Okla. Stat. tit. 17 § 86
The Oklahoma Corporation Commission shall have the authority, after having made proper investigations, to designate those grade crossings which are extra hazardous. At all such crossings so designated, the Commission shall have the authority to order the installation of appropriate protective devices. All such installations to be performed by the railroad. The Commission shall have the authority to determine the number, type, and location of such signs, signals, gates or other protective devices, which, however, shall conform as near as may be with generally-recognized national standards, and said Commission shall have authority to prescribe the division of the cost of the installation of such signs, signals, gates or other protective devices between the public utility and the state or its political subdivisions; provided, however, that the cost to the utility shall be not less than ten percent (10%) or more than twenty-five percent (25%) of the total costs. The railroads shall be responsible for all subsequent maintenance and cost thereof. Provided, however, that the results of investigation or investigations, findings, determinations, or orders of the Corporation Commission shall not be admissible in any civil action.
Okla. Stat. tit. 17, § 86