All connecting railroads, doing business in this State, and under the management or control, by lease, ownership, association or otherwise, of one and the same person, firm, corporation or association, shall, for purposes of transportation, in applying freight and passenger tariffs, be considered as constituting but one and the same road, and the rate shall be computed as upon parts of one and the same road, unless otherwise specified by the Public Service Commission.
Pursuant to Section 58-17-2610, S. C. Code 1976.
S.C. Code Regs. § 103-21