Chapters 4901., 4903., 4905., 4907., 4909., 4921., 4923., and 4925. of the Revised Code do not prevent concentration, commodity, transit, and other special contract rates, but all such rates are subject to such chapters as to their printing and filing. Such rates shall be open to all shippers for a like kind of traffic under similar circumstances and conditions and shall be under the supervision and regulation of the public utilities commission.