a. The tree inventory will focus on street trees and stumps on maintained rights-of-way, vacant planting sites in the sidewalk “tree pits”. There are approximately 21,482 street trees identified in the Durham Street Tree Inventory Tree Viewer. This captures approximately 75% of existing street trees located within the City’s rights-of-way. b. Perform a GIS-based tree Inventory using pre-programmed computers or ground-level LiDAR collection platforms that collect tree data and various site attributes. c. Methods for mapping tree locations include a three-tier system: (a) GPS technology, (b) GIS and map data on a handheld computer, and (c) an experienced arborist’s field judgment and ground-level data collection using vehicle-mounted LiDAR platforms that map existing street trees and compare data with ownership criteria extrapolated from ROW width, public/private roadway status and other ownership categories. i. GPS technology, which shows up as a locator on the map, will serve as the first tier of tree location efforts during the Inventory. ii. GIS and map data on a handheld computer will serve as a second tier of tree location efforts. iii. Experienced arborist’s field judgment is the third tier in the system, and this will draw from the arborist’s experience. This will require an application of field judgment to make the final assessment decision based on field observations. The arborist shall also resolve potential inconsistencies that arise from using map data and GPS signals.
