diagnostic techniques for assessing tree risk
TRAQ Objectives Gather and synthesize information to assess tree risk
TRAQ Objectives Make reasoned judgments and recommendations for mitigating identified risk
TRAQ Course Topics Overview of tree risk assessment Target assessment, site assessment Tree biomechanics Assessment levels and techniques Categorizing and evaluating risk Mitigation Reporting
TRAQ Course Materials Manual detailed information Workbook activities, case studies, class exercises
ISA Tree Risk Assessor Qualification Courses Check with UK/I Chapter for upcoming events or Check ISA online calendar
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