§ 509-b. Qualifications of bus drivers. Notwithstanding any other provision of law, a person shall be qualified to operate a bus only if such person: (1) is at least eighteen years old; (2) has been issued a currently valid driver's license or permit which is valid for the operation of the bus in this state; (3) has passed the bus driver physical examination administered pursuant to regulations established by the commissioner; and (4) is not disqualified to drive a motor vehicle pursuant to section five hundred nine-c or any other provision of this article.