Outside Right-of-Way Tree Risk Along Electrical Transmission Lines
May 12, 2015
This paper reports on the quantification of tree exposure outside National Grid’s transmission corridors and examines the variables impacting the risk of a line contact by trees.
For power transmission systems compliant with safety codes and reliability standards, there remains a risk of tree-caused interruptions from the in-fall of trees from outside the right-of-way. This paper reports on the quantification of tree exposure outside National Grid’s transmission corridors and examines the variables impacting the risk of a line contact by trees. Correlations between the variables and National Grid’s tree-caused interruption experience were tested. Regression analysis was applied to a calculated risk factor and the annual interruption frequency. Two mitigation approaches are compared for cost and efficacy in improving line security. One is based on a regulator suggested use of minimum right-of-way width, while the other is site specific, based on specific site risk versus the voltage class mean risk.
