Okla. Stat. tit. 51, § 51-155.1: Claims relating to roads, streets or highways -

Limitation.

Nothing contained in this act shall be construed as allowing an

action or recovery against the state or any of its officers or

employees on a claim or cause of action founded upon any loss

occurring from a defect or dangerous condition on any road, street

or highway which was in existence, whether known or unknown:

1. On October 1, 1985; or

2. When an existing facility became or becomes a part of the

state highway system; or

3. When an existing facility became or becomes the maintenance

responsibility of the state, to the extent of that responsibility as

required by law.

To the extent that the state is required by law to maintain a

road, street, or highway within the territorial limits of a

political subdivision, the political subdivision shall not be liable

for any loss occurring from a defect or dangerous condition in the

area required to be maintained by the state.