(a) Permittees may excavate openings in state highways to make repairs in cases of emergency requiring immediate action. In such cases, the appropriate representative of the department shall be promptly notified of any such action, and such permittee, at his own expense, shall immediately replace the state highway in as good condition as before such excavation.
(b) A city or public corporation supplying water service to its inhabitants may, within its corporate limits, excavate a state highway without a permit in cases of emergency requiring immediate action. In such cases, the state highway shall, at the expense of the city or public corporation, be replaced in as good condition as before such excavation.