(a) Regulations Not Retroactive. The regulations prescribed by this chapter shall not be construed to require the removal, lowering or other changes or alteration of any structure or tree not conforming to the regulations as of May 13, 1980, or otherwise interfere with the continuance of nonconforming use.

(b) Marking and Lighting. Notwithstanding the provisions of subsection (a) of this section, the owner of any existing nonconforming structure or tree is hereby required to permit the installation, operation and maintenance thereon of such markers and lights as shall be deemed necessary by the Executive Director of the Metropolitan Airport Authority to indicate to the operators of aircraft in the vicinity of the airport the presence of such airport hazards. Such markers and lights shall be installed, operated and maintained at the expense of the Metropolitan Topeka Airport Authority. (Code 1981 § 4-60. Code 1995 § 22-31.)