A bill to amend the National Highway System Designation Act of 1995 to modify the applicability of requirements concerning hours of service to operators of commercial motor vehicles transporting agricultural commodities and farm supplies.

Amends the National Highway System Designation Act of 1995 to retain the exemption from certain maximum hours of service requirements granted to operators of commercial vehicles that transport certain agricultural commodities and farm supplies. Exempts such operators, specifically, from the authority of the Secretary of Transportation to conduct a rulemaking proceeding to determine whether granting such an exemption is not in the public interest and would have a significant adverse impact on the safety of commercial motor vehicles.

Redefines agricultural commodity to reflect the definition in the Agricultural Trade Act of 1978.