(a) to proceed expeditiously with and complete the bridge improvements as approved by the commissioner;

(b) to apply for and/or make reasonable efforts to secure federal assistance, if any, for the bridge improvements;

(c) to secure the approval of the commissioner before applying for such federal assistance, in order to maximize the amounts of such assistance received or to be received for all improvements in New York state;

(d) to maintain the municipal bridge improvements at its own expense in accordance with the requirements of the commissioner for the period of time corresponding to the period of useful life for such improvements as determined by reference to section sixty-one of the state finance law;

(e) to certify to the commissioner that the amount of funds historically appropriated for highway and bridge capital purposes by that municipality shall not be reduced because of the availability of the proceeds of the sale of bonds authorized in the Accelerated Capacity and Transportation Improvements of the Nineties Bond Act; and

(f) to pay twenty percent of the cost of the municipal bridge improvements; provided, however, that a municipality may be exempted from payment of such share when such share does not exceed one thousand dollars. Municipalities shall be authorized to enter into specific municipal bridge improvements contracts with the commissioner to advance any phase or phases of the municipal bridge improvements with their resources. The unreimbursed municipal costs attendant to the use of such resources may be credited as all or a portion of the municipality's twenty percent share of such municipal bridge improvements, as approved by the commissioner.