(i) At the option of the contractor and in lieu of the payment of any interest as hereinbefore provided in subsection (h), amounts withheld pending completion of any highway improvement under this act may, in whole or in part, be withdrawn by the contractor as soon as such amounts are credited to his account under either of the hereinbefore mentioned methods for making partial and final payments upon depositing with the Secretary of Transportation securities of a market value equal to the amount so withdrawn. Such securities shall be of a character approved by the Secretary of [Highways] Transportation and shall include, but not be limited to, certificates of deposit issued by, or savings accounts in national or state banks authorized to do business in the Commonwealth, savings accounts in savings and loans, savings associations, building and loan associations and Federal savings and loan associations authorized to do business in the Commonwealth, bonds or notes of the United States of America, the Commonwealth of Pennsylvania, or any political subdivision thereof and, upon approval, such certificates of deposit, bonds, notes or other obligations as may be issued by any national or state bank, state savings association or Federal savings and loan association authorized to do business in the Commonwealth, authority, agency or instrumentality created by the United States of America, the Commonwealth of Pennsylvania, or any political subdivision thereof. The Secretary of Transportation shall, from time to time, collect all interest or income on the securities so deposited and shall pay the same, when and as collected, to the contractor who deposited the securities. If the deposit be in the form of coupon bonds, the coupons as they respectively become due shall be delivered to the contractor. Upon default, the Secretary of Transportation may apply such securities, interest, coupons or income therefrom as may be necessary to correct said default and the contractor shall not be entitled to the balance thereof, if any, until the work remaining to be done under the contract has been satisfactorily completed.