Except as otherwise provided in section thirty-five of this article, when the particular bonds issued for any bridge or bridges and the interest thereon shall have been paid, or a sufficient amount shall have been provided for their payment and shall continue to be held for that purpose, and there are no operating or maintenance expenses outstanding, and any advances made from the state road fund toward the construction, operation and maintenance of such bridge or bridges shall have been repaid, the authority operating such bridge or bridges shall cease the collection of tolls for the use thereof: Provided, That the commissioner may, in his discretion, continue thereafter tolls for a period sufficient to accumulate sufficient funds to pay for major maintenance and repairs foreseeable as being needed on such bridge or bridges in the immediate future: Provided, however, That tolls may be imposed or reimposed on any such bridge or bridges in the manner provided in section twenty-three-b of this article. Thereafter, and as long as the cost of maintaining, repairing and operating such bridge or bridges is being provided for through means other than tolls, no tolls shall be charged for transit thereover and such bridge or bridges shall be free: Provided further, That notwithstanding any other provision of law, if any portion of the cost of construction of a toll bridge is financed, with the aid of federal funds under federal-aid road legislation and the share of the cost of such bridge borne by the state or its subdivisions shall have been repaid from tolls, or a fund sufficient for such repayment shall have been provided or set aside for that purpose, tolls for the use of such bridge shall cease and such bridge shall thereafter be maintained and operated as a free bridge.