A “corridor” is a physical right-of-way. In the Corridor Form below, the top panel shows the layout of a corridor named ZBR. Each shaded rectangular block within the corridor is a “constructions”, a single, continuous run of one kind of tower. The text within each construction symbol is the name of the tower type.
There are four horizontal rows of constructions in this corridor. The top one is built using the “Ironwood” tower type. The second one has three tower types “Eucalyptus”, “Laurel” and “Wondering”. The third one with tower type “Laurel” goes from 18 to 25 miles. The bottom one with tower type “PSA-1-500” goes from about 22 to 25 miles.
The cross-section view in the bottom panel of the Corridor Form shows the circuits at mile 18 in the corridor. The picture is drawn from the perspective of an observer standing on the right-of-way looking in the direction of the conductors. In this case, the cross-section shows the towers from two constructions with tower types “Wandering” and “Laurel”.