29 C.F.R. § 4.118
The Act, in paragraph (3) of section 7, exempts from its provisions "any contract for the carriage of freight or personnel by vessel, airplane, bus, truck, express, railway line or oil or gas pipeline where published tariff rates are in effect". In order for this exemption to be applicable, the contract must be for such carriage by a common carrier described by the terms used. It does not, for example, apply to contracts for taxicab or ambulance service, because taxicab and ambulance companies are not among the common carriers specified by the statute. Also, a contract for transportation service does not come within this exemption unless the service contracted for is actually governed by published tariff rates in effect pursuant to State or Federal law for such carriage. The contracts excluded from the reach of the Act by this exemption are typically those where there is on file with the Interstate Commerce Commission or an appropriate State or local regulatory body a tariff rate applicable to the transportation involved, and the transportation contract between the Government and the carrier is evidenced by a Government bill of lading citing the published tariff rate. An administrative exemption has been provided for certain contracts where such carriage is subject to rates covered by section 10721 of the Interstate Commerce Act and is in accordance with applicable regulations governing such rates. See § 4.123(d) . However, only contracts principally for the carriage of "freight or personnel" are exempt. Thus, the exemption cannot apply where the principal purpose of the contract is packing, crating, handling, loading, and/or storage of goods prior to or following line-haul transportation. The fact that substantial local drayage to and from the contractor's establishment (such as a warehouse) may be required in such contracts does not alter the fact that their principal purpose is other than the carriage of freight. Also, this exemption does not exclude any contracts for the transportation of mail from the application of the Act, because the term freight does not include the mail. (For an administrative exemption of certain contracts with common carriers for carriage of mail, see § 4.123(d) .)
29 C.F.R. §4.118