§ 93.22 EXCEPTIONS.
   None of the terms or prohibitions of §§ 93.20 and 93.21 shall apply to or be enforced against:
   (A)   Emergency vehicles. Any police or fire vehicle or any ambulance, while engaged upon emergency business.
   (B)   Highway maintenance and construction. Excavations or repairs of bridges, streets, or highways by or on behalf of the city, county, or the State of Michigan, during the night, when the public safety, welfare, and convenience renders it impossible to perform such work during the day.
(1990 Code, § 9.12)