Utility Pruning of Trees
United Illuminating and Eversource Line Clearance Standards for Pruning and Removal of Trees: (to be updated)
United Illuminating's Line Clearance Standards, as revised in 2008, and used until its 11/01/13 Vegetation Management Plan, when it adopted Enhanced Tree Pruning (ETT) called for use of directional pruning and call for individual evaluation of each tree and consideration of its "growth rate, species, shape, condition and location of the tree." Eversource has long used ETT.
Alternatives to ETT:
Directional Pruning for Line Clearance in Pennsylvania. This appears to be the approach favored by the Arbor Day Foundation's TreeLine USA, since it promotes both dependable utility service and a healthy urban forest along the roadside. There are numerous TreeLine USA utilities throughout the United States that meet the requirements of the TreeLine USA program.
Directional pruning appears to use branch reduction, an alternative to ETT that does not require removal of healthy tall trees. See "Assessing the Potential of Reduction Pruning in Mitigating the Risk of Branch Failure," by Biocompliance Consulting, October, 2012. Also, see Testimony of Goodfellow and Townsley to PURA, April, 2012, questioning ETT and discussing branch reduction.