(a) On or after two years from the effective date of this Act, no bus which was first placed in service after July 1, 1969, or which has undergone complete renovation and restoration since July 1, 1969 shall be operated as a part of any local mass transit system in this State unless the vehicle is equipped with radio facilities permitting two-way vocal communications between the bus and a local transit control office. This Section does not apply to buses used for charter service, school buses, intrastate carriers while not providing transportation services pursuant to contracts with any local mass transit system, private non-profit carriers receiving assistance under Section 16(b)2 of the Urban Mass Transportation Act of 1964 as amended, carriers receiving assistance pursuant to Article III of the Downstate Public Transportation Act, or interstate carriers and buses owned by a private local mass transit system;
     (b) A local mass transit system operating a bus not in compliance with the requirements of subsection (a) shall not be in violation of that subsection, provided that the bus is brought into compliance within a reasonable time (in no event to exceed 1 week) following written notification to the mass transit system of the fact that the bus is not in compliance.