Okla. Stat. tit. 69, § 69-1717: Project to become part of state highway system -

Continuation of tolls until bonds are paid.

When all bonds issued under the provisions of this article and

the interest thereon shall have been paid or a sufficient amount for

the payment of all such bonds and the interest thereon to the

maturity thereof shall have been set aside in trust for the benefit

of the bondholders, such projects, if then in good condition and

repair to the satisfaction of the Commission, shall become part of

the state highway system and shall thereafter be maintained by the

Commission free of tolls. Provided, that when all bonds for any

turnpike project and the interest thereon shall have been paid or

such provision for payment made, prior to payment of the bonds and

interest on any other project or projects, such project shall

continue to be operated as a toll facility at toll rates not less

than the lowest rate being charged on any project, until all bonds

issued by the Authority and the interest thereon shall have been

paid or such provisions for payment made. The revenues of such

paid-out projects shall be used and applied by the Authority in

paying the obligations or depositing in the sinking fund of such

other turnpike projects in the following order: (a) To any project

or projects in default on interest: (b) to any project or projects

in default on principal; (c) to any project or projects having

insufficient reserves or sinking fund under its trust agreement. If

all such other projects have sufficient reserves then the revenues

from such paid-out project shall be prorated between such other

projects on the basis of the outstanding bonds of each project. If

two or more projects fall within any of the above categories, then

the revenues shall be prorated between them on the basis of the

outstanding bonds of each project.