Ill. Admin. Code tit. 92 § 1535.209
To the extent that it legally has power, every railroad company shall prohibit or prevent the placing upon its right-of-way of any pole, structure or object in a position to cause an obstruction to view of any signal or sign, or within a rectangular area 14 feet wide, being 7 feet on either side of such signal or sign measured at right angles to the highway, and 30 feet long, being 15 feet to the front and to the rear of such signal or sign, measured longitudinally to the highway. Exceptions may be granted by the Commission where local conditions are such that the application of this Section as to specific measurements would be unreasonable, and this Section shall not be deemed to forbid the maintenance of poles and structures now lawfully in place.
Ill. Admin. Code tit. 92, § 1535.209