Definitions for "clear zone"
an area adjacent to the traffic lane that should be kept free from features that would be potentially hazardous to errant vehicles
the recommended area alongside a roadway clear of all potential hazards (something an automobile might strike) such as trees, rocks, utility poles and the like. The recommended width of a clear zone varies based on the functional classification of the road.
The unobstructed, relatively flat area provided beyond the edge of the traveled way for recovery of errant vehicles. The travel way is the portion of the roadway not including shoulders. It is desirable to provide a roadside clear of hazardous objects or conditions for a distance consistent with speed, traffic volume and geometric conditions of the site.
Keywords:  runway, glide, airport, plane, approach
That section of an approach zone of an airport where the plane defining the glide path is 50 feet or less above the center line of the runway. The clear zone ends where the height of the glide path above ground level is above 50 feet. Land use under the clear zone is restricted.