A volume shall be established on the development parcel between a line that is 300 feet south of the North Loop Road and a line that is 300 feet north of the South Loop Road. Such volume shall extend from the East Loop Road to the West Loop Road along a line that is within 30 degrees of the line connecting true east and true west. The minimum width of such volume shall be 50 feet, with its lowest level 60 feet above the base plane. Such volume shall be open to the sky. No obstructions of any kind shall be permitted within such volume.