The township board has the power to make an improvement named in this act, to provide for the payment of an improvement by the issuance of bonds as provided in section 15, and to determine that the whole or any part of the cost of an improvement shall be defrayed by special assessments against the property especially benefited by the improvement. The cost of engineering services and all expenses incident to the proceedings for the making and financing of the improvement shall be deemed to be a part of the cost of the improvement.