The Department of Transportation is hereby authorized to furnish municipalities road maintenance equipment to aid such municipalities in the maintenance of streets upon such rental agreement as may be agreed upon by the Department of Transportation and the said municipality. Such rental, however, is to be at least equal to the cost of operation, plus wear and tear on such equipment; and the Department of Transportation shall not be required to furnish equipment when to do so would interfere with the maintenance of the streets and highways under the control of the Department of Transportation. (1941, c. 299; 1957, c. 65, s. 11; 1973, c. 507, s. 5; 1977, c. 464, ss. 7.1, 19.)