(a) Advertising sign means any outdoor sign, display, device, or billboard registered with the department pursuant to Part 150 of this Title. Multiple signs located on a common structure shall be treated as a single sign for purposes of section 134.11 of this Part and section 126.5(V)(d)(7) of this Title.

(b) Department means the New York State Department of Transportation.

(c) Clear zone means the area, starting at the edge of the traveled way, available for safe use by errant vehicles, as determined by the department.

(d) Right of way means the entire width between the boundary lines of all property on the State highway system.

(e) State highway means a highway under the jurisdiction of the Commissioner of Transportation.

(f) Topping means cutting the main leader or leaders of a tree.

(g) Trunk diameter means the diameter of a tree, measured outside the bark at a height of four feet (1.2m) above ground level.

(h) Vegetation means plant life of any kind, including, but not limited to trees, shrubs and ground cover.

(i) Vegetation control means any activity intended to limit or regulate the growth or survival of vegetation, including, but not limited to, cutting, excavating, pruning, removing, trimming or mowing.

(j) Viewing zone means the triangular shaped area bounded by a line perpendicular to the highway center line and starting at the point on an advertising sign furthest from the highway center line and a line continuing along the highway center line for a distance of 500 feet (152.5m) in the direction the sign is facing, to a third point on the highway center line, and then closing by a hypotenuse between the first and third points. An example of a viewing zone is depicted in Appendix A of this Part. A sign structure may have two viewing zones if signs on the common structure face in substantially different directions.