Approaches to bridges and culverts constructed under the provisions of Section 5-501 shall be maintained by the respective road districts or municipalities, and approaches to bridges or culverts constructed under the provisions of Section 5--503 shall be maintained by the respective counties, within which such approach or approaches may be located, and all approaches to any and all such bridges and culverts as have heretofore been constructed.
605 ILCS 5/5-506