§ 91. Powers and duties of commissioner. The commissioner, subject to the provisions of law and ordinances of the common council, has cognizance, direction and control of the construction, maintenance, alteration, repair, care, cleaning, paving, flagging, lighting and improving of the streets, highways, sidewalks and public places of the city; of the construction, alteration and repair of all city buildings and of all docks and bridges belonging to the city; of all public sewers and drains in the city; of the construction, maintenance, extension, repair and care of the city waterworks; of the care, superintendence and management and improvement of all parks and grounds, public baths and recreation piers belonging to the city. Except as otherwise provided by law, the commissioner shall have supervision of, control over and jurisdiction and authority to make all ordinary repairs or improvements upon the streets, parks, sidewalks, crosswalks, gutters, vaults, drains, culverts, bridges and public ways and places of the city, including the cleaning, sprinkling, laying of dust with substances other than water, watering and flushing of the same, and may employ such laborers and teams and incur such expenditures as may be necessary within the limits of the appropriations made therefor. It shall be his duty to inspect the same with sufficient frequency to ascertain their condition and cause the same to be kept free from obstructions and in good condition and repair and reasonably safe for public use. The commissioner shall also have general supervision and control of all work performed under any contract of the city for local or other improvements to be performed within or upon any of the public streets, parks, ways and places, or with reference to the public works and ways within the jurisdiction of his department, including the lighting, sprinkling, laying of dust with substances other than water, watering or flushing of the streets or public places, and shall cause the same to be performed in full compliance with the provisions of any contract therefor. Except as otherwise provided by law or ordinance of the common council, the commissioner of public works has, over the streets and public places within the city, all the jurisdiction and is charged with all the duties of commissioners of highways within the towns of the state.