Ohio Rev. Code Ann. § 5528.18

When the moneys to the credit of the highway improvement bond retirement fund, created by section 5528.12 of the Revised Code, are sufficient to meet in full all payments of interest, principal, and charges for the retirement of all bonds and other obligations which may be issued pursuant to Section 2g of Article VIII, Ohio Constitution, and sections 5528.10 and 5528.11 of the Revised Code, the commissioners of the sinking fund shall certify such fact to the treasurer of state.