Tenn. Code § 65-11-110
The commissioner of transportation or the commissioner's designee may, by agreement or contract with any railroad company, apportion the work to be done in the construction of any such underpass or overpass between the railroad company and contractors acting under the control and supervision of the commissioner or the commissioner's designee, and contracts for the construction of the portion of such underpass or overpass assumed under such contract or agreement by the commissioner or the commissioner's designee shall be made in the manner and under the same conditions as contracts are made by the commissioner or the commissioner's designee for the construction of other portions of the state highway system as provided by law; provided, that when the commissioner or any of the department of transportation's employees or contractors, or any person acting under the orders of the commissioner or the commissioner's contractors, shall go or be upon the right-of-way of any railroad company, they shall be subject to any reasonable rules and regulations of such railroad company made for the protection of its traffic employees and passengers.
T.C.A. § 65-11-110