The state highways and transportation commission is authorized, when considered by it to be in the public interest, to provide liability insurance covering the operation of all motor vehicles and equipment, including airplanes and boats, owned, leased, rented, or operated pursuant to commission authorization and used in the performance of official commission or department business. The commission is authorized to provide such insurance coverage for all authorized operators, as determined by the commission, and the commission’s liability by a plan of self-insurance operated in accordance with commercial insurance industry standards for fleet vehicle coverage or by a plan partially self-insured and partially insured by a contract of insurance with an insurance company or by a plan fully insured by a contract of insurance with an insurance company as the commission deems to be in the public interest. If the commission provides for a plan of self-insurance or partial self-insurance, it shall annually determine the amount of contribution to the plan required to pay all accrued and anticipated claims and the cost of administering the plan and shall include such amount in its budget request for contribution to the commission’s self-insurance plan. The commission may contract for the services of such actuaries, consultants, and claims administrators as it deems necessary for the effective administration of a self-insurance plan and is authorized to contract for excess insurance coverage with an insurance company authorized to write such coverage in this state. The immunity in tort actions of the state and the commission shall not be in any way affected by this section.