The contractor, upon the request of the department shall provide vehicles, manpower and equipment to perform emergency towing on or from a parkway, under the supervision of an authorized representative of the department. This service will be paid for on an hourly basis by the department and no charge will be made to the parkway motorist. This rental system will be put into effect by the department at its discretion during emergency periods. The rental rate to be paid by the department shall be considered as reimbursement for all costs during such emergency periods, including breakage, furnishing of equipment, furnishing of personnel, etc. The department specifically reserves the right to set the hours that such rental will be in effect, as well as the number of trucks and workers to be utilized. The rental rate for towing under this section is $20 per hour for use of a tow truck, including operator, plus $5 per hour for an additional operator when authorized by the department.