©2023 International Society of Arboriculture Arboriculture & Urban Forestry 49(3): May 2023 145 the use of additional vegetation management resources across a utility’s grid can be costly and result in exces- sive pruning, exacerbating poor tree health along a utility’s ROWs (Kuntz et al. 2001, 2002; Radmer et al. 2002; Guikema et al. 2006; Miller et al. 2015; Good- fellow 2020). Furthermore, foot patrol for visual inspection of electrical distribution corridors often relies upon an individual forester’s subjective interpretation of vegetation conditions and as such may not be accu- rate or comparable between different individual utility foresters or arborists (Ferguson et al. 2012; Koeser and Smiley 2017). From 2001 forward, the American Society of Civil Engineers (ASCE) has released an Infrastructure Report Card every 4 years which details the current infrastructure conditions and needs within the US. For the 2017 report, the USA received a score of “D+” under the “Energy” category due to aging infra- structure and a lack of resilience in the face of severe weather events. A list of recommendations provided by the ASCE included, “Promote usage of remote sens- ing and inspection technologies to lower the cost of energy system monitoring; focus operation and main- tenance spending on highest-risk system compo- nents” (ASCE 2017). Targeted prescriptive management of individual trees and problematic areas may be prioritized due to t.e r..id .nd .ccur.te identi.c.tion o. .e.et.tion threats (Miller et al. 2015). Most electric utility com- panies already use some form of geographic informa- tion system (GIS) to map their electrical transmission and distribution systems. In the past decade, some utilities have augmented their GIS through the inte- gration of airborne LIDAR data as a tool to verify compliance of the United States’ transmission system with federal regulations. These LIDAR systems have generally been mounted on small aircraft, such as helicopters and airplanes, and have relatively high costs of operation (Chen et al. 2018). Yet the advent of affordable unmanned aerial systems (UAS), collo- quially called drones (Figure 1), and the falling costs of LIDAR technology have facilitated the potential regulation, mapping, and modelling of the electrical distribution system, which could very well be the next step in developing a more reliable grid. While these technologies may allow for more pre- cise .nd cost.e..cient ... ...ro.c.es. .t t.e moment t.ere is . rese.rc. ... s.eci.c to t.e ...li- cation of UAS-based LIDAR for distribution-level Institute (EPRI) study estimated that US business sectors lost between $104 to $164 billion in 2001 due to power outages in either the transmission or distri- bution grid (Lineweber and McNulty 2001). Other challenges of managing the ROWs around utility infrastructure include: the sheer scope of the current electrical grid in the United States, issues of comparability stemming from non-standardized report- ing methods across states and utilities, state versus federal regulations based on voltage, and state to state variability in state-level regulations. To demonstrate, the North American Electric Transmission System consists o. .ll electric.l lines c.rr.in. 3. .. .nd higher, stretches approximately 476,398 linear miles (766,688 km), and requires the management of an estimated 8.6 million to 11 million acres (3.5 million to 4.5 million ha)(Miller et al. 2015; Warwick et al. 2016), while the associated electrical distribution sys- tem is comprised of approximately 6,332,236 linear miles (10,190,746 km) of lines carrying less than 3. .. (..r.ic. et .l. .0..). ..us. i. t.e distri.ution is patrolled on a 5-year cycle, each year would require over 1 million miles (1.6 million km) of line to be patrolled annually. ..e .o.l o. ... is to .ro.ide s..e .nd reli..le electrical power, and multiple specialized personnel play integral roles in the maintenance and monitoring of vegetation conditions. Utility foresters manage on a larger scale, usually associated with a service area, region, or across an entire utility. Meanwhile, utility arborists are tasked with monitoring vegetation con- ditions on the ROW, as well as monitoring and auditing line clearance contractors. Line clearance contractors .re t.e l.r.est se.ment o. t.e ... industr. .nd .ll numerous. ..ried roles. includin. .u.li.ed line cle.r.nce arborists, heavy machine operators, and groundmen. Standardized tree risk assessment protocols are .ene.ci.l to ... in t..t t.e. .ro.ide t.e most con- sistent qualitative assessment of a tree’s likelihood of failure, likelihood of impact, and overall risk (Smiley et al. 2017; Goodfellow 2020). Yet, due to constraints such as accessibility and time, utility foresters and arborists do not often inspect off-ROW vegetation, leaving many off-ROW trees unmonitored or with limited monitoring (Goodfellow 2020). While short- ening pruning cycles, and therefore decreasing the time frame of the risk assessment, has been found to both decrease the number of interruptions and decrease the time and cost to prune individual trees,
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