Electric Utility Rights-of-way Danger TreeHazard TreeTree Pruning and Removal Risk Rating Matrix (utilizing results of table 1)LikelihoodofFailure andImpactConsequences of FailureNegligibleMinorSignificantSevereVery LowLowLow- Table 2 -ĪNSI Standard A300 Integrated VegetationManagement - Part 7a. Likelihood of Failure and Impacting a TargetLikelihoodofFailureImminentLikelihood of Impacting TargetVery LowUnlikelyLowMediumHighSomewhatLikelyLikelyVery obableUnlikelyUnlikelyUnlikelyUnlikely- Table 1. climbers, rigging)Wind Force (dynamic)Directionįorces affecting trees ShearTensionFMDTorsionCompression Loads on Trees:Gravity Self weight Rain, snow, ice Other (e.g. Types of Failures: Entire tree failure (uprooting) Trunk failure Branch failure What about Tree Structure?Defects Architecture Loadsįailure occurs when load exceeds strength Tree Structure Assessment Tree StructureTree RiskResidual RiskĪNSI Standard A300 Tree RiskAssessment - Best Management Practices Key Points What is ANSI A300 (Part 9)?How does it relate to IVM?How does it apply to utilities?ĪNSI Standard A300 Tree RiskAssessment - Part 9a. Reality BitesPuget Sound Energy, 1998 – 2007 34,000 tree-caused outages Trees were primary cause of unplannedservice interruptions 95% due to tree failureFrom Arboriculture & Urban Forestry July 2011. Texas Chapter ISA Annual ConferenceSeptember 28 2012ANSI A300 Part 9:in a utility world Michael SultanDavey Resource Group

Ansi standard a300