11. a. Each project when constructed and completed shall be maintained and kept in the condition and repair as the authority determines, or the bond covenants require. Each project or any part thereof may be policed and operated by the force of police, toll-takers, operating employees and other persons as the authority may employ or authorize.
b. Subject to the terms of any agreement by the authority with the holders of bonds or notes, if the authority finds that any part of an expressway project is not suitable or sufficient as a highway to carry mixed traffic, the authority may exclude from that part any traffic other than passenger motor vehicles.