Ohio Rev. Code § 4955.321
The public utilities commission may evaluate alternative systems for providing an audible warning of an approaching locomotive. The commission may approve the use of an audible warning system as an alternative to the horn sounding required under division (B)(1) of section 4955.32 of the Revised Code only if it determines that the alternative audible warning system complies with applicable federal requirements for an audible warning of an approaching train and only if train-activated warning devices also are present at any public highway or grade crossing at which the alternative audible warning system is installed. The commission shall establish guidelines for the use and operation of any alternative audible warning system it approves.
R.C. § 4955.321