The Property Tax Administrator in May of each year shall proceed to ascertain all operating property of any railroad company owning, operating, or controlling any railroad or railroad service in this state. Operating property is property that contributes to the operation of a railroad and which for the purpose of this section shall be held to include the main track, sidetrack, spur tracks, warehouse tracks, roadbed, right-of-way and depot grounds, all machine and repair shops, general office buildings, storehouses, and all water and fuel stations, buildings, and superstructures located on any of such property, any manufacturing plant necessary in the operation of such railroad and any property used or held in connection with the manufacturing plant, all machinery, rolling stock, telegraph lines and instruments connected with such lines, all material on hand and supplies provided for operating and carrying on the business of such road, in whole or in part, franchises, all personal property of such railroad company, and all other real property of such railroad company which is adjacent and contiguous to the railroad right-of-way and is used or held for the sole purpose of operating the railroad. Nonoperating property is property owned or leased by a railroad company that does not contribute to the operation of a railroad. The Property Tax Administrator shall value operating property as other real and personal property.