(a) The proceeds of such bonds shall be used solely for the payment of the cost of the project or combined projects. They shall be disbursed upon requisition or order of the chairman of the authority or its duly bonded agents, under such restrictions, if any, as the resolution authorizing the issuance of the bonds or the trust indentures may provide.

(b) If the proceeds of such bonds, by error of calculation or otherwise, are less than the cost of the project or combined projects, unless otherwise provided in the resolution authorizing the issuance of the bonds or in the trust indenture, additional bonds may in like manner be issued to provide the amount of such deficit. Such additional bonds, unless otherwise provided in the resolution authorizing the issuance of the bonds or in the trust indenture, shall be deemed to be of the same issue and shall be entitled to payment from the same fund without the preference or priority of the bonds first issued for the same purpose.

(c) If the proceeds of the bonds of any issue exceed the amount required for the purpose for which such bonds were issued, all surplus shall be paid into the sinking fund provided for the payment of principal and interest of such bonds or shall be used for construction of additional projects, as the resolution creating such bonds and the trust indenture securing them may provide. Any additional projects constructed with such excess moneys shall be included in the lease the rentals from which are pledged to the payment of such bonds by an appropriate amendment thereto, but no additional rental shall be charged merely on account of such additional projects.